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Full text of "The silver sunbeam : a practical and theoretical text-book on sun drawing and photographic printing: comprehending all the wet and dry processes at present known, with collodion, albumen, gelatin, wax, resin and silver; as [sic] also heliographic engraving, photolithography, photozincography, celestial photography, photography in natural colors, tinting and coloring of photographs, printing in various colors, the carbon process, the card-picture, the vignette, and stereography"

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% Practical attir Ocorcfial &tzt-'§aak 


Sun Drawing and Photographic Printing: 




Collodion, Albumen, Gelatine, Wax, Resin, and Silver ; 

Heliographie Engraving, Photolithography, Photozincography, Ce- 
lestial Photography, Photography in Natural Colors, Tinting 
and Coloring of Photographs, Printing in Various Col- 
ors ; the Carbon Process, the Card-Picture, 
the Vignette, and Stereography. 

J". TOWLEE, M.D., 


1 And God said, Let there be light : and there was light/ 




Entered, according to Act of Congress, in the year 1863, by 


in the Clerk's Office of the District Court of the United States fo>- t.lie 
Southern District of Xew-York. 




History of Photography, 9 


Preliminary Observations, 21 

List of Photographic Outfit, 25 

Specialties in reference to the Articles in the preceding Chapter — the Glass- 
house, etc., 27 


Specialties continued — The Camera and the Lens, 34 

To find the Principal Focus of a Lens, 36 

To find the Equi-distant Conjugate Foci of a Lens, 36 

To find the Comparative value of two Lenses or Combinations which produce the 

same sized image of an object at the same distance, 87 

To find the magnifying power of a Lens or Combination, 37 

To find the comparative magnifying power of Lenses or Combinations, 37 

To find a Single Lens equivalent in power to a Compound Lens, 37 

To ascertain whether a Combination is corrected for Spherical Observation, 37 

To ascertain whether a Lens or Combination is corrected for Chromatic Observation, 35 

How to buy a good Lens, 39 


Specialties continued — The Camera, 42 


Specialties Continued, 46 

Dark-Room, 4g 

Work-Room, 49 


Collodion, 51 

Preparation of Pyroxyline, 52 

Formula, No. 1, for the preparation of Pyroxyline, 53 

¥' Tinula, N'o. 2, for the preparation of Pyroxyline, 55 

Formula, Xo. 3, for the preparation of Pyroxyline, 55 

Formula, No. 4, for the preparation of Pyroxyline, 55 


Ether and Alcohol, 56 

Ethy le Group, 56 

Ether, 58 

Alcohol, 59 

Decomposition of Collodion, 61 

Preparation of Glycyrrhizine, 63 

Preparation of Nitro-glucose, 6i 


Collodion Sensitizers — Iodides and Bromides, 65 


Preparation of the Iodides, 69 

Iodine, 69 

Properties of Iodide, 711 

Preparation of Hydriodic Acid 70 

Iodide of Barium, 7 1 

Iodide of Calcium, !....!'..'.".!!!! 72 

Iodide of Lithium, 72 

Iodide of Potassium 72 

Iodide of Sodium and Iodide of Ammonium, 7:5 

f Cadmium, 7:j 

Impurities of the Iodides, :..................... IS 

Tests of the purity of the Iodides, \ 74 



Bromine, 75 

Preparation of Bromine, 75 

Hydrobromic Acid, 76 

Bromides, 76 

Preparation of the Chlorides, 76 

Preparation of Chlorine, 77 

Properties of Chlorine, 77 

Chloride of Lime — Chlorinetted Lime, etc., 78 


Normal or Plain Collodion, Iodized Collodion, Bromo-iodized Collodion, 79 

Bromo-iodizing Solutions, , 80 

Formula of Lieut.-Col. Stuart Wortley, 80 

Ommeganck's Formula for Portraits and Landscapes, 81 

Formulas of Disderi, 81 

Formula for copying Collodion, 83 


Silver— Salts of Silver, 84 

Properties of the Nitrate of Silver, 88 

Photographic properties of the Nitrate of Silver, 88 

Preparation of the other Salts of Silver, 90 

Hyposulphite of Silver, "0 

Iodides of Silver, 90 

Iodide of Silver for the Silver Bath, 90 

Bromide of Silver, 91 

( Ihloride of Silver, 92 

Photographic properties of the Chloride of Silver, 93 

Other uses of the Chloride of Silver, 93 


Reducing Agents — Developers, 94 

Iron Developers, 97 

Nitrate of the Protoxide of Iron, 97 

Sulphate of the Protoxide of Iron, 97 

Double Sulphate of Iron and Ammonia, 98 

Sulphide of Iron, 98 

Tannic Acid — Gallic Acid— Pyrogallic Acid, £, 98 

Preparation of Tannic Acid, .' 99 

Preparation of Gallic Acid, 100 

Preparation of Pyrogallic Acid, 101 

Acids in Developing Solutions, 102 

Acetic Acid, 108 

Formic Acid, 104 

Photographic uses of Formic Acid, 105 

Citric Acid : 105 

Citrate of Soda 106 

Photographic uses of Citric Acid, r 106 

Tartaric Acid, 107 

Preparation of Tartaric Acid, 107 


The Nitrate of Silver Bath, ., 109 

Preparation of the Sensitizing Solution, 110 

Formula, No. 1 , 110 

Formula, No. 2, Ill 

Formula, No. 3, Ill 


The Developing Solutions, 114 

Sulphate of Iron Developer, Formula No. 1, for Ambrotypes and Melainotypes, 114 

Formula, No. 2, for Negatives, 115 

Formula, No. 3, for Negatives, 115 

Formula, No. 4, for Negatives, 115 

Disderl's Developer, 115 

Lieut.-Col. Stuart Wortley's Developer, 116 

Meynier's Developer, 116 

Hocking's Developer, 116 

V/aldack's i'ormulas, 11C 


Fixing Solutions, 118 

Cyanogen, 113 



Preparation of Cyanogen, 113 

Hydrocyanic Acid — Prussic Acid, 119 

Cyanide of Potassium, 1 10 

Sulphocyanide of Potassium, 120 

Sulphocyanide of Ammonium, 120 

Hydrosulphocyanic Acid, 120 

Hyposulphite of Soda, 120 

Formulas for fixing Solutions, 121 

Formula, No. 1, with Cyanide of Potassium, 121 

Formula, No. 2, with Hyposulphite of Soda, 121 

Formula, No. 3, with Sulphucyanide of Ammonium, 1-1 


Preparation of Bichloride of Mercury — Corrosive Sublimate, 125 

Preparation of Sulphide of Potassium — Hepar Sulphuret, 125 

Preparation of Sulphide of Ammonium, 125 


Wet Collodios Process, 127 

Collodion Positives — The Jlelainotype — the Ambrotype, 127 

Ambrotype, 128 

Fir?t Subdivision — Preparing the Glass, 128 

Second Subdivision — Coating the Glass with Collodion, 129 

Third Subdivision — Sensitizing the Collodion Film, 130 

Fourth Subdivision — Exposing the Plate in the Camera, 131 

Fifth Subdivision — Developing the Picture, 131 

Formula for Developers, 

Sixth Subdivision — Fixing the Image, 133 

Remedy for Fogginess, 133 

Seventh Operation — Drying the Plate, 135 

Formula for subdued Contrasts, 13o' 

Eighth Operation — Coloring the Picture, 136 

Ninth Operation — Varnishing the Image, 136 

Varnishes, 137 

Tenth Operation — Background for Collodion Positives, 138 

Black Varnishes, 13S 


Alabastrine Positives, 1-10 

Alabastrine Solution, , 140 


Melainotype — Ferrotype, 142 

Operation, 142 


Collodion Negatives, 144 

Negative Developers 145 

Formula, No. 1, Iron Developer 145 

Formula, No. 2, Pyrogallic Acid Developer, 14<> 

Fixing Solutions for Negatives, 147 

Formula, No. 1 — Hyposulphite of Soda, 147 

Formula, No. 2 — Cyanide of Potassium, 147 

Intensifying or Re-developing Process, 147 

Formula, No. 1 — Depositing Fluid 147 

Formula, No. 2— Stock Bottle of do., 147 

Depositing Operation, 117 

Intensifying Operation, 147 

Formula, No. 1 — Nitrate of Silver, 147 

Formula, No. 2 — Pyrogallic Acid, (Stock,) 14s 

Formula, No. 3 — " " ll> 

Varnish — Formula for do., 140 


Transfer Process of Collodion Positives on Japanned Leather, Linen, Paper, etc. 150 

Black Japan, '. 1 50 

Transfer Paper, 101 


Coixodioh Positives on Glass by transmitted Light — Transparent Positives, 153 


Enlargement of Negatives by the Ordinary Camera, 157 

Rejectors used as Condensers of Light, 158 


Transparent Positives by Contact by the Wet Process, 159 

Collodion Negatives or Positives copied from Collodion or Paper Positives,... 160 


Stereographic Negatives and Landscape Photography, 164 

Instantaneous Stereographs, 166 

Instantaneous Process of Lieut.-Col. Stuart Wortley, 167 

Valentine Blanchard'a Bromo-iodized Collodion, 168 

Hockins's Iodized Collodion, 169 

Claudet's Developer, 169 

Instantaneous Shutters, 169 


Negatives on Paper, 171 

The Talbotype or Calotype Process, . . 171 

To Sensitize Calotype Paper, 171 

Fixing of the Negative,. 172 

Wax-Paper Process of Legray 173 

Geoffray's Process with Cerolein for taking Paper Negatives, 178 

Turpentine and Wax Process of Tillard, 1,9 

Wet Paper Negative Process of Humbert de Molard, 1 80 

Improved Calotype Process by Pilchard, ISO 


Printing on Plain Paper, on Albumenized Paper, on Arrow-Root Paper, 182 

Description of the Materials used in Positive Printing, 183 

Albumen, 184 

Gelatine, 185 

Amylaceous or Non-Azotized Substances, 186 

Starch 1S6 

Gam-Arabic 187 

Chloride of Gold, '. 187 

Nitrate of Uranium, 1S9 

Acetate of Soda, Citrate of Soda, Phosphate of Soda, 190 

Carbonate of Soda, 190 

Carbonate of Lime, 190 


Manipulation of Positive Printing, 192 

Preparation of Salted Paper 192 

Preparation of the Albumenized Paper, 1 94 

Preparation of Arrow-Root Paper, 195 

Formula for Salting Solution 195 

Sensitizing Bath, 196 

Formula for the Plain Silver Solution, 196 

Formula for the Ammonio-nitrate of Silver Solution, 197 

Fuminatiug Process, 19S 


The Printing of Sensitized Paper, 200 

Toning of the Prints, 201 

Formulas for Toning Solutions, 202 

Fixing Solution 203 

Self-acting Photographic Washing-Machine, 205 

Mounting of Photographs, 205 

AVhat to do with the Clippings, 207 

Mounting Stereographs,. 207 


Bertrand's New Process for Positive Printing, 209 

Glover's Resinized Printing Process, 210 

Printing by Development, 212 

Second Method of Printing by Development, with a Chlobide and a Bromide,.. 213 

Third Method of Printing by Development, with an Iodide, 245 

Formula for Salting Solution, 215 

Method of Sensitizing by Means of Nitrate of Uranium, (The Process of Niepce 
de Saint Victor,) 216 



Ttie Card-Picture, 213 

Lenses for the Card-Picture, 219 

Development, 219 

Fixing, 221 

Printing of Card-Pictures, 222 

• Printing, 223 

Toning, Fixing and Mounting, 224 

Ox tue Tinting and Coloring of Photographs, 224 

Coli is used most frequently,. . . 225 

Other indispensable articles 225 

Coloring of a Portrait, 235 

Coloring of the Face, 226 

Blonde hair, chestnut-colored hair, black hair, 227 

Gray hair, red hair, white hair, 228 

Blue drapery, green drapery, red drapery, rose-colored drapery, brown drapery, pink 

drapery, white drapery, yellow drapery, 229 

Pearl Gray, 230 

Violet, 230 

Background 930 

llo w to imitate Metals, etc. , with colors, 230, 231 


Dry Collodion Process — Drt Processes, 232 

The Albumen Process, 283 

Formula for Iodized Collodion, ; . . 233 

Formula for Bromo-Iodized Collodion, 234 

Drying Process, 235 

Sensitizing the Film, 235 

Exposure in the Camera, 236 

Development of the Image, 23T 

Taupenot Process — Collodion-Albumen Process, 237 

Preparation of the Glass Plates, 238 

Formula for the Collodion, 23S 

Sensitizing of the Taupenot Plates, 239 

Exposure, 239 

Development, 239 

Fixing of the Taupenot Plates, 240 

Modified Albumen Process, by James Larpet, 240 

Modified Collodio- Albumen Process, by James Mudd, 2 U 



Dr. Hill Norris's Process— Gelatine Process, 244 

Preservative Solution 244 

Tannin Process of Major Russell, 245 

The Tannin and Honey Process, 248 

Resin Process, 249 

Sutton's Rapid Dry Process, 250 

Keene's Rapid Dry Process, 250 


Printing of Transparent Positives by the Dry Process, 252 

To take copies of any given size, 253 

Table for enlarging or diminishing Photographs 256 

Application of the preceding table, 25T 

Microphotography and Macrophotography, 257 

Solar Microscope, 25T 

How to tinil the point where the Lens is to be placed, 2G0 

Macrophotography, or the Art of taking enlarged Photographs, 262 

The Negative for enlargement, 262 

The quality of the Negative, 202 


The Daguerreotype, 268 

First operation, or the cleaning and polishing of the Silvered Plates, 268 

Second operation, or the Sensitizing of the Silvered Plate, 269 

Third operation, or the exposure to light 269 

Fourth operation, or Developing by the Vapor of Mercury, 270 

Fifth operation, or the Fixing of the' developed Image, . . . 270 

Sixth operation, or the Toning with Gold, ■ 271 

* ul C02STTEXTS. 


Printing •without the Salts of Silver 272 

Process with the Suits of Iron, J 272 

Cyanotype, 273 

Tl'E, -73 

] i. ss with the Salts of Uranium, -'■'> 

- for Red Pictures, 274 

- - for Green Pictures, 274 

Process for Violet Pictures, 274 

- for Rlie Pictures, i'7"> 

Carbon Process 27"> 

Pouncy's Process 277 

Pi idnct's New Carbon" Process 2 7 7 

Pri cesses of Salmon and Garnier, 278 

Farmer's Process 280 

Carbon Processes with the Salts of Iron, 281 

Process with Sesquichloride of Iron and Tartaric Acid 281 

To Transfer the Carbon Print from Glass to Paper, 283 

Printing directly on Paper by means of the Sesquichloride of Iron and Tartaric 

Acid, 285 

Photographic Engraving, 286 

Engraving on the Daguerreotype Plate, 286 

- of Fizkao 287 

Process of Talbot, . 288 

Asphalto-type of Nicephore Niepce, 291 

Etching on Glass, 29<> 

Negre's Process for Heliographic Engraving, 296 

Copies for the Engraver to work from, 296 

Photo-Lithography and Photo-Zincography, 297 

Asphalto-Photo-Lithographic Process 297 

Bichhi oio-Photo-Lithographic Processes of Poitevin, 299 

Photo-Typographic Process of Poitevin, 300 

Photo-Lithographic Process of Newton, but) 

Photozincography by Colonel Sir H. James, R. E. ; and Photo-Lithography by Mr. 

Osborne 301 

Photo-Papyrography by Colonel Sir H. James, R. E., 308 

On the production of Photographs, etc., on Glass ln Enamel Colors by Joubert,. . 3oS 


Stereoscopicity, 310 

Strabonic Stereograph, , 316 

" " 319 

Celestial Photography, 320 


Heliochromy, or the Art of taking Photographs in Natural Colors, 323 


Imperfections ln Collodion Negatives and Positives and their Remedies, 326 

Fugginess, 82<j 

Sp ts and Apertures 

Ridges and Undulating Lines, 330 

Streaks and Stains, 331 

Feebleness of the Image or Deficiency of Contrast, 331 

Harshness or Excess of Contrast, 3i 2 

Imperfect Definition, 332 


Tender and Rotten Films, 332 

Imperfections in Paper Prints, 333 

Weights and Measures, 337 


Comparison of Theometric Indications on tile Principal Thermometers in use, 340 


Comparison of Hydrometric and Specific Gravity Indications 342 

Table of the Elements of Matter, with their Symbols and Chemical Equivalents,. 344 




Every step, whether thoughtlessly or discreetly taken, is 
the commencement of a new era in a man's life. As in a 
game of chance — where either red or black must occur at 
the cessation of motion in the finger of the dial-plate — the 
probability that red will prevail over the black the next 
time, because black has occurred for twenty times in succes- 
sion, is not valid ; it is equally probable that black will be 
the successful color ; so, in the game of life, each successive 
move is a new beginning ; and, as a single twirl of the rou- 
lette may be the bane or the boon of the career of an indi- 
vidual, so the slightest event, the most insignificant indeed, 
may turn out to be the center of incalculable results. New 
developments in the science of nature are not limited to 
their own immediate sphere ; they act and react upon the 
past and the future, by illustrating phenomena that before 
were dark and not understood, or by eliciting truths which 
hitherto were utterly unknown. Thus it is that the inven- 
tion of a machine, the improvement of a part of a machine, 
or the discovery of some new chemical ingredient, may ho 
the date of the commencement of a new history. The verifi- 
cation of this idea is pertinently made manifest in the change 
from the simple double convex lens to the achromatic com- 
bination by Dolland;* in the change from*the signal tele-' 
graph on the mountains to the electric telegraph in the 
closet; in the improved application of steam by Watt; in 
tlie development of a picture on the iodized plates of silver 
by the vapor of mercury; and in the discovery of the hypo- 

* Dolland, J., was bom in London, in the year 1706, and died in 1762. 


sulphite of soda, cyanide of potassium, pyrogallic acid, and 
the protosalts of iron. For from the moment that chro- 
matic and spherical aberration could be reduced, the tele- 
scope and the microscope became altogether new instru- 
ments in the hands of the natural philosopher, by which 
many crude notions were quickly laid aside as false, and 
many new truths as quickly denuded of their cloudy habili- 
ments. Astronomy, one of the oldest of sciences — one whose 
history can be traced back to the time of the Chaldeans — 
entered, at the time of the introduction of the achromatic 
refracting telescope, upon an epoch as distinct in its history 
as the transition from the system of Hipparchus to that of 
Copernicus. At the same time, too, Physiology received a 
new impetus, by the deductions drawn with the aid of the 
compound achromatic microscope, so that Biology, since 
then, is gradually becoming more and more of a science. 
By means of the former improved instrument, our eyes are 
permitted to revel amid the enchanting scenes of the starry 
firmament, by the latter to scrutinize the realms of minute 
organisms of the earth, and by both to become acquainted 
with the secrets of creation. For the investigator of nature 
in the great and the minute, this is a new era in the history 
of the world as it exists and acts. In like manner the age 
of steam and the telegraph commenced a new history in the 
social existence and actions of men. The mild tenets of the 
Gospel, which would seem to have no connection whatever 
with the subject, have been more powerfully, more effica- 
ciously implanted in foreign soils, by the accessory instru- 
mentality of these agents, than by any preceding direct 
operations of the missionary organization ; the superiority 
of the race of men that have invented and that wield su<-h 
mighty instruments for weal and for woe, is so distinctly 
marked, that admiration and awe have en gender oK? in the 
minds of the ignorant and less enlightened, respect for the 
creeds of religion and morality of their superiors. Co- 
existent with the steam-engine and the electric telegraph, 
and equally important as these in its influence on the way-; 
ami means of life, is the art of sun-drawing. It is one of 
the great wonders of the phenomena of created matter, so 
far eclipsing the seven vaunted wonders of the world, that 
these recede into dark nooks, like the wired dolls of an au- 
tomatic puppet-show. This art, and the science that ex- 
plains the different effects produced in its manipulations, 
form the subject of the present volume. The art and the 
science are of modern origin and of recent date. 


Sun-drawing, Heliography, and Photography are synony- 
mous expressions for the same phenomenon, although ety- 
mologically the two latter are somewhat different — helio- 
graphy signifying sun-icriting, whilst the word photography 
signifies light-writing. Xot one of these expressions is 
strictly correct, because actinic impressions can be obtained 
from rays emanating from the moon, from artificial light, or 
the electric spark. Actinic drawing would probably be the 
best name, although as regards the representation of facts 
by words, it is immaterial for the masses of mankind whether 
these words have an intrinsic or root-meaning or not. The 
phenomena comprehended under any one of the above syn- 
onymous expressions, depend immediately upon what is 
termed light as the force or cause, and upon the property, 
which only certain substances apparently possess, of being 
affected according to the intensity of the light employed. 
The principal of these substances are the salts of silver, the 
salts of iron, bichromate of %)Otassa, and certain resins, as 
the oil of lavender and asphaltum. That light acts upon or- 
ganized substances is a phenomenon which must have been 
observed by the first occupants of earth ; they could not 
fail to remark the brilliant hues on the side of an apple that 
received the direct rays of the sun, and to contrast these 
resplendent mixtures of red, crimson, green, purple, yellow, 
orange, and other colors, on the one side, with the white, 
or greenish white, on the side exposed simply to the diffused 
light of day. The variegated foliage of a tropical clime, as 
contrasted with the continual merging into green, according 
to the increase in latitude, gives evidence of the influence 
of actinic action ; and this change of green into white in 
the leaves and stalks of similar plants, when supplied with 
heat and air, and not with light, is a still stronger proof of 
heliographic influence. But this species of influence is not 
limited to the vegetable part of the earth ; it is perceived, 
in all its beauties, in the blooming cheeks of a maiden from 
Kaiserstuhl in the Black Forest, or from the pasturing de- 
clivities of the Tyrolese Alps ; and its deficiency is quite as 
apparent in the pale, white, and lifeless facial integuments 
of the unfortunate denizens of crowded cities, as in the 
blanched stalks of celery in a dunghill, or the sickly white 
filiform shoots of potatoes in a dark cellar. These phenom- 
ena are full of wonder, no less so than any of the opera- 
tions of sun-drawing on paper or collodion, and quite as in- 
explicable ; but they have long failed to excite astonishment, 
from the frequency and commonness of their occurrence. 


The first remark in reference to the cause of the change 
of color in silver salts is due to the distinguished Swedish 
chemist, Scheele.* He regarded the blackening effect of 
chloride of silver, when exposed to the rays of the sun, as 
caused by a species of reduction of the salt to the metallic 
state and the accompanying formation of hydrochloric acid. 
He undertook a course of experiments, to ascertain whether 
all the colors of the spectrum had an equal influence in col- 
oring or blackening this salt, and arrived at the conclusion 
that the maximum chemical or decomposing action of the 
spectrum was in the neighborhood of the violet part, and 
that it gradually diminished toward the red, where it was 
scarcely perceptible. The researches of Scheele in this track 
terminated here ; and no application of the property of black- 
ening of the chloride of silver to photogenic purposes wrs 
made until after the lapse of several years. 

In 1801 Ritterj- not only corroborated the experiments of 
Scheele, but demonstrated that chloride of silver was black- 
ened to some distance external to the spectrum, on the violet 
side. The scientific investigators of the time repeated the 
experiments without any further developments. 

Dr. WollastonJ published a report of experiments which 
he made with gum-guaicum, when acted upon by the dif- 
ferent colored rays of the spectrum. The violet rays turned 
paper, stained yellow by a solution of this gum in alcohol, 
to green, which was soon changed back to yellow by the 
red rays ; he discovered afterward, however, that the heat of 
the red rays was sufficient of itself to reproduce the yellow 
color of the tincture of the gum. 

The same results were obtained by Berard. He exjjcri- 
mented with half the spectrum at a time, which was con- 
densed by a lens to a focus, and made to impinge at this 
point upon chloride of silver. The half next the violet, or 
more refrangible rays, were very efficacious in discoloring 
this salt of silver; whilst the other half, or red side, and 
least refrangible rays, although far more luminous, produced 
no blackening effect. The experiments of Seebeck seem 
to show that light transmitted through colored glass pro- 

* Scheele, Charles William, was born on the nineteenth of December, 
1742, at Stralsund, Sweden. lie died on the twenty -first of May, 17S6, at 
Koepin<r, on Lake Moeler. 

f Ritter, John William, was born at Samitz, in Silesia, in 1776, and died 
in 1810. 

\ Wollaston, William Hyde, M.D., was born on the sixth of August, 
1766, at East-Dereham, and died December twenty-second, 1S28, in London. 


duced the same general effect as the different colored rays 
of the spectrum. He furthermore ascertained that a piece 
of paper dipped in a rather concentrated and neutral solu- 
tion of chloride of gold, in the dark, was not reduced, as 
long as it was kept in the dark ; whereas if it had previously 
been exposed to the direct rays of the sun, it gradually 
turned purple in the dark chamber. Sir Humphry Davy 
observed that the oxide of lead, in a moist condition, is acted 
upon very differently by the red and the violet rays of the 
spectrum ; by the latter, the puce-colored oxide is turned 
black — by the former, red. He ascertained, too, that hy- 
drogen and chlorine, when exposed to the rays of the sun, 
frequently enter into combination so vividly as to produce 
an explosion in the formation of hydrochloric acid ; but the 
two gases may be kept in contact, in the dark, without un- 
dergoing much change. A solution of chlorine in water re- 
mains unchanged, as long as it is kept out of the light ; but, 
is soon converted into hydrochloric acid, by decomposing 
the water, when exposed to the sun. A similar case of de- 
composition is effected by light, when carbonic oxide and 
chlorine are exposed to light ; they then enter into combi- 
nation chemically, condensing into a substance denominated 
phosgene gas. 

The preceding remarks comprehend the sum and substance 
of the knowledge of the chemical effects of light previous to 
its application to the taking of impressions of pictures by 
the salts of silver or otherwise. It is true that a certain 
Hoffmeister published some vague remarks about the sun 
being an engraver, several years previous to Daguerre's 
publication ; but they were the mere remarks of one who 
probably thought the thing possible without possessing the 
most distant idea of the mode of its effectuation. And in 
the report which Arago made to the Chamber of Deputies 
in reference to Daguerre's discovery, this distinguished 
philosopher mentions the name of Charles as having been in 
possession of a process for communicating pictures, by the 
aid of the sun, to prepared surfaces. No publication has 
been discovered to corroborate this assertion, and the details 
of the operation have never been disclosed. 

The first recorded attempts by Wedgwood* and Davy,f 
to take pictures by the rays of the sun on a prepared silver 

* Wedgwood, Josiah, was born at Ncwcastle-uuder-Lyne, in 1*730, and died 
in the year 1795. 

f Sir Humphry Davy was boru at Penzance, in 1*1*18, and died at Geneva, 
in 1S23. 


surface, were published in the year 1802. The receptacle 
of the picture was either paper or leather, or some other 
convenient material, stretched upon a frame, and sponged 
over with a solution of nitrate of silver ; over this prepared 
surface a painting on glass was placed in direct contact and 
exposed to the rays of the sun. It is evident that the pic- 
ture thus obtained would be inverted as to light and shade. 
The difficulty, which at this time could not be overcome, 
was the fixing of the picture ; and the process was aban- 
doned on this account. No chemical substance was known 
whose peculiar properties were of such a nature as to dissolve 
the unaltered salt of silver and leave the portions on which 
the image was projected untouched or uninjured. These ex- 
periments of Wedgwood were actually made several years 
previous to the publication in 1802 ; because at that date he 
had been dead for seven years. The surface prepared with 
nitrate of silver was not sensitive enough to receive an im- 
pression in the camera obscura, although Sir Humphry Davy 
succeeded in getting a very faint image in the solar micro- 
scope, where the picture was very much condensed in size or 
situated very near the focus of parallel rays. From that date 
to the year 1814 not only no other publication appeared, but 
there are no accounts of any one having prosecuted the study 
of sun-drawing. At this time a new laborer entered the field 
of investigation and directed all his mental energies to the 
discovery of means of making sun-pictures. From the work 
of Daguerre, which was published several years later, it ap- 
pears that Niepce* was the first who obtained a permanent 
sun-picture ; to him we are indebted for the first idea of a 
fixing material ; it was he who first employed silver and 
the vapor of iodine. The process of Niepce had been so far 
perfected as to admit the use of the camera, which, by 
reason of the want of sensitiveness in the materials used-, 
had remained a useless optical arrangement. Niepce, in his 
experiments, discarded the use of the silver salts, and sub- 
stituted in their place a resinous substance denominated the 
"Bitumen of Judaea." He named his process " Heliogra- 
phy," or " Sun-drawing." His pictures were produced by 
coating a metal plate with the resinous substance above 
alluded to, and then exposing this plate, under a picture on 
glass, or in the camera, for several hours in front of the ob- 
ject to be copied. By this exposure to light the parts of 

* Niepce, Joseph-Nicephore, was born at Chalon-sur-Saone, and died in 


the bitumen which had been acted upon by the rays under- 
went a change according to the actinic intensity, whereby 
they became insoluble in certain essential oils. By treat- 
ment afterward with these essences, as, for instance, the oil 
of lavender, the picture Avas developed, the shadows being 
formed by the brilliant surface of the metal exposed, by 
the solvent action of the essential oil in those parts of 
the resin on which the rays of light had not impinged ; 
whilst the lights were represented by the thin film of 
bitumen which had become altered and insoluble in the 
oleaginous substance employed in fixing. Some of the 
specimens produced by this method at this period exist still 
in the British Museum ; some of them are in the form of 
etchings, having been acted upon probably by the galvanic 
current. It is evident that Niepce was acquainted with a 
method of fixing his sun-drawings ; but his successes were 
limited to productions which now would be regarded very 
trivial and unsatisfactory. After ten years' labor in the 
prosecution of his favorite investigation, by some accidental 
disclosure, Niepce became acquainted with Daguerre,* who 
had been experimenting independently in the same path. 
Daguerre's experiments with chemical processes and the 
camera date from the year 1824; and in 1829 these two 
great originators of sun-drawings entered into partnership 
for mutually investigating this enchanting art. In 1827 
Niepce had presented an article to the Royal Society of 
London on this subject ; but as yet Daguerre had not ar- 
rived at any successful results, nor had he published any 
thing in reference to them. The process of Daguerre aimed 
to perform the same operation by the same method, that is, 
by light ; the materials for the sensitive surface, for devel- 
oping and fixing alone, being different. In this process are 
found the use of the camera, iodide of silver on a metal 
plate, mercury as a developer, and hyposulphite of soda as a 
fixing agent ; in that of Niepce, bitumen on a metal plate, 
iodine as a developer, and oil of lavender in place of the 
hyposulphite of soda. The use of the latter substance was 
probably suggested to Daguerre by the publication of a 
paper, by Sir John Herschel, on the solubility in this men- 
struum of the insoluble salts of silver. The image formed 
on the iodized surface was quite latent until brought out by 
the vapor of mercury. It seems wonderful Iioav" Daguerre 
should hit upon the idea of using this vapor, or that a latent 

* Daguerre, L. J. M., was born at Cormeilles, in lYSY, and died in 1851 


image was on the surface. Knowing the latter and the 
possibility of such a development, the chemist has only to 
persevere in a systematic exploration among the infinite 
number of chemical substances, in order finally to meet with 
success ; but Daguerre could not a priori be furnished with 
such positive knowledge ; hence our admiration at his suc- 
cess, at the hardihood and perseverance of his character in 
search of this success, can not be otherwise than boundless. 
Xiepce, too, is entitled to an equal share of honor ; for 
without Xiepce, in all probability, sun-drawing would still 
be a latent property of nature ; as also, without Daguerre, 
the discoveries of Xiepce would not stand out in that bold 
relief in which they are now exhibited. 

The plates which Daguerre used for the reception of the 
heliographic image were of silver, or of copper plated 
with silver. The silver surface, highly polished, was sub- 
jected to the vapor of iodine in the dark-chamber ; the 
iodide of silver thus formed being very sensitive to the 
actinic influence, the plate was ready for the reception of 
the latent image. This mode of sensitizing the surface 
had reduced the time of exposure from hours to minutes ; 
and an increase of sensitiveness was attained at the sug- 
gestion of Fizeau. who recommended the use of bromine- 
water ; and about the same time the chloride of iodine 
was recommended as an accelerator byClaudet; and the 
bromide of iodine by Gaudin. By means of these ac- 
celerators the time was again reduced from minutes to 
seconds. In this state of perfection we will now leave the 
art of heliography, or of the Daguerreotype as it is more 
frequently denominated, and observe only, in conclusion, that 
this discovery of Daguerre was reported to the world in 
January, 1839 ; but the process was not communicated until 
after a bill had been passed by the French government, 
which secured to Daguerre a pension of six thousand francs 
a year, and to Isidore Xiepce, the son of Daguerre's part- 
ner, an annual pension for life of four thousand francs, one 
half of which was to revert to their widows. 

That Mr. Fox Talbot was acquainted with the experi- 
ments of Xiepce and Daguerre is very doubtful, because the 
result of these experiments was kept secret until the pen- 
sions had been granted ; but Mr. Talbot states, in the com- 
munication which he made to the Royal Society on the 
thirty-first of January, 1839, six months before the publica- 
tion of Daguerre's process, that he had been applying the 
property of discoloration of the silver salts by light to use- 


ful purposes. This application consisted in preparing a sen- 
sitive paper for the copying of drawings or paintings, by- 
direct contact. The paper was dipped, in the first place, in a 
solution of chloride of sodium, and afterward in one of 
nitrate of silver, whereby a film of chloride of silver was 
formed — a substance much more sensitive to light than 
the nitrate of silver, which had heretofore been employed 
for photographic purposes. The object to be copied, which 
had to be transparent, or partly so, was applied in direct 
contact with the sensitive paper, and exposed to the rays of 
the sun. By this means, a copy of the object was obtained, 
in which the lights and shades were inverted. This was 
the negative, which, when fixed, was superimposed on an- 
other piece of the sensitive paper, and exposed in its turn to 
the rays of light, whereby ^positive print was obtained of 
the object, in which the lights and shades were exhibited in 
their natural position. 

The communication of Talbot is the first, which laid the 
foundation of multiplying copies of a picture by the com- 
bined action of light and chemical material ; it gave the 
first idea of photographic printing. 

In the year 1841 another method was devised and pa- 
tented, called Tcdboti/pe or Calotte. The process con- 
sisted in preparing paper with the iodide of silver, which, 
when exposed to light, became the recipient of a latent 
image, which afterward was made to appear by the applica- 
tion of a developer, and was fixed with hyposulphite of 
soda. Thi^ method is the essential point in the present col- 
lodion process; it is, in fact, the very foundation of photo- 
graphy. Talbot, therefore, merits an equal position in his- 
tory with Xiepce and Daguerre. These three — this much 
to be honored trio — are the undisputed originators of that 
branch of natural science which hereafter will occupy a 
prominent part of human intelligence. 

The paper, in the Calotype process, was immersed in a 
solution of iodide of potassium, or floated on its surface ; as 
soon as dry, it was floated on a solution of nitrate of silver 
for a certain time. By this operation, a film of iodide of 
silver was formed by the double decomposition of the two 
salts in contact. The excess of iodide of potassium, or of 
nitrate of silver and the nitrate of potassa were afterward 
removed by washing in several waters. These operations 
had to be performed in the dark chamber, by the aid of a 
small candle or lamp. When the paper was required to be 
used, it was brushed over with a solution of one part of 


nitrate of silver, containing fifty grains to the ounce, two 
parts of glacial acetic acid, and three of a saturated solution 
of gallic acid ; or the pajDer was floated on the surface of 
this gallo-nitrate of silver, as it is called, for a few seconds, 
and the excess of fluid removed by blotting-paper. By this 
mode of treatment, the paper was rendered very sensitive, 
sufficiently so to receive an inrpression of a living person, by 
means of the camera obscura. An exposure of one second, 
or of a fraction of a second, was found effective in produc- 
ing an impression on the Calotype paper. This impression 
might be totally invisible, partly visible, or distinctly visible, 
according to the circumstances of time, intensity of the 
light, and sensitiveness of the prepared paper. The latent 
image, or partially visible image, was then developed to any 
degree of depth of shades, by washing the surface of the 
paper with one part of a solution of nitrate of silver, of the 
same strength as before, and four parts of the saturated so- 
lution of gallic acid. The image gradually becomes devel- 
oped by this treatment, and in a few minutes reaches its 
maximum degree of intensity. The fixing solutions were 
bromide of potassium and hyposulphite of soda. The first 
impression, thus obtained, was in this process, as well as in 
that with chloride of silver, a negative, which, by continu- 
ing the process and using this negative as an original object, 
either in the camera or by direct application, produced a 
positive, with the lights and shades in their appropriate 

The difficulty in this process is the want of homogeneity, 
and of a sufficient transparency, in the structure of paper. 
The want of transparency probably was regarded the great- 
est drawback in the production of negatives ; whilst the ir- 
regularities in the fiber of the paper could never yield a sur- 
face to compete with the brilliant and even surface of a 
polished piece of silver for the reception of positive pictures. 
To obviate these disadvantages, Sir John Herschel proposed 
the use of glass plates, and was the first to employ them. 

In the year 1847 Xiepce de St. Victor, the nephew of 
Daguerre's partner, to whom we are indebted for many in- 
teresting publications on the Chromotype, managed to fix a 
film of albumen on the glass plates. This film is intimately 
mixed with the iodides or bromides, and floAved upon the 
surface of the glass. Such albumen plates are employed by 
many very distinguished artists at the present day, who ex- 
hibit specimens of fine and sharp definition and softness of 
tone in their stereographs, that have not been surpassed by 


any other process ; as, for instance, regard those beautiful 
productions of Ferrier. 

The next important improvement in photography was ef- 
fected in 1851; it is the foundation-stone of a new era. Le- 
g-ray originally suggested that collodion might he used as 
the receptacle of the sensitive material, in place of albumen ; 
but we are indebted to Archer for the practical application 
of the solution of gun-cotton, and of the mode of employ- 
ment, pretty much as it now stands. Archer substituted pyro~ 
gallic acid for the gallic acid that had been previously used 
in the development of the latent image. Pyrogallic acid, 
although still used as a developer, has been since pushed 
aside, in a great measure, by another substitute, the sulphate 
qf the protoxide of iron, at the suggestion of Talbot. It is 
now limited principally to the operation of intensifying. 

Collodion is a solution of a substance very much resem- 
bling pun-cotton in ether and alcohol. A decided improve- 
ment, in many respects, has been made in this solution, at 
the suggestion of Sutton, the editor of the Photographic 
Notes, who recommends an excess of alcohol. When this 
solution is poured upon a piece of clean glass, it firms a 
very thin, even, and ti'ansparent film, which quickly dries, 
and can scarcely be distinguished from the surface of the 
glass beneath it. It contains the materials for sensitization. 
The discovery and application of this substance have given 
rise to what is denominated the collodion process. It is im- 
l>le to calculate the impetus given to photography by 
this discovery, or its value to society, in the promotion of 
comfort and happiness ; much less can an idea be conceived 
of the resources to which it may give rise by its future de- 

In the year 1838 or 1839, Mr. Mungo Ponton pointed out 
a very important discovery in reference to bichromate of 
potaasa, when acted upon by light, whereby this salt, the 
chromic acid, or (as Mr. Talbot advances) the organic mat- 
ter with which the salt is in combination, becomes insoluble. 
The paper for experimenting on this point is uniformly c< 
with a mixture of bichromate of potassa, gelatine, and lamp- 
black in cold distilled water, and allowed to dry in the dark 
room. When dry, it is ready to be placed beneath a nega- 
tive. The time varies from four or five minutes to a quarter 
of an hour or upward. The impression obtained in this 
way is quite latent, and is made to appear by dissolving off, 
with hot water, those parts that have been entirely or par- 
tially excluded from the actinic influence of the light. The 


picture resulting from this treatment is a positive print, in 
black and white, of which the shades are produced by the 
carbon of the lampblack. This discovery gave rise to car- 

In the year 1852 a patent was taken out in England by 
Talbot, reserving to himself the sole use of bichromate of 
potassa and gelatine in the production of photo-engravings 
on steel. Three years after this date, that is, in 1855, 
Poitevin patented a process for making carbon prints by 
means of the same materials combined with coloring matter, 
as well as for obtaining a photographic image on a litho- 
graphic stone, capable of being printed from by the ordinary 
lithographic press. In Talbot's process the steel plates were 
covered with a coating of bichromate of potash and gelatine, 
the operation taking place in the dark chamber. A trans- 
parent positive is then placed on its surface, and the plate is 
then exposed to the light. The latent image is developed 
as before alluded to. Afterward the edges of the plate are 
raised with wax, or some resinous preparation, so as to form 
a sort of dish, into which is poured the acid or etching-fluid, 
which etches away the parts exposed by the removal of the 
soluble gelatine. The etching-fluid used by Talbot was the 
bichloride of platinum. Poitevin's process is in principle 
the same. The disadvantage in the latter process arises 
from the want of durability in the image, which, being 
formed out of organic matter lying, as it must do, between 
the ink and the stone, is liable to be soon abraded after a 
few pictures have been printed from it. These attempts 
have created a number of improvements, by which matrixes 
can now be furnished, by the aid of photography, for the 
engraver's press, the lithographic press, and the typographic 

Messrs. Cutting and Bradford took a patent out, in this 
country, for a process in which the image is formed directly 
of greasy ink used in lithography. 

The next important step in photo-lithography is that in 
which the picture is first formed by bichromate of potash 
and gelatine on lithographic fr-cms/er-paper, that is, paper 
coated with a layer of albumen. A negative is placed in 
direct contact with paper so prepared, from which an image 
is obtained, that is, after certain other operations, transferred 
directly, in lithographic ink, to the stone. This process was 
patented in 1859^ at Melbourne, in Australia, by Mr. Osborne, 
for which he was awarded by the government of the colony 
of Victoria the sum of one thousand pounds. This process 


promises to be the basis of the most successful operations iu 

Asser, of Amsterdam, invented or used the transfer pro- 
cess at the same time that Osborne was using it in Aus- 

Colonel Sir Henry James makes use of zinc, upon which 
he transfers the image formed in ink ; the image having been 
produced on engraver's tracing-paper by the means adopted 
by Talbot, Poitevin, and Osborne. 

In the year 1859 another pi*ocess for photo-lithographic 
purposes was patented in Vienna, in Austria, in which as- 
phaltum is again brought into the field. The developer is 
oil of turpentine and water. The latent image is produced 
in a film consisting of a solution of asphaltum in chloroform, 
by means of a collodion negative exposed for a number of 
hours. As soon as the soluble asphaltum has been removed, 
the remaining insoluble parts which form the shades of the 
image are coated with a layer of ink by the printer ; the 
image is then gummed in, and slightly etched; after which 
it is ready for the press. 

Poitevin has just published a new method of direct car- 
bon-printing on paper. It depends upon the insolubility 
communicated to certain organic matters, such as gum, al- 
bumen, gelatine, etc., by the per-salts of iron, and on a new 
fact observed by him, namely, that this matter, coagulated 
and rendered insoluble in cold and even in hot water, be- 
comes soluble under the influence of light, and in contact 
with tartaric acid, which, by the reduction of the iron salt, 
restores to the organic matter its natural solubility. The 
paper for carbon-printing is floated in a bath of gelatine 
dissolved in water and colored with a sufficient quantity of 
lampblack, or other coloring matter, and maintained at a 
lukewarm temperature. The paper becomes thus uniformly 
covered with the colored gelatine. 

The sensitizing part is performed in the dark room by 
plunging each sheet into a solution of sesquichloride of iron 
and tartaric acid in water. By this immersion the gelatine 
becomes quite insoluble even in boiling water. The sheets 
are taken out and dried. The prints are obtained by placing 
transparent positives in direct contact with the paper in the 
printing-frame. Two or three minutes' exposure to the rays 
of the sun will be found sufficient to render those parts 
through which the light has passed soluble in boiling water, 
which is the developer and fixing agent at the same time. 
A little acid water is used toward the end of the washing, in 
order to remove all traces of the ferruginous compound. 


Poitevin has other methods of producing direct carbon- 
prints, which, together with this and others preceding, will 
be fully discussed in their proper place. 

Niepce de St. Victor has long been experimenting in his 
favorite study of the chromotype. He has succeeded in pro- 
ducing photogenic impressions endowed with certain colors 
of the original. Yellow is found very difficult to transfer to 
the heliochromic plate at the same time with other colors. 
Red, green, and blue, it appears, could be formerly repro- 
duced satisfactorily. In the fifth memoir of Niepce on this 
subject, the author states that he can now reproduce yellow 
along with other colors in a definite manner. The trouble 
with these heliochromic specimens is still their want of per- 
manence. At the very most, the colors can not be preserved 
longer than two or three days. The problem to be settled 
is the means and mode of fixation. 



The art of Photography comprehends all the operations 
of taking a picture on a sensitive surface by means of light 
and chemical reagents. These operations are as varied as 
the different substances on which they are taken, or by 
which they are taken. In all cases, whatever may be the 
process, the conditions required in the operation of pro- 
ducing a photographic image are, firstly, a suitable ground- 
work or receptacle, such as paper, metal, glass, or stone ; 
secondly, a coating of substances called sensitizers, which 
are very sensitively affected by light and altered according 
to its intensity; thirdly, chemical ingredients, denominated 
developers, that act differently upon the parts that have 
been changed by light from what it does upon the parts 
upon which light has not acted at all or feebly ; fourthly, 
fixing agents or chemical solvents of the sensitizing agents 
that have not been changed by light. Other important con- 
ditions are comprehended in the light, requiring it to be of 
a certain intensity, in a certain direction, and in a certain 

The various sorts of matter for the reception of the pho- 
tographic image have given rise to a variety of processes, 
whose appellations refer rather to the material employed 
than to any difference in the actinic principle ; thus, on 
paper, exist a number of so-called processes, as, for instance, 
printing by direct contact, and printing by development ; 
the plain-paper process, the wax-paper process, the resin 
process, and the albumen process. On glass are found the 
negative process, the positive or ambrotype process, and the 
transfer process. On metal the melainotype and daguerreo- 
type processes and photo-engraving ; and on stone, photo- 
lithography. In addition to these may be mentioned the 
card-picture process and that of the stereograph. In refer- 
ence to the materials used in the sensitized photographic 
film, or rather to contain the sensitizing ingredients, stand 


out most prominently ; the Collodion processes, wet and dry, 
the Tannin process, and the Albumen pi*ocess. 

The sensitizing substances most generally used are the 
salts of silver in combination with organic matter. In the 
carbon process, as also in photo-lithography, photo-engrav- 
ing, photo-zincography, and photo-glyphography, the sensitive 
materials are gelatinous or resinous substances in combina- 
tion with certain chemical reagents that render them insolu- 
ble, and in which the solubility, in certain menstrua, is again 
restored by the agency of light. The salts that have hitherto 
been used are the bichromate of potassa and the sesqui-salts 
of iron ; the receptacles, asphaltum and gelatine ; and the 
solvents, hot water, oil of turpentine, and oil of lavender. 
The fixing agents or solvents of the undecomposed iodides, 
bromides, and chlorides of silver in the collodion, albumen, 
or surface-sensitized film, on which the rays of light have 
not acted, or but partially acted, are hyposulphite of soda, 
cyanide of potassium and sulphocyanide of ammonium. The 
chemical reagents that either develop the latent image or 
perfect that which light has already commenced, are the 
proto-salts of iron, ammonia, gallic and pyrogallic acid, 
formic acid, and, in the daguerreotype-plate, mercury. 
Other materials are used in addition to intensify the image 
already formed by the ordinary developers. The principle 
involved in the strengthening of negatives is, first, probably 
by certain electrical decompositions, to produce a deposit 
on the shadows formed by means of silver, mercury, lead, or 
iodine ; and secondly, to blacken this deposit by sulphuriz- 
ing or reducing agents, or by the alkalies. 

The great divisions into which photographic operations 
may be divided are those which treat of negatives and posi- 
tives. A negative is an actinic impression on glass or waxed 
paper, in which the lights and shadows are inverted, as also 
the figures and the different items that form the picture ; 
that is, right becomes left, and left right. The negative is 
the matrix from which photographic prints are obtained 
either on paper or other material ; these prints are produced 
either by direct contact of the paper or glass with the nega- 
tive, or the negative is placed in one focus of a camera, and 
the paper or glass in its conjugate focus. Such prints or 
impressions, whether by reflected or transmitted rays, are 
jiositives, in which the lights and shades, as well as all the 
delineations, are in their true and natural position. There 
is another class of positives in which the shading is natural, 
but the delineations are inverted ; these are exemplified in 


the daguerreotype, ambrotype, and melainotype, which are 
exhibited only by reflected light. 

As the present work is intended for practical men, it will 
be necessary at the very outset to give a list of all the arti- 
cles and arrangements required in the successful pursuit of 
the photographic art. 


1. Glass-house, or room in the garret furnished with a 

2. Dark room, for sensitizing plates or papers. 

3. Operating room, for coliodionizing plates, mounting- 
prints, etc. 

4. Screens (white, gray, blue, and artistic) for the glass- 

5. Lenses, Q-, i, f , etc., stereoscopic and orthoscopic.) 

6. Cameras, (for portraits, views, stereographs, and for 

7. Ornamental carpets, chairs, stands, curtains, pillars, 
balustrades, etc. 

8. Head-rests, etc., camera-stands, mirrors, brushes, combs, 
pins, needle, and thread. 

9. TVashhand-stand, pitcher and basin, soap and towels, 
clothes-brush and nail-brush. 

10. Stove, tongs, shovel, poker, coal or wood-box. 

11. Antechamber, suitably furnished with lounges, etc. 

12. Show-cases for artistic productions, and cases for 
chemicals, etc. 

13. Collodion, (negative and positive,) acetic acid, nitric 
acid, citric acid, tartaric acid, protosulphate of iron, gallic 
acid, pyrogallic acid, formic acid, carbonate of soda, car- 
bonate of lime, (chalk,) chlorinetted lime, nitrate of silver, 
citrate of soda, phosphate of soda, blue litmus-paper, red 
litmus-paper, sulphide of potassium, sulphocyanide of am- 
monium, ammonia, oxide of silver, iodide of potassium, 
iodide of ammonium, iodide of cadmium, iodine, tincture of 
iodine, bromide of potassium, bromide of ammonium, bro- 
mide of cadmium, bromine, nitrate of uranium, bichloride 
of mercury, gum-arabic, starch, gelatine, glue, shellac, 
chloride of gold, acetate of soda, alcohol, ether, distilled 
water, loaf-sugar, cyanide of potassium, hyposulphite of 
soda, pyroxyline, sulphuric acid, rotten-stone, tannin, sesqui- 
chloride of iron, oxalic acid, varnish, hydrochloric acid, 
acetate of lead, caustic potassa, salts of tartar, chloride of 
sodium, chloride of ammonium, bichromate of potassa, as- 



phaltum, copal, chloroform, cotton, nitroglucose, mastic, 
resin, thus, benzoin, benzine, wax. 

14. Funnels, filtering-stands, collodion-glasses, developing 
and fixing-glasses, porcelain or photographic-ware baths and 
dishes, filtering-paper, plain paper, plain-salted paper, albu- 
men paper, arrowroot paper, tinted paper, resinized paper, 
Avax paper, blotting paper, plate-cleaners, plate-holders, Can- 
ton flannel, cotton cloths, silk cloths, brushes, colors, pencils, 
scale and compasses, magnifying-glass, cases, mats, preserv- 
ers, glass plates of various sizes, (transparent and ground,) 
melainotype-plates, black leather, black velvet, black var- 
nish, black paper, scissors, pliers, pens, ink, paper, post- 
stamps, envelopes, pocket-knife, black lead-pencils, gutta- 
percha dishes, pails, towels, pitcher, ice-cooler, soft water, 
focussing-cloths, brooms, hand-brush, diamond, cutting- 
board for glass, shelves for negatives, drawers for mounts, 
papers, etc., beaker-glasses, wash-tubs, scales, weights and 
graduated measures, dropping-tubes, test-tubes and rack, 
evaporating-dishes, crucibles and furnace, tongs, coal or 
wood, door-mats, hat-stand, artificial paraphernalia, as stuffed 
birds, beasts, etc., skeletons, vases, printing-boxes, fuming- 
boxes, forms for cutting out stereographs, card-pictures, etc., 
card-board, mounts of various sizes, spatula, pestle and mor- 
tar, India-rubber, lamps, candles, frames for photographs, 
solar camera and its appendages, solar microscope and acces- 
sories, glue-pot, tea-kettle, changing-box for dry plates. 

15. For out-door work will be required extra : a small 
hand-cart and tent, or dry collodion or tannin-plates, wax- 
paper, graduated tape, saw, hatchet, hammer and nails, 



The first thing which claims the attention of the photo- 
grapher, is to secure to himself suitable rooms. In many 
instances the artist has the privilege of sivperintending the 
construction of his glass-house or operating-rooms ; in this 
case he must not only know what is required in such a con- 
struction, hut he must know what arrangements are the 
most appropriate. The success of many an artist depends 
upon the fortuitous advantages of his glass-house ; hut these 
fortuitous advantages depend upon fixed laws and principles 
which the photographer must learn, if he is still ignorant 
of them. To be brief, contrast between light and shade is 
agreeable to the eye, whether tutored or untutored ; where- 
as uniformity of light or of shade is very displeasing. It is 
not known why this is so any more than why harmonious 
combinations of notes are delightful to the ear, or why non- 
coincident vibrations produce discord. By means of a hap- 
pily arranged contrast of light and shade, a stereographic 
roundness is communicated to pictures which, where this 
contrast is deficient or quite wanting, are flat and in no way 
satisfactory ; and where the contrast is exaggerated — where 
the lights are very bright and the shades very deep — where 
the transition from one to the other is direct, and the line 
of demarcation between them is almost visible — the round- 
ness becomes a complete distortion of solidity. This distor- 
tion, arising from a vulgar contrast, is sometimes so great 
as to cause the sitter to disclaim his own picture. The 
qualifications of an artist are very distinct from those of a 
mere operator ; the former, by reason of his qualifications, 
can associate with gentlemen and the intelligent ; the latter 
can aspire to no higher companionship than with the igno- 
rant and vulgar. But the qualifications in question are at- 
tributable, in a great measure, to a thorough knowledge of 


light in reference to Lis art, whereby nature becomes na- 

If an object be placed so that the light in one direction, 
whether brilliant or dull, falls perpendicularly upon its sur- 
face, the picture will be flat and disagreeable, because there 
is no contrast ; if the light falls obliquely, the contrast will 
be displeasing according to its intensity, because the shadows 
will be elongated and distinctly marked from the lights. A 
single light, therefore, can scarcely be said to produce an 
artistic satisfaction. 

Two equally bright lights, in opposite directions, or rather 
in directions at right angles to each other, are very objection- 
able, because either produces a bright circle of light in the 
eyes, which is repugnant to an artist's feelings, from the fact 
that the picture is severely flat for want of contrast. 

If lights proceed from two directions, at right angles to 
each other, or somewhere in the neighborhood of this angle, 
of tchich one is more brilliant than the other, then it is pos- 
sible so to arrange the sitter or model as to satisfy a culti- 
vated taste. 

The greater the brilliancy of the light, the more unman- 
ageable it becomes in the production of that soft merging of 
light into shade which in photography is so much required. 
It is, therefore, quite objectionable to use the direct rays of 
the sun in taking portraits. But during the clay these rays 
proceed from three directions of the compass — in the morn- 
ing from the east, at noon from the south, and in the evening 
from the west ; from the north alone, in the northern hemi- 
sphere, the rays never emerge. But the northern sky or 
space is illumined by the direct light from the sun, which, 
by reflection and diffusion, has parted with much of its of- 
fensive brilliancy, and is rendered soft and manageable. 
The direct light into the glass-house, therefore, must enter 
from the north,' this is the light which performs, or is to per- 
form, the principal part in the production of a negative. 
K"ow this single light, which enters from the northern part 
of the hemisphere, or a portion of it at least, may be soft- 
ened down by reflection from side-screens, and so directed 
by them upon the sitter as to make any degree of agreeable 
contrast. With these principles in view, the glass-house 
must be constructed. If the operating-room is situated in 
the highest story of a house, this house ought to be at least 
as high as the adjoining or contiguous buildings; and the 
glass window on the roof must be quite unobstructed by 
chimneys or trees in a direction perpendicular to its surface. 


Supposing the ends of the building in which it is required to 
construct a photographic establishment face east and west, 
the following arrangement is one which I would recommend : 
Let the southern side-wall be raised until it is as high as the 
ridge of the roof; in like manner fill up to the same height 
the triangular space in the end-wall between the chimney 
and the southern wall now raised, either on the eastern or 
western end, as it may happen to be ; at' a distance of fif- 
teen feet from the end-wall raise another, equally high, and 
parallel with it, from the southern side to the ridge of the 
roof. Xext construct a water-tight fiat roof, beginning at 
the side and running toward the north about ten feet. \Vhere 
this terminates, introduce the wooden frame, the southern 
portion inclining to the horizon toward the north at an angle 
of forty-five degrees, to contain the sky-light which may be 
fifteen feet wide by twelve feet deep, and inclined at an angle 
of forty-five degrees with the horizon and facing the north; 
the southern part of the frame and the window, therefore, 
comprehend a right angle. Where it is practicable, it is 
well to have a window in either of the end-walls, furnished 
with sets of tight shutters about four feet wide, and pro- 
ceeding (in direct contact, at the commencement, with the 
part of the sky-light nearest the north) downward to within 
two feet from the floor. Such side-lights can frequently be 
used instead of screens ; and by the adjustment of the shut- 
ters, light can be admitted as required, either as regards 
quantity or direction, that is, from the west in the morning, 
and from the east in the evening. From the lowest part of 
the skylight downward, and right across the room, the space 
is boarded up about four feet deep, and then the remaining 
part overhead is a flat ceiling as far as the northern side of 
the building. The length of this room must he about thirty 
feet. The dark-chamber ami the ordinary work-room may 
be constructed on the northern side, the window of one 
being glazed with an orange-yellow colored glass, in order 
to absorb the actinic rays, ami the other with common crown- 
glass. On the outside of the side-windows, small platforms 
are formed for the reception of the printing-frames, where 
no other room can be had separately and especially for the 
direct-printing department. The sky-light and the side- 
lights have to be furnished with curtains, in order to soften 
or modify the light, which has access according to the cir- 
cumstances of the case or the taste of the artist. The back- 
grounds are placed iu the space beneath the flat roof, on the 
southern side, and so far back as to cut oft", as much as pos- 


sible, the direct rays upon the head of the sitter. The 
northern end must be papered with a grayish-colored paper 
— the more uniform the better — so as to keep this part as 
feebly lighted as possible. It is even advisable to have the 
part where the camera is situated entirely curtained off from 
the remaining space ; by such an arrangement, the operator 
requires no focussing-cloth, and the curtains being of some 
material such as wool, and of a deadened color, the sitter's 
eyes are never strained by looking in this direction. 

It happens, however, very frequently, that photographers 
can not direct the construction of their rooms, and that the 
sky-light is inserted directly into the slanting side of the 
roof. In this case, if the light comes from the north, the 
room will have a direction from east to west, the sitter being 
placed at either end, according to circumstances. Here only 
one side-light can be used ; to compensate the want of a 
southern side-light, a screen, movable on an axis, is placed 
in its stead, which, receiving light either from above or the 
opposite side, can be made to reflect the same in the direc- 
tion required. 

Where the ridge of the roof of a building is directly 
north and south, and a sky-light has to be constructed on the 
slanting roof, there seems to be no alternative but to make 
two sky-lights, one on either side, furnished with thick cur- 
tains within, and on the outside with a tall partition be- 
tween them, as also one on the southern side, to exclude the 
direct rays of the sun ; or to construct a suite of rooms, by 
raising one of the side-walls of the building as nearly in ac- 
cordance with the plan first jjroposed, with those exceptions 
only which the nature of the building would demand. For 
instance, if the building were somewhat wide, there would 
be only one side- window, and the facilities for printing would 
not be so great, unless some room could be fixed up with a 
southern aspect. The illumination of the background by 
the light from the sky-light, just described, is uniform, be- 
cause the construction of the frame admits an equal quantity 
at the top as well as at the bottom. The ordinary mode of 
erecting the southern part of the frame, which supports the 
sky-light in a position perpendicular to the horizon, excludes 
much of the light, and forms a shadow on the upper part of 
the background, unless a contrivance of reflection over- 
head causes the illumination to be equally and uniformly 

The screens or backgrounds for placing behind the model 


are various. If the background is to be quite white, the 
screen must be white ; if intermediate between black and 
white, the screen may be gray, grayish-blue, blue, and vio- 
let. A red, orange-red, yellow, and black screen will pro- 
duce a dark-colored background, from the fact that light, 
impinging upon such surfaces, reflects scarcely any but three 
colors, and absorbs almost all the rest ; but these colors are 
known by experience to be possessed of little or no actinic 
influence. Screens with graduated tints, shading off from 
one color into another, or gradually shading off from a deep 
to a light color, are to be highly recommended to an artistic 
operator. Other screens again represent landscapes, castles, 
shipping, city scenery, etc., in dark-colored outlines and 
shading, on a gray or bluish-gray foundation. Such repre- 
sentations are very pleasing to the uneducated taste ; the 
true artist sometimes seems to regard them as finical. If 
such backgrounds are in true perspective, are correct repre- 
sentations of natural objects and scenery, and can be well 
focussed on the ground-glass, I would not hesitate to pro- 
nounce them legitimately artistic, and as such they must en- 
hance the value of a card-picture or other photograph. On 
the contrary, if the productions are rude, faulty, and care- 
lessly shaded, their images on the collodion-film will be 
equally so, and even more so, by distortion from the louses, 
and will tend to communicate to the photograph a vulgar 

On the subject of light, a few words more will suffice in 
this section. Place the model in a very easy and graceful 
manner, either standing or sitting, leaning on a pillar, balus- 
trade, or small stand, in such a manner that every part is 
nearly equally in focus, but especially the hands, face, and 
feet, (if the latter are to be visible.) Avoid as much as pos- 
sible that silly clinging to uniformity in the position of the 
sitter, which some operators fall into, as of laying the hands 
folded together on the lap, or of fixing the thumb in the arm- 
hole of the vest. Such sameness becomes a characteristic 
of the gallery, and renders the specimens that proceed from 
it ridiculous. Old and young, handsome and ugly, the 
grieved and the joyous, have all been invested in the same 
exuviae, have all been grouped or posed amid the same ac- 
coutrements. Above all things, endeavor at least to pro- 
duce a variety of position and paraphernalia in the respect- 
ive members of one and the same family ; otherwise, your 
photographs will be no better than the ■ painting of Dr. 


Goldsmith's family in the Vicar of Wakefield, in which is 
beheld an orange in the hand of each figure. As soon as 
the figure or group is fixed in a pleasing, an easy, and artistic 
position, the next and a very important business presents it- 
self, which consists in illuminating this figure or group in 
such a way as to obtain a clear and distinct image on the 
ground-glass of the camera. If the light falls too much on 
the head, prevent this by means of the curtain on the sky- 
light; if the shadows are too strong, and apparent beneath 
the eyebrows, nose, or chin, correct this defect by means of 
the side-light or the movable screen, recollecting the first 
law of reflection of light, which teaches that the angle of 
incidence is equal to the angle of reflection, so that, if the 
screen be inclined to the horizon at an angle of forty-five 
degrees, rays that fall upon it through the sky-light will pass 
oft* from it in a direction parallel with the horizon, and in a 
good condition for destroying those horrid black specks of 
shadow wherever there exist prominences or cavities. The 
great art in photography is to simplify the light to the very 
utmost, to use if possible light from two directions alone, 
and only that sort of light which is endowed with actinic 
influence on the sensitized plates. It will frequently hap- 
pen that, with the most brilliant illumination, no other but 
a hazy image of the model can be obtained on the ground- 
glass ; and where this image is thus indistinct and fuzzy on 
the ground-glass, it is utterly impossible to obtain any better 
result on the film of collodion. The haziness in question is 
caused by a multiplicity of reflections of light, by which 
rays interfere, cross each other, and are jumbled together in 
a very irregular and heterogeneous manner, and also by the 
impure and unequally dense layers of air and vapor set in 
motion in the room, which produce an atmosphere in front 
of and around the sitter similar to those dazzling ascending 
columns of air visible at the sides and on the top of a stove. 
To avoid the first cause, it is recommended to glaze the sky- 
light with glass containing cobalt, which communicates to it 
a blue or violet tinge. Such glass excludes all superfluous 
light, allows only actinic rays to penetrate, and subdues the 
illumination to such a degree as to render the image on the 
ground-glass quite distinct and agreeable to the eye. Al- 
though the room, by such glazing, is considerably darkened, 
the operations in photography are incomparably superior in 
result, and the time of exposure is not lengthened. The 
second cause is obviated by preserving a uniform tempera- 


turc In the room, and by having the currents of ventilation 
proceeding to their exit at some distance from the sitter. 
Let me finally impress upon every photographer the abso- 
lute necessity he is placed in of learning to manage the 
lights before he can ever hope to be successful in the subse- 
quent operations with chemical materials. An imperfectly 
lighted picture can never be metamorphosed afterward into 
a respectable production. 



The second most essential thing after a good light, and a 
successful illumination of the object, is a compound lens, so 
far corrected for spherical and chromatic aberration as to 
reproduce on the ground-glass an image in which straight 
lines are exhibited straight, and all the parts, both in the 
central and peripheral portions, are clearly defined and free 
from spectral colors. Xo single lens can be practically 
ground and polished so as to be free from spherical aberra- 
tion ; which means that no lens can be constructed so that, 
with the whole opening, the rays both through the center 
and all the way to the edges shall be refracted to one point. 
The focus of those rays which are transmitted through the 
lens near the periphery, is nearer to the lens than of those 
which pass through the center. Hence exist a multiplicity 
of foci, thus converting that which ought to be a point into 
a circular space ; and that which ought to be a line, into a 
rectangular or curvilinear space; hence the origin of indis- 
tinctness and haziness in the photograph — the picture is de- 
void of sharpness and fine definition. If the optician were 
able to grind lenses with ellipsoidal surfaces, then a single 
lens might be constructed so as to be totally free from this 
sort of error or aberration. This, however, is manifestly a 
practical impossibility. The form of lens which distorts 
the least, that is, which has the least spherical aberration, 
is the one which is well known as the crossed Jens, whose 
radii of curvature are in the proportion of one to six. 
Spherical aberration may be corrected partly by a combina- 
tion of lenses and partly by the use of diaphragms, the lat- 
ter of which exclude all but the central rays, or all but the 
peripheral rays. 

Chromatic aberration arises from the difference in the re- 
frangibilities of the colored rays in the spectrum, and the 
decomposition of white light into the colored or spectral 
light, whenever it is transmitted through a homogeneous 


transparent medium whose two surfaces are not parallel. 
But the two surfaces of a lens are never parallel ; therefore 
every simple and homogeneous lens must decompose light 
into the spectral colors of which the violet on one side is 
much more refrangible than the red on the other. On this 
account the focus of the red light will be more remote from 
the lens than that of the violet light. This sort of aberra- 
tion, therefore, has the same tendency as spherical aberra- 
tion to convert points and lines into circular, rectangular, 
or curvilinear spaces, with an additional inconvenience aris- 
ing from the different colors, which it is well known are 
possessed of very different degrees of actinism. Now, 
when both these causes of distortion and indistinctness ex- 
ist in a lens or in a combination of lenses, it is not in the 
power or skill of the photographer to obtain a well-defined, 
sharp, and actinically well-developed picture. Some sorts 
of glass refract light more than others ; again, some decom- 
pose light into the spectral colors differently, so that the 
angle between the extreme rays, the red and the violet, 
where the refracting angle of the prism or lens is the same, 
but the material different, is not a fixed quantity. Com- 
bining these angular differences, the differences in the re- 
fracting powers of transparent media and the varying radii 
of curvature, mathematicians are now able to devise a variety 
of combinations of lenses which are practically free from the 
aberrations in question. Generally crown-glass and Hint- 
glass are combined in accordance with the principles just 
alluded to. Such a combination corrects partially; it i- a 
decided improvement over any single lens as regards fine 
definition ; but what it gains in definition it loses in magni- 
fying power. A triplet, or a combination of three 1< 
properly constructed, is an improvement upon the doublet ; 
and a pair of doublets whose radii anil distances are mathe- 
matically and optically calculated, can be made to produce 
more correction than it i- possible to obtain from a triplet. 
Three pairs, too, will effect more than two ; but, unfortun- 
ately, whatever is now gained in focal sharpness is diminished 
in value by the absorbing power of the different lenses ; so 
that when the combinations increase in number, the light 
which finally emerges, however much corrected, becomes 
more and more actinically weak. For photographical pur- 
3, a pair of compound lenses con be constructed and 
adjusted so as to he practically perfect. We are indebted 
to Dolland for the first achromatic combination. Doublets 
and triplets are decidedly the best arrangements for land- 


scape photography ; whereas two pairs of doublets, adjusted 
at a given distance apart, or at a variable distance apart, 
arc preferred for portraiture. The nearer the pairs of com- 
binations approach each other, the greater the magnifying 
power ; the maximum power existing when they are in jux- 
taposition. When a tube is fitted up so that one of the 
combinations admits of motion by a rack and pinion, its focal 
length can be thus changed, and is practically good within 
certain limits. With such tubes, too, it becomes an easy 
matter to adjust a pair of them for stereoscopic purposes. 

The following rules and information will be found useful 
for ascertaining the comparative value of the different tubes 
in the market. 

To find the Principal Focus of a Lens. — Fix the lens in a 
tube or aperture in the camera ; then turning the camera 
to the moon, adjust the slide until the image on the ground- 
glass is perfectly in focus ; measure the distance from the 
ground-glass to the nearest surface ; then with a pair of cal- 
lipers take the thickness of the lens and divide this thickness 
by two ; now add this half to the first distance, which will 
be the focal distance exactly if the lens is double-convex and 
its radii of curvature are equal. Proceed in bke manner 
with a compound lens ; the result will be very nearly cor- 
rect. Where the tube contains two pairs of combinations, 
a similar method may be adopted without much error. In 
speaking of the focal distance of a lens, or of a combination, 
it is customary simply to measure the space between the 
ground-glass and the nearest surface ^of the last combina- 
tion, after focussing the moon or the sun. 

To find the Fqui-distant Conjugate Foci of a Lens or 
Combination. — Adjust the object, as, for instance, a card- 
picture, in front of the lens or combination in the camera, 
until the image on the ground-glass is of an exactly equal 
size with the object when in perfect focus. Measure the 
distance from the image to the object and divide this dis- 
tance by two ; the quotient will be the quantity required. 

To find the Comparative Value of Two Lenses or Com- 
binations which produce the same Sized Image of an Object 
at the same Distance. — Take the difference between the equi- 
distant conjugate focus and the principal focus of either lens : 
the smaller this difference the better the lens, because the 
focal depth or penetration is greater; that is, objects farther 
apart can be brought into focus consentaneously and with 
more facility when this difference is small than when it is 
large. If this difference were zero, a lens would be perfect, 


To find the Magnifying Poicer of a Lens or Combination. 
— On a sheet of card-board, in the middle, construct a circle 
one inch in din meter, for instance ; place this sheet on a 
table. Insert the lens or tube into a piece of wood placed 
horizontally over the circle, and raise or depress it by blocks 
or books until the circle is seen most distinctly when viewed 
with one eye. Xow, by a little practice, with both eyes 
open, one looking through the tube and the other on the 
side upon the paper, marks can be made on the board at 
the extremities of a diameter of the magnified circle ; be- 
cause the eye which is free can, by sympathy, see the mag- 
nified image which the other eye beholds, and the pencil at 
the same time. After this, measure the distance between 
the pencil-marks, and divide this distance by the diameter 
of the real circle ; the quotient "will indicate the number of 
times the image is larger than the object, which number is 
the magnifying power. 

To find the Comparative Magnifying Poicer of Lenses or 
Combinations. — Measure the distance in either between the 
lens and the ground-glass when the moon is in focus, or 
measure the size of the image ; the greater this distance or 
image, the less the magnifying power. The quotient aris- 
ing by dividing one distance with the other will give the 
amount of magnifying power in favor of the lens, whose dis- 
tance is the shorter. 

To find a Single Lens equivalent in Power to a Compound 
Le?is. — If a compound lens and a single lens be placed so 
that their centers are at the same distance from the moon or 
a distant object, for instance; then, if they produce the same 
sized picture, one will be equivalent to the other. (For 
further information vide chapters on Microphotography and 

To ascertain whether a Combination is corrected for 
Spherical Aberration. — Draw two parallel straight lines, ex- 
actly an inch apart, and two or three inches long, on a piece 
of card-board. Move the slide until they are correctly in 
focus on the ground-glass, and until the width between the 
lines is two inches. If this distance remains the same, that 
is, if the lines do not deviate from straight lines and from 
parallelism, the combination is aplanatically correct ; if, on 
the contrary, the images of the straight lines are curves, the 
spherical aberration has not been corrected. Apply a dia- 
phragm of small opening in front of the combination ; it will 
be perceived that the curvature of the lines will diminish 
as the aperture diminishes. If with a very small aperture 


the lines are still curved, the combination is worthless ; 
whereas, it' the lens or combination can be used without a 
diaphragm and still produces straight and parallel lines in 
the images, such a magnifier%ill be very valuable. 

To ascertain whether a Lois or Combination is corrected 
for Chromatic Aberration. — Adjust the slide most accur- 
ately, so that the image of an object is very clear and dis- 
tinct. Next see thai the surface of the collodionized plate is 
exactly coincident with the ground-surface of the glass, that 
is to say, at the same distance from the nearest surface of 
the lens. Sensitize the collodion film and take a picture. 
If, when developed and fixed, this picture is as sharp and 
well-aefined as it was on the ground-glass, the lens is achro- 
matic : if, on the contrary, the contrast between light and 
shade is imperfect, and the definition and sharpness feeble*, 
the continuation has been either over-corrected, under-cor- 
rected, or not corrected at all. The actinic rays are on the vio- 
let side whose refrangihilities are greater than those of the red 
rays ; their focal distance, therefore, is shorter, focus again, 
and after this has been accomplished draw the slide contain- 
ing the ground-glass outward about one sixteenth part of an 
inch, insert the sensitized plate, expose, develop, and fix, as 
before. If the picture is better than before, it shows that 
the actinic focus is longer than the luminous, and that the 
combination has been over-corrected. By proceeding in this 
way, it can he ascertained exactly how much the slide has to 
be drawn out in order to produce a picture as sharp as that 
on the ground-glass. Alter this distance is found, the ground- 
glass has to be advanced or sunk deeper in its frame by this 
amount, whereby the camera becomes adjusted to the tube. 
Should it happen that the slide has to be pushed in after 
focussing in order to obtain sharp definition on the collodion, 
it is an indication that the lens is under-corrected or not cor- 
rected at all. Where a lens requires no adjustment of the 
ground-glass, it is said to be ^chromatically correct, or that 
the actinic and luminous foci are coincident. The value of 
a lens in this respect is inversely proportionate to the amount 
of adjustment required ; that is, the greater the amount of 
adjustment, the less its value. 

Other methods have been proposed to test the coincidence 
of the actinic and luminous foci. One consists in pasting a 
newspaper on a flat board, and erecting the latter perpen- 
dicular to the horizon and in front of the opening of the lens, 
so that the axis of the lens passes through the center of the 
newspaper and at right angles to it. The operator next ob- 


tains a sharp focus upon the central parts, and afterward ob- 
tains a positive of the object. If the central parts are still 
in focus in the picture, the combination has been achromat- 
ically corrected ; if the parts intermediate from the center to 
the periphery are in focus, the lens has been over-corrected ; 
and more so if the marginal portions alone are in focus ; 
whereas, if the picture is nowhere sharp, it is probable the 
lens has not been sufficiently or not at all corrected for chro- 
matic aberration. 

A second method is to focus -first in the ordinary way ; 
then, placing a piece of violet-colored glass in front of the 
Ions, to focus again ; if the two foci coincide, the actinic and 
luminous foci coincide. 

A third method is that proposed by Claudet, which consists 
in placing printed cards at short distances apart, as, for in- 
stance, of one tenth of an inch, in grooves on an inclined 
plane resting on a table in front of the tube. Let there be 
five cards so arranged, and focus upon the middle one. If 
the first or second is in focus, the lens is under-corrected ; if 
the middle one is sharp, the lens is unexceptionable ; and if 
the fourth or fifth is Avell defined, the combination is over- 
" corrected. 

For an over-corrected lens or combination the ground-glass 
has to be set back by introducing thin pieces of card-board 
between it and the ledge of the slide in which it rests ; and 
where the correction has been defective, the glass has to be 
sunk deeper as before mentioned. 

If a combination has been thoroughly corrected, I throw 
aside the ordinary ground-glass slide entirely, and focus upon 
a piece of glass of the same size as the collodionized plate, 
and introduced into the selfsame aperture which is to con- 
tain the negative. In this way the collodion-surface and the 
ground-surface must necessarily coincide. 

How to buy a Good Lens. — Do not purchase a second- 
hand tube of any one, if you are a beginner in the art of pho- 
tography ; but throw yourself implicitly and in full confidence 
into the hands of a photographic house ai decided reputation, 
who will furnish yon with a lens and camera in perfect ad- 
justment and in working condition. The tubes manufac- 
tured in this country by two or three different firms, are not 
inferior to the best from abroad ; and the advantage you 
have in dealing directly with them or their immediate agents 
is, that if by chance a lens turns out in any way defective, 
you can immediately obtain redress by an exchange. As 
soon as an operator is sufficiently skilled in optics and their 


application to the lieliographic art, he will be in a condition 
to rely upon his own judgment, and to make his purchases 
where pecuniarily they are the most advantageous. The 
best criterion by which to ascertain whether, after purchas- 
ing an adjusted tube and camera, the actinic and luminous 
foci coincide, is to take the plate-holder containing a plate of 
glass with the slide drawn and place it upon a table, collo- 
dion side uppermost ; by the side of this place the ground- 
glass slide with the ground-surface uppermost. Placing a 
rigid flat ruler over either of these, it will be easy to measure 
the distance from each glass surface to the edge of the ruler. 
Where these two distances coincide, there has been no need 
of adjustment ; and the lens may be regarded as good. If 
the difference is well marked, I would recommend you +o 
return the tube and get a better. 

Supposing, furthermore, lenses to be aplanatic and achro- 
matic, there exist special differences by which their relative 
values can be distinctly estimated. The value of such in- 
struments depends upon the extent of picture in perfect de- 
finition winch can be obtained by them, with a given open- 
ing, focal distance, and diaphragm, and on the velocity with 
which this work can be accomplished. If of two lenses of 
equal opening and equal focal distance, the one will produce 
as sharp and large a picture without a stop as the other 
can with a diaphragm ; the former is very much superior, 
because, witli much more light, the operation of actinism 
will be relatively quicker. In like manner, if of two lenses 
whose three parts, as enumerated above, are all equal, but 
the picture of one is considerably larger than that of the 
other, and in every respect as well defined, the comparative 
value is easy to determine. AYherever this difference in the 
size of the picture exists, other things remaining the same, 
it will be found that the lens which produces the larger 
picture will likewise comprehend a larger angular space con- 
taining objects. Drawing imaginary lines from the two ex- 
tremities of the landscape, for instance, through the center 
of the lens or combination, to the corresponding extremities 
of the picture, two isosceles triangles are formed with their 
vertical angle at the center. This angle or opening of the 
two outside rays constitutes what is denominated the angu- 
lar aperture of the lens. The greater this angle, the other 
values remaining the same, the greater the practical worth 
of the lens. For the purposes of portraiture, the lenses in 
general have but a small angular aperture, and produce a 
picture but little more in diameter than half the focal dis- 


tanee. The relation between the opening of the lens, the 
aperture in the diaphragm, the focal distance and the dia- 
meter of the picture, as given in the Chlmie Photographiquo, 
are as follows : Calling the focal distance unity, then the 
diameter of the lens will be \ of this unity, that of the stop 
5*5-, and that of the picture f. If the diameter of the dis- 
tinct picture is equal to the focal distance, the angular aper- 
ture will be about 53° ; and if this angle be 90°, the dia- 
meter of the picture will be about twice as great as the 
focal distance. It is asserted that the new globe-tubes, the in- 
vention of C. C. Harrison, have an aperture of ninety degrees, 
and that they are free from spherical and chromatic aberra- 
tion ; they will therefore be in a condition to produce large* 
pictures with a small focus. The only disadvantages which 
they probably possess will be a deficiency of light, owing to 
the smallness of the aperture in the stops ; an inequality of 
action from the center to the peripheral parts ; and the pro- 
duction of what is denominated the " ghost" on the center 
of the picture, owing to reflections between the lenses of 
the combination. For architectural and landscape photo- 
graphy they must be inestimable, if the assertion of their 
merits is true. 

The firms in this country that have gained a well-earned 
reputation for the manufacture of portrait, etc., lenses are 
those of C. C. Harrison & Co., and of Holmes, Booth, and 
Haydens ; in Great Britain, those of Ross, Dallmeyer, Grubb, 
etc. ; in France, of Jamin, etc. ; in Germany, of Yoightkender, 



Tlte camera obscura was the invention of Porta,* a Nea- 
politan ; this instrument is, in fact, a miniature glass-house, 
a conjugate glass-house, which admits no light but that which 
passes throusjfa the lens. The ground-glass is the screen, 
which must be at right angles, and slide at right angles with 
the axis of the lens. The model, therefore, or sitter, must 
likewise be so arranged that the various component parts 
that have to appear in the picture shall be as much as pos- 
sible in a plane perpendicular to the optical axis. In this 
cas .it becomes the duty of the photographic artist, as soon 
as his model is gracefully and compactly arranged, to fix 
upon the point which is to be the center of the picture, as, 
for instance, the eye of the sitter, then to reconnoiter the 
ground, and examine the inclination of the different parts of 
the figure forming the visible surface, and to ascertain the 
direction of a line drawn from the eye at right angles to this 
surface ; now bring the camera, raise it and incline it until 
the axis of the lens coincides with this previously deter- 
mined direction. In this position, it will be possible to ob- 
tain a picture in which the different parts are almost equally 
in focus. Before you begin to obtain the focus on the 
ground-glass, fix the lens in its brass slide in the middle of 
its motion by the rack and pinion. Xext move the bellows- 
slide of the camera until the image on the glass is distinct, 
and clamp the slide; finally obtain a sharp focus by means 
of the thumb-screw on the pinion-wheel. With a quick 
motion backward and forward of the lens, the point of 
sharpest definition can easily be descried with the naked eye, 
as long as the image is much smaller than the object ; but 
in copying photographs or engravings, where the picture is 
to be of equal size with the original, it is not easy to obtain 
the exact focus ; in this case the microscope is called into 

* Porta, Giovanni Battiste Delia, was born at Naples, in 1540. 


requisition. The first tiling to be clone, "where this difficulty 
exists, is to hunt about upon the original photograph or en- 
graving for some distinct landmark, as a- very minute circle, 
or a couple of lines in apparent juxtaposition, or the open- 
ing in the letter e or o, or the extreme lines on the sides of 
a blade of grass ; the space between these will become very 
manifest under the microscope, and by a sweep of the lens 
backward and forward, the boundary-lines can be designated 
when most sharp. It requires much practice to focus well 
in copying ; hence it? is that few photographers are good 
copyists. The microscope suitable for such purposes may 
be a common magnifying-glass, the front lens of one of the 
stereoscopic tubes, or a compound microscope of low power. 
An error in the focal distance of one sixteenth of an inch, 
in portraiture, is scarcely perceptible ; whereas the same 
amount of error in copying will produce a total failure in 
the negative or positive. In taking a view, and in copy- 
ing, it is frequently a plan to be recommended, to focus a 
point midway between the center of the picture and the out- 
side. This is said to equalize the definition ; it is essentially 
a means of dividing the error of spherical or chromatic 
aberration, where either exists. The eye of the sitter may 
regard some fixed point on a level with its direction ; eai - e 
must be taken that it is neither raised nor depressed nor in 
any way strained. By looking at some point on the camera, 
which is situated in the darkest part of the glass-house, the 
eyes will be able to remain quite at ease, even whilst stead- 
fastly gazing at this point ; if, however, the sight were 
directed to a point brilliantly lighted, the eyelids would in- 
voluntarily close, and the pupil contract, by which the pic- 
ture would be impaired. 

The photography of architecture and of landscapes re- 
quires absolutely that the camera be horizontal, and so does 
that of card-pictures, when the whole figure is compre- 
hended, in order to avoid the pyramidal inclination of parts 
which in nature are parallel. This pyramidal distortion is 
the consequence of the obliquity of the rays as they are 
thus made to enter the lens, and for which obliquity the 
lens has not been corrected. On account of the large angle 
which a card-picture must necessarily comprehend, a long- 
focussed lens i*: preferred, much longer than is required for 
taking a portrait at the same distance. It is a frequent oc- 
currence to those who occupy themselves with out-door pho- 
tography not to be able to comprehend certain very desir- 
able elevations within the compass allotted to the photo- 


grapii without inclining the tube upward; lint the tube 
must remain horizontal ; therefore the only alternative re- 
maining is to raise the camera upon a platform or to place it 
on a window-sill, on the roof of a house, on the branch of a 
tree, or on the spokes of two ladders, tied or hinged at the 
1op, and with the feet drawn out so as to form a large base 
between them. Lenses with large aperture are exceedingly 
useful in such cases, as, for instance, in taking views of 
churches, public buildings, etc., from the opposite side of the 
street. The great desideratum has been* to find a lens of short 
focus and large angle for such sort of work, which can not be 
performed with lenses of long focus and small aperture. 

If the objects in the foreground of a view, as is the case 
with a stereograph, are to be the principal items of atten- 
tion, the lens will have to be focussed either upon the cen- 
tral object or upon one intermediate between the center and 
the edge. In this case, unless the difference between the 
focus of parallel rays and the focus at an infinite distance be 
exceedingly small, almost all remote objects will be slightly 
out of focus, and the picture in the distant background will 
be defective. To counteract this effect, a much larger lens 
is employed, which is carried to some distance from the 
principal objects, until the picture be of the same size as 
was intended to be taken with the lens of shorter focus. The 
camera, too, in such a case, must be raised above the hori- 
zon, but focussed parallel to it. The scenery in close prox- 
imity can be thus excluded, and the distant view will be 
nearly equally well defined and in true perspective. A 
small view taken in this manner can be enlarged afterward 
either into a negative or positive, as may be required, by the 
method which is fully explained hereafter. 

There are certain rules to be observed in field-photography 
in reference to the light, as in room-photography. 

The first is, not to place the axis of the camera in the 
same straight line with the sun and the object. This means 
that a picture is not to be taken in the direction of the sun's 
rays, where the front and central objects are equally illu- 
mined, and consequently must be very fiat in the photo- 
graph; it would be equally absurd to attempt a picture in 
the shade, whilst the sun is shining, as it were, into the 
camera through the lens. 

An inclination of the axis of the camera with the direc- 
tion of the sun's light, to the amount of forty-five degrees, 
will produce an agreeable contrast of light and shade. It 
is very possible and very probable that such an illumina- 


tion from the unobscured rays will produce too strong 
a contrast, and thus give rise to a very hard picture. The 
best effects are attained when the sun is obscured by a 
white cloud ; the lights and shades still exist with the addi- 
tion of decided middle tints, giving the photograph the ap- 
pearance of an artistic production. 

With these recommendations in view, the photographer 
must visit the ground previously to his taking a picture, in 
order to ascertain at what time of the day the light falls 
upon it, or can fall updh it. so as to produce the best photo- 
graphic illumination ; this sort of proceeding distinguishes 
the artist from the operator, and gives the same distinction 
to his work. It may happen that the principal object in a 
landscape, Avhich it is required to photograph, is so situated 
as not to receive the direct light of the sun, a* is the case 
with many northern aspects. The artist, in such a case, will 
have to wait for a cloudy day, when the direct light of the 
sun can produce no real shadows, and when perhaps a white 
cloud in the north-east or north-west may be found to make 
sufficient contrast. 

Cameras for lenses of short focus can be roughly adjusted 
to focus by means of the bellows-slide, aim afterward finely 
adjusted with the thumb-screw on the lens; but when the 
focus is long, the thumb-screw is useless, unless attached to 
a long lever, as was formerly used in the Lucernal micro- 
scope ; in such cameras, the bellows-slide lias a rough or 
quick motion, and a slow or fine motion by means of a 
thumb-screw in front of the operator or on the posterior 
part of the slide. Such cameras, too, by reason of their 
length, have to be supported on two camera-stands, in order 
to make them rigid. 


specialties continited.-^daek-eoom:. 

The chamber intended for fill operations of sensitizing, 
commonly called the Dark-Room, ought to lie contiguous to 
and open into the common operating or work-room of the 
photographer ; and both these rooms ought to open di- 
rectly into the glass-house. As before recommended, they 
can be constructed on the northern aspect of the gallery, 
each being seven and a half feet wide — that is, half the widi h 
of the glass-room — and about ten or twelve feet long. The 
Avork-room may be that on the left, whilst the remaining cham- 
ber is on the right, with a door in the middle of the parti- 
tion between them. A single pane of orange-yellow colored 
glass on the northern end is all that is needed ; this window 
may be about four feet from the ground, in order that, when 
the operator is standing, the light whilst developing may 
come from beloAV and through the negative. This mode of* 
admitting light permits the progress of development to be 
distinctly watched much more effectively than by reflected 
light. The elevation of the pane of glass above the floor 
must be regulated in accordance with the stature of the 
operator and. his habits of standing or bending during the 
process, so that sometimes an elevation of two or three feet 
above the floor of the room will be found sufficient. The 
size of the pane will be adequately large, if its sides are 
eight niches by six, and a dark-colored curtain is adjusted 
over this, so as to render the room almost dark in case of 
need. On the north, east, and south sides a shelf is con- 
structed twelve inches wide, and three feet from the floor. 
In the north-west corner the pail or barrel is placed to con- 
tain water for washing the negatives ; this pail or barrel is 
supplied with a brass stop-cock, such as is used for beer or 
wine ; beneath the stop-cock, and on the floor, is placed the 
large wash-tub or sink for containing or carrying off the re- 
fuse dirty water. Beneath the north-west and the north-east 
corner there will be found abundance of space for the gutta- 


percha developing and fixing' dishes, as also for the respective 
solutions used in these processes, and for intensifying, as, for 
instance, protosulphate of iron, pyrogallic acid, cyanide of 
potassium, hyposulphite of soda, solution of iodine in iodide 
of potassium, tincture of iodine, nitrate of silver, bichloride 
of mercury, and sulphide of potassium. Each of these so- 
lutions must be legibly labeled, always placed in the same 
position, and always carefully corked. As regards the solu- 
tion of the sulphide of potassium, the necessity for accurate 
closing of the bottle which contains it is absolute, because 
the fumes of hydrosulpnuric acid, if allowed to escape into 
the room, would decompose the sensitizing-bath, and injure 
the prints and negatives. As soon as a negative or positive 
is complete, the developing and fixing solutions are poured 
back into their respective vials. Care must be taken here 
also not to interchange dishes ; for the cyanide of potassium 
decomposes the iron-salt into what soon becomes Prussian 
blue by oxidation of the iron, and thus renders it a difficult 
task to clean the dish afterward. The first things in order 
on the eastern shelf are the plate-holers, leaning in their re- 
spective places against the wall : after this comes the sen- 
sitizing-bath, on an inclined frame fixed upon the shelf. The 
inclination may be about fifteen degrees from the perpendic- 
ular ; if it were more than this, the light particles of the 
undissolved iodide of silver, and of other insoluble sub- 
stances, would be apt to settle upon the tender surface of the 
collodion, and give rise to apertures in the negative. To 
avoid this calamity of photographers, it is preferable to have 
some arrangement by which the collodionized plate can be 
introduced into the sensitizing-bath with its collodion sur- 
face downward. For this purpose fiat dishes are used Avith 
a glass or porcelain ledge on the right side to support one 
end of the plate, whilst the other end rests on the bottom 
of the dish on the left side. In this way the left end of the 
collodionized plate is introduced first into the bath, whilst 
the right end is gradually and quickly lowered, by means of 
a silver or glass hook, until it comes in contact with the ele- 
vated ledge which is to support it. The plate is to be com- 
pletely covered with the nitrate of silver when thus lowered 
upon its support, which need not be more than a cptarter of 
an inch above the bottom of the dish. Naturally, when the 
plate i^ in this position, the collodion is nowhere' in contact 
with the vessel which contains it, excepting at the upper 
and lower edges. By making the above-mentioned ledge 
still more shallow, a very small quantity of the silver sola- 


tion will suffice to cover the plate, and the solution can be 
filtered, if necessary, after each operation ; whereby there 
can be but small risk of any damage from the deposition of 
particles of undissolved matter upon the film of collodion. 
In this country, the vertical or slightly inclined sensitizing- 
baths are preferred, and consequently in most general use ; 
in France and Germany, the horizontal baths are frequently 
to be met with, and are certainly to be recommended in 
order to avoid the trouble above alluded to. 

To the right of the silver-bath for collodion-plates is the 
appropriate place of the horizontal dish to contain the sen- 
sitizing solution for the chloridized paper. This dish will 
have a capacity to meet the requisitions of the establish- 
ment, and may contain a whole sheet, a half-sheet, or even 
less, as the case may be. On a small shelf two feet abov^ 
this dish are placed, in separate bottles, the plain silver and 
the ammonio-nitrate of silver solutions, a small filtering- 
stand and funnel, ammonia, alcohol, and distilled water; and 
running from the dish to the southern side is constructed an 
inclined plane with a semicircular groove covered or lined 
with plates of glass or porcelain, each one overlapping its 
fellow like tiles. The first one just projects over the edge 
of the dish. This grooved inclined plane is screwed to the 
eastern side of the room, and being thus tiled, is situated in 
the right position for receiving the droppings of nitrate of 
silver from the sensitized sheets when removed from the 
dish, and attached by pins through an upper angle to a soft 
wooden slip immediately above. The first sheet that is 
taken from the bath is fixed at the most distant point, and 
so that the lowest angle is just in contact with the upper- 
most inclined glass tile; the next is pinned close to it, until 
the row is complete. If the lower corners or angles of the 
silvered paper touch the glass, the superfluous fluid will 
easily flow off and down the inclined plane into the dish ; if 
the corners curl up, it will then be necessary, with a small 
pad of cotton-wool or a glass rod, to remove the accumu- 
lated solution, by bringing the corner in contact with the 
grooved channel. By this arrangement the photographer is 
able to economize his time and his solution. As soon as one 
row is thus filled with sensitized papers, those first pinned 
up will probably be sufficiently dry for removal to another 
slip situated on the southern side of the dark-chamber, thus 
making room for a fresh quantity of papers. 

The semicircular grooves of glass can be manufactured as 
follows : Take, for instance, a piece of iron plate about fif 


teen inches long and two inches wide, and get it hammered 
longitudinally into a hollow groove ; next cut up slips of 
glass of the same length, and about an inch and a half wide. 
Place one of these slips of glass in the iron channel so that 
it lies uniformly in the middle. Now heat the iron carefully 
red-hot, when it will he found that the glass will soften, 
sink, and assume the shape of the mould. When this has 
succeeded, allow the iron to cool gradually, in order that 
the glass may he properly annealed. By arranging these 
cylindrical glasses so that they overlap each other about 
half an inch, in the form of tiles, there is no need of apply- 
ing cement. 


The collodion can be kept on a small shelf in the dark- 
room, close by the door, in a very convenient place to seize 
when occasion requires. With this convenience, the plates 
are flowed in the doorway between the two rooms. At the 
north end of the work-room there is a good, large window, 
with the lower part about two feet from the floor, flush with 
the upper part of a shelf or table constructed right across, 
from side to side. On the sides of the window-frame, on 
nails or hooks, hang the various-sized mats for cutting albu- 
men, etc., papers or photographs, as well as the diiferent- 
sized plate-holders, diaphragms, pliers, scissors, diamond-, 
rulers, brushes, pencils, etc., used in mounting, printing, etc. 
On the left side of the table, on small shelves, are kept acetic 
acid, nitric acid, hydrochloric acid, sulphuric acid, protosul- 
phate of iron in crystals, distilled or rain-water, citric acid, 
pyrogallic acid, alcohol, pestle and mortal', stirring-rods of 
glass, weights and scales, graduated measure for drachms 
and ounces, another for minims and drachms, cyanide of 
potassium, hyposulphite of soda, gun-cotton, iodide and bro- 
mide of cadmium, iodide and bromide of ammonium, nitrate 
of silver, ammonia, chloride of ammonium, gum-arabic 
latine, solution of gum-arabic, etc., brush, spatula, and bur- 
nishing-tool, carbonate of lime, chlorinetted lime, acetate 
of soda, phosphate of soda, iodine, iodide of potassium, 
bromide of potassium, bichromate of potassa, and other 
chemical materials for experimentation. The precedin. 
tides have to be arranged on narrow shelves in the order in 
which they can be most conveniently laid hold of, accord- 
ing to their respective merits as necessary or accessory in- 
gredients. On the right side of the window arrange the 
various-sized glasses, already cut, bath for negatives and 


positives, the patent plate-holder or vice for cleaning glass 
plates, rotten-stone, alcohol, solution of salts of tartar, dilute 
solution of nitric acid, cotton or linen rags, patches of Can- 
ton-flannel, silk cloths, broad camel-hair pencil for dusting off 
particles or fibers from the polished glasses, triangular file, 
alcohol-lamp, shell-lac for mending the glass-corners, box of 
pins, box of tacks, small hammer, large and thick glass 
plate for cutting out photographs, etc., scale and compasses, 
vignette-glasses, the different-sized printing-frames, varnish, 
mats, preservers, cases, transfer-liquid, leather, black pajjer 
or velvet, etc., mounts of various sizes. 

The sides of this room are furnished with wooden strips 
to which photographs can be attached by pins in order to 
dry them after fixation and washing. The toning and fix- 
ing dishes are situated on the shelf on the west side ; as ara 
also the chloride of gold, test-paper, nitrate of uranium, 
acetate and phosphate of soda, rain-water, alcohol, and 
hyposulphite of soda. Beneath the shelf place the tubs for 
washing prints. In drawers preserve the different sorts of 
paper in use. Have one drawer for dry but uncut positives, 
one for the cut positives, one for uncut stereographs, one for the 
right stereographs and one for the left, one for card-pictures 
not cut, and one for the prepared card-pictures. One writ- 
ing-desk near the door and between the door and the win- 
dow, for containing the day-book, etc. Photographic stock 
can be stored away on shelves on the southern end and on 
the sides of this room. Both these rooms are to be supplied 
with stoves or other means of warmth and ventilation. On 
the entrance-door affix the sign forbidding all intrusion. 
Keep all visitors in the antechamber, which must be made 
comfortable, and somewhat artistically furnished for their 
reception. The photographer can not perform his duties 
with ease if crowded with inquisitive, meddling, and talking 
parties ; the lenses do not operate well if the air is saturated 
with vapor, and the health is impaired in the midst of the 
mixed effluvia arising from degenerate lungs. 



fcr 1851 Legray first suggested the application of collodion 
for the receptacle of the photographic picture ; and in the 
same year Messrs. Archer and Fry published a detailed ac- 
count of the practical mode of its application. Collodion is 
a solution of gun-cotton in ether and alcohol ; and gun-cot- 
ton, of which there are several varieties, is cotton or linen 
fiber (that is, cellulose or lignine) altered by combination 
with peroxide of nitrogen and probably with nitric acid. 
Cotton consists chemically of carbon, hydrogen, and oxygen; 
whilst gun-cotton contains an additional element, namely, 
nitrogen, which communicates explosive tendencies to several 
of the metalloids. The altered cotton employed for photo- 
graphic purposes is not the same as gun-cotton proper ; in 
the first place it is not so explosive ; it is, secondly, almost 
perfectly soluble in alcohol and ether, which is not the case 
with gun-cotton. It is denominated pyroxt/Hne. Pyroxy- 
line is soluble also in acetic ether. "When this soluble cot- 
ton is dissolved in a mixture of ether and alcohol, and after- 
ward poured upon a piece of glass, it leaves on evaporation, 
when of a normal condition, a transparent film ; whereas 
gun-cotton so dissolved, orxyloidine, (another form of altered 
cotton.) leaves an opaque film after evaporation. 

Cotton or ligneous fiber is transformed into pyroxyline by 
immersing it in a mixture of nitric acid and sulphuric acid ; 
the latter seems necessary only to concentrate the nitric acid; 
for neither sulphur nor any of its oxides are found in pyroxy- 
line by analysis. This, although the accepted theory, is not 
satisfactory, because it is found necessary to add water to 
certain specimens of nitro-sulphuric acid. Another reason 
for the use of sulphuric acid arises from the fact that pyroxy- 
line is soluble into a gelatinous form in nitric acid, but not 
in the mixture of nitric and sulphuric acids. Gun-cotton 
may be precipitated from its ethereal and alcoholic solution 
into a fibrinous mass like the original, almost. This curious 


fact exhibits quite an analogy between solutions of salts and 
the mineral kingdom, and the gelatinous solutions in the 
organic kingdom. In the former the precipitate is either 
amorphous or crystalline, as in chloride of silver and car- 
bozotate of potassa ; whilst in organic solutions the precip- 
itated ultimate atoms seem to exist, even in solution, in the 
form of fiber. This peculiar fibrinous deposit is thrown 
down by adding water to the mixed ethereal and alcoholic 
solution of pyroxyline, because this substance is insoluble in 
water. For this reason the necessity of using only concen- 
trated ether and alcohol is apparent ; another deduction is 
equally apparent from this circumstance, which consists in 
the employment of such iodizing materials in the prepara- 
tion of sensitive collodion, as are soluble in ether and alco- 
hol, and in discarding those which are soluble principally in 
water, or only partially in ether and alcohol. Collodion 
containing a small proportion of water is thick and flows 
unevenly, and when dry is not quite transparent ; whilst the 
film from anhydrous collodion is very thin, transparent, and 
uniform, and flows on the surface of glass very easily. 

Preparation of Pyroxyline: — For this purpose the finest 
cotton or the best Swedish filtering-paper, or old white cotton 
rags are procured. These materials, especially the first, are 
not quite pure ; a sort of resinous cement adheres with great 
tenacity to its fibers, and must first be dissolved before the 
cotton is fit for transformation into pyroxyline. The cotton 
is therefore boiled in a solution of carbonate of potassa in 
the following proportion: take one hundred parts of rain- 
water, two parts of cotton, and one of carbonate of potassa. 
These materials are maintained at a boiling temperature for 
a few hours, after which the cotton is taken out and thor- 
ny washed in several waters, and then left in clean 
rain-water for at least twenty-four hours, stirring the same 
from time to time, until every trace of the alkali is removed. 
It is then taken out, pressed, and dried in thin layers spread 
upon clean sheets of paper in the sun or on a steam-bath. 
Care must be taken that all moisture be entirely expelled. 
In this condition it is ready for the action of nitric acid. 
Certain rules have to be minutely observed in regard to the 
temperature of the nitric acid, the quantity of water which 
it contains, the length of time of immersion, and the inti- 
mate mixture of the ingredients ; for as these conditions vary 
so will the pyroxyline. If, for instance, the acids are too 
strong, or the temperature too low, the pyroxyline will be 
much heavier than the weight of the cotton used, without 


apparently having undergone any other outward change. 
Such gun-cotton will produce a thick and gelatinous collo 
dion, giving rise to streaks in the film. If, on the contrary, 
the resulting pyroxyline is less in weight than the cotton 
introduced, or about equal to it, this indicates that the acids 
are too wreak or the temperature too high, whereby a portion 
of the pyroxyline is dissolved. Such a species of gun-cotton 
is not wholly soluble in a mixture of ether and alcohol ; it 
yields, however, a collodion which flows easily over the 
plate, is very adhesive to the glass, and yields a soft nega- 
tive. Any little particles of dust that may fall on the plate 
are liable to produce with this collodion transparent specks 
on the positive or negative. The rule, therefore, on the 
whole is to steer between these two results, in order to ob- 
tain a pyroxyline in which the cotton fiber shows an incipi- 
ent gelatinization in the acids. When the operation is suc- 
cessful, the weight of the dry pyroxyline will be somewhere 
about twenty-five per cent heavier than the cotton from 
which it was formed. 

No. 1 . Formula for the Preparation of Pyroxyline. 

Commercial sulphuric acid, spec, grav., 1.8-13 at 00 Fahr.,. .24 fluid ounces. 
Commercial nitric acid, " " 1A51 " " " . . 8 " " 

Water, 1 " " 

Cotton, 1 ounce. 

The vessels used in the preparation of pyroxyline may be 
large porcelain or glass evaporating-dishes, sitting closely in 
the cover of a water-bath, maintained at a temperature of 
150° Fahrenheit. Each dish is furnished with a pane of 
glass, fitting upon it as a lid or cover. Let the water-bath 
be first raised to the indicated temperature ; then pour the 
sulphuric acid into one of the dishes, add to this the water, and 
mix intimately by stirring with a glass rod with a rounded 
end ; finally pour in the nitric acid, and perform the same 
operation to insure an intimate mixture. The temperature 
of this mixture will rise from 15 to 20 degrees above the 
point required. Remove the dish, therefore, from the bath 
until the temperature falls to 150°. The temperature can 
be lowered by stirring the mixture with cold stirring-rods or 
spatulas of porcelain or glass. "Whilst the acids are cooling 
the cotton can be divided into about a dozen lots, and each 
lot must be gently separated into a loose condition. As 
soon as the proper temperature has been attained, the dish 
is reinstated in its position in the water-bath, and the cotton 
is introduced one lot at a time, so that each is carefully 


pressed, clown beneath the surface by the glass rod. As 
soon as all the cotton has been introduced, and completely 
covered by the acid mixture, the lid is placed, on the dish 
for six or eight minutes. 

The thermometer used, on such occasions for ascertaining 
the temperature of the water or mixed, acids, must be strong- 
ly made, so that the bulb can be moved about in the fluid 
with some degree of briskness without any liability to break ; 
it is furnished with a hinged back, which allows the lower 
portion to be reflected on itself, and the bulb and the lower 
part of the stem to be exposed. Such thermometers are 
manufactured for the chemist, and can be purchased at the 
photographic establishments. 

The acids are now poured into another dish close by, 
allowing the largest portion to drain off, and preventing the 
cotton from falling out at the same time by the cover which 
is retained in its place. The dish containing the pyroxyline 
is then quickly immersed in a large tub of water, and the 
cotton is well stirred about so as to part with the largest 
portion of its acidity ; it is then taken out with a pair of 
glass rods and plunged into fresh Avater in another tub, and 
again thoroughly washed. After this operation the pyroxy- 
line is placed in a wooden chamber through which a current 
of water is kept running for twenty-four hours or more, or 
at least until every trace of-acidity has been removed. Dur- 
ing this time the agglutinated or adherent portions are care- 
fully separated, so that the stream of water can more easily 
act upon each fiber. "When blue litmus paper is no longer 
turned red by the water as it proceeds from the cotton, the 
latter is taken out, again carefully separated and placed in 
thin patches on sheets of paper in the sun to dry ; or it may 
be dried on zinc jilates, being part of a hot-water bath, 
whose temperature is maintained at about 120° Fahrenheit. 
At this temperature pyroxyline will not explode. In the 
hot days of summer, however, it can be dried quite effica- 
ciously when placed out in the sun. 

Pyroxyline, when exposed to the air, absorbs moisture ; it 
undergoes decomposition, too, in an air-tight vessel, if light 
reaches it ; the products of decomposition being nitric acid, 
peroxide of nitrogen, and probably other compounds. It 
lias not yet been thoroughly ascertained by what means it 
can be preserved in a normal condition permanently; ab- 
sence of moisture and of light have been found to assist in 
this preservation. 


If a specimen of pyroxyline by keeping manifests an acid 
reaction, it is advisable to wash the cotton in several waters, 
as before, and again to dry it. To neutralize the cotton by 
an alkali, or a carbonated alkali, is scarcely to be recom- 
mended, because they both have a tendency to decompose 
it ; and especially if any trace of these should be left in the 
fiber, decomposition is likely to ensue in the drying. 

JVo. 2. Formula for the Preparation of Pyroxyline. 

By Weight. 

Commercial sulphuric acid, spec, grav., 1.843, at 60° Fahr., 18 ounces, 

Commercial nitric acid, " " 1.43, " " " 14 " 

Cotton, 2 " 

Proceed with these ingredients in all other respects as 
with those in Formula Xo. 1. 

No. 3. Formula for the Preparation of Pyroxyline. 

Commercial sulphuric acid 40 ounces, 

Pure nitrate of potassa, 20 " 

Cotton, 1 ounce. 

As soon as the mixture of acid and nitre has been thor- 
oughly mixed, and almost cool, the cotton is introduced in 
small portions and Avell stirred. In about a quarter of an 
hour the whole mixture is thrown into a large tub full of 
water ; in this way the pyroxyline is freed as much as possi- 
ble from the acid ; after this it is washed in warm water, 
and finally in a running stream, as in Formula Xo. 1. 

JVb. 4. Formula for the Preparation of Pyroxyline. 

Disderi's Pyroxyline. 

Sulphuric acid, 4000 grains. 

Pulverized pure nitrate of potassa, 2000 " 

Place these in a glass vessel provided with a close-fitting 
cover, and stir them intimately together with a glass rod. 
Xext add 150 grains of fine cotton-wool, in small flocks at a 
lime, and immerse them thoroughly with the glass rod. 
When all the cotton has been introduced, close the vessel 
and set it aside for ten or fifteen minutes. After this, the 
pyroxyline is withdrawn by means of a pair of glass rods, 
and well washed, as before recommended, and dried. 

In all these formulas the acids, when once used, can not 
be employed a second time ; by distillation, the nitric acid 


that has not been decomposed might he obtained and used 
over again, if other combinations and decompositions did 
not result from the application of so high a temperature. 
In general the mixture is regarded as useless, and. thrown 



The next ingredients employed in the manufacture of 
plain or normal collodion are alcohol and ether. Both 
these substances belong to a group of hydrocarbons whose 
basic compound radical, although hypothetical, is denomin- 
ated ethyle, consisting of four equivalents of carbon com- 
bined with five of hydrogen, and represented in symbols by 
C 4 H 5 . Ether is the oxide of this base, and alcohol the hy- 
drated oxide ; that is, chemically regarded, the only differ- 
ence between ether and alcohol is, that the latter contains 
one equivalent of water, constitutionally combined, which is 
wanting in ether. The hypothetical compound base, ethyle, 
enters into combination with several of the alkaloids and 
acids, giving rise to distinct chemical combinations. This 
fact will lead us to seek a clue for various untoward and, 
as yet, unaccountable phenomena in the constitution of sensi- 
tized collodion, aud its frequent want of permanency. 

Ethyle Group. 

Ethyle, Symbol Ae., Ci H.i. Cyanide of ethyle, Ae Cy. 

Oxide of ethyle, (ether.) . . . Ae 0. Nitrate of the oxide of ethyle,. . Ae 0, NO s . 

Ilydrated oxide of ethyle, (alcohol,). AeO.nO. Nitrite of the oxide of ethyle... Ae 0. NO3. 

Br imide of ethyle, Ae Br. Oxidate of the oxide of ethyle, .Ae 0, d 63. 

Chloride of ethyle, Ae CI. Hydride of ethyle Ae H. 

Iodide of ethyle, Ae I. Zinc ethyle, Ae Zn, etc. 

Some of the compounds of the ethyle series are crystalliz- 
able salts ; but the most of them are volatile aromatic fluids, 
denominated ethers. 

Although an equivalent of water is the only difference 
between alcohol and ether, yet no direct means have yet 
been discovered whereby an atom of water can be so com- 
bined with other as to form alcohol, nor abstracted from al- 
cohol constitutionally so as to leave ether. It is supposed, 
therefore, that the elements that enter into the formation of 
ether, and water and ether, owe their difference to a differ- 
ence in the grouping of the elementary atoms. 



Ether, sometimes denominated, but very wrongly, sul- 
phuric ether, is obtained by decomposing alcohol by means 
of sulphuric acid. One method consists in the distillation 
of equal weights of rectified alcohol (spec. grav. .835) and 
sulphuric acid. As soon as ebullition commences, a color- 
less and highly volatile liquid passes over and is condensed 
into a receiver surrounded with ice or snow. This method 
is far from being a profitable one ; for at a temperature be- 
low 260° Fahr. alcohol distils over; and, if the heat be greater 
than 310°, another of the numerous hydrocarbons, olefiant 
gas, is generated, together with other gaseous and liquid 
bodies. By a second method the sulphuric acid is main- 
tained at a temperature of about 300° Fahr., and a stream 
of alcohol is made to enter the acid gradually. In this way 
a large quantity of alcohol becomes converted into ether. 
There are two stages in the preparation of ether; by one an 
impure and crude ether is the result ; by the latter the ether 
is rectified. The minutiae are as follows : 

Take of alcohol four pints/ sulphuric acid, one pint ; 
potassa, six drachms; distilled water, three fluid ounces. 
Add gradually fourteen fluid ounces of the acid to two pints 
of the alcohol in a tubulated retort, and shake frequently in 
order to produce an intimate mixture. Connect the retort 
when placed on a sand-bath with a proper condensing ap- 
paratus, furnished with a long connecting-tube, so as to re- 
move the vapors, if any should escape, as far as possible 
from the flame. Explosions are very apt to take place in 
the preparation of ether, unless great caution be taken. 
The temperature is now raised quickly until ebullition com- 
mences. As soon as half a pint of ether has distilled over, 
the remainder of the alcohol previously mixed with two 
fluid ounces of the acid is allowed to enter gradually through 
the tubulated aperture by means of a tub.e dipping beneath 
the mixture in the retort, and in quantity as near as can be 
equal to that which distills over. In this way continue the 
distillation until about three pints have passed over into the 

The product thus obtained contains sulphurous acid, sul- 
phuric acid, sulphovinic acid, and other impurities. By 
rectification most of these arc removed as follow* : 

Add to the ethereal contents in the condenser the solution 
of the potassa in the distilled water, and shake them fre- 
quently during the twenty-four hours they are kept together 


in a stoppered bottle. After subsidence separate the super- 
natant ethereal solution by means of a syringe, and distill oif 
two pints of this solution at a low and gentle heat. The 
specific gravity at this stage will be about .750. By further 
rectification over newly burnt quicklime and chloride of cal- 
cium, ether may be obtained of a specific gravity of .720, or 
even lower. When perfectly pure its specific gravity is .713, 
and it boils at 95°. The sulphuric ether of commerce is not 
sufficiently concentrated for photographic purposes ; and 
none can be relied upon excepting that which is obtained 
direct from establishments that prepare chemical ingredients 
for the photographer. When the specific gravity is .720, 
ether boils at 98° ; this is the kind which is generally used 
in the preparation of collodion. When too long kept it un- 
dergoes decomposition, being converted partially into acetic 
acid. It is a very important solvent of oils, resins, and al- 
kaloids, and certain metalloids, as iodine, bromine, sulphur, 
and phosphorus. It does not dissolve potassa and soda, a 
very distinct characteristic from alcohol. It unites in all 
proportions with alcohol and with one tenth its volume of 
water. The impurities, as before mentioned, are acids, al- 
cohol, water, and oil of wine. The presence of acids are 
shown by litmus ; alcohol combines with water when added 
in excess, and settles and forms the lower stratum ; by de- 
cantation the upper stratum is removed, which now contains 
one tenth its weight of water ; water is removed by distilla- 
tion from fresh chloride of calcium ; the acids by distillation 
from lime or potassa ; the oil of wine is shown by the pro- 
duction of a milkiness when mixed with water. 


Alcohol is the rectified spirit of wine of the specific gravi- 
ty of 0.835, containing eighty-five parts of anhydrous aleo- 
rfol and fifteen of water/ When pure and anhydrous it is 
the hydrated oxide of ethyle, (Ae O, IIO.) It contains six 
equivalents of hydrogen, four of carbon, and two of oxygen= 
II R C 4 2 . All saccharine substances undergoing vinous fer- 
mentation give rise to the vapors of alcohol, which by dis- 
tillation are obtained in a separate and more concentrated 
form. By the vinous fermentation sugar is converted wholly 
into alcohol and carbonic acid ; and it is only from sugar, or 
substances which by chemical processes are converted into 
sugar, that the vinous exhalation can be obtained. The or- 
dinary alcohol of commerce is not sufficiently concentrated 


for the purposes of the photographer, because the water 
which it contains would precipitate a solution of pyroxyline, 
or produce an opaque solution. Like ether, therefore, it has 
to undergo a process of concentration. Whisky is the spirit 
from which the first alcohol is obtained, which contains 
water, a peculiar oil, and extractive matter. By distilling a 
hundred gallons of whisky, between fifty and sixty gallons 
of alcohol are received in the condenser of a specific gravity 
of 0.835. By a second distillation, taking care to collect 
only the first portions and cautiously managing the heat, so 
as not to allow it to rise to the temperature of boiling water, 
alcohol may be obtained of a specific gravity of 0.825, which 
is the lightest spirit that can be received by ordinary dis- 
tillation. At this stage it contains eleven per cent of water 
and some small portions of fusel oil. 

The process by which most of the remaining water is 
separated from the alcohol is as follows : 

Take one gallon of the alcohol of commerce ; chloride of 
calcium, (freshly made,) one pound. Throw the chloride 
into the alcohol and, as soon as it is dissolved,, distill olf 
seven pints and five fluid ounces. Or, take of rectified 
spirit one pint, (imp. meas. ;) lime, eighteen ounces. Break 
the lime into small fragments, mix with the alcohol in a re- 
tort properly connected, and expose the mixture to a gentle 
heat until the lime begins to slake ; then withdraw the heat 
until the slaking is finished. Xow raise the heat gently and 
distill off seventeen fluid ounces. Alcohol thus obtained will 
have a density, when the operation is carefully managed, of 

^Neither of the preceding fluids, taken separately, dissolves 
pyroxyline, a mixture of the two is required to perform this 
operation; the proportion in which they exist in this mix- 
ture, in order to attain to the maximum degree of photo- 
graphic excellence, is a problem which has not yet been 
absolutely solved. When there is a large excess of ether 
over the alcohol, the former menstruum will easily dissolve 
from one to one and a half per cent of the prepared cot- 
ton ; and this proportion will scarcely exceed, under the 
most favorable conditions, from two to three per cent with- 
out producing a precipitate in the solution. On the con- 
trary, if the alcohol, in its purest state, exists in the mix- 
ture in greater quantity than the ether, three per cent of 
pyroxyline is easily dissolved, producing a collodion of the 
proper consistency; the mixture, however, will dissolve 


from eight to ten per cent without producing any deposit in 
the collodion. 

The property of ether in collodion is to communicate te- 
nacity to the film, which, owing to the excess of this fluid, 
frequently peels oft' from the glass in one adherent sheet; 
beside this, ether is more liable to decomposition than alco- 
hol, and is perhaps one of the causes of the want of perma- 
nency in collodion, although most probably pyroxyline is the 
principal cause. This want of stability, even in normal col- 
lodion, is increased by the quantity of air contained in the 
same vessels, giving rise to an ethereal effluvia which it did 
not possess before. This decomposition is much more rapid 
when the collodion is exposed to light. 

Decomposition of Collodion. — The decomposition of nor- 
mal or plain collodion is a fact that can easily be verified ; 
but experience shows also that the iodides and bromides 
when dissolved in piire alcohol and ether are not decom- 
posed, or at any event in a very trifling degree, when pro- 
perly protected in accurately closed bottles ; the fluid does 
not change color materially, nor does it show the presence 
either of free iodine or bromine ; furthermore the solutions 
in question, when kept for any length of time, produce the 
same sensitive effects on plain collodion as if they were 
freshly made. The decomposition in collodion does not 
seem, therefore, to be superinduced by ether, alcohol, the 
iodides, or the bromides ; for each, taken separately or in 
combination, when pure and properly protected, is not liable 
to any perceptible decomposition. But Van Monckhoven 
maintains, and all photographers are aware of the fact, that 
there is a very perceptible difference between freshly-made 
plain collodion and old plain collodion. The difference is 
this : if a plate be coated in newly-made plain collodion and 
then immersed in a solution of nitrate of silver and exposed 
before an object, and afterward submitted to the action of 
the developing fluid, no traces of the picture will appear; on 
the contrary, if the plain collodion be old, and a plate be 
treated with this as in the preceding case, the fihff will be 
whitened by the sensitizing solution, and will be sensitive to 
the action of light when exposed before an object, and will 
yield a picture. A second difference is this: the collodion, 
before thick and consistent, becomes thinner and exhales an 
odor of nitric ether as it grows older. 

Such being the case, it seems evident that the pyroxyline 
is the cause of the decomposition, or that .the pyroxyline 


contains sometimes extraneous matter that produces this de- 
composition ; and when the change has once set in, the new- 
ly formed bodies may react upon the iodides or bromides 
when introduced, and tend to produce a variety of decom- 
positions according to the facility or difficulty with which 
they undergo change. 

But the next question is : What are the differences be- 
tween freshly-made iodized collodion and an iodized collo- 
dion that has been kept long ? They are as follows : 

Firstly. New collodion is more sensitive to light than old 

Secondly. Although more sensitive, it produces images 
which are much less intense than those produced by old col- 
lodion, that is, the shadows are not so deep or black. The 
images are mere surface-pictures Avhen developed with thu 
sulphate of the protoxide of iron. 

Thirdly. If the plates be washed after sensitizing, (in the 
dry process,) when freshly '-made collodion is used, no image 
will appear ; on the contrary, with old collodion the washing 
does not prevent the picture from appearing. 

Fourthly. The shadows of the picture developed by the 
protosulphate of iron are entirely soluble in nitric acid when 
a freshly-made collodion is used; and are not entirely solu- 
ble with an old collodion. 

Fifthly. Xew collodion is colorless, or nearly so ; whereas 
old collodion sometimes is as deeply red as a strong solution 
of burnt sugar. 

Sixthly. Xew collodion has the odor only of alcohol and 
ether ; but old collodion has a peculiar ethereal smell resem- 
bling that of nitric ether and aldehyde. 

We are indebted to Van Monckkoyen for the summation 
of these differences in juxtaposition, and many photographers 
will recognize the truth of them. 

The third question to be asked is then the following : 
What substance in solution will communicate to recently 
prepared iodized collodion the properties of old collodion ? 
Hardwich says that grape-sugar, glycyrrhizine, and nitro- 
glucose will render fresh collodion much more intense, but 
that they diminish its sensitiveness. Such is also the action 
of the substance, be it what it may, contained in altered 
collodion, it renders collodion more intense but less sensi- 

Furthermore Hardwich remarks, that, if these substances 
be employed to increase the intensity of the shadows in the 


image, they ought to he added cautiously hecanse they de- 
teriorate from the keeping properties. But nitro-glucose is 
said to he an impurity in pyroxyline ; it is analogous in 
several respects to pyroxyline ; and it is prepared with sul- 
phuric acid, nitric acid, and sugar / hut lignine or cellulose 
yields sugar when treated with sulphuric or nitric acid ; 
hence iu the preparation of pyroxyline grape-sugar is formed 
at the same time, and hy the further action of the acids, 
nitro-gliccose is produced. That there exists a duplex com- 
pound in collodion may he shown by adding water to it ; a 
precipitate will he formed, of which one part is fibrous and 
the other gelatinous. 

But the identity between the unknown substance and ni- 
tro-glucose is apparently shown by the identity of proper- 
ties. If nitro-glucose be dissolved in alcohol, it forms a 
colorless solution with an odor of alcohol, which has no effect 
at this stage on collodion, nor on an alcoholic solution of 
nitrate of silver; but, after the expiration of a few days, it 
assumes a rose-colored tinge and the odor peculiar to old col- 
lodion ; furthermore, at this second stage, it now communi- 
cates to fresh collodion all the properties of old collodion, 
and forms a jjrecipitate in nitrate of silver in alcohol. Van 
Monckhoven in addition has convinced himself that the pre- 
cipitate formed in old collodion by an alcoholic solution of 
nitrate of silver is six times as bulky as that which would 
be the result from the iodide of silver, and that its proper- 
ties were the same as those in the precipitate formed by 
mixing the rose-colored nitro-glucose with alcoholic nitrate 
of silver. 

Preparation of Glycyrrhizine. — This substance is obtained 
by boiling liquorice-root ia water for some time, and adding 
sulphuric acid to the concentrated syrup. A Avhite precipi- 
tate is funned, containing glycyrrhizine, albumen and sul- 
phuric acid. The albumen is removed by washing the pre- 
cipitate, first in acid-water, then in water, and afterward by 
solution in alcohol. Carbonate of potash is then added to 
decompose the alcoholic solution, and to precipitate the sul- 
phuric acid. By evaporating the liquid, glycyrrhizine re- 
mains as a yellow, transparent mass. 

Preparation, of Nitro-glucose. — Add one ounce of pow- 
dered sugar to a mixture of two fluid ounces of sulphuric 
acid, one of nitric acid. Stir the mixture for a few minutes 
with a class rod ; a tenacious mass may thus be collected 
from the fluid, and washed in warm water by kneading it 
until every trace of acid is removed. 


Collodion iodized with the ammonium salt is the least 
stable ; whilst a cadmium collodion is the most permanent. 
Collodion in which the alcohol is in larger abundance than 
the ether is more stable, and at the same time more fluid ; it 
adheres well to.the glass, forms no ridges in flowing, aud is 
in fact quite structureless. 



The salts employed for sensitizing plain collodion for the 
reception of the actinic impression, are the iodides and bro- 
mides of different metals, as of potassium, sodium, ammo- 
nium, lithium, zinc, iron, calcium, cadmium, etc. 

Iodides and bromides, which are soluble in ether and al- 
cohol, can alone be employed in the preparation of sensitized 
collodion, in order to produce, by decomposition in and on 
the film, an iodide and a bromide of silver, which are insolu- 
ble. In so extensive a choice of materials it is a difficult 
matter to collect all the advantages of a given iodide or bro- 
mide over its neighbors ; so that it has not yet been decided 
which is the most appropriate iodide or bromide. 

If each soluble iodide or bromide were equally applicable 
in a photographic sense, then the choice would be influ- 
enced by pecuniary considerations of cost and the quantities 
required ; and if by weight the iodides and bromides were 
equal in price, the selection would fall npon that iodide and 
bromide whose chemical equivalent is the least ; for the less 
the combining proportion of a given chemical substance, the 
less ihe quantity required to produce a given effect. Guided 
by this consideration of the subject, the iodide and bromide 
of lithium would claim our first attention ; after lithium 
come magnesium, ammonium, calcium, sodium, iron, zinc, 
potassium, cadmium, etc. The solubility of the respective 
iodides and bromides in a mixture of ether and alcohol will 
naturally form a second consideration ; and, thirdly, a very 
important property must have its due weight in the scale-, 
and that is the stability of the given salt in the ethereal solu- 
tion. The alkaline iodides and bromides are all soluble, so 
that lithium stands, perhaps, quite as high as the rest in this 
respect. In absolute alcohol the iodide of potassium is not 
soluble to the same extent as iodide of ammonium. The lat- 
ter iodide is the most easily decomposed. On this account 
it is regarded as a more sensitive iodizer ; it is also quicker ; 


but on the same account it is unstable and undergoes spon- 
taneous decomposition. The iodide of ammonium, as well 
as that of potassium, is very capricious. 

The bromide of silver is sensitive to light as well as the 
iodide and the chloride ; but the spectral rays have not the 
same influence on either of these three salts. The actinic 
impression on the iodide and bromide of silver is invisible or 
latent, and requires the aid of some developing agent to 
make manifest the effect of light ; whilst the impression 
made on the chloride of silver becomes manifest in propor- 
tion to the intensity and duration of light. 

The photographed image of the solar spectrum is much 
broader on the bromide of silver film, than on the iodide 
film. In the former case, the violet, the indigo, the blue, 
and partially the green produce actinic action ; whilst in the 
latter the blue part is but partially represented. Equal por- 
tions on the violet side and external to the violet color pro- 
duce an equal impression on either of the films. The greater 
capacity of the bromized film has induced photographers to 
attribute to bromine qualities specially adapted to land- 
scape-photography, where the greens occupy so large a space 
By the introduction of the bromides into collodion, together 
with the iodides, much discussion has arisen to determine 
the precise action of the former. Certain collodions with 
certain baths are acknowledged to undergo an improvement 
when a bromide is a part of the sensitizer ; the picture is 
softened, that is, the middle tints are more pronounced, or 
the lights and shades more agreeably graded with the bromo- 
iodizer, than with the simple iodizer. On this account, pro- 
bably, bromides have been regarded by many as accelera- 
tors, or substances which render collodion more sensitive to 
light. On this ground alone the deduction would be false. 
The capacity for comprehending a greater range of colors is 
possessed by the bromo-iodized collodions. This, perhaps, is 
the only true and legitimate deduction that can be drawn in 
the case ; they are considered by very high authority, on the 
contrary, as deduced from experiments carefully conducted, 
to be retarders of the actinic action. In consequence of the 
greater comprehensiveness, as regards colors, of the bro- 
mides over the iodides, it may be concluded, that there are 
very few cases in which the bromo-iodized collodion can not 
be appropriately preferred to the simply iodized collodion ; 
the exceptions being the copying of engravings, plain or un- 
colored photographs, maps, letter-press printing, etc., where 


the iodized collodion alone possesses all the capacity re- 

A peculiarity has been discovered in reference to iodized 
collodion. Some sorts of collodion are suitedfor one iodizer, 
and some for another. As a general rule, a cadmium iodide 
glutinizes collodion ; whereas an alkaline iodide liquefies it. 
The natural deduction from these circumstances is this : a 
glutinous or tenacious collodion is suited for sensitizing with 
iodide of ammonium, or iodide of potassium ; for it becomes 
thereby less tenacious, and flows better. Such collodion 
soon attains its maximum amount of sensitiveness, and al- 
most with the same facility begins to deteriorate; it is very 
unstable, and not permanent in any degree of sensitiveness. 
On the other hand an alcohol collodion, which is in a con- 
dition to flow easily, is, in fact, thin and liquid, can be ren- 
dered more glutinous by a cadmium iodide. Collodion thus 
iodized is much more stable than when iodized with the 
alkaline iodides, but it attains its maximum degree of sensi- 
tiveness very slowly, that is, it takes a longer time to ripen 
than the first-mentioned collodion; but when ripe, it retains 
its sensitiveness much longer, is in fact a stable collodion. 
Coupling these two facts together, attempts have been made 
to combine the iodide of cadmium with an alkaline iodide in 
such proportions as to comprehend the peculiar advantages 
of either, that is, the stability and permanency of the one 
with the quick sensitiveness of the other, and the mutual 
tempering of either toward a medium giutinosity or lique- 
faction. The result of such experiments indicates that the 
cadmium salt must exceed the alkaline salt in quantity. As 
soon as the highest degree of sensitiveness and stability can 
be established by means of the iodides alone, it remains then 
to combine with these a certain proportion of a bromide to 
communicate to the collodion a greater capacity for colors. 
Notwithstanding that this is, in my opinion, the view we 
have to take of the matter, it must be confessed that the 
best working quantities of the iodides, or of the bromo- 
iodides have not yet been satisfactorily determined. The. 
difficulty that stands in the way of this determination is in- 
creased by the peculiar condition of the nitrate of silver 
bath, whether it be acid, neutral or alkaline; and further- 
more whether it be rendered acid by nitric acid or acetic 
acid ; or whether it contain carbonate of soda or acetate of 
soda. A cadmium iodized, or bromo-iodized collodion sensi- 
tized in a bath of nitrate of silver rendered slightly acid 
with nitric acid, produces irreproachable pictures, but not 


more rapidly than a bath containing acetic acid, acetate of 
soda, or carbonate of soda, when these happen to be in a 
happy mood; but the latter are very unstable, whilst the 
former remains for a long time constant, and is regarded ac- 
cordingly the proper bath for the cadmium collodion. It 
must not be forgotten that acids are retarders of sensitive- 
ness, and that consequently a bath that yields a picture with- 
out spots, stains, or fogginess is preferable in the ratio as it 
approaches neutrality. A bath containing either acetate of 
soda or carbonate of soda is, when in its best condition, an 
accelerator ; but it is very unstable, deteriorates very quick- 
ly, and at present no means are known to rectify the evil 
and preserve or restore the sensitiveness. 

The iodides and bromides most generally employed by 
the photographer are those of lithium, potassium, sodium 5 
ammonium, cadmium, and silver. 



Several of the iodides are formed by the direct contact of 
the elements, as, for instance, the iodide of iron and the 
iodide of phosphorus. Others by double decomposition, as 
iodide of silver from a soluble iodide and nitrate of silver. 
And, finally, others are obtained by combining chemical 
equivalents of hydriodic acid with the carbonates of the 
liases required, as, for example, iodide of potassium from 
hydriodic acid and carbonate of potassa, iodide of barium 
from hydriodic acid and carbonate of baryta, etc. Iodine 
or hydriodic acid is the material from which the iodides may 
be and are prepared. 


Symbol, I. Chemical Equivalent, 127 y" , T ; Specific Gravity, 4. 948. 

Iodine was discovered in 1812, by Courtois, a chemical 
manufacturer in Paris. This substance exists in nature com- 
bined with metals, such as calcium, magnesium, and sodium ; 
and these are found in many saline springs and mineral waters, 
as also in sea-water. These salts are absorbed by several 
marine plants and animals; and it is from such plants that 
iodine is obtained in considerable abundance. The sea-plants 
are collected, dried, and burned in large pits, the ashes of 
which are called kelp. Formerly this kelp was collected on 
account of the carbonated alkali which it contains; its value 
now- is enhanced on account of the iodides and chlorides 
which are found in it. The powdered mass is dissolved in 
cold water, which is afterward evaporated until a scum forms 
on the surface. The solution is then set aside to cool, when 
a quantity of crystals will be deposited. By a further evap- 
oration, more crystals may be obtained, until finally the 
mother-liquor ceases to yield any more. The dark-colored 
liquid contains the iodides, which may be precipitated by a 
mixture of live parts of sulphate of iron and two parts of sul- 
phate of copper. The precipitate is subiodide of copper, 
which, by treatment with sulphuric acid, the deutoxide of 


manganese and heat, yields iodine in violet vapors, which by 
condensation form the metallic-looking crystals of iodine. 
There are other methods of separating the iodides. 


Iodine resembles plnmago or black lead, in outward ap- 
pearance ; it is a crystalline substance, soft and brittle. It 
melts at 224°, and sublimes at 347°. Its taste is very acrid 
and astringent ; its smell is somewhat like that of chlorine. 
Water dissolves about one part in seven thousand parts, and 
receives a brown color. Alcohol and ether dissolve it 
abundantly; and so do iodide of potassium and hydriodic 
acid, forming brownish red solutions. Iodine in solution, as 
tincture, or in iodide of potassium preferably, has very val- 
uable medicinal properties. It is regarded as a specific in 
the redaction of glandular swellings, and in scrofulous dis- 
eases. It is said to cause the pustules of small-pox to abort. 
In photography, it is impossible to estimate its value; for 
without it, the art could not exist in its present state. 

The impurities in iodine are plumbago, sulphide of anti- 
mony, and iodide of cyanogen. If by evaporation on apiece 
of porcelain there be any residue, one or both of the former 
impurities may be present; the latter impurity is of rare 

Tests : Free iodine is easily recognized by the formation 
of a deep blue color when mixed with a solution of starch ; 
and this blue color is volatilized by heat. The iodine in an 
iodide has first to be set free before it can be thus tested. 
To effect this, either a current of chlorine is passed through 
the solution, or nitric acid is added to it ; by boiling the solu- 
tion afterward, the fumes may be obtained and thus tested. 

Preparation of Hydriodic Acid. 

Hydriodic Acid. — Symbol, I H. Combining Proportion, 128^. Specific 
Gravity, 4.43. 

This substance is a condensable gas ; at a temperature of 
59°. 8, it solidifies into a transparent, colorless mass ; and 
water absorbs a large quantity. The strongest liquid hydri- 
odic acid has a specific gravity of l-jL, when it boils at a 
temperature between 257° and 2*62°. It is not a stable com- 
pound ; oxygen from the air is absorbed, ami iodine is lib- 
erated and dissolved by it. Chlorine and bromine decom- 
pose it. 

Hydriodic acid may be obtained by several methods. 


From the property which iodine possesses of abstracting 
hydrogen from several of its compounds, as from phosphide 
of hydrogen, hydrosulphuric acid, ammonia and organic 
compounds, methods have been devised to obtain hydriodic 
acid by their mixture. Thus, by diffusing iodine in powder 
through water, and then passing a current of hydrosulphuric 
acid through the solution as long as iodine is thus taken up 
and the fluid is rendered colorless. By this process, sulphur 
is deposited and iodine takes its place. By filtration, the 
sulphur is removed ; by heat, the superfluous hydrosulphuric 
acid is driven away. The remaining transparent solution is 
hydriodic acid. 

A solution of iodide of barium may be decomposed by an 
equivalent proportion of sulphuric acid, and by filtration from 
the insoluble sulphate of baryta, hydriodic acid is obtained in 

Phosphorus combines very vividly with iodine, and the 
iodide of phosphorus, when it comes in contact with water, is 
decomposed into hydriodic acid and phosphoric acid. Liebig 
has availed himself of this property in the preparation of the 
iodide of lithium, barium, calcium, potassium, sodium, etc. 

Lithium. — Symbol, Li. Combining Proportion, 6-j%. 

Barium. — Symbol, Ba. Combining Proportion, 68-pl.. Specific Gravity, 4. 

Calcium. — Symbol, Ca. Combining Proportion, 20. 

Potassium. — Symbol K. Combining Proportion, 39. 

Sodium. — Symbol, Na. Combining Proportion, 23. Specific Gravity, 0.97. 

Ammonium. — Symbol NH4=Am. Combining Proportion, 18. 

Cadmium. — Symbol, Cd. Combining Proportion, 56. Specific Gravity, 8.6. 

Take one part of phosphorus, twenty-four parts of iodine, 
and forty of warm water ; mix them intimately in a Wedg- 
wood mortar by means of the pestle. The color of the fluid 
is at first dark brown, but becomes transparent as soon as 
the decompositions are effectuated. The heat of a water- 
bath and friction will soon complete the action. By this 
operation, iodine and phosphorus combine, so as to form 
iodide of phosphorus, which becomes resolved into hydriodic 
acid and phosphoric acid by the decomposition of the water. 
A little free iodine added to the transparent solution prevents 
the formation of phosphorous acid. 

Iodide of Barium. 

To the transparent solution above obtained, by decantation 
from any remaining phosphorus, add, in the first place, carbo- 
nate of baryta as long as effervescence ensues, and afterward 


a little water of baiyta, so that the mixture becomes slightly 
alkaline. By this decomposition phosphate of baryta is 
formed from the phosphoric acid and the carbonate of 
baryta ; and from the hydriodic acid, and the carbonate of 
baryta, iodide of barium is the resulting formation ; and car- 
bonic acid is liberated as gas. The iodide of barium, being 
soluble,: is separated from the insoluble phosphate by filtra- 
tion. A current of carbonic acid is now passed through 
the nitrate, in order to combine with any remaining solution 
of baryta, and the mixture is again filtered. 

Iodide of Calcium. 

This salt is obtained precisely in the same way as the pre- 
ceding substituting only milk of lime for the barytic salt. 
Both these salts crystallize, when slowly evaporated ; the} 
are, too, both deliquescent. From either iodide of barium 
or iodide of calcium the alkaline iodides are easily formed. 

Iodide of lithium. 

Add two ounces of carbonate of lithia to tbe iodide of 
either barium or calcium solutions produced from seven 
ounces of iodine by the preceding manipulation. The car- 
bonate is previously levigated in water to an impalpable 
consistency. The mixture is frequently stirred during the 
twenty-four hours it is allowed to stand, in order to effect 
the complete precipitation of baryta or lime. The solution 
of iodide of lithium is now separated by filtration from the 
insoluble carbonate of baryta or lime. If the iodide of ba- 
rium or of lime has not been thoroughly decomposed, add a 
cold solution of carbonate of lithia as long as any precipitate 
is formed. 

Iodide of Potassium. 

Digest a hot solution of sulphate of potassa in a solution 
of iodide of calcium in the proportion of their equivalents 
for six or eight hours. Double decomposition ensues, the 
sulphuric acid and oxygen of the potassa combine with the 
lime to form sulphate of lime, whilst the iodine and potas- 
sium enter into combination to form iodide of potassium. 
By filtration through cloth these two salts are separated. 
The liquid, containing probably still some iodide of calcium 
and solution of sulphate of lime, is evaporated and then 
treated Avith pure carbonate of potassa as long as any pre- 
cipitate is produced. The insoluble lime is again separated, 


and the filtrate is evaporated to crystallization. The mother 
liquor is afterward evaporated to dryness. 

Iodide of Sodium and Iodide of Ammonium. 

These two salts may he prepared in like manner, either 
from the iodide of barium or of calcium, by the substitution 
in one case of sulphate and carbonate of soda, and in the 
other of sulphate and carbonate of ammonia. The results 
are better with the iodide of barium, owing to the more 
perfect insolubility of the sulphate of baryta after decompo- 
sition. Both of these iodides, as well as that of potassium, 
may be obtained by the direct action of iodine on the caustic 
alkalies. In this way iodine is added to a solution of potassa, 
for instance, until the latter becomes slightly colored ; the 
solution so obtained contains iodide of potassium and iodate 
of potash ; it is evaporated to dryness, and then heated to 
redness, in order to convert the iodate of potash into iodide 
of potassium by driving off its oxygen. The fused mass is 
afterward dissolved and crystallized. Sulphuretted hydro- 
gen is sometimes used to decompose the iodate. 

Another method, similar to the first, consists in first ob- 
taining either the iodide of iron or of zinc, by mixing iodine, 
water, and iron-filings, or iodine, water, and zinc-filings, to- 
gether, and then heating the mixture until the combination 
is complete, which is indicated by its becoming colorless. 
The filtered solution is next decomposed completely by add- 
ing solution of carbonate of potassa as long as any precipi- 
tate takes place. The precipitate, which is either carbonate 
of iron or of zinc, is removed by filtration ; and the filtrate 
is evaporated to crystallization. 

Iodide of Cadmium. 

This very important iodide is formed precisely in the 
same way as iodide of iron or of zinc, by gently heating a 
mixture of the filings of cadmium, water, and iodine, until 
the solution becomes colorless. 

Impurities of the Iodides. 

The iodides which are formed by the direct contact of the 
two elements are quite pure if the materials are pure ; where- 
as, if the iodides arise from double decomposition, the com- 
bination may sometimes fail in accuracy, in which case car- 
bonates and sulphates of foreign ingredients and iodates of 
the same base may be found in such iodides ; chlorides may 


be present, too, in the decomposing carbonates and sulphates, 
so that we may sometimes expect to find them with the other 

Tests of the Purity of the Iodides. 
No precipitate is produced in a pure iodide by solution of 
chloride of barium. If a precipitate results from the introduc- 
tion of this test, one or all of the following acids are probably 
indicated : carbonic, iodic, and sulphuric. Other acids might 
be indicated, but not probably, because materials are not used 
in the preparation of the iodides containing the acids hinted 
at, as, for instance, oxalic, sulphurous, silicic, chromic, hydro- 
fluoric, phosphoric, and boracic. Supposing, however, a pre- 
cipitate is formed when the test is added, then a carbonate, 
iodate, or sulphate may be one or all present. The next test 
is to find out which or how many of the three are present. 
Add, therefore, nitric acid to the precipitate ; if it becomes 
dissolved, there is no sulphate in the iodide. Carbonic acid 
or an alkaline carbonate added to lime-water produces a 
milkiness caused by the formation of the insoluble carbonate 
of lime ; and an iodate in solution is recognized by the addi- 
tion of chlorine-water, or citric, or tartaric acid, which liber- 
ates free iodine, afterward made manifest by solution of 
starch. The chlorides are tested for as follows : in a given 
quantity of the iodide precipitate with solution of nitrate of 
silver, until nothing more falls as sediment ; dissolve this 
sediment in ammonia, and then add nitric acid ; if a chloride 
is present, a white flocculent precipitate will be produced, 
which is chloride of silver. 



Bromine. — Symbol, Br. Combining Proportion, 80. Specific Gravity, 2.966. 

This peculiar substance was discovered in 1826 by Balard, 
of Montpellier. It was originally obtained from the uncrys- 
tallizable mother-liquor of sea-Avater, called bittern. It oc- 
curs in sea- water in small quantity as bromide of magnesium, 
or of an alkali ; but in much larger quantities in several 
mineral springs, as, for instance, at Kreuznach, Cheltenham, 
etc., and is naturally found in many marine plants and ani- 

Preparation of Bromine. 

The solution of the bromides obtained by evaporation of 
sea-water, spring-water, or from the ashes of certain plants 
and animals, is submitted to a current of chlorine, which 
takes the place of the bromine in the salts.. When the 
liquid ceases to assume a deeper color from the introduction 
of chlorine, (and great care must be taken not to add too 
much, because it combines with the bromine as soon as there 
is no base present for it to combine with,) it is well shaken 
with ether, which, taking up the bromine, ascends and swims 
on the surface. This film is then decanted, or otherwise 
separated, and mixed with a strong solution of potassa, by 
which both bromate .and bromide of potassium are formed ; 
the ether may now be removed by distillation, and the re- 
maining solution is evaporated to dryness. The residual 
mass is then fused, whereby the bromate of potassa is con- 
verted into bromide of potassium, analogously with the 
iodate or chlorate under similar circumstances. By distill- 
ing the resulting bromide with sulphuric acid and peroxide 
of manganese, bromine passes off as vapor, and a sulphate of 
the base remains in the retort together with the manganese 
in a lower state of oxydation. 

Bromine thus obtained contains water and bromide of car- 


bon. The water is removed by a second distillation over 
recently fused chloride of calcium. Bromine is a brownish- 
red liquid, which solidifies at — 7° T 2 o, volatilizes very rapidly 
when exposed to the air, and boils at about 145°. Its smell 
is very disagreeable and pungent. A drop on the cuticle 
destroys it and produces a sore. It is soluble in 33 T \ parts 
of water, and this solution is decomposed by exposure to 
light into hydrobromic acid. 

Test : Chlorine liberates bromine from all its soluble com- 
pounds. Ether combines with it and collects it ; solution of 
starch produces a yellowish-red color with it ; it distills as a 

Hydrobromic Acid. 
Symbol, Br H. Combining Proportion, 81. Spec. Grav., 2.73. 

This acid is very analogous in its formation and reactions 
to hydriodic acid. It can be prepared by mixing directly 
phosphorus, water, and bromine, or from a mixture of six 
parts of crystallized sulphite of soda, three parts of bromine, 
and one of water, and by distillation. It can be obtained 
also by transmitting a current of hydrosulphuric acid through 
water, holding in solution or suspension a small quantity of 
bromine ; sulphur is deposited ; the hydrogen combines with 
the bromine. By a gentle heat the fumes of hydrosulphuric 
acid are expelled ; and by filtration the hydrobromic acid is 
obtained in solution. 


These binary combinations can be obtained, as a general 
(liing, by manipulating precisely as in the preparation of the 
iodides, with the single substitution of bromine for iodine. 
They contain in like manner, and for the same reason, the 
same impurities which may be manifested by the same tests, 
with the exception of bromic acid instead of iodic; the 
former of which is decomposed by chlorine. 

Preparation of the Chlorides. 

Chlorine. — Symbol, CI. Combining Proportion, 35.5. Spec. Grav., 2.47.' 

This substance was discovered in 1774 by Scheele. Its 
affinity for other elements is very great, so that it does not 
exist free or uncombined. The great geological formation 
of rock-salt is a chloride of sodium, to which the ocean owes 
its saline taste. It combines with most of the metalloids as 
well as the metals, giving rise to some of the most import- 
ant and interesting combinations in chemistry. Chlorine, 
iodine, bromine, and fluorine form analogous binaries with 


hydrogen and the metals ; but chlorine has greater affinities 
for bases than any of the others ; it is, therefore, employed 
in separating iodine and bromine from their combinations. 


Chlorine may be obtained from any of its binary combina- 
tions by double decomposition. Thus hydrochloric acid is a 
binary consisting of chlorine and hydrogen ; now by adding 
to hydrochloric acid a material in which oxygen is loosely 
combined, hydrogen and oxygen unite to form water, chlo- 
rine is liberated, and a chloride of the base is at the same 
time formed. Take, for instance, four parts of hydrochloric 
acid, one part of the binoxide or black oxide of manganese, 
and the same quantity of water. 3Iix these ingredients in a 
flask or retort connecting with a jar filled with warm water 
and inverted over the pneumatic trough, or by a tube dip- 
ping to the bottom of a large tumbler. By applying heat, 
either from a lamp or sand-bath, an effervescence is pro- 
duced, being the result of the decomposition just alluded to. 
The gas as it passes out displaces the water in one case and 
the air in the latter. 

The mode by which it is procured from a chloride consists 
in first obtaining from the chloride hydrochloric acid, and 
then proceeding as before. But the two operations are com- 
bined in one, that is, they take place consentaneously by 
mixing all the materials together which are required in their 
separate formations as follows : take three parts of common 
salt, five of sulphuric acid, five of water, and four of binox- 
ide of manganese, and apply heat as before ; the same re- 
sult will ensue as in the first case. 


This substance is a heavy gas of a greenish-yellow color, 
and exceedingly suffocating* odor. Under a pressure of four 
atmospheres thia gas is condensed into a liquid of a bright 
yellow color, Avhose specific gravity is 1.33. It is soluble in 
"water, which takes up and dissolves about two volumes of 
this gas, and receives the taste, odor, and other properties 
of the gas. With very cold water chlorine enters more 
abundantly into combination, forming a crystalline hydrate. 
Chlorine in solution, when exposed to the light, soon de- 
composes the water, giving rise to hydrochloric acid. Chlo- 
rine has an exceedingly great affinity for hydrogen, and re- 
moves this latter body from many of its combinations, a-, 
for example, from ammonia ; still dry chlorine and hydro- 


gen, when mixed and kept in the dark, do not combine ; if 
brought into the full blaze of the sun, they combine and ex- 
plode ; if exposed to diffused light, they combine silently into 
hydrochloric acid. Its action upon metals in a state of fine 
division is in many cases very energetic ; if a piece of bronze 
or gold-leaf be injected into a tumblerful of the moist gas, 
the combination is so energetic as to produce flame. The 
moist gas combines with the hydrogen of organic colors and 
bleaches them ; these colors can not be restored, because the 
hydrogen can not be restored organically ; hence we say in 
such an instance that the color has been destroyed. In like 
manner moist chlorine removes the hydrogen from putrid 
and miasmatic substances, as from fish, meat, and offensive 
localities. It is, therefore, denominated a disinfecting agent. 
Its combination with the hydrate of lime is the form in jvhieh 
it is used both for bleaching and disinfecting. 

Chloride of Lime, Chlorinetted Lime, etc. 

This substance is prepared by passing chlorine through 
sets of chambers or compartments of wicker-work containing 
layers of hydrate of lime. The lime absorbs a large quantity 
of the gas, and probably combines with it in the formation 
of a hypochlorite of lime. Chloride of lime is soluble to 
some extent in water, giving to it an alkaline reaction ; its 
bleaching powers are more effectual when an acid is added, 
which liberates the chlorine. This substance is now used in 
photography in the preparation of the gold-toning bath. 
When added to chloride of gold, which is slightly acid, it 
renders it alkaline, and at the same time chlorine is liberated, 
which assists in producing pure whites on the paper, and in 
furnishing a chloride of gold which is more effectual in ton- 



Normal or plain collodion is a solution of pyroxyline in a 
mixture of ether and alcohol, ready for being iodized or bro- 
mo-iodized. This sort of collodion when preserved in well 
corked bottles becomes clearer with age, and the sediment 
occupies continually less space. After it has stood for a week 
or two, the clear supernatant solution is decanted by means 
of a syphon, syringe, or stop-cock from the residue of undis- 
solved pyroxyline beneath, and again put aside to settle. 
There is no fixed rule, arising from chemical equivalents or 
combining proportions, by which to institute a fixed formula 
for the preparation of normal or plain collodion. I have se- 
lected those which may be relied upon. 

Take of ether, specific eravitv, .715 1000 parts bv weight 
" " Alcohol, (absolute,) ." . . 1000 " " " 

In another vessel shake together thoroughly — 

Alcohol, (absolute,) . . . 850 parts. 
Pyroxyline, 45 " 

As soon as the pyroxyline is completely covered and satu- 
rated with the alcohol, add the mixture of alcohol and ether, 
and shake well until the cotton has completely disappeared. 
Cork the vessel carefully, which is supposed to be full, and 
put it aside in a cool, dark place for a week or two, as before 

If a glutinous collodion, or a collodion with more body be 
desired, such as is required in the transfer of the collodion 
film upon glazed leather, etc., as much as fifty parts of py- 
roxyline may be dissolved in the above proportions of alco- 
hol and ether ; on the contrary, if a thin collodion be required 
for the flowing of large plates, the proportion maybe as low 
as thirty-six or forty parts of the prepared cotton. Xormal 
collodion for present use may be filtered ; but it is far from 
being as pure by filtration as by subsidence. Filters for such 



purposes may be procured of the photographic establish- 
ments, by which the filtration proceeds without the contents 
coming in contact with the atmosphere. The above propor- 
tions are for the preparation of what is denominated alcohol 
collodion, which produces a soft, short, and structureless him 
on the glass plate. 

JBromo-idiozing Solutions for the same. 

Take of Alcohol, (absolute,) 100 parts. 

" Iodide of sodium, 8 " 

" Iodide of cadmium, 3 " 

" Bromide of cadmium, 4 " 


Take of Alcohol, (absolute,) 100 parts. 

" Iodide of lithium, 10 " 

" Bromide of lithium, 5 " 

Or, xy, 

Take of Alcohol, (absolute,) 100 parts. ^ X « 

" Iodide of lithium, 6 " 

" Iodide of cadmium, 6 " JL. 

" Bromide of cadmium, 2 " 


Take of Alcohol, (absolute,) 100 parts. c^ iki 

" Iodide of cadmium, .... 10 " *-\ \ /Vv 
" Bromide of ammonium, . . . 5 " A 

Dissolve the salts in each case in the given quantity of al- 
cohol, shaking the mixture frequently, and preserve it in 
well-closed bottles and in a dark place. 

Collodion for photographic purposes is prepared from a 
mixture of plain collodion, and one of the bromo-iodizers 
above given, in the proportion of ten parts of the former to 
one of the latter. The mixture requires to be placed aside 
for a day or two, before it arrives at its maximum sensitive- 

Many operators prepare their collodion directly with the 
requisite quantity of iodizing and bromo-iodizing materials, 
of which the following selection contains some of the best .^ 
formulas. >^\ 

Formula of Lieut.- Colonel Stuart Worthy. 

Ether, 1 ounce. 

Alcohol, .802, 1\ " 

Iodide of lithium, 15 grains. 

Bromide of lithium, .... 6|- " 

The pyroxyline is first steeped in the bromo-iodiozed alco- 
hol, and the ether then added. These proportions produce 


a very fluid collodion, which is quite an advantage in coat- 
ing large plates, "where a very even film is required. It is 
said to be well adapted for instantaneous pictures. The sen- 
sitizing bath, which is used with this collodion, will be found 
amongst the list of silver baths given hereafter. 

OmmegancTcs Formulas for Portraits and Landscapes. 
Fur Portraits of short exposure. 

Ether, 667 parts. 

Alcohol, 333 " 

Iodide of ammonium, .... 6 " 
Iodide of cadmium, .... 6 " 
Bromide of cadmium, .... 3 " 
Pyroxvline, 12 " 

This collodion is sure to be thick enough ; if too thick, 
however, it can be rendered more fluid by the addition of an /(pC 
appropriate quantity either of ether or absolute alcohol. If 
more than one tenth of the original volume be added, it will 
be necessary to mix with this the corresponding quantity of 
the bromo-iodizers. 

For Landscapes, Yieics, and Direct Transparent Positives. 

Ether, 667 parts. 

Alcohol, 333 

Iodide of zinc, 6 " 

Iodide of cadmium, .... 6 " 
Bromide of cadmium, .... 3 " 
Proxyline, 12 " 

In this, as also in the preceding formula, weigh out the salts 
first ; put them into a bottle of the proper capacity ; add the 

A-*> alcohol, and dissolve them by frequent shaking ; next arid the 
ether and mix ; finally introduce the pyroxvline in small flocks 
at a time, and shake until the cotton is dissolved. After the 
solution is effected the collodion is put aside in a cool, dark 
chamber, and allowed to settle for a couple of weeks. The 

^ first collodion will keep for a long time ; the latter is less 

stable, but more sensitive to certain colors of foliage. v "*~ 

* Formulas of Disdiri. 


First Formula. J y 

Alcohol — spec. gray. .813, . 4000 grains. 
Ether, " " " .720, . 6000 " 

^\* \ Iodide of ammonium, .... 60 

Iodide of cadmium, .... 40 

Liutr, .i-i./, . ouuv 
\& Pvroxvline 110 

V) ■ 

L*S j Bromide of ammonium, ... 6 


Bromide of cadmium, .... 4 
Iodine, 5 


Second Formula. 

Alcohol — spec. grav. .813, . 4000 grains. 

Ether, " " .720, . 6000 " 

Pyroxyline, 110 " 

Iodide of ammonium, ... 50 " 

Iodide of potassium, .... 50 " 

Bromide of ammonium, ... 10 " 

Bromide of potassium, .... 10 " 

Iodine, 5 " 

The iodide and bromide of potassium are dissolved in the 
smallest quantity of water. A quarter of the prescribed quan- 
tity of alcohol is poured into a clean bottle ; the pyroxyline 
is then introduced, and the mixture is well shaken. After 
this operation the ether is added. The salts of iodine and 
bromine are next weighed and dissolved in the remaining 
quantity of alcohol, and then mixed with the solution con- 
taining the cotton. The collodion is put aside for a day or 
two, and then either decanted or filtered. 


Alcohol, (as before,) . . . 5000 parts. 

Ether, . " 5000 " 

Pyroxyline, 100 " 

Iodide of ammonium, . . . . 50 " 

Iodide of cadmium, .... 50 " 

Bromide of ammonium, ... 10 " 

Bromide of cadmium, .... 10 " 

Iodine, 5 " 

Second Formula. 

Alcohol and ether, of each, 5000 grains. 

Pyroxyline, 100 " 

Iodine of ammonium and of potassium, of each, ... 50 " 
Bromide of ammonium, and bromide of potassium, of each, 5 " 
Iodine, .... 5 " 


Alcohol, (as before,) . . . 4000 grains. 

Ether, " 6000 " 

Pyroxyline 80 " 

Iodide of ammonium, .... 50 " 

Iodide of cadmium, .... 30 " 

Bromide of ammonium, ... 5 " 

Bromide of cadmium, .... 2 " 

Iodine, 2 " 

For copying engravings, etc., all that is required is a very 
simply iodized collodion, without any bromide. 


Formula for Copying GoUodion. 

Alcohol, (absolute,) . . . 5000 grains. 

Ether, .720, 5000 " 

Iodide of cadmium, .... 100 " 
Pvroxyline, from . . . 75 to 100 " 
Iodine, 2 " 

The collodion film, -whether iodized or bromo-iodizecl, is ren- 
dered sensitive by immersion in a bath of nitrate of silver, 
-which will be described in the following pages. 

(Owing to the instability of collodion when once iodized, 
it has been proposed to invert the operations, and to mix with 
the collodion an equivalent quantity of the nitrate of silver, 
instead of the iodizers or bromo-iodrxers, and then to sensi- 
tize the film in a bath as follows : 

Distilled water, 100 parts. 

Alcohol, 25 " 

Iodide of ammonium, .... 2 " 

Iodide of cadmium, 4 " 

Iodide of zinc, 2 " 

Bromide of zinc, 2 " 

As soon as withdrawn from this bath, the collodion plate 
ia washed in distilled water, and either used immediately by 
immersing it in a weak solution of nitrate of silver, or put 
away to dry. This process is due to Ch. D'Orma, and re- 
mains to be tried.) Whatever may be the difference of the 
composition of the collodion, arising, from the variety of for- 
mulas that exi>t — for there is scarcely a single operator that 
does not boast of his own formula — each collodionized plate, 
when the film has sufficiently dried, is submitted to the chem- 
ical influence of a solution of nitrate of silver, in order to ob- 
tain by double decomposition in and on the film an iodide, 
or a bromo-iodide of silver, which is sensitive to the actinic 
influence of light. If the film contained a pure iodide, or a 
pure bromo-iodide of silver, without the presence of a nitrate, 
the results would not be satisfactory. The nitrates, or nitro- 
genized organic substances seem to be essential as ace 
ries in the photographic operation of producing collodion posi- 
tives and negatives. The most important salt in photogra- 
phic chemistry is nitrate of silver; it is the salt from which 
of the other silver salts are obtained, and is besides a 
a ery costly article, and deserves therefore to be treated with 
all due respect. Hence the following chapter is devoted to 
its service chiefly. 



Silver. ■ — Symbol, Ag. Combining Proportion, 108. Spec, grav., 10. 474. 
Oxide of Silver. — Symbol, Ag 0. Combining Proportion, 116. 
Chloride of Silver. — Symbol, Ag. CI. Combining Proportion, 143.5. 
Iodide of Silver. — Symbol, Ag. I. Combining Proportion, 234.36. 
Bromide of Silver. — Symbol, Ag. Br. Combining Proportion, 188. 
Sulphide of Silver. — Symbol, Ag. S. Combining Proportion, 124. 
Cyanide of Silver. — Symbol, Ag. Cy. Combining Proportion, 134. 
Nitrate of Silver. — Symbol, Ag 0. N0 5 . Combining Proportion, 170. 
Hyposulphite of Silver. — Symbol, AgO. S2O2. Combining Proportion, 164. 
Sulphate of Silver. — Symbol, AgO. S0 3 . Combining Proportion, 156. 
Nitrite of Silver. — Symbol, AgO. N0 3 . Combining Proportion, 154. 


Silver, like gold, is found in a native state ; frequently 
too it occurs as an alloy containing gold, which is recog- 
nized, when the silver is dissolved in nitric acid, as the Mack 
sediment or oxide of gold. Arsenic and antimony are found 
also alloyed with it. Several of the ores of lead and copper 
contain silver. 

As an ore, the sulphide is the most abundant ; horn silver, 
or the chloride, occurs native, as also the carbonate in small 

Native silver, and the silver in the native sulphide, are 
separated in one case from the investing rocky materials, 
and in the other from sulphur by a process called that of 
amalgamation. The ores and the rocky mass are reduced 
to powder, and then roasted in a reverberatory furnace with 
about ten per cent of chloride of sodium, which converts the 
silver into chloride of silver. The pulverized mass is next 
put into barrels, hung horizontally and capable of being- 
rotated by machinery. It is mixed with a certain quantity 
of icater, iron and quicksilver. By being kept in continual 
agitation for eighteen or twenty hours, the chloride of silver 
becomes decomposed by the iron, whereby chloride of iron 
is formed, and the silver set free. Coming in contact with 
the mercury, an amalgam is formed, which flows oif out of 


the barrel when the contents are made fluid by the addition 
of water, and by rotating the barrels very slowly. The 
amalgam is then subjected to pressure through chamois 
leather, which allows the mercury to permeate through its 
pores, but retains the amalgam. By distillation, the mercury 
can be expelled from the silver residue. Copper and lead 
ores, containing silver, are treated in the same way. 

In certain ores of copper and lead, silver exists in small 
quantities, and is melted or separated by amalgamation 
along with them. If the quantity is sufficiently great, the 
silver is separated by a process called cupeUation, which is 
practised in the mint in the assay of metals containing sil- 
ver. A cupel is formed out of well-burnt and well-washed 
bone ashes, kneaded into a thick paste with water, and 
forcibly pressed in an iron ring. Cupels vary in size from 
one to two inches in diameter or more, and from a quarter 
of an inch to three fourths of an inch thick, hollowed on one 
side in the concave form of a watch-glass. They are after- 
ward dried by a gentle heat, as on a stove, when they are 
ready for use. The metal, consisting of copper, silver and 
a large excess of lead, to be assayed, or the silver to be 
purified, is placed in the concavity of the cupel, which rests 
on a muffle in a furnace, over which a current of air can 
flow with some force. It soon melts, and by the access of 
the draft of air, the surface becomes covered with a film of 
oxide ; this, as it forms, is removed. Lead oxidizes first, 
and finally the copper is induced to oxidize by means of the 
oxide of lead, and forms with it a fusible compound, which 
sinks into the pores of the cupel. As soon as the foreign 
metals are nearly removed, the silver assay assumes a rounder 
shape, and when the last trace of oxide disappears, there 
is a beautiful play of prismatic colors, and finally the silver 
button becomes very brilliant, and exhibits a bright flash of 
light, indicative of the completion of the operation. 

A second process of purifying silver, and one which will 
be found better adapted to the wants of the photographer, 
consists in dissolving the silver of commerce, or of the coin- 
age of the country, in pure nitric acid. Take one ounce 
and a half of silver, in thin laminae, or in filings, one fluid 
ounce of nitric acid, and two ounces of pure rain or distilled 
water. Mix the acid and the water in a glazed porcelain 
dish, or in a glass dish ; then add the silver, and place the 
i with its contents in a sand-bath, and apply a gentle 
heat. The silver will soon disappear in the solution. By 
this operation, the nitric acid is easily broken up into its com- 


binations ; one portion oxidizes the silver and liberates per- 
oxide of nitrogen ; whilst a second combines with the oxide 
so formed, and produces the nitrate of the oxide of silver. 
If the metal was impure, as is most likely, and it contained 
copper, the solution will be tinged blue according to the 
quantity of impurity. A small drop at the end of a glass 
stirring-rod, will give rise to a brilliant blue color, in a 
wine-glass full of water, made alkaline with ammonia, if 
there be any copper present; or a steel knitting-needle, 
dipped in the solution, becomes coated with a film of copper, 
on the same conditions. 

Supposing the solution, therefore, contains copper, we may 
proceed as follows to separate it from the silver. Add 
to the solution of the nitrate, a small quantity of common 
salt dissolved in water, drop by drop, as long as a floccu- 
lent precipitate is formed. When flakes of the chloride of 
silver, thus produced by double decomposition by means of 
the chloride of sodium, no longer appear on the addition 
of the salt solution, the precipitate is allowed to subside in 
a dark room, or it is poured directly on a filter, and the 
fluid containing copper, etc., is thrown away. The precipi- 
tate is now well Avashed by repeatedly filtering pure hot 
water over it, until a drop no longer produces a blue tinge 
with ammonia. The chloride is now dried. Xext weigh 
the chloride, and take twice its weight of carbonate of 
potassa, and fuse the latter in a crucible ; when fused, add 
gradually to it the dry chloride of silver, which will be de- 
composed, as well as the carbonate of potassa. The chloride 
leaves the silver and gives rise to chloride of potassium, 
whilst the carbonic acid and oxygen escape, and the silver 
remains diffused through the mass. By raising the tem- 
perature, the silver sinks into a button at the bottom, and 
the fused chloride of potassium swims on the surface. The 
melted mass may now be poured out into a pail of water, or 
upon a hollow stone. The silver thus obtained and washed, 
will be quite free from copper, and all other metals, except- 
ing load or mercury, which might be present. If lead were 
present in the nitrate, the addition of sulphuric acid would 
produce a precipitate ; and the presence of mercury is easily 
shown by introducing a piece of polished copper wire into 
a small quantity of the nitrate in solution, by which it will 
be covered with a film of mercury when the latter is pres- 

Chloride of silver may be reduced, also, by fusing it with 


seventy per cent of chalk, together with four or five per 
cent of charcoal. 

A third method of reduction of the chloride, is one which 
is very convenient for those who do not possess a furnace, 
or have the convenience of fusing ore- or residues. Moisten 
the chloride with dilute hydrochloric acid, and immerse 
a plate of zinc in the moistened mass for several hour-. 
Decomposition will gradually take place, the silver hein^ 
deposited, whilst the soluble chloride of zinc is formed. 
At'ter the chloride has been thus completely decomposed, 
the remaining zinc is withdrawn, and the precipitate is 
washed with dilute hydrochloric acid, until there is no 
longer any precipitate .formed in the decanted fluid by 
means either of ammonia or of sulphide of ammonium. The 
precipitate is next well washed with warm water. It is 
now in a condition for being dissolved in nitric acid. 

Instead of precipitating the silver as chloride, in order to 
separate it from the copper, the solution is evaporated to 
dryness, and then heated nearly to redness. By this pro- 
cess the nitrate of silver is fused, but suffers no other change; 
whilst the nitrate of copper is decomposed, yielding up per- 
oxide of .nitrogen and oxygen, and leaving the insoluble 
black oxide of copper mixed witli the fused silver salt. By 
dissolving a small portion of the fused mass from time to 
time in water, and testing the solution, after filtration, with 
ammonia, it can easily be ascertained whether it be free 
from copper or not. As soon as no copper is indicated, the 
fused mass is dissolved in pure water and separated from 
the insoluble residue, evaporated and crystallized. 

The oxide of copper may be separated from the nitrate 
of copper in the solution by substitution of oxide of silver. 
This oxide of silver is obtained by precipitating a quantity 
of the given solution by a solution of potassa. The collected 
precipitates of oxide of copper and of oxide of silver, are then 
well washed, and afterward boiled with the remaining parts 
of the impure nitrate. The solution is then finally separated 
from the residue, evaporated and crystallized. 

Finally, the mixed solution may be treated with plates 
of copper, whereby the silver is precipitated in a state of 
very tine division, which is afterward obtained on the filter, 
and" thoroughly purified by washing. This silver is then 
treated with pure nitric acid until dissolved ; the solution 
is then evaporated to dryness, redissolved, evaporated and 

In every case where the salt thus obtained is intended for 


photographic purposes, the crystals when thoroughly dried 
are dissolved in pure water, and again crystallized; or the 
solution of the crystals is boiled for some time in a glass 
flask containing fragments of pure silver, or perfectly well- 
washed oxide of silver, (procured as just indicated.) In this 
way the nitrate of silver, after evaporation and crystalliza- 
tion, can be had in an absolute neutral condition. 

The mother-liquor remaining after the crystals have been 
removed, is evaporated to dryness, fused and poured into 
cylindrical moulds of the size of a quill. In this form it is 
denominated lunar caustic, and used principally by sur- 
geons for cauterizing erysipelatous, ulcerated, etc., surfaces. 
From this mode of its manufacture, it can not always be 
relied upon by the photographer as pure. In fact it fre- 
quently blackens by exposure to light, whilst pure crystal- 
lized nitrate of silver, does not change by a similar exposure. 
In addition to impurities of an organic nature, it frequently 
contains, besides, nitrite of silver, produced by the decom- 
position of the nitrate by the heat of fusion. 


Nitrate of silver crystallizes in colorless square tables ; 
it is an anhydrous salt, and neutral when carefully prepared. 
This salt may be fused, as before mentioned, into lunar caus- 
tic; but if the heat be too great, it is decomposed into nitrite 
of silver, oxygen being liberated ; and by a still greater heat 
the nitric acid is entirely removed, and pure silver left be- 
hind. Nitrate of silver dissolves in one part of cold water, 
and in less of boiling water. It is soluble also in about four 
parts of alcohol. The oxide of the nitrate of silver, is pre- 
cipitated by any of the alkalies or alkaline earths. In am- 
monia, added in excess, the oxide is redissolved, forming a 
definite compound of the formula AgO, NO,„ 2XII 3 , denom- 
inated ammonio-nitrate of silver, which by evaporation is 
obtained in the crystalline form. 

Photographic Properties of the JVitrate of Silver. 

Collodion iodized with a solution of iodide of silver in 
iodide of potassium does not produce a picture when ex- 
posed and developed by the ordinary process ; nor is a col- 
lodion film, when sensitized in the bath of nitrate of silver, 
and carefully washed in the dark-room after the operation of 
sensitizing, any longer as sensitive to the actinic influence 
as before ; or supposing it to be so, it no longer yields a 
picture by ordinary development. It' is, therefore, not the 


iodide of silver alone which undergoes the actinic impres- 
sion, but the iodide in connection with the nitrate of silver, 
or the nitrate of the new base, and probably with free nitric 
acid, which is easily broken up or decomposed, and yields 
thus its oxygen to produce or induce further decompositions. 
Whatever the theory or the true explanation of the photo- 
graphic impression on the iodides or bromides may be, 
whether physical, chemical, electrical, or mixed, that is, 
physico-chemical, etc., one thing as yet is quite certain, 
(and this is certainly the beginning of knowledge,) that the 
rationale of actinism on any substance or surface is a mystery, 
has not been hitherto explained on unexceptional ground-;, 
is not satisfactorily deduced from experiments. It is useless 
then to give a long dissertation on a mere hypothesis. But 
we do know, if not with certainty, at least nearly so, by 
what conditions the best results can be obtained in refer- 
ence to the nitrate of silver bath in combination with the 
iodized or bromo-iodized collodion. For instance, collodion 
containing, amongst other chemical ingredients, free iodine, 
indicates at once that the silver-bath may be neutral, even 
slightly alkaline; whilst if the collodion be new, contain no 
free iodine or bromine, be colorless, then the bath appro- 
priate for producing a good picture must be the very con- 
trary of the preceding, it must be slightly acid. We know 
that acids retard the action of development, limit this action 
to the parts impressed actinically, prevent in consequence 
what is denominated fogging. We know, moreover, from 
repeated experiments, that it is immaterial whether the col- 
lodion or the silver-bath be slightly acid, the result is the 
same, the production of a clear picture accompanied with 
the disadvantage of lengthening the time of action. But we 
do not yet know the exact conditions of collodion and hath 
by which clearness and sensitiveness can be attained in a 
maximum degree in the shortest time without exception. 

The iodide of silver, whether produced by the decomposi- 
tion of iodide of cadmium, of lithium, or of any other b;;se, 
is, in all probability, equally sensitive ; but this sensitiveness 
i- found to be materially changed by the presence of the 
other salt in the decomposition. From experiments in this 
direction it is known that the greatest degree of sensitive- 
ness is arrived at when the collodion contains iodide of iron, 
and this probably because the proto-nitrate of iron is very 
unstable and easily broken up. With such an iodizer, how- 
ever, the silver-bath would soon be entirely deteriorated by 
the continual introduction of a developing material : so that 


many points have to "be taken into consideration before 
normal conditions can be isolated or legitimate deductions 

Preparation of other Salts of Silver. 

Other Salts of Silver. — Sulphate of Silver. — This salt is 
obtained by dissolving silver in concentrated sulphuric acid 
by the aid of heat; or by double decomposition of nitrate of 
silver with sulphate of soda. Sulphate of silver is soluble in 
eighty-eight times its weight of boiling water, from which 
it crystallizes on cooling. Like the nitrate it is anhydrous, 
and forms in like manner a distinct and definite combination 
with ammonia, whose equivalent is Ag O. S0 3 + 2 ISTII 3 in 
fine transparent crystals. 

Hyposulphite of Silver. — This combination is obtained by 
tlic double decomposition of an alkaline hyposulphite and 
nitrate of silver. For instance, add a dilute solution of 
hyposulphite of soda to a similar one of nitrate of silver ; a 
white precipitate is formed which is soon dissolved in the 
menstruum ; after a while, when the hyposulphite of soda 
has dissolved the newly formed precipitate to saturation, a 
flocculent substance is formed of a dull gray color, which is 
permanent. This second precipitate is hyposulphite of sil- 
ver in an isolated state. But the hyposulphite of soda con- 
tains a large quantity also, thus giving rise to a soluble 
double salt, which has a very sweet taste. Hyposulphurous 
acid has a very powerful affinity for silver, so that hydro- 
chloric acid or a soluble chloride produces no precipitate in 
the solution of the double salt of hyposulphite of silver and 
of soda. In such a solution, containing a large proportion 
of waste silver, the best way to obtain or separate the silver 
is to pass a current of hydrosulphuric acid through the solu- 
tion, in order that the silver may be precipitated as sulphide 
of silver. Hyposulphite of silver undergoes spontaneous 
decomposition into sulphate and sulphide of silver ; on this 
account the fixing-bath is found to contain in general a large 
quantity of black sediment, which is sulphide of silver. This 
sulphide, when a sufficient quantity has been collected, is re- 
duced by heat into sulphurous acid and metallic silver. 

Iodide of Silver. — This salt is found native, and some- 
times in the form of hexagonal prisms. It may be formed 
artificially by allowing the vapor of iodine to play upon 
polished plates of silver, as in the Daguerreotype process, or 
by double decomposition. When excess of nitrate of silver 
hi solution is added to a solution of iodide of potassium or 


to hydriodic acid, a yellow precipitate is produced ; this is 
iodide of silver ; whereas if the iodide of potassium be in 
excess, the precipitate is nearly white, its soluble and yellow 
part having been dissolved by the alkaline iodide. The 
yellow precipitate is that form of the iodide which is best 
adapted for photographic purposes. It is insoluble in water 
and in dilute nitric acid ; almost insoluble in ammonia ; and 
is not so soon colored by the action of light as the chloride. 
It is very soluble in the alkaline iodides, in cyanide of potas- 
sium, and hyposulphite of soda, and by evaporation may be 
crystallized out of them as double iodides, etc. When silver 
is dissolved in hydriodic acid, crystals of the iodide of silver 
may be obtained in the solution by spontaneous evaporation. 
Iodide of silver may be reduced in the same way as the 
chloride by means of zinc. Hydrochloric acid converts it 
into chloride of silver. It is decomposed by both chlorine 
and bromine which liberate iodine. It is soluble to a small 
extent in solution of nitrate of silver. 

Iodide of Silver for the Silver- Bath. — Add to a small 
quantity of iodide of potassium in solution a larger quantity 
of dissolved nitrate of silver; allow the canary-yellow colored 
precipitate to subside ; decant the supernatant liquid ; wash 
with water and again decant, and repeat the washing several 
times. Let this operation be performed in the dark-room. 
The yellow precipitate, whilst still moist, is added to the 
bath of nitrate of silver in proper quantity as long as it is 
dissolved by the same ; the solution is then filtered ; and as 
regards saturation with the iodide of silver, is ready for 

Bromide of Silver. — This salt is found native in Mexico 
and in Bretagne, sometimes in an amorphous condition, and 
sometimes crystallized of a greenish-yellow color. It is 
formed artificially by exposing plates of silver to the vapor 
of bromine, or by decomposing nitrate of silver by an alka- 
line, or any other soluble bromide. The precipitate is white 
at first, but becomes yellow afterward. It may be fused, and 
when cool its color is intensely yellow. Bromide of silver 
is very sensitive to light, but the color when so acted upon 
by light is very different from that of the chloride. It is 
soluble in strong ammonia and in chloride of ammonium, as 
also in hyposulphite of soda and cyanide of potassium. The 
bromides are decomposed by chlorine, whereby bromine is 
liberated, and maybe collected by ether, which, by agitation, 
collects the bromine and carries it to the surface, from which 
it may be decanted. 


Chloride of Silver. — Next to the nitrate of silver, the 
chloride is perhaps the most important combination of this 
metal. It occurs native as horn-silver in translucent cubes 
or octohedra of a grayish-white color ; its specific gravity 
in the native form is 5.55. Like the iodide and bromide of 
silver, it may be obtained by exposing plates of silver to the 
vapor of chlorine. The surface of the plates soon becomes 
covered with a chalky film, which is the chloride in ques- 
tion. It is obtained as an insoluble white powder by de- 
composing nitrate of silver, or any other solution of silver 
excepting the hyposulphite, by means of hydrochloric acid 
or a soluble chloride, by which a complete interchange takes 
place, and a dense curdy precipitate falls gradually to the 
bottom. After subsidence the liquid is poured off, and the 
residue is well washed in several waters. This operation 
must be performed in the dark-room, because the chloride 
of silver is very sensitive to light, and soon changes from a 
white to a violet color in the sun or in diffused light. This 
violet-colored substance is a sub-chloride or an oxy-chloride, 
and may be formed directly by chemical means as follows : dip 
a plate of polished silver into a solution of sesqui-chloride 
of iron, or of bichloride of mercury ; the surface becomes 
stained black ; the iron or mercury parting with a portion of 
its chlorine, is reduced to a lower chloride, whilst the silver 
film becomes converted into a sub-chloride of silver. Chlo- 
ride of silver *is insoluble in water ; it is very soluble in am- 
monia, in cyanide of potassium, in hyposulphite of soda, as 
also in concentrated and boiling solutions of chloride of 
potassium, chloride of sodium, and chloride of ammonium, 
from which may be obtained, by evaporation in one case 
and by cooling in the other, crystals of double salts of chlo- 
ride of silver and the other substances in the solvents. Hy- 
drochloric acid in a very concentrated state dissolves a 
minute quantity of chloride of silver, which crystallizes on 
evaporation of the acid. It is precipitated from all solutions 
of silver salts, as before mentioned, except from hyposulphite 
of silver, by means of hydrochloric acid. At a temperature 
of 500° Fahr. it fuses into a transparent yellowish fluid, 
which when cool may be cut with a knife like a piece of 
horn, and has beside some other resemblance to horn ; it 
hence received the name of horn-silver by the older phar- 
maceutists. Chloride of silver can not be volatilized like the 
protochloride of mercury. The mode of its reduction into 
pure silver by two or three different processes has already 
been given under the head of Silver. It may be reduced 


also by a mixture of carbonate of potassa, cane-sugar, or 
starch-sugar and water. 

Tests : Chloride of silver is distinguished from all other 
precipitates, having the same color, by the property which 
it possesses, when exposed on a white saucer or evaporat- 
ing-dish, of becoming changed into a violet-colored sub- 
stance. Its insolubility in nitric acid, and solubility in am- 
monia, is also an excellent test when combined with the 

Photographic Properties of Chloride of Silver. 

There is quite an analogy in the application of iodide of 
silver and chloride of silver ; the former being essentially in 
combination with a nitrate or free nitric acid, the sensitive 
.collodion film ; whilst the latter, in combination likewise 
with a nitrate or free nitric acid, forms the sensitive film 
on gelatine, albumen, arrow-root, resinized, gutta-percha, or 
plain paper. These papers have first imbibed, or have been 
invested with, certain soluble chlorides, as of ammonium, 
sodium, etc.. by floating or otherwise, and then dried. By 
double decomposition afterward these chlorides are con- 
verted, by floating the papers on a solution of nitrate of 
silver, into chloride of silver. Organic salts of silver are 
formed simultaneously, such as the albuminate, etc., which 
assist in, or detract from, the photographic operation. Of 
this I shall speak more extensively when I have to discuss 
the theory and practice of Positive-printing on paper. 

Other Uses of Chloride of Silver. — The solution used 
in galvano-plasty, or electrolysis, for plating with silver is 
made by dissolving in a saturated solution of cyanide of 
potassium the moist and undecomposed chloride of silver to 
saturation, and then diluting this solution by four or five 
times its bulk of water. 

The grayish-colored powder used for dry-plating or for 
silvering dial-plates, thermometer-scales, etc., consists of 
one part of chloride of silver, five parts of cream of tartar, 
and four of common salt, rubbed on with a piece of flannel 
or sponge dipped in solution of salt. 



As already remarked in a preceding chapter, the actinic im- 
pression of an object on the prepared collodion film is invisible 
or latent ; it is like the impression of the finger on a plate of 
copper, or of a warm piece of metal on a glass mirror; after 
the removal of the finger, or of the metal, the eye can not 
distinguish the spot where the impression was made ; but, as 
Moeser first illustrated, breathing upon the glass will make 
the impression manifest, will show that the image was there 
in a latent or invisible condition. In like manner a plate of 
polished silver may be substituted for the glass mirror, and 
excised metallic figures be placed when warm on its sur- 
face ; the impression is quite invisible, but becomes visible 
when the silver plate is exposed to the vapor of mercury. 

Furthermore, if the glass mirror, or the polished metallic 
plate be exposed in the camera before an object, and the for- 
mer be breathed upon, and the latter exposed to the vapor 
of mercury, in either case the picture becomes visible ; but 
the picture in either case is a mere breath, an evanescent 
shadow. It gives us, however, a distinct idea of what is 
meant by a developer, it is the prototype of a reducing agent. 
In chemistry is understood by a reducing agent, a substance, 
which, when applied to a combination, properly speaking of 
a metal, will decompose the compound in such a way as to 
leave the metal in the reguline condition, isolated from the 
other combining materials. Hydrogen and carbon are the 
best chemical reducing agents. Pass a current of hydrogen 
through a glass tube containing oxide of copper heated to 
redness ; in this state the hydrogen has more affinity for the 
oxygen of the oxide than the copper possesses ; the two me- 
talloids therefore pair and pass off in combination as the va- 
por of water, leaving the copper reduced to the metallic state. 
A solution of nitrate of silver, impressed by blocks upon silk, 
is reduced to a bright film of silver when exposed to hy- 
drogen eras. Heat a mixture of charcoal and oxide of lead 


in a crucible, carbonic acid results from the combination of 
charcoal and oxygen, whilst the metal lead is reduced. Elec- 
tricity, Heat and Light are all reducing agents. Fill a tum- 
bler with the solution of chloride of silver in cyanide of potas 
shun, just above mentioned. Next take two copper wires, 
to the end of one solder a quarter of a dollar, to the other 
attach on a hook any clean and well-polished article of brass 
or copper ; the other end of the latter wire is now fastened 
to the negative or zinc side of a galvanic battery, whilst the 
end of the other copper wire is fixed on the positive or pla- 
tinum side of the battery. Insert the piece of silver and the 
brass, etc., object in the tumbler, but not in contact ; the sil- 
ver in the solution will immediately begin to be reduced, and 
by the electrical current, will be carried to the negative side 
and deposited on the object to be plated. 

By heat alone several of the oxides are reduced to the me- 
tallic state, as for instance, oxide of mercury, of silver, etc. 
Some are reduced by light, as those of gold. 

Many of the salts of the metals are reduced by the supe- 
rior affinity of other metals. Immerse a piece of copper wire 
in a solution of nitrate of mercury; nitrate of copper will be 
formed and mercury precipitated on the copper. Mercury 
precipitates silver from nitrate of silver ; zinc precipitates 
lead from the acetate of this metal, and iron precipitates cop- 
per from its nitrate. 

Potassium and sodium by their very superior attraction 
for oxygen are regarded as among the best reducing agents ; 
cyanide of potassium unites the properties of carbon and po- 
tassium in the way of reduction. The protosalts of iron are 
easily changed into the persalts when brought into contact 
with oxides in which the oxygen has been loosened in its af- 
finities, or when in contact with chlorine or nitric acid ; and 
the metallic base is precipitated. Tannic acid, gallic acid, 
pyrogallic acid and formic acid are all excellent reducers. 
The last substances enumerated are those in general use as 
reducers or developers in photography ; but the substance re- 
duced or precipitated by them is not always a pure metal ; 
in some instances it appears pure and metallic, in others black 
and free from metallic lustre, as if it were mixed with organic 
material. The act of reduction in photography consists in 
reducing a silver compound; this reduction is aided by the 
presence of nitric acid or a nitrate ; without nitric acid or 
a nitrate the development in question seems impossible, and 
it is equally impossible without the previous action of light. 
Now let us see what the action of the protosulphate of iron 


is upon the oxide of silver in solution, as also of nitric acid 
upon the protosulphate of iron. In the first place dissolve a 
crystal of green vitriol in a drop or two of nitric acid : decom- 
position ensues ; the nitric acid is broken up into parts, fumes 
of the peroxide of nitrogen are liberated, and a reddish col- 
lored persulphate of iron is produced from the absorption of 
oxygen. Secondly, dissolve a small quantity of the oxide of 
silver in nitrate of ammonia, and add solution of the proto- 
sulphate of iron to the ammonio-nitrate. The mixed solution 
becomes colored and turbid, and a deposit subsides, which 
is found to be pare silver. 

By experience we know that the film on a collodion plate, 
after development with protosulphate of iron, is also pure sil- 
ver, soluble in nitric acid. Now coupling the two facts together 
that both light and nitric acid are required before the reduc- 
tion can take place, and also that there must be present the 
oxide of silver in solution, (for the reduction is ineffectual 
with the iodide of silver,) it seems as if we were indicated to 
believe that the action of light produced an oxide in all those 
parts where it struck, or loosened the oxide of the nitrate of 
silver present on the film, wherever the actinic rays made an 
impression. This loosening of the oxide of silver from its 
connection with the acid may be effectuated by the conjoint 
action of light and iodine or bromine, whereby a double de- 
composition is instituted the very reverse of that which or- 
dinarily takes place, that is, iodide of silver and nitrate of 
potassa are reconverted by light into iodide of potassium and 
nitrate of the oxide of silver in the act of formation, or prop- 
erly speaking, into nitric acid and oxide of silver, held in 
abeyance by some power (light or electricity) which pre- 
vents their union. If this were so, it seems to me, we have 
an assemblage of materials in the . right condition for pro- 
ducing the effects which in reality take place. With such 
circumstances and conditions it is easy to see how a solution 
of protosulphate of iron would reduce the oxide of silver into 
a film of pure silver, whose thickness would vary as the in; 
tensity of the actino-chemical action. There is no absurdity 
in supposing the possibility of the inversion alluded to. The 
vapor of water, by passing through an iron or porcelain tube 
heated to a white heat, is decomposed into its elements ; 
whereas if the heat of flame be applied to a mixture of these 
gases, they recombiue instantaneously and reproduce the 
vapor of water. Other analogous inversions of chemical af- 
finity are known to the chemist. 


Iron Developer. 

Iron. — Symbol, Fe. Combining Proportion, 28. Spec. Grav., 7.8. 

Protoxide of Iron.— Symbol, FeO. " " 36. 

Sesquioxide of Iron. — Symbol, Fez 3 . " " 80. 

With iron, as with some metals, we have two classes ot 
salts, the protosalts ■and the persalts, that is, the salts of the 
protoxide and the salts of the peroxide. The two classes 
are not equally permanent, sometimes the protosalts being 
the stable salts, and sometimes the other. Those salts which 
are not stable are liable to part with their oxygen, or to take 
np more oxygen, according to their condition of stability. 
Thus it happens with the iron compounds. The protoni- 
trate, for instance, is changed by boiling into a salt of the 
sesquioxide ; and the proto-sulphate is apt to undergo decom- 
position and assume a coppery appearance, by changing into 
the persalt. This property in salts and acids of communicat- 
ing to, or of abstracting oxygen from other chemical substances 
in contact with them is made available in various reactions ; 
as, for instance, in toxicological investigations, arsenic acid is 
reduced by sulphurous acid, into arsenious acid ; on this ac- 
count sulphurous acid is properly called a reducing agent. 
In photography, as already remarked, the sulphate of the 
protoxide of iron passes easily into the sesquisalt, by ab- 
stracting oxygen from somewhere, whereby a picture on the 
collodion film becomes visible. 

Nitrate of the Protoxide of Iron. 

Symbol, FeO, X 5 . 

This substance is obtained best by decomposing the sul- 
phate by means of nitrate of baryta. The solution has a green 
color, like all the protosalts ; it can not easily be crystallized, 
because a high temperature decomposes it into a sesquisalt. 

Sulphate of the Protoxide of Iron. 
Symbol, Fe 0, SO3, H + 6 Aq. Combining Proportion, 139. 

Sulphate of iron is obtained by dissolving iron to satura- 
tion in a dilute solution of sulphuric acid, decanting the su- 
pernatant liquid, evaporating and setting aside for crystalliza- 
tion. These crystals have a slightly bluish-green color. "When 
exposed to the air the crystals become colored of a brick- 
red color, by decomposition ; and if the crystals be exposed 
to a temperature of 212° Fahr., or a little upwards, they part 
with the six equivalents of the water of crystallization, and 


crumble into a grayish-white powder ; at a higher tempera- 
ture the remaining equivalent of water may be expelled. It 
is from the anhydrous salt now left that anhydrous sulphu- 
ric acid is obtained, or at least the very strong and fuming 
sulphuric acid of Nordhausen. In the preparation of this 
acid from the residual salt above mentioned, a high temper- 
ature is required, by which the affinity of the acid for the 
base is destroyed, and is expelled, leaving in the retort a 
pulverulent red mass, the colcothar of the alchemists, or ses- 
quioxide of iron. Sulphate of iron is soluble in two parts of 
cold water and three fourths of a part of boiling water ; the 
solution is neutral. This salt is not soluble in alcohol ; if al- 
cohol be added to a solution of sulphate of iron, the salt is 
precipitated in a white granular form, which is very conve- 
nient for photographic purposes ; by this process it is purified 
from any superfluous acid which it may contain. 

Double Sulphate of Iron and Ammonia. 

It has been proposed by Meynier to substitute this double 
salt for the protosulphate of iron, because of its permanency 
when exposed to the air, or its less liability to decomposi- 
tion. This double salt was described by Mitscherlich. 


Take equivalent proportions of sulphate of iron and sul- 
phate of ammonia, that is, 139 parts of the former to 75 of 
the latter, and dissolve the salts in four or five parts of water ; 
when the solution is complete, filter and evaporate, and af- 
terward set aside to crystallize. The solution for photo- 
graphic purposes can be prepared in quantity, and it keeps 
well without undergoing much change. The formula for 
development with this double salt does not differ from the 
simple protosulphate ; it contains alcohol, water, and acetic 

Sulphide of Iron. 
Symbol, Fe S. Combining Proportion, 44. 

This substance is not used directly in any photographic ope- 
ration ; but for the chemist and experimental photographer 
it has great value, because it assists in the formation of hy- 
drosulplmric acid, Avhich is by far the most valuable reagent 
in chemistry. 


Heat a bar of iron in a blacksmith's forge to a welding 
heat, and then rub it on a stick of sulphur ; combination will 


take place very vividly, and the new compound will drop oft 
like melted wax. When cool it has a dark gray color and 
metallic appearance. Pulverized and thrown into dilute 
sulphuric acid, it gives rise to hydro-sulphuric acid, which 
may he collected or used immediately hy passing it through 
a given fluid, as for instance, an old hyposulphite bath, in 
order to reduce the silver in the form of the sulphide of silver. 

Tannic Acid — Gallic Acid — Pyrogallic Acid. 

The first substance exists in the vegetable kingdom, and 
is obtained from the astringent materials in various plants, 
but especially from oak bark and nutgalls, which are ex- 
crescences on the leaves of an oak (quercus infectoria) pro- 
duced by an insect. The second does not exist naturally, 
or at least in very minute quantity, but is rather a produc- 
tion arising from tannic acid when exposed to moisture and 
the atmosphere ; and the third is obtained from the second 
by sublimation at a given temperature. The peculiar prop- 
erty of the astringent principle in various barks, is to occa- 
sion a precipitate in solutions of gelatine, and in several me- 
tallic salts. It produces in solutions of the persalts of iron a 
dark blue or dingy green color, according to the bark from 
which it is extracted. From the property of acting upon 
gelatine, by which skins are converted into leather, it is de- 
nominated tayxnin; and from its power of combining with 
metallic bases, and forming precipitates, etc., it is i - egarded 
as an acid, and termed tannic acid. 

The tannin extracted from the wood, the bark, the leaves 
and the galls of oak, the twigs of the black currant and of 
the sumac, the petals of the pomegranate, etc., and from the 
roots of several plants, produces in solutions of the. sesqui- 
salts of iron, a deep blue color, the foundation of writing-ink. 

Whereas the tannin from horse-chestnuts, the different 
varieties of tea, from catechu and kino, cinchona bark, cin- 
namon, cassia, etc., yields a green precipitate with solutions 
of the persalts of iron. 

Tannic Acid.— Symbol, C„H::0 3 .,. 
Gallic Acid.— Symbol, C 14 H, ; 10 . 
Pyrogallic Acid. — Symbol, C 6 H 3 3 . 

Preparation of Tannic Acid. 

Tannic acid is prepared by a process suggested by Pelouze. 
Take an elongated glass funnel, terminating at the upper 
orifice like a bottle, which can be closed by a cork. The 
lower orifice is loosely closed by a plug of cotton-wool, or a 


piece of sponge; the body of the funnel is then half filled 
with powdered nutgalls, over which is poured a quantity of 
commercial ether, so as to fill the remaining part of the fun- 
nel. The cork is then replaced loosely, admitting a little air 
as the filtration proceeds. The liquid that passes through 
the funnel, and accumulates beneath, forms two layers ; the 
upper one light and very fluid, and the lower heavier and 
of a yellowish tinge. Ether is added above the galls, from 
time to time, until the lower stratum of the filtrate no longer 
increases in depth. The funnel is then removed from the ves- 
sel beneath, and the lower stratum is separated by means of 
a glass syringe inserted to the bottom ; or the whole con- 
tents can be placed in a funnel, of which the lower aperture 
is closed by the finger. In this way the dense fluid is 
allowed to flow off, and when the whole has been thus re- 
moved, the aperture is again closed with the finger, and the 
light fluid is poured into a retort, and distilled at a gentle 
heat. It consists principally of ether. The dense fluid is 
then washed with concentrated ether, from which it is sep- 
arated as before, and afterward evaporated at a low tem- 
perature to dryness. The resulting substance is light and 
spongy, of an ochreous color. It is pure tannin or tannic 
acid, in quantity about thirty-five per cent of the galls em- 
ployed. It has a slightly acid reaction, is very astringent, 
not hitter. It is soluble in water and alcohol, but sparingly 
soluble in ether. With mineral acids, albumen, gelatine, 
suits of the alkaloids, mineral bases, it forms precipitates. 
Salts of the protoxide of iron are not changed by tannic 
acid ; but those of the sesquioxide give a deep bluish-black 

Tannic acid is used extensively in photography in the 
preparation of the dry plates by the Tannin Process of Ma- 
jor Russell. This process is fully described in a subsequent 

Preparation of Gallic Acid. 

As before observed, gallic acid exists in minute quantity 
in nutgalls; but it is rather a product of the decomposition 
'of tannin, than a naturally existing Bubstance. 3Iix pow- 
dered nutgalls into a thin paste, and expose it to the air for 
two or three months, taking care to replace the water as it 
evaporates. The mass becomes mouldy, and darker in color 
by this exposure; it is then pressed in a cloth; afterward, 
the residue is boiled in water and filtered whilst hot. On 
cooling, crystals of gallic acid are deposited, which are puri- 


fied by boiling in eight parts of water and one fifth of their 
weight of animal charcoal. After filtration and cooling, pure 
crystals of gallic acid are deposited, in the form of long 
silky needles. During exposure to the atmosphere, moist 
tannic acid absorbs oxygen, and liberates carbonic acid, so 
that gallic acid is altogether a definite and distinct com- 
pound. When quite purified, it has no effect upon a solu- 
tion of gelatine ; it has an acid and astringent taste. The 
solution is soon decomposed. Gallic acid is soluble in one 
hundred parts of cold water, and in three of boiling water. 
It has no effect upon the solution of salts of the protox- 
ide of iron, but upon those of the sesquioxide, it produces 
a deep bluish-black precipitate, which disappears when the 
liquid is heated, the sesquioxide being converted into the 
protoxide by the decomposition of the gallic acid. Gallic 
acid meets with an extensive application in photography, in 
various processes^ as in the Tannin Process of Major Russell, 
the Dry Process of Taupenot, etc., and in the process of Posi- 
tive Printing by Development. 

Preparation of Pyrogallic Acid. 

The etymology of the word indicates the origin of this 
substance. When gallic acid is heated to the temperature 
of 410° Fahrenheit, and kept at this temperature, in an oil- 
bath, a volatile substance sublimes of a beautiful white color, 
in crystalline plates. This is pyrogallic. acid, which is sol- 
uble in water, alcohol, and ether. The solution of pyrogallic 
acid soon turns brown when exposed to the air, by becom- 
ing oxidized. It communicates a blackish-blue color to the 
solutions of the salts of the protoxide of iron, and reduces 
those of the sesquioxide to the state of the protoxide. When 
mixed with an alkaline solution, it absorbs a large quantity 
of oxygen from the atmosphere, and has been used in the 
analysis of air for this special purpose. When gallic acid is 
raised to a higher temperature than 410° Fahrenheit, that is, 
to 480° Fahrenheit, it is decomposed into carbonic acid, 
water, and a new substance denominated mctagallic acid, 
being the black shining residue left in the retort. Pyrogal- 
lic acid, at the proper temperature, is in Hke manner decom- 
posed into metagallic acid and Avater. 

Owing to the property possessed by pyrogallic acid of ab- 
sorbing oxygen from bodies with which it is in contact, it is 
as yet the second best developer of the latent image in the 
collodion process ; and taking into consideration the nature 
of the image produced, where the time of exposure is not 


important, it certainly is the most easy and reliable devel- 
oper. There is no doubt that a solution of protosulphate of 
iron acts more quickly ; or, what is meant, requires a much 
shorter time of exposure. From the experiments in ordi- 
nary landscape photography, I have frequently observed a 
difference of three to one in the time in favor of the sul- 
phate of the protoxide of iron. 

Acids in Developing Solutioyis. 

The solution of protosulphate of iron, or of pyrogallic 
acid, is frequently much more energetic in redaction than is 
manageable, and proceeds, after the image has been thor- 
oughly developed, to act upon those parts on which the 
actinic influence has been but very feeble or almost imper- 
ceptible. The difficulty in such a case is two-fold. It con- 
sists in flowing the plate uniformly and instantaneously ; 
otherwise lines of demarkation will be quite visible at those 
edges where the fluid was momentarily retarded ; and sec- 
ondly, in stopping the progress of development uniformly 
and instantaneously. Many excellent negatives have been 
ruined by the misfortunes arising from the difficulties alluded 
to ; and yet Instantaneous Photography has to search in this 
direction for the surest means of success, rather than upon 
any fortuitous advantages in the collodion. The operation of 
light is, practically speaking, instantaneous, because its ve- 
locity is greater than conception. A certain time always 
elapses between the opening and closing of the shutter, be- 
fore the lenses, in the operation of instantaneity; and in this 
time light has traveled thousands of miles, or rushed with its 
thousands of miles' momentum on the sensitized plate. The 
picture, therefore, is already there; because the impression 
has been made. It remains, consequently, to find a reduc- 
ing agent so refined and energetic as to effectuate the proj>er 
reduction. With the ordinary quantity of acids in our de- 
velopers, we can scarcely hope for success ; but with their 
diminution, and a proportionate increase of velocity in the 
manipulation of flowing the plates, and of stopping the fur- 
ther advance of reduction, instantaneous photography has, in 
my opinion, to seek a clue for its reliable performance. As 
a general rule in practice, the photographer requires less acid 
in the developer according as the time of exjDOSure is less ; 
consequently, the positive on glass, or prepared iron plate, 
called the ambrotype and the melainotype, requires a much 
less acid developer than the negative, where the time of ex- 
posure is much longer. In like manner, two photographers 


maybe in the habit of operating, the one with short expo- 
sures, and the other with long exposures; but it will be 
found that the developer of the former is much less acid 
than that of the latter. ISTow it may be asked : What is the 
reason that the same developer can not be used for the two 
kinds of pictures ? Because, in the case of ambrotypes, if 
the developer be acid as is the case for negatives, the reduc- 
tion will be very slow, and most likely ineffectual; whilst in 
the case of a negative, the non-acidified developer would be 
too rapid and too unmanageable. 

The temperature is a very influential item in modifying 
the operation of development. The higher the temperature 
the greater the quantity of acid required to preserve the ex- 
act equilibrium between fogging on the one hand and defi- 
ciency of development on the other. 

The principal acids used for this special purpose are acetic 
acid, tartaric acid, citric acid, and formic acid. The latter 
may be regarded at the same time a developer from its 
power of reducing metallic salts, and from its analogy to 
acetic acid as a check upon development. 

Acetic Acid. 
Symbol, C 4 H 3 3 HO. Combining Proportion, GO. Specific Gravity, 1.0G3. 
Acetic acid belongs to a small group of which acetyle is 
the base or compound radical derivative from ethyle by the 
oxidation of two equivalents of its hydrogen in the formation 
of water. When alcohol and ether burn in the air the pro- 
ducts of combustion are carbonic acid and water. But some- 
times the oxidation of the hydrogen alone takes place, and 
water only is formed, together with a small series of new 
bodies containing the same number of equivalents of carbon. 
Some of the substances arise from the decomposition of col- 
lodion, such as aldehyde, etc. This acid may be formed 
directly from the oxidation of alcohol or by substituting two 
equivalents of oxygen in the place of two of hydrogen. 
Platinum-black acting upon the vapor of alcohol will pro- 
duce this reaction ; or a small quantity of yeast, or almost 
any other nitrogenized organic material undergoing putre- 
factive decomposition, added to dilute alcohol and exposed 
to the air induces the same reaction. In this manner vinegar 
and alecar arise from the slow acetic fermentation, as it is 
denominated, of weak wines and beer. When hard dry 
wood or twigs, or oak, beech, etc., are submitted to destruct- 
ive distillation at a red heat, acetic acid is one of the pro- 
ducts of the distillate. The first part of the sour liquor 


which distills over by a second operation is not acetic acid ; 
the second, however, contains the acid, but is impure. It is 
now saturated with hydrate of lime or carbonate oflime, by 
which process acetate of lime is formed. Sulphate of soda 
is then added in solution to the acetate of lime as long - as 
any precipitate of sulphate of lime falls. The resulting ace- 
tate of soda is filtered from the lime salt, and evaporated to 
its crystallizing point and then set aside until crystals are 
formed. The latter are drained as much as possible from 
the water and adhering tarry licpior, and then heated cau- 
tiously to fusion, by which the tar is decomposed and ex- 
pelled. The fused mass is again dissolved and crystallized. 
By decomposing this salt by means of an equivalent of sul- 
phuric acid and by distillation we obtain strong acetic acid, 
which, by rectification over red oxide of lead, can be con- 
centrated so as to yield crystals at a low temperature. This 
is denominated glacial acetic acid, and melts into a colorless 
liquid above 60° Fahr. It boils at a temperature of 240° ; 
its vapor is inflammable. It mixes in all proportions with 
Avater, alcohol, and ether. The acetates are very numerous; 
all of them are soluble ; those of silver and mercury the 
least so. 

Its photographic uses are, as above described, to check 
the vehemence of reduction by the developers ; it is used 
also to acidify the nitrate of silver bath in connection some- 
times with acetate of soda, and with this connection it is 
said to yield much sensitiveness and intensity with a plain 
iodized collodion. 

Formic Acid. 
Symbol, G z H0 3 HO. Combining Proportion, 46. Specific Gravity, 1.235. 

This acid is so -called because it is found in ants, from the 
Latin of which the word is derived. It bears the same re- 
lation in the methyle group as acetic acid does in the ethyle 
series ; acetic acid being formed by the substitution of two 
equivalents of oxygen for two of hydrogen in the formula 
for alcohol, whilst formic acid arises from the substitution 
of two equivalents of oxygen for two of hydrogen in the 
formula for vjood-spirit, a substance very analogous to alco- 
hol. This acid can be obtained by distilling ants in water. 
It is an organic acid, however, Avhich can be formed artifi- 
cially by heating organic substances, such as sugar, starch, 
etc., with oxidizing agents. Thus : mix one part of starch 
or sugar or tartaric acid with four of the binoxide of man- 
ganese, four of water, and four of sulphuric acid. By this 


mixture carbonic acid will be liberated with effervescence. 
As soon as this is over the materials are subjected to distill- 
ation until four parts and a half have passed over. The acid 
liquor thus obtained is impure formic acid, -which is purified 
by neutralizing it with carbonate of soda, and evaporating 
the solution so as to obtain formiate of soda in crystals 
which may be freed from all impurities in the same manner 
as acetate of soda in the preceding paragraphs. From the 
pure formiate of soda, any other formiate, or formic acid, 
may be obtained by neutralizing the formiate with sulphuric 
acid and by distillation. Hydrated formic acid is a limpid, 
colorless fluid, of an intensely pungent odor ; it fumes slight- 
ly ; at a temperature below 32° Fahr. it crystallizes in bril- 
liant plates; it boils at 212°. It produces a blister on the 
skin when concentrated. In very many respects it is very 
similar to acetic acid, but may be distinguished from the 
latter by its comportment with oxide of silver or mercury, 
in which, when heated, it reduces the metal after a while 
and liberates carbonic acid. This acid is obtained, and per- 
haps most easily, by the decomposition of oxalic acid in con- 
tact with glycerine and by distillation. 

Photographic Uses of Formic Acid. 

From the similarity between acetic and formic acid it may 
easily be inferred that either might be substituted for the 
other in the developer, but the reader will have remarked a 
decided difference in their action on silver salts ; and it is 
just on these salts that the acid is brought into action ; it is 
in fact an excellent reducing agent, and when heated is used 
by several distinguished photographers in their developing 
solutions, of which the formula will be given in the proper 

Citric Acid. 
Symbol, G i2 Hs O u + 3 HO + 2 Aq. 

This acid is obtained from the juice of limes, lemons, 
orange, currant, quince, cranberry, red whortleberry, and 
other fruits. The juice is imported in the liquid state from 
the West-Indies, and being in connection with much mucil- 
age and other organic impurities, it is liable to undergo de- 
composition on the way, and to yield in the preparation of 
citric acid other acids endowed* with different properties 
On this account it is advisable in many instances for the 
photographer to prepare his own citric acid. 

Take ten ounces of expressed lemon-juice ; boil the juice 
for a few minutes, then add to it after it is cool the whites 
of three eggs, and stir the mixture so that the albumen is 
intimately broken up and mixed with the juice. Boil the 
mixture again, stirring it all the while, and allow the coagu- 
lum to settle. When cool, filter the sour liquor and boil it 
again, adding to it gradually powdered chalk as long as 
effervescence is produced ; citrate of lime is formed, which is 
but sparingly soluble in water. The dark-colored mucilagi- 
nous liquor is filtered off; the residue is well washed, and 
afterward decomposed by a quantity of sulphuric acid equal 
in weight to the chalk employed in the previous decomposi- 
tion. The sulphuric acid is diluted with about seven times 
its weight of water ; and the mixture is stirred about for 
some time until the citrate of lime is completely decom- 
posed. By filtration the citric acid is separated from the 
insoluble sulphate of lime, and is afterward evaporated 
until a pellicle forms on its surface ; it is then set aside to 
crystallize. The dark-colored crystals are removed from 
the supernatant liquid by a strainer and again dissolved in 
pure Avater ; the liquid is again evaporated as before, until 
the formation of a pellicle takes place, and is again set aside 
to crystallize. By repeating the operation several times the 
crystals become quite clean and purified. Citric acid has an 
agreeably sour taste ; like phosphoric acid it is trib'asic, and 
gives rise to three classes of citrates. It is soluble in less 
than its own weight of cold water, and in half its weight of 
boiling water ; it is not very soluble in alcohol. 

Citrate of Soda. 

This salt is prepared by dissolving citric acid in pure 
water and throwing into the solution, by degrees, pulver- 
ized carbonate of soda as long as effervescence is produced. 
The liquid is afterward evaporated to a crystallizing consist- 
ency and then set aside. In this case, as well as in the pre- 
ceding, the mother-liquor can be made to yield new crops 
of crystals by further evaporation or by a repeated decom- 
position and a repetition of the other proceedings arising 
out of it. 

Photographic Uses of Citric Acid. 

This acid is frequently mixed with pyrogallic acid in pro- 
per quantity for solution in water instead of acetic acid. It 
is used as a check on the too rapid action of pyrogallic acid, 
and as a reducing agent. A frequent inrpurity in this sub- 


stance is malic acid, and sometimes aconitic acid. Citric 
acid is recognized by its pixxlucing in a diluted state no im- 
mediate precipitate with Chloride of Calcium ; but an im- 
mediate precipitate is formed when the solution is boiled. 

Tartaric Acid. 
Symbol, C 8 H 4 Oi + 2 Aq. 

This acid exists in combination with potassa in most kinds 
of fruit, and sometimes in a free state. Its combinations in 
fruit are cream of tartar and tartrate of lime. The former 
exists in abundance in grape-juice, and is denominated, in 
the crude state, Argol or Tartar, which is either red or 
white according to the Avine from which it is deposited dur- 
ing fermentation. 

Prex>aration of Tartaric Acid. 

This acid is obtained from argol, or from cream of tartar, 
which is a bitartrate of potassa, by two processes ; one con- 
sists in abstracting one equivalent of tartaric acid from the 
bitartrate, and the other in decomposing the residual tar- 
trate in the solution. Following the formula of the London 
College, and using the imperial gallon, which contains ten 
pounds of water, the method stands thus: take of bitartrate 
of potassa four pounds ; boiling distilled water, two gallons 
and a half; prepared chalk, twenty-five ounces and six 
drachms ; diluted sulphuric acid, seven pints and seventeen 
fluid ounces; hydrochloric acid, twenty-six fluid ounces and 
a half, or as much as may be sufficient. Boil the bitartrate 
of potassa with two gallons of the distilled water, and add, 
by degrees, the half of the chalk ; when the effervescence is 
over, add the remainder of the chalk, previously dissolved in 
the hydrochloric acid, diluted with four pints of the distilled 
water. Then set aside until the tartrate subsides ; after 
which pour off the liquor, and wash the tartrate of lime fre- 
quently with distilled water as long as it has any taste. 
Next pour on the diluted sulphuric acid, and boil for a 
quarter of an hour. Having filtered the liquor from the in- 
soluble sulphate of lime, evaporate it by a gentle heat until 
a pellicle is formed on its surface ; then set it aside to crys- 
tallize. By dissolving the crystals in pure water, filtering, 
and recrystallizing, and by repeating these three operations 
several times, pure tartaric acid may be obtained. 

Tartaric acid is not volatile; when heated it leaves an 
abundant coaly residue. It is soluble in half its weight of 
water ; it dissolves also in alcohol. The salt itself under- 


goes no change when exposed to the atmosphere ; but its 
solution, when long exposed, absorbs oxygen and forms 
acetic and carbonic acid. When boiled over an excess of 
oxide of silver, the same decomposition is produced, and 
metallic silver is liberated. When fused with potassa it is 
decomposed into acetic and oxalic acid ; whilst with bin- 
oxide of manganese and sulphuric acid, it gives rise to car- 
bonic and formic acid. Concentrated sulphuric acid, when 
heated with the crystals of tartaric acid, decomposes it and 
separates carbon, which renders the mixture black ; and car- 
bonic oxide is evolved at the same time, which burns with a 
blue flame. 



NoTHrxG can be easier to prepare than the bath of nitrate 
of silver, and yet there is no preparation in the art of pho- 
tography which produces so many difficulties and troubles to 
surmount as the sensitizing bath for the iodized or bromo- 
iodized collodion plates. In consequence of this it becomes 
a difficult task to prescribe rides by which such a bath can 
be preserved sensitive under the troubles with which it is so 
frequently beset. The origin of these troubles may be traced 
to the materials introduced by the immersion of the collo- 
dion plates ; but these deteriorating materials are of such a 
heterogeneous nature, arising from the decomposition of the 
pyroxyline, of alcohol, of ether, of the iodides, the bromides, 
their bases, and of the elements combining with them, that 
it is as yet an unsolved problem, that of determining precise- 
ly the cause of any given abnormal action in the nitrate bath. 
It is true, as regards the introduction of injurious substances 
into the bath, all effects resulting therefrom can be avoided 
by using the solution of nitrate of silver only once. If this 
salt were not so expensive, this mode of avoiding trouble 
would be by far the wisest and the safest. In such a case 
the photographer would flow his plate with the silver solu- 
tion in the same manner as Avith the developing or fixing so- 
lution, using just sufficient to cover the film and to sensitize 
it. All the residual part might be collected, decomposed, 
and fresh nitrate prepared. But because the silver salt is a 
dear material, we aim to economize by using the solution 
over and over again. For this purpose, glass, porcelain or 
photographic-ware baths are constructed, for containing the 
fluid. They are made so as to accommodate the largest 
plate with the least quantity of the solution, a great mistake 
superinduced by false economy. In this country vertical 
baths seem to be the only ones employed ; whereas in France 
and Germany, for economical and other special reasons al- 
ready alluded to, horizontal dishes contain the solution, and 


the plates lie, as it were, collodion side downward in a thin 
layer of the same. Some of these baths are especially adapted 
for the tourist, admitting the fluid to be closed hermetically 
by means of India-rubber caps, screws and clamps. Nitrate 
of silver will permeate through the parietes of porcelain baths; 
the photographic-ware bath and the glass are not subject to 
this inconvenience. 

Preparation of the Sensitizing Solution. 
An ounce Avoirdupois contains 437.5 grains ; the druggists 
and photographic dealers retail all their chemicals accord- 
ing to this weight, and not, as many suppose, according to 
the Troy weight, of which the ounce contains 480 grains. 
The sensitizing solution is found by experience to be suffi- 
ciently strong if it contain from 35 to 40 grains to the fluid 
oun#e of water, or from 8 to 10 per cent. 

Formula No. 1. 

Nitrate of silver, (recrystallized,) . . 3 ounces. 

Distilled or pure rain-water, 3G ounces. 

Washed iodide of sdver, 6 grains. 

Washed oxide of silver, 6 grains. 

Dissolve the nitrate of silver in half the water, then add to it 
the washed iodide of silver, prepared as directed on a preced- 
ing page, afterward add to the mixture the six grains 0|" ox- 
ide of silver, which is prepared as follows : Take a solution of 
ten grains of nitrate of silver and drop into it a solution of 
pure caustic potash, as long as a brown precipitate is formed. 
Then filter and wash the brown oxide on the filter many 
times with cold water, and afterward with warm water, until 
the filtrate ceases to have any action on red litmus paper. 

The mixture is now boiled in a large glass flask on a sand- 
bath, and when cold the remaining water is added to it, and 
the whole of it is filtered through a double filter of Swedish 
filtering paper. The solution so prepared will be saturated 
with iodide of silver, so that it will not dissolve any of the 
iodide of silver on the collodion film ; it will be besides per- 
fectly neutral, if the oxide of silver has been thoroughly 
washed from any adhering alkali. "With a collodion con- 
taining free iodine, either from decomposition or by insertion, 
this bath is exceedingly sensitive, and produces at the same 
time clear pictures. For colorless collodions it is not suit- 
able, nor for collodions which are quite freshly made, with- 
out the addition of iodine, that is, for those which have not 
had time to ripen, as it is termed in ordinary language. 

For such collodions, the colorless and pale colored collo- 


dions, containing-, as they generally do, cadmium salts, the 
following hath will he found to he quite effective in produc- 
ing good results : 

Formula JVo. 2. 

Nitrate of silver, (recrystallized,) . . 3 ounces. 

Distilled or rain-water, 30 ounces. 

Iodide of silver, (washed,) .... 6 grains. 

Mix as hefore, and filter without hoiling. For each ounce of 
nitrate of silver add one drop of nitric acid. This amount will 
prohably he found sufficient to produce a clear picture ; should 
the picture show any signs of fogging, add another drop, and 
so proceed until the details of the development appear with- 
out a universal cloudiness over the plate. 

Formula JVo. 3. * 

Nitrate of silver, (recrystallized,) . . 3 ounces. 
Distilled, or pure rain-water, .... 36 ounces. 
Iodide of silver, (washed,) 6 grains. 

Prepare as hefore, and after filtration divide the quantity into 
two lots of 18 ounces each. Neutralize one of these with 
washed oxide of silver by boiling, and then filter. Add to 
the other 18 drops of a solution of acetate of soda, (contain- 
ing 1&0 grains to the ounce of water,) and 10 drops of gla- 
cial acetic acid. Each of these baths may be used separate- 
ly, or in mixture. The neutral bath is kept neutral without 
admixture ; but to the second, containing the acetate of soda 
and accetic acid, a portion of the first may be added as re- 
quired from time to time, if it is found to work too slowly. 
As a general thing the acetate of soda bath produces very 
vigorous pictures, and renders the collodion film quite sensi- 

In summer the bath need not be so strong in nitrate of sil- 
ver as given in the preceding formulas. Six or seven grains 
of silver per cent of the water will be sufficient when the 
temperature is high ; on the contrary, from eight to ten per 
cent may be used when the temperature is moderate or low. 
The sensitizing solution works quicker when warm than when 

T\ nen the sensitizing solution becomes weak by exhaus- 
tion, it can be restored to a good working condition by the 
addition of a stronger solution of nitrate of silver, containing 
40 or 50 grains to the ounce of water. After a bath has been 
in operation for some time, it becomes saturated with a va- 
riety of impurities, such as ether, alcohol, acetic acid, aldehyde, 
the various nitrates in the collodion, and a variety of sub- 


stances arising from the decomposition of this heterogeneous 
mixture. The best way to get rid of all volatile material is 
to subject the solution to distillation, until all the ether and 
alcohol, at least, have been expelled, and then to filter the res- 
idue in the retort, and to mix it with a new bath. Although 
such a restored bath will give good results for a while, it soon 
gets out of order, and can no longer be relied upon. In such 
a case it is far more expedient to set it aside for reduction, 
and to form a totally new bath, than to be at the trouble of 
a second distillation, because the fixed salts have Accumulat- 
ed to such a degree as to render the bath very capricious and 

When a bath does not yield clear pictures when first formed, 
or ceases to do so after a given time with the same collodion, 
or happens not to do so with a new collodion, it is advisable 
not to trifle with the bath by adding either acid or alkali. 
It may be well to ascertain by test-paper whether the trouble 
is attributable to alkalinity or acidity. If no alkali has been 
added to the bath, it will probably have an acid reaction. 
In this case it is preferable to boil the bath with the washed 
oxide of silver, as before prescribed, and then to filter it. 
Should the bath turn out to be neutral to test-paper, it will 
be found in general a better practice to add a few drops of 
tincture of iodine to the collodion, rather than to acidify the 
sensitizing solution ; because the iodine in the collodion lib- 
erates an acid by decomposition on and in the film of collo- 
dion, which rectifies the evil where the rectification is wanted, 
and at the proper time, without changing materially the con- 
ditions of the bath. Thus the operator will learn to use up 
a highly colored collodion by mixing it gradually, as it is 
wanted, with new and almost colorless collodions, in order 
to clarify his pictures, without resorting to methods of at- 
taining to the same result by adding acid to the bath. 

During the time the bath is in use, a quantity of insoluble 
material of a gray or violet-gray color is precipitated on 
the bottom and sides of the bath, and frequently floats 
about in the sensitizing fluid. The particles of this material, 
as well as of the acicular crystals of acetate of silver in a weak 
bath are apt to attach themselves to the moist collodion film 
on its immersion, and thus give rise to the innumerable small 
apertures sometimes exhibited on the developed negative. 
These particles are not the sole cause of this evil, so much 
dreaded ; but they frequently cause it by their attachment to 
the film during the exposure, and owing to their opacity, pre- 
vent the actinic action from taking effect on the film be- 


neath, and becoming loosened by the developing and fixing 
solutions, afterward expose the transparent parts on which 
they had rested. It is advisable, therefore, to expose the 
bath in a crlass vessel to the rays of the sun as often as possi- 
ble, in order that the organic matter may be precipitated. 
The bath, too, ought to be filtered very frequently in the 
same filter, at least once a week; and if every evening, so 
much the better. After filtration the bath can be strength- 
ened by an addition of fresh solution, in proportion to the daily 
work performed. See. during filtration, that the sidles and 
the bottom of the vessel are perfectly clean before the solu- 
tion is poured back again. Along thin wooden spatula, with 
a piece of sponge at the end, will be found very convenient 
for clearing away the adhering gray deposit. Use only rain- 
water for rinsing ; rinse thoroughly; then turn the bath wrong 
side up, and rear it on one corner, in order that every drop 
of water may thus be removed. "Wipe the edges before the 
sensitizing fluidis again introduced. This exposure to the 
rays of the sim, and frequent filtration will remedy in a great 
measure the trouble alluded to, and there is no fear of in- 
juring the property of the solution, for nitrate of silver alone 
is not acted upon by light, does not change at all when pure. 

By exposing the solution in a vessel, such as a 2,'lass eva- 
porating dish, much of the superfluous ether and alcohol will 
pass oft' in vapor, and thus produce a remedy for another evil 
which an old bath invariably cdves rise to, namely, that of 
causing oilvdookiug stains and streaks on the surface of the 

Where the trouble of reerystallizing the nitrate of silver 
would be deemed too great, and neutral nitrate of silver 
can not easily be purchased, I would recommend that the 
photographer should fuse the nitrate of silver in a porcelain 
evaporating dish, at a gentle heat, and afterward pour out the 
fusel ma^s on a silver or marble plate, as directed in the 
manufacture ot' lunar caustic. The same proportions of the 
fused nitrate are used as in the formulas for the recrystallized 
nitrate. Or a strong solution of the nitrate may be boiled with 
the washed oxide of silver, filtered, and evaporated to dry- 
ness, and used in the same way. 




In the ordinary, or -wet-collodion process, there are three 
Developing Solutions, the Protosulphate of Iron Develo])er, 
the Pyrogallic Acid Developer, and the New Developer, 
with the double salt of the sulphate of the protoxide of iron, 
and the sulphate of ammonia. 

Sulphate of Iron Developer. 

Formula No. 1. For Ambrotypes and Melainotypes. 

Crystals of the protosulphate of iron, . 3 drachms. 

Rain-water, .4 ounces. 

Acetic acid, 3 drachms. 

Alcohol, 2 drachms. 

Pulverize the iron salt, if it has not been precipitated in al- 
cohol, and mix it intimately with the rain-water in the mor- 
tar ; then add the acid and the alcohol, and see that the so- 
lution is complete ; then filter and use. From a previous ob- 
servation on the subject of developing, it will be conceived 
that the quantity of acid must vary according to several cir- 
cumstances. In summer, that is, when the temperature is 
high, more acid will be required to keep the reducing agent 
in check ; in like manner, if the time of exposure has been 
too long, the development or decomposition is more easily 
accomplished, and on this account more acid is required. On 
the contrary, in winter, when the temperature is low, as also 
when the time has been very short, as for example, for in- 
stantaneous operations, the proportion of acid maybe dimin- 
ished, until finally the solution of the iron salt may be used 
without any acid. In such cases it is well to have a bath of 
the solution, into which the exposed plate can be immersed 
almost instantaneously, and treated with the ordinary acid 
solution afterward. Considerable dexterity is required in 
this twofold operation. Of course diminishing the iron salt, 
or increasing the acid are' correlative expressions, and signify 
almost the same thing, the slight difference depending upon 


the influence of the water which remains stationary, or rela- 
tively increases sometimes in favor of the iron, and some- 
times of the acid. 

Formula No. 2. For Negatives. 
Crystals of the sulphate of the protoxide of iron, . 2 drachms. 

Distilled, or rain-water, 32 drachms. 

Acetic acid, 3 drachms. 

Alcohol, 3 drachms. 

Pulverize and mi^ as before. A negative requires a longer 
exposure than the ambrotype, or the melainotype ; the iron, 
therefore, is diminished whilst the other ingredients remain 
the same. In the first formula a drop or two of pure nitric 
acid may be added, because it produces a more reguline 
reduction of the silver salt, and leaves a very beautifully 
white metallic-looking film where the light has acted. Too 
much nitric acid would spoil the picture by producing too 
intense a reduction, accompanied with irregularity of depo- 

Formula No. 3. For Negatives. 

Pyrogallic acid, (pure,) . . . 24 grains. > x 1 Solution _ 

Acetic acid, 2 ounces. J 

Shake the solution well, and keep in a dark place. 

Of Xo. 1 Solution, .... 2 drachms. ) -.r „ <? i ,.• 
Distilled water, .' 14 drachms. \ ><°- 2 Solution. 

The reduction by this developer is quite appropriate for ne- 
gatives ; its color is grayish, but not metallic in appearance. 
This developer is very manageable, and very successful. It 
requires, however, a longer exposure than the iron develop- 
er, in the. ratio of three to one, from my own experience in 
out-door photography. It is not so apt to fog a picture as 
the iron developer. 

Formula No. 4. For Negatives. 

Pyrogallic acid, . . 24 grains, j Diyide intQ doges of 2 .,_ 
Citric acid, .... 24 grains. ) b 

Tvlien required, dissolve a two-grain dose of the preceding 
in four drachms of distilled water. The amount of citric 
acid can be modified according to the same circumstances 
which regulate the treatment with acetic acid. 

Dlsdcris Developer. 

Sulphate of the protoxide of iron, ... 4 drachms. 

Water, 12 ounces. 

Acetic acid, 4 drachms. 


Lieut.- Colonel Stuart Worthy's Developer. 

Sulphate of iron, 20 ounces. 

Distilled water, 120 ounces. 


Acetate of lead, £ ounce. , 

Water, 5 ounces. 

Mix the above solutions, and as soon as the precipitate has 
settled, decant off very carefully. Add * 

Formic acid, 5 ounces. 

Acetic ether, 1^ ounces. 

Nitric ether, l\ " 

This mixture is the stock solution, from which a portion is 
taken, when required, and filtered for use. 

Meynier's Developer. 
Double sulphate of the oxide of iron and ammonia, . 100 grains. 

Water, 23 ounces 

Acid acetic, . . 4 to 8 drachms. 

Alcohol, 4 " 

Or the preceding formula may stand as follows : 

Sulphate of the protoxide of iron, 69 grains. 

Sulphate of ammonia, 37 " 

Water, 24 ounces. 

Acetic acid, 4 to 8 drachms. 

Alcohol, 4 drachms. 

Hockirfs Developer. 

Formic acid, (strong,) 2 drachms. 

Pyrogallic acid, 20 grains. 

Distilled water, 9£ ounces. 

Alcohol, £ ounce. 

This developer is poured upon the plate, and kept there un- 
til the intensity is deep enough. It acts more quickly than 
the pyrogallic acid containing-acetic acid, but less so than 
the iron developer ; but it is less liable to fog than the iron 
developer, and can consequently be retained longer on the 

Waldack's Formulas for Collodion Positives. 

Formula 2fo. 1. For Dead -Whites. 

Sulphate of iron, 3 drachm3. 

Water, 6£ ounces. 

Acetic acid, 4 drachms. 

Alcohol, 3 drachms. 

Nitrate of potassa, ... 30 grains. 



Formula No. 2. For Brilliant and Metallic Whites. 

Sulphate of iron, 85 grains. 

Water, 6J ounces. 

Acetic acid, 1 drachm. 

Alcohol, \\ drachms. 

Nitrate of potassa, SO grains. 

Solution of nitrate of silver, 30 grains. 

Nitric acid, 10 drops. 

In all the preceding formulas, alcohol may or may not be 
added, according to circumstances. It is used when the de- 
veloper does not flow easily over the plate, forming, as it 
were, oily streaks on the surface. It remains, therefore, with 
the artist to use or reject it, as it may be found necessary. 

tap > 



Fixing solutions consist of chemical substances that dis- 
solve the sensitized salts of silver on plates or paper, on which 
] thotograpMc images have been developed. The parts which 
form the image are covered with reduced silver, or an altered 
iodide or chloride of silver, which is insoluble in the fixers ; 
whereas those parts which have not been impressed by the 
actinic rays are made transparent with the fixing solutions, 
which dissolve the opaline silver compounds, and cause the 
picture afterward to be unchangeable when exposed to light. 
The fixing solutions at present in use are : Cyanide of po- 
tassium, Hyposulphite of soda, and Sulphocyanide of ammo- 


Symbol, C^N, or Cy. Combining Proportion, 26. Spec. grav. 1.819. 

This substance is properly a Bicarbide of Nitrogen ; it is a 
very important material, as being the type of what are de- 
nominated compound salt-radicals ; it was the first of this 
class of bodies discovered. Cyanogen is always produced in 
combination when an alkaline carbonate is heated with or- 
ganic matter containing nitrogen. It does not exist either 
in a free or combined state in nature ; it is a production of 
decomposition, in which the elements contained in it are 
brought together in the nascent state, in connection with 
some metallic base. 

Preparation of Cyanogen. 
This compound radical is obtained by heating either a cya- 
nide of silver or of mercury in a flask of hard glass ; a gas, 
the substance in question, is produced, which may be col- 
lected, by reason of its greater specific gravity than air, in 
a tall glass jar, by directing the outlet tube to the bottom ; 
or it may be collected over mercury. It is colorless, but its 
odor is quite peculiar and characteristic. It burns with a 
peach-colored flame, yielding carbonic acid and nitrogen. 
Water dissolves four volumes of this gas, and alcohol as 
much as twenty-five volumes. An aqueous solution is de- 


composed when exposed to light into a variety of ammonia- 
cal compounds. By the pressure of four atmospheres it is 
reduced to the liquid state. It combines "with alkaline solu- 
tions precisely in the same way as chlorine, iodine and bro- 
mine, and gives rise to salts denominated cyanides. 

Hydrocyanic Acid — Prussic Acid. 
Symbol, H Cy. 
This acid is obtained from the cyanides or the ferrocyan- 
ides by the superior affinity of the mineral acids for their 
bases in a manner similar to that by which the other hy- 
dracids are obtained. Take, for instance, three parts of the 
yellow prussiate of potash (ferrocyanide of potassium) in 
fine powder, two parts of sulphuric acid, and two of water, 
and distill the mixture in a flask or retort ; the vapor which 
passes over is condensed in a receiver surrounded by ice. 
Prussic acid is a colorless liquid of the specific gravity of 
0.6969. It is exceedingly poisonous. 

Cyanide of Potassium. 
Symbol, K Cy. 
This substance, so exceedingly useful to the photographer, 
might be formed by passing the vapor of hydrocyanic acid 
through a solution of potassa to saturation, and then evapo- 
rating to dryness without access of air. It is formed, how- 
ever, by heating ferrocyanide of potassium in an iron bottle 
to an intense red heat; the tube of the bottle dips into water 
to conduct away the gases. The cyanide of iron becomes 
decomposed into carbide of iron and charcoal, and its nitro- 
gen is given off, whilst the cyanide of potassium remains un- 
decomposed, and when melted swims on the surface of the 
porous black mass below. It is afterward pulverized and 
dissolved in boiling weak alcohol, from which it crystallizes 
as the alcohol cools ; or whilst in a fused condition it is 
poured upon marble slabs and afterward broken up and 
bottled. This substance is almost as poisonous as hydro- 
cyanic acid, but being a fixed salt it is easily detected in 
the stomach ; whereas hydrocyanic acid, by reason of its 
volatility, seldom leaves any trace behind by which the 
cause of death can be recognized. This salt is decomposed 
by the red oxide of mercury into cyanide of mercury and 
potassa, showing the superior affinity of cyanogen for mer- 
cury. On this account the ordinary tests for mercury do 
not act on cyanide of mercury, with the exception of hydro- 
sulphuric acid ; analogous to hyposulphite of silver in which 
hydrochloric acid or a soluble chloride docs not precipitate 


the chloride of silver, hydrosulphuric acid alone being capa- 
ble of forming a precipitate. 

Sulphocyanide of Potassium. 
Symbol, Cy S* K. 
This salt is obtained by a process similar to the last with 
an addition of sulphur to the amount of half the weight of 
the ferrocyanide of potassium used. It is an excellent test 
of the persalts of ii*on, with which it produces blood-red pre- 
cipitates. I do not see why this salt may not be used in- 
stead of the following as a fixer ; it certainly can be more 
easily procured, and is no doubt just as poisonous. 

Sulphocyanide of Ammonium. 
Symbol, Cy S 2 NH*. 
This is the new fixing salt of JMeynier which is said to be 
endowed with properties for photographic purposes as pow- 
erful as those of cyanide of potassium, without having the 
poisonous and otherwise deleterious properties of this salt. 
Meynier, I think, must have made a mistake as to this latter 
property. Sulphocyanide of ammonium may be formed by 
distilling the vapor of hydrocyanic acid into a solution of 
sulphide of ammonium and evaporating the solution at a 
very gentle heat ; or still better by neutralizing hydrosul- 
phocyanic acid by means of potassa. 

Hydrosulphocyanic Acid. 
Symbol, Cy S 2 H. 
This acid is analogous with the hydracids ; it is obtained 
as a colorless liquid by decomposing sulphocyanide of lead 
by means of dilute sulphuric acid ; and sulphocyanide of 
lead results from the decomposition of sulphocyanide of po- 
tassium with acetate of lead. 

Hyposulphite of Soda. 
Symbol, N* 0, S 2 <X 

This very important salt is obtained by digesting sulphur 
in a solution of sulphite of soda, which dissolves a portion 
of sulphur. By slow evaporation the salt crystallizes. Hy- 
posulphurous acid can not be isolated from any of its com- 
binations. When this salt is pure it produces no precipitate, 
with nitrate of baryta. The crystals contain five equivalents 
of water, and are soluble in a very high degree in this men- 
struum. Its taste is nauseous and bitter. 

The photographic properties of the three salts, whose pre- 
parations have been just indicated, are to dissolve the chlo- 
ride, iodide, and bromide of silver in their recently formed 


state, without acting as solvents on the altered chloride, 
iodide, and bromide, after decomposition by light and de- 
velopers. In all cases of solution they form cyanide, sulpho- 
cyanide, or hyposulphite of silver, which frequently enters 
into combination Avith the solvent and gives rise to a double 
salt, as the hyposulphite of silver and the hyposulphite of 
soda, together with either chloride, bromide, or iodide of 
sodium. Chloride and bromide of silver are soluble to a 
greater extent than iodide of silver in hyposulphite of soda. 
Cyanide of potassium is not only a solvent of the silver salts 
above mentioned, but also a reducing agent ; it thus pro- 
duces in the ambrotype and the melainotype a whiteness in 
the silver film which can not be effected with hyposulphite 
of silver. For this reason it is regarded by many photo- 
graphers as the fixing agent peculiarly adapted for collodion 
positives by reflected light ; whereas in the negative, where 
the whiteness of the silver film is of little or no consequence, 
hyposulphite of soda is regarded as the proper fixer. Many 
photographers disregard these refined distinctions, and use, 
in consequence of the superior solvent properties of cyanide 
of potassium, this substance as a fixing agent indifferently 
for negatives and positives. But because cyanide of potas- 
sium dissolves the silver salts so easily, it has to be used in 
a dilute condition, and to be watched very closely, other- 
wise it will dissolve at the same time the fine parts of the 
image. Another reason why cyanide of potassium is pre- 
ferred in all collodion operations, arises from the difficulty 
of washing the hyposulphite of soda and of silver from the 
collodion film ; for if any trace of these salts be left, the col- 
lodion film will eventually be destroyed by crystallization 
taking place on its surface, accompanied with a decoloration 
and soiling of the image. 

Formula JVo. 1. 

Fixing Solution with Cyanide of Potassium. 

Cyanide of potassium, 1 drachm. 

Rain-water, 4 ounces. 

Formula JVo. 2. 
Fixing Solution with Hyposulphite of Soda. 

Hyposulphite of soda, 2 ounces. 

Water, 4 " 

Formula JVo. 3. 
Fixing Solution with Sulphoeyanide of Ammonium. 

Sulphocyanide of ammonium, 1 drachm. 

Water, 12 ounces. 




Intensifiers are substances which, when applied in solu- 
tion to the developed image, increase the opacity of the 
shadows and middle tints, rendering them more imperme- 
able to light in direct positive printing. With a proper ad- 
justment of light and developer, and especially in ordinary 
landscape-photography, an intensifier is seldom needed ; bat 
many artists prefer the use of the intensifier on every occa- 
sion ; they maintain that a negative can always be preserved 
as clear and transparent in the lights as a positive by this 
process, and yet the density of the shadows may be increased 
to any extent without any fear of fogging. The intensifying 
process becomes, therefore, a fixed part in the preparation 
of a negative. The operation is partly physical and partly 
chemical ; physical, because whatever may have been the 
action of the light on those parts in which the image is now 
apparent, they seem still to be endowed Avith properties of 
attraction of an intensity in proportion to the development 
produced, just as they were at the commencement of reduc- 
tion ; but the nitrate of silver, iodide or bromide of silver, 
having been exhausted, the application of any developer, 
however sensitive or intense, could produce no more opacity 
on the shadows for want of material to be reduced — but, 
mark it well, the physical condition is there to institute this 
reduction the moment material is supplied. 

From my preceding remarks it is supposed that the de- 
veloped image consists of reduced silver, or an altered salt 
of silver very different from any with which we are ac- 
quainted ; there is no more iodide or nitrate of silver ; these 
have been removed in the fixing and washing. Now in order 
to restore the partially developed image to the chemical con- 
dition requisite for the recommencement of the development, 
a solution of iodine in iodide of potassium, or a dilute solu- 
tion of tincture of iodine, is flowed over the plate, and kept 
in motion over the image in order to preserve uniformity 


of action. The iodine thus coming 1 in contact with the 
silver shadows enters into combination with this metal, 
and forms a new and thicker deposit of iodide of silver 
with all the gradations of opacity of the image, and not a 
uniform film of deposit. The solution of iodine on the col- 
lodion loses color all the while ; but the collodion film as- 
sumes at first a grayish and then a yellowish-gray hue. 
Even at this stage there is much more opacity in the shadows of 
the picture than before, and the negative by this proceeding 
may probably be dense enough :"ff not, proceed to the second, 
stage. The first stage is the depositing stage ; the second, 
the reducing or developing stage proper ; and yet this de- 
posit of the first stage is a chemical combination of iodine 
and silver which is now soluble in the fixing solutions, and 
before it was not. By this process of depositing and fixing, 
and by regulating the quantity of the iodine solution, a nega- 
tive which is too opaque may be rendered more transparent 
and less dense ad libitum. Osborne has availed himself of 
this property to clarify his negatives for the photolithographic 
process ; I would recommend it also in the preparation of 
clear and sharp negatives for obtaining enlarged positives 
in the solar camera. As soon as the depositing stage is 
complete, and the film has been washed, the collodion film 
is ready for the reception of the next operation. 

The second stage consists in communicating to the iodized 
image a minute quantity of nitrate of silver, either alone and 
diluted, or in connection with the developer ; it is, in fact, a 
mere repetition of the original process of development ; the 
surface of the collodion is in the same condition as at the 
commencement when it left the camera ; there are present 
iodide of silver, nitrate of silver, iodide of potassium, the 
peculiar and unknown physical attraction existing in the 
formed image, where before the image as yet was unformed, 
and the developing solution either of sulphate of iron or 
pyrogallic acid. The second stage is then a system or pro- 
cess of redevelopment. By this operation the intensity may 
be increased to any extent ; the shadows can be made quite 
opaque and utterly impermeable to the actinic influence. 
The intensifying part of the collodion process is very much 
in the power of the artist ; success, therefore, will depend 
principally on the artistic condition of what I denominate 
the Foundation Negative. If the foundation negative, how- 
ever thin the shadows may be, contain lights, shades, and 
middle tones in perfect detail, then the artist has it in his 
power to raise these three conditions gradually and uni- 


tbrmly higher, until the shadows become endowed with a 
proper opacity. At the end of this stage fixing solutions 
have but little effect, which seems to demonstrate that the 
yellowish-gray iodide has been converted into an insoluble 
metallic film or an unknown insoluble silver salt. It is not 
necessary to use the fixing solution. All that is required is 
to wash the image well before it is dried and varnished. 

Other deposits and other metals may be introduced in the 
intensifying operations, which will be found described below. 

From the recent experihfents and observations of Blon- 
quart Evrard,* it appears that a negative may be intensified 
by a second exposure to light before fixing. Thus, suppos- 
ing a negative be developed as far as it seems possible to 
carry on the reduction, in this condition let it be exposed 
for a short time to diffused light. This physical force, it 
is said, again acts actinically, but now only upon the parts 
which contain the image, communicating to these new vigor, 
and a fresh impulse, which, on the application of the devel- 
oper, again will assist in the formation of further reduction. 

As soon as the image has been fixed, as in the first exam- 
ple, it is sometimes flowed with a saturated solution of bi- 
chloride of mercury, by which p>robably the bichloride is re- 
duced to the protochloride, and the liberated chlorine goes 
over to the silver, and forms chloride of silver. This appli- 
cation communicates a whiteness to the image, and thickens 
the deposit. When the negative has been washed, it is flowed 
with an iodizing solution, containing five per cent of iodide of 
ammonium in water. In this way the image becomes con- 
verted into a double iodide of silver and mercury, which, 
when washed, is treated with the iron or pyrogallic devel- 
oper, containing a few drops of nitrate of silver, as before. 
It frequently happens in this, as in the preceding case, that 
the film at the end of the first stage is opaque enough. In 
this case it may be rendered black by flowing it with ammo- 
nia, hyposulphite of soda, or cyanide of potassium. 

A third method of strengthening the dark parts of a ne- 
gative takes advantage of the alkaline sulphides, which con- 
vert the developed film into a sulphide. By this operation, 
however, the film as a rule is not increased in thickness, its 
color alone being changed, which is frequently more agreea- 
ble to look at, and apparently more dense, because it is black, 
or bluish-black. These alkaline sulphides may be used with 
advantage at the end of the first stage or deposit, in order 

* Vide Humphrey's Journal. Yol. XV. No. 1. 


to blacken this deposit ; but by this mode of intensifying 
there is a great liability to unequal action, to decomposition 
after the negative is varnished, to contraction of the collo- 
dion film, and its separation from the glass ; besides this, sul- 
phur seems to be precipitated sometimes in very irregular 
patches, giving a speckled appearance to the negative. 

Preparation of Bichloride of Mercury— Corrosive 

Symbol, Hg. CI. Combining Proportion, 136.9. Spec, grav., 5.4. 

Dissolve red oxide of mercury in hydrochloric acid; eva- 
porate and crystallize ; or sublime a mixture of equal weights 
of sulphate of mercury and common salt in a stoneware re- 
tort by heating to redness in a sand-bath. The bichloride, 
being volatile, passes out, whilst sulphate of soda remains 
behind in the retort. This substance melts at 509°, and 
boils at 563° ; it dissolves in twenty parts of cold water, in 
two parts of boiling water, in two and one third of cold al- 
cohol, and in three of cold ether. When hydrosulphuric acid 
is passed through a solution of this salt, a brownish preci- 
pitate is first formed, which eventually becomes quite white. 
This is a chlorosulphide. 

Preparation of Sulphide of Potassium — Hepar Sulphur is. 
Symbol, K S3. 
Fuse together, at a low red heat, one part of sulphur, and 
two of carbonate of potash, as long as effervescence takes 
place ; then pour on to a marble slab, and when cool, break 
up the mass, and keep it in well-closed bottles. This sul- 
phide has a liver-brown appearance. By the addition of an 
acid to a solution of the sulphide, hydrosulphuric acid is lib- 
erated, a soluble salt formed, and sulphur precipitated of a 
milk-white color. The alkaline sulphides have the same re- 
action on metallic salts as hydrosulphuric acid, forming pre- 
cipitates of different colors, by which frequently the metals 
can be recognized, as, for instance, antimony, cadmium, etc. 

Preparation of Sulphide of Ammonium. 
Symbol, NH 4 S.HS. 
Let a current of hydrosulphuric acid pass through concen- 
trated ammonia to saturation ; then add an equal bulk of 
ammonia. This is one of the most important reagents in 
chemistry. Hydrosulphuric acid produces precipitates in 
metallic salts, some of which are soluble in sulphide of am- 
monium, and others not ; from this fact we can distinguish 


one metal from another, thus the sulphide of arsenic is yel- 
low, and so is that of cadmium ; but the former is soluble in 
sulphide of ammonium, the latter is insoluble. The alkaline 
sulphides precipitate silver black from its solutions ; thus 
nitrate of silver, as a dye for the hair, is turned of an intense 
black, if followed up with sulphide of ammonium. 



If the collodionized plate, after sensitization in the silver 
hath, is exposed whilst still moist, the process by which the 
image is obtained, is called the Wet Collodion process ; 
whereas if the sensitized plates are dried, and used after- 
ward at any indefinite time, the process of the operation is 
denominated the Dry Collodion process. The Wet Collo- 
dion process will form the subject of the following chapters. 
This process is divisible into two branches, comprehending 
the methods of preparing collodion positives and collodion 

Collodion Positives — TJie Melainotype — T/ie Ambrotype. 

A collodion positive may be viewed either by reflected 
light or transmitted light; by reflected light, in the same 
manner as any picture or engraving is beheld, that is, by 
looking at it ; and by transmitted light, when the picture is 
seen in or on glass, by looking through it, such as the picto- 
rial representation on stained glass, or altar-pieces, etc. 
Collodion positive pictures, or portraits on glass, when re- 
garded by reflected light, are denominated ambrotypes. 
Every, part of such a picture is laterally inverted ; it does not 
therefore represent nature as it is. For portraits this inver- 
sion of the left side for the right side is of no great conse- 
quence, excepting in the representation of objects in action, 
such as a sportsman firing at a woodcock, a soldier parry- 
ing off the blows of an antagonist, or a lady sewing, etc., in 
all which cases the fowling-piece, the sword, and the needle 
will be exhibited in the left hand, or on the left side. The 
artist, therefore, has to rectify his model in such a way that 
he holds, when posed, all these accessories in an inverted or- 
der. Landscapes, houses, churches, etc., can not be properly 
represented in an ambrotype directly photographed from the 
objects ; the application of collodion positives, therefore, is 
limited to portraiture. 



There are several things which the photographer must 
possess, and several arrangements to be made before he can 
take an ambrotype. He must have a glass-honse, or operat- 
ing room, of course, with all its accoutrements ; glass, collo- 
dion, developer, and fixer must all be ready, and in their 
proper places, as already described ; the sensitizing bath, 
plate-holders, water-tanks, etc., all adjusted. 

The operation of taking a collodion positive on glass con- 
sists of the following subdivisions : 

First. Preparing the glass. 
Second. Coating it with collodion. 
Third. Sensitizing it. 
Fourth. Exposing it in the camera. 
Fifth. Developing the picture. 
Sixth. Fixing the image. 

First Subdivision. — Preparing the Glass. 

Glass suitable for the photographer must be free from 
flaws on the surface or in the mass, flat, and quite transpar- 
ent. It can be procured already cut for the various sizes 
required ; or the photographer can cut it himself from plates 
of the proper quality. There is quite a knack to cut with a 
diamond ; the line made by a diamond on glass is like the cut 
made with a sharp razor on a piece of soft wood ; it is by no 
means a scratch. A diamond is wedge-shaped, and its edge 
not a straight line, but a curved line, something like the edge 
of a cook's ckopping-knife ; the edge first makes an incision, 
and the wedge splits its way as the diamond proceeds. The 
position of the edge has to be found out, and the diamond 
studied, before you can cut with it, and not scratch with it. 
If you are determined to cut your own glass, prepare a gla- 
zier's board and a ruler for this purpose, and mark off with 
marks the different-sized glasses used in the art, as one ninth, 
one sixth, one fourth, one half, four fourths, and steresocopic, 
etc., plates. 

N ext see that your glasses, so far cut, are of a right size 
for your plate-holders ; for it is very annoying when the film 
is sensitized to find that the plate is either too big or too 
small for the holder. Never omit this precaution. 

The next duty is to take the glass in the left hand, and 
with the right hand to run a file along each edge of the cut 
glass, beginning at the left-hand corner, and proceeding to 
the right-hand corner all the way round ; the glass is then 


turned round to the other side, and its edges are treated in 
the same manner. The object in view, by thus abrading the 
edges, is firstly to take precautions against the cutting pro- 
perties of such sharp edges ; and secondly, it is found that 
the collodion film adheres better to the edges of the glass 
when it is so prepared. 

If you are provided with a patent vice, placed right in front 
of you in an appropriate place, on the table or bench in the 
operating room, (and such a vice is a very useful accessory.) 
the plate is fixed in this horizontally. Now take the bottle 
containing prepared rotten-stone, covered at the wide-mouthed 
orifice with a piece of gauze, instead of being closed with a 
cork, and dust a small quantity of rotten-stone upon the cen- 
ter of the plate ; then drop upon the rotten-stone on the plate 
from ten to twenty drops of alcohol, and witha piece of Canton 
flannel, rub the mixture about from side to side, and in the 
center until the surface of the glass is perfectly clean. .V 
clean piece of the flannel is then used to remove all the re- 
maining particles of rotten-stone, after which the plate of 
glass is seized with a silk handkerchief, so that the fingers 
do not come in contact with the glass, which is turned round, 
clamped, and its sm'face is cleaned in like maimer. Both 
sides being now apparently clean, again seize the plate with 
a clean silk handkerchief in the left hand, remove it from the 
vice, and, holding a clean silk cloth in the right hand 
round the edges, remove all dust from them, aud from 
either side, then breathe upon either side ; if the breath 
forms a uniform film, and vanishes uniformly without any 
irregularity, the surfaces are cleaned. By this system of 
friction the glass becomes electrified, and small fibers of cot- 
ton or silk and small particles of dust are very apt to be at- 
tracted to the surface ; these must be removed by a flat sable 
or camel's hair pencil. The plate is now ready for the sec- 
ond operation. 

Second Subdivision. 

Holding the plate horizontally by the smallest portion 
possible of the left-hand corner, between the thumb and the 
first finger of the left hand, pour over its surface, beginning 
at the right-hand corner, a sufficient quantity of collodion to 
cover it ; when it is supposed that there is sufficient collo- 
dion poured out, lower the nearest edge and the nearest 
right-hand corner, so that the collodion can, by the inclina- 
tion of the plate, be made to flow uniformly over the sur- 
face, and its superfluous quantity can be drained into the 


collodion bottle. A wide-mouthed bottle containing a couple 
of ounces "will be found to be an appropriate shaped vessel 
to contain the collodion for present use when the pictures 
are small. Collodion is apt to indurate around the orifice 
of the bottle ; and if this dry film is not carefully removed 
(.•very time, it may cause trouble by flowing off in fragments 
along with the collodion, and thus spoil the collodion film. 
This trouble is obviated in a great measure by the use of 
what are denominated " cometless vials;" they are made 
for this special purpose. If the collodion is thick and glutin- 
ous, it will be no easy matter to obtain a film on the glass 
free from ridges. In such a case an additional quantity of 
alcohol generally renders the collodion thinner, less glutin- 
ous, and more structureless. Supposing the film to be even, 
free from ridges, from wooliness, and specks of every kind, 
allow every drop of the collodion to drain off, then wait until 
it has set, which will be effected in a very short time. It is 
very easy to ascertain by a touch of the finger on the right- 
hand corner, whether the film is sufficiently dry or not ; if it 
no longer yields beneath a slight touch, the plate is ready 
for the next step. By the way, I may here remark, that it is 
by far the most advisable plan for a practical photographer 
not to manufacture his collodion ; unless he be in some de- 
gree a chemist, acquainted with the neatness and accuracy 
of chemical manipulations, and have plenty of leisure time 
as an amateur, he can seldom succeed in preparing at all 
times when required a reliable specimen of collodion; and 
to prepare small quantities of collodion, as well as of any 
other chemical compound, seldom comports itself with econo- 
my. Beside this, there is no necessity for such a sacrifice of 
time and economy in a country like this, where collodion can 
be purchased of so superior a quality for all the ordinary 
operations of the practical photographer. Only observe this 
rule, make your purchases at first-class houses in large cities, 
who make it their sole business to supply unadulterated ma- 

TJi ird tSuMiv ision. 

When the film has indurated place it upon the ledge of 
the dipper and lower it in one continuous and rather quick 
motion into the sensitizing bath. Take care that no actinic 
rays get to the bath during this operation. After three or 
four minutes raise the dipper a moment and examine the 
collodionized plate ; if the film is still bluish, and as if covered 
with streaks or specks of oil, lower it again and let it remain 


until the collodion has a yellomsh-white creamy appearance, 
and is free from all oiliness. Withdraw it from the bath, 
seize the right-hand corner between the thumb and finger 
of the right hand ; allow the silver solution to drain off thor- 
oughly into the bath ; with a piece of blotting-paper remove 
all specks of collodion from the back of the plate, taking 
care not to disturb the collodion along the edges of the plate 
or on the film side ; remove the last drop of silver from the 
lowest corner, place it in the plate-holder, and close the slide 
and the shutter. Previous to this, the camera is supposed to 
have been fixed before the sitter, and the picture accurately 
focussed. It is supposed, moreover, that the surface of the 
ground-glass and the collodion film are exactly at an equal 
distance, when placed in the groove, from the back lens. 
As before observed, unless the picture is correct on the 
ground-glass, free from all haze, bright, sharp, and the light 
uniformly subdued, it will be very unlikely that the collo- 
dion picture will be a successful one ; in fine, the image on 
the film will never be better than the one on the ground- 
glass where the lens has been accurately adjusted ; and 
furthermore, that if the picture on the ground-glass be clear, 
sharp, distinct, and agreeably contrasted with light and 
shade, you are legitimately authorized to expect a similar 
favorable result on the collodion. Be careful, therefore, in 
bringing every part of the model into as accurate a focus as 
possible — be careful in the management of the light. 

Fourth Subrfiv ision. 
Place the cap on the lens ; let the eye of the sitter be di- 
rected to a given point ; withdraw the ground-glass slide ; 
insert the platcdiolder ; raise or remove it> slide : Attention! 
One, two, three, four, five, six ! (slowly and deliberately pro- 
nounced in as many seconds, either aloud or in spirit.) Cover 
the lens. Down with the slide gently but with firmness. 
"Withdraw the plate-holder and yourself into the dark-room, 
and shut the door. Xow comes the 

Fifth Subdivision. 
Placing the plate-holder, still containing the plate, in an 
inclined position against the wall in its regular and proper 
position, open the shutter and take out the collodion plate 
carefully, so as not to injure the film, by inserting the nail 
of the first finger along the cavity on the upper part of the 
plate-frame, and drawing forward the plate so as to let it 
fall into the left hand ; the plate is then seized by the left- 


hand comer between the thumb and the finger. In this 
position the plate can easily be covered with the developing 
fluid in precisely the same way as with collodion, only the 
operation must be much quicker, in order to cover the sur- 
face without producing any lines of stoppage, which invaria- 
bly happens unless the plate be flowed all at once. When 
the plate is large, it is preferable to take it by the right-hand 
corner and lay it in the left-hand corner of a gutta-percha 
di*sh, whose lateral dimensions are about twice as large as 
those of the plate. Then, holding the dish in the left hand, 
incline the right side downward, and pour into it a quantity 
of the developing fluid. By a quick motion the fluid can be 
made to cover the surface of the plate in one continuous 
flow. As soon as every part is thus covered the plate is 
taken out with a quantity of the solution upon it, and the 
operation watched. By proceeding in this way two diffi- 
culties are avoided ; the first of which consists in washing 
away a portion of the nitrate or iodide of silver, etc., on that 
part on which the solution is allowed to fall if the first 
method be adopted, whereby a diminution of reduction is 
observable in this part ; secondly, you avoid the liability of 
forming islands and curved lines of demarkation where there 
is the slightest stoppage in the flowing of the developer. 
Supposing the plate to be covered, however, you (lien watch 
proceedings. If a bright silver-white film be desired, it is 
well to make use of a slow developer, such as is used for 
negative purposes, containing in addition a few drops of 
nitrate of silver, nitrate of potassa, and nitric acid. Take, 
for instance, the following, which is found to work well with 
a white background, giving a roundness of figure more like 
that of a daguerreotype. 

Formula for Developer. 

Sulphate of iron, 2 drachm*. 

Rain-water, 8 ounces. 

Acetic acid, 2 drachms. 

Alcohol, 1 drachm. 

Nitrate of potassa, \ drachm. 

Nitrate of silver solution, ... 30 drops. 

Nitric acid, 12 drops. 

The image will gradually appear, and if the time of ex- 
posure has been right, you will be able to observe the three 
grades of contrast in the development, that is, dark parts or 
shades, middle tones, and lights. You will sec, moreover, 
whether the relative conditions of the collodion and the 
silver-bath are in good working order, by the mode in which 


the development takes place. If the whole surface of the 
collodion plate soon assumes a foggy, milky, or clouded ap- 
pearance, with but faint contrast between the lights and 
shades, (and knowing that the camera is quite impermeable 
to light excepting through the lens,) you may fairly con- 
clude one of two things, either that the time of exposure 
was too long, or the condition of the materials was not 
normally good. Of these difficulties I will speak shortly. 
By carefully watching the development it is not difficult to 
observe how the shades increase in density, how, in fine, the 
picture becomes more and more developed; and particularly 
the photographer can distinguish the regular shading of the 
background. At last the development arrives at its culmin- 
ating point ; if it were to proceed any further, the back- 
ground and the transparent parts would begin to be foggy ; 
the contrast diminishes, and finally the picture is spoiled. 
The rule is this : the moment the image is complete and the 
background has received its first shade, pour off the remain- 
ing part of the developer, and wash immediately and thor- 
oughly by allowing a small stream of rain-water to play upon 
the surface until every trace of the iron is removed. Wash 
also the posterior side of the glass in like manner. We now 
proceed to the sixth and last operation. 

Sixth Subdivision. — Firing Solution. 

Form" hi. 
Cyanide of potassium, .... 1 drachm. 
Rain-water, 4 ounces. 

Have this solution ready. With the right hand place the 
collodionized plate in a gutta-percha dish held in the left 
hand, and pour upon the developed image a quantity of the 
above solution in a gentle stream, until all the white or yel- 
low iodide of silver has been completely dissolved, taking 
care in the'' mean while that the fluid is kept moving back- 
ward and forward, so as to preserve uniformity of action. 
After this operation wash the plate again in many waters on 
both sides and until all traces of the cyanide are removed. 
Holding the positive now over a piece of black velvet in 
such a position by a window that the impingent rays shall 
reach the eye, the quality of the ambrotype can be deter- 
mined. The picture must be quite clear; the shades dark, 
almost black ; the lights brilliant and white ; and in every 
respect the lines and points must be sharply defined. If 
there is no regular gradation of light into shade, bat almost 
one mass of shade, ami the picture is offensively black, the 


time of exposure -was too short or the development not car- 
ried on far enough ; but if in this case the development had 
been continued until the retrograde action had set in, then 
certainly the time was too short. The remedy in such a case 
is quite natural ; rub the picture out and take another with 
a longer exposure. If, on the contrary, the picture is hazy, 
or foggy as it is technically denominated, and the lights and 
shades too much blended or too little distinct from each 
other, and the development was rapid, and a difficulty pre- 
sented itself in discriminating when the reduction began to 
assume a retrograde action, in such a case it may be confi- 
dently concluded that the time of exposure was too long. 
The remedy of course is known. But the defects just men- 
tioned might have been caused by canying on the develop- 
ment too long ; and it would be very proper to attribute 
these defects to this cause, if the development had been slow 
<md carelessly watched. But if the haze and fogginess com- 
menced almost as soon as the developing solution was poured 
upon the surface, you would be justified in ascribing the 
cause of this veil over the picture to an abnormal condition 
of the silver-bath or the collodion. This evil indicates, as a 
general thing, alkalinity in either one or the other, or in 
both, and can be remedied by rendering either one or the 
other acid. It may be caused by a new bath and a new 
neutral silver solution. 

Remedy for Fogginess. 
If the collodion is nearly colorless and new, this material 
is probably the cause of the want of contrast in the picture, 
of the feebleness in the development, and, it is possible, of 
the veil that covers the whole plate. Take some highly 
colored old collodion and add it to the new in the propor- 
tion of one drachm in ten, and try another picture ; or add 
to the collodion tincture of iodine, that is, a solution of 
iodine in alcohol. In either case, most likely, under the cir- 
cumstances, an improvement will be manifest. If the pic- 
ture is not yet perfectly clear, proceed in the same direction, 
that is, add more of the old collodion or of the tincture. If 
the bath is quite neutral or alkaline, it will be well indeed to 
drop in a minim or two of nitric acid. To do this take a 
drachm of distilled water and drop into it five minims of 
nitric acid. The mixture contains about sixty drops, of 
which six drops will contain about half a drop of nitric acid. 
Begin, therefore, and add six drops of the solution to the 
bath) and keep doing so until the picture is perfectly satis- 


factory. I prefer myself keeping the bath as nearly neutral 
as possible, and to apply the remedial action to the collodion, 
by adding free iodine or old collodion, of which the former 
seems by decomposition to liberate an acid in and on the 
collodion film in proper quantity, at the right time, and in 
the proper place ; and the latter, that is, old collodion, effects 
the same result, because it has already undergone the de- 
composition of the pyroxyline that is called ripening, and 
contains the materials for producing intensity and for avoid- 
ing fogginess. 

In taking collodion positives beginners are very apt to de- 
velop the plate too long, as well as frequently to expose in 
the camera too long. The right time in both instances can 
be attained only by practice, after having consulted the best 
instructions. As soon as the picture is distinctly visible by 
reflection, stop the development; if it is then faulty, the time 
was either too long or too short ; too short, if the shades are 
altogether too black, and transparent by transmitted light, 
and vice versa, if the reverse. 

Supposing the picture to be correct and satisfactory, we 
proceed next to the 

Seventh Operation, 

which consists in drying the plate. The operation is per- 
formed by means of the large flame of an alcohol lamp, or 
by the radiating heat from a stove. Holding the plate by 
the left-hand comer, between the finger and the thumb of 
the left hand, first allow all the water to drain off at the 
nearest right-hand corner, by inclining the plate for this 
purpose; then holding the lamp in the right hand, move the 
flame gently over the back of the plate, so as to avoid frac- 
ture, beginning at the top and proceeding from side to side, 
and gradually downward, until the film is thoroughly dried. 
A second inspection now, by viewing the picture, as before, 
on a dark background, and by reflected light, decides whether 
the positive is good, tolerable, or indifferent, because now 
the final colors of the shaded parts are attained. These 
shaded parts are of a bright, white silvery hue, with the de- 
veloper above given. Borne tastes are more .gratified with 
a more subdued contrast in whieh the whites are more dead- 
ened. This can be effected by making use of a much more 
rapid developer, and by omitting the nitrate of silver, and 
the nitric acid. For this purpose the following formula will 
bo foimd practicable. 


Formula Wo. 2. For Collodion Positives. 

Sulphate of the protoxide of iron, 4 drachms. 

Acetic acid, 6 drachms. 

Water, 8 ounces. 

Alcohol, 2 ounces. 

Nitrate of baryta, 2 drachms. 

Alix intimately, and filter before using. Prepare fresh 
every clay. 

Eighth Operation. 

The next step which the artist has to take consists in re*- 
moving any particles that may have settled upon the surface 
of the picture, and in coloring the cheeks, hands, and dra- 
pery where required. Dry colors are used; those of New- 
man are regarded as the best. Very little color will produce 
an agreeable effect. With a fine sable or fitch pencil, take 
a small portion, and rub it gently on either cheek, on the 
lips, the hands, and forehead ; then brush off the extraneous 
quantity, or shade the color off from the center of the cheeks, 
for instance, to the edges. On the lights of the drapery the 
requisite coloring may be laid on in like manner. This op- 
eration of colorino- is frequently performed on the varnished 
surface. Finally with a large broad sable pencil remove all 
loose coloring particles, and now the positive is ready for the 

Ninth Operation. 

Whilst the plate is still warm, uniformly warm from the 
drying operation, flow it with the purest and most transpar- 
ent crystal varnish, precisely in the same manner as the 
plate was covered with collodion. The operation must be 
performed with dexterity and care ; with dexterity in order 
to avoid all ridges caused by stoppage, and with care to 
avoid loss of varnish by escaping to the posterior part of 
the plate, upon the fingers, and upon the sides of the bottle, 
and the floor. The indurated varnish on the back of the pos- 
itive may be removed by a tuft of cotton wool, dipped either 
in alcohol, benzole, or chloroform, according as the resins in 
the varnish are dissolved in either of these menstrua. Do 
not apply any heat from a large flame on the back of the 
plate before the varnish has dried, otherwise the ethereal 
fluid in which it is dissolved will take fire in many instan- 
ces, and spoil the varnished surface. When the film is some- 
what dry and indurated, and not quite smooth, heat maybe 
applied carefully, in order to remove the imevenness, or the 
want of brilliancy. 


Varnishes for Collodion Pictures. 
Formula No. 1. 

Copal, 1 ounce. 

Pure benzole, 15 ounces. 

Dissolve and filter through Swedish or ordinary filtering 

Formula Xo. 2. 

"White stick lac, 3 ounces. 

Picked sandarac, 3 drachms. 

Alcohol, spec, grav., .S13, . . . 40 ounces. 
Oil of beigamot, 6 drops. 

Dissolve the resins in the alcohol by means of a waiter-bath, 
and filter. This varnish is immediately ready for use ; and, 
like all varnishes, is the best when new. 

Formula No. 3. Crystal Varnish. Soft Copal Varnish. 
Finely powdered Dammar resin, . 5 ounces. 
Benzole,- 50 ounces. 

Set aside in a closed vessel for a week, shaking the mixture 
from time to time for a day or two ; then allow the insoluble 
gum to subside. Draw otf the supernatant liquid, which, 
when clear, is ready tor use. The collodion plate must bo 
quite dry and cold when this varnish is applied, and the lat- 
ter is allowed -to dry sj>ontaneously. 

Formula No. 4. Amber Varnish, (with Chloroform.) 
Amber in fine powder, .... 3 ounces. 
Chloroform, 50 ounces. 

Shake the mixture from time to time for eight or ten days, 
and then filter. This varnish, like the preceding, is poured, 
like collodion, upon the cold plate, but with great dexterity, 
because it dries very rapidly. 

Formula No. 5. Amber Varnish, (with Benzole.) 

Amber, 3 ounces. 

Benzole, 50 ounces. 

Heat the amber first in a close vessel to a temperature of 
about 570° Fahr., when it begins to soften and swell, yielding 
white fumes. It is then dissolved in the benzole. This var- 
nish too is flowed upon the cold plate, and allowed to dry 
spontaneously. These two varnishes are more especially 
adapted for negatives. 

If it should happen that a collodion picture becomes some- 
what spoiled by the cracking of the varnish, it is recommend- 
ed, if its restoration or preservation be of great importance, 
to take the following method. First ascertain whether the 


solvent of the varnish on the plate be alcohol, chloroform, or 
benzole, by dropping on one corner a minute drop of each of 
these menstrua, to ascertain which dissolves the varnish. 
Next take a tin box, somewhat larger than the picture, about 
one inch deep. At the bottom of this box solder a ring of 
tin, about half an inch wide, of the same shape, and nearly 
of the same size, as a support for the glass plate. Pour a 
small quantity of the solvent on the outside of the support ; 
place the plate collodion-side upward on the ring; cover 
the box as nearly air-tight as jjossible with a piece of glass, 
and place it in a water bath. The vapor of the solvent will 
soon cause the varnish to swell, and the edges of the cracks 
to coalesce. As soon as this end in view is accomplished, the 
plate is carefully withdrawn, and, when cool, is again var- 
nished with a similar varnish. 

The plate having been varnished with a transparent resin 
varnish, we proceed finally to the last operation. 

Tenth Operation. 
"We have now to make a background for the positive, of 
some black material, which may consist of a piece of black 
velvet, black paper, etc., of the same size as the plate ; or we 
may apply a coating of black varnish, either to the collodion 
surface, or to the posterior surfiice of the glass. If the var- 
nish on the background be applied to the collodion side, the 
picture is not laterally inverted, but it loses considerably in 
transparency by the intervening collodion; in consequence 
of this inconvenience, the background is generally placed on 
the side of the glass without the collodion. 

Formula N~o. 1. For Black Yarnisli. 

Oil of turpentine, 50 ounces. 

Asphaltum, 2 ounces. 

Canada balsam, 4 ounces. 

Formula 2fo. 2. For Black Varnish. 

Benzole or coal-tar naphtha, . . 50 ounces. 

Asphaltum, 2 ounces. 

India-rubber, -i drachm. 

Formula No. 3. For Black Varnish. 

Camphene, 50 ounces. 

Pulverized bitumen, 10 ounces. 

White wax, 2 ounces. 

Lampblack, 1 ounce. 9 

Mix these ingredients together, and dissolve by a gentle 
heat ; afterward filter and preserve in a well-corked bottle. 


Varnish with bleached Shell-lac. 


Freshly bleached shell-lac, ... 4 ounces. 

Alcohol, 1 quart. 

Camphor, 2 drachms. 

Canada balsam, 2 drachms. 

Dissolve at a warm temperature ; allow to settle, and decant 
the clear portion for use. 

The following varnish is used on the cold plate, is very- 
hard when dry, and is not softened at a high temperature 
when printing. 

Gum sandarac, 4 ounces. 

Oil of laveuder, 3 ounces. 

Alcohol, 2S ounces. 

Chloroform, 5 drachms. 

Digest, dissolve, and decant as usual. 

The positive print, denominated an ambrotype, is now fin- 
ished. It remains only to fix it in a case or frame. In the 
first 2^1ace a piece of very transparent and unblemished glass, 
of the same size as the type, is thoroughly cleaned, and its 
edges filed, as for collodion purposes, and all particles are 
brushed from its surface. It is then placed in a Preserver ; 
over this comes a Mat ; next the Ambrotype. The two lat- 
ter are then firmly folded within the flexible edges of the 
preserver, and the compact mass is finally adjusted in its ap- 
propriate case. 



The coloring of collodion positives, as already remarked, 
may be effected on the whites of the picture, either before 
the varnish is flowed on, or upon the varnish itself. When well 
performed, it communicates life and roundness to a picture 
which before was flat and lifeless. The colors in use are in 
fine powder, and are laid on with a dry and very fine pencil 
of camel's, etc., hair. Naturally the operation must be very 
simple, and but a very small quantity of color must be used, 
otherwise the operation will become a work of art, and none 
but an artist could perform it. In all ordinary cases the 
color lies on the surface, and does not penetrate into the ma- 
terial of the film. In the Alabastrine process, however, the 
film is so treated as to become permeable to varnish, and thus 
to exhibit the color, as it were, in the collodion ; besides this 
the Avhites are still retained white, notwithstanding the im- 
pregnation of the film with the penetrating varnish. Posi- 
tives treated in this manner are regarded through the glass 
and the collodion film ; the pictures, therefore, are direct as 
they ought to be. The mode by which the tones are pre- 
served soft and white, and rendered at the same time per- 
meable, is the following : 

Alabastrine Solution. 


Sulphate of the protoxide of iron, . 20 grains. 

Bichloride of mercury, 40 grains. 

Chloride of sodium, (salt,) ... 15 grains. 
Rain-water, 2 ounces. 

Select for this operation a vigorous good positive ; a faint 
and thin firm does not answer well. One that has been ra- 
ther under-exposed is most suitable. Then, whilst the collo- 
dion film is still moist from fixing, pour upon it a quantity 
of the above solution, and keep it in motion. At first the 
picture assumes a dead and gray appearance ; but this soon 
changes, and becomes continually more and more brilliant. 


It is sometimes necessary to add a little more of the fresh 
solution, and to retain this solution on the surface until the 
•whites are perfectly clear. The time required for this oper- 
ation varies according to the temperature and the thickness 
of the film. Heat promotes the effect ; the plate is therefore 
frequently supported on the ring of a retort-stand, with the 
fluid on its surface, whilst a small flame is kept in motion 
beneath it. Unless this precaution be observed, there will 
be a liability to break the plate. It happens sometimes that 
a few minutes are sufficient ; but generally more time is re- 
quired. If no heat is applied, the operation may require in 
some cases as much as an hour. As soon as the whites have 
attained their utmost purity, the operation is complete. It 
is better to be quite certain that the whites have attained the 
purity required, than to shorten the time, and have the ef- 
fect underdone. There is no danger in giving too much 
time; but it is a disadvantage to remove the fluid from the 
plate too soon ; because in drying, the whites in such a case 
are apt to grow darker again, and the picture assumes then 
the cold blue tone, which arises from treatment with corro- 
sive sublimate alone. 

As soon as the effect has been reached, the plate is tho- 
roughly washed in several waters, and then dried over the 
spirit-lamp. The plate is now ready for the first coating of 
varnish, which communicates transparency to the shadows, 
without at all impairing the whites. 

The next operation is to lay on the colors carefully and ar- 
tistically on those parts that require them. It is unnecessary 
to apply any to the shades. Where much color is desired on 
a given surface, it is better to apply it by repetition, and not 
in one thick blotch. Colors thus tastefully laid on produce 
a very brilliant effect, by reason of the purity of the whites ; 
and this effect is again increased by the softness communi- 
cated to the whole picture by the application of the penetrative 
varnish, which causes the color to permeate into the pores of 
the film, or to be seen at least in full beauty from the oppo- 
site side. This varnish is nothing more than a very pure 
strong-bodied protective varnish. The picture so far finish- 
ed is backed up with a piece of black velvet, but never with 
black Japan, which would injure the film. 



The melainotype takes its name from the WacA background 
upon which it is taken. Ferrotype from the iron of which 
it is composed. Veiy thin plates of sheet-iron are covered 
with a protective varnish or Japan, of which one is of a rich 
black or brown-black color, highly polished, and without 
flaw, for the reception of the collodion and the collodion pic- 
ture. Glass in this sort of picture is entirely dispensed with, 
and so is also the black Japan, the black velvet, and paper. 
This type is by fir the easiest and the quickest to take, and 
in general the most satisfactory when taken. Melainotype 
plates of all the variable photographic sizes, and of variable 
qualities, can be obtained from the photographic warehouses. 
The Excelsior plate and the Eureka plate in my opinion are 
the best ; the Ferrotype is very good, and much cheaper. 

With a fine flat sable pencil dust off any particles from the 
black surface of the plate, and then flow it with collodion in 
the same way in which the ambrotype glass was covered. 
Wait for the congelation, or partial desiccation of the film, 
and then immerse it in the silver until it assumes a creamy 
opacity, (not blue,) and until the solution flows off without 
apparent oily streaks. Then raise it from the bath ; allow 
the superfluous fluid to drain off into the bath, and with bib- 
ulous paper remove the last drop from the pendent corner of 
the plate. The plate is next inserted in its holder, and a 
piece of the same size placed over it. Previous to this part 
of the operation, the photographer must never forget to clean 
out the lower corner of the plate-holder, by means of blotting 
paper or old rag. Nitrate of silver is apt to settle in these 
corners ; and these being formed of separate pieces of glass, ce- 
mented together, and not of one solid mass, (which is Lewis 
and Holt's patent,) the nitrate of silver becomes frequently de- 
composed by the material of the cement, and running up the 
plate on the collodion side by capillary attraction, it pro- 


duces dark-colored stains and streaks. Make it your duty, 
therefore, a part of the collodion operation in fine, to clean 
these corners carefully before you take out the plate from 
the silver bath. 

The time of exposure of a melainotype is the same exactly 
as for an ambrotype. All the instructions, too, for develop- 
ing, fixing, coloring, and varnishing the positive on glass 
are valid here. I regard it as preferable to color after the 
plates are varnished, both in this as well as in the preceding 
type. Owing to the better conducting qualities of heat in 
iron plates over those of glass, more caution is required lest 
the Japanned film becomes raised into blisters. This misfor- 
tune is very common with beginners on certain plates, with 
the Excelsior, perhaps, less frequently than with some others. 

This type is mounted with glass, mat, and preserver, and 
fixed in a case like an ambrotype ; or it may simply be covered 
with a mat, and thus prepared for mailing in a letter. For 
this purpose each corner is cut off with a pair of shears, at 
a distance of one quarter of an inch from the apex, and the cor- 
responding corners of the mat are folded or reduplicated over 
and under it, so as to form a compact piece out of the two. 
The melainotype, as thus taken directly from the model, is an 
inverted picture, like the ambrotype, but, unlike the ambro- 
toype, it can never by a single operation be otherwise. In 
the alabastrine process just described, the ambrotype, it will 
be observed, is not an inverted picture ; the plate is inverted, 
and the image is beheld through the collodion in its natural 
and direct position. 



A collodiox negative is an actinic impression, in which the 
different parts of the image are, as in the positives just de- 
scribed, laterally inverted, and, when viewed by transmitted 
light, the shades are where the lights ought to be, and vice 
versa. It is the matrix from which positives are obtained 
by direct contact, either on glass, or on paper, as also by 
means of the lens in the ordinary, or in the solar camera. 
Most of the details of the operation in the negative process 
are the same precisely as in the positive process. 

The glass is filed, cleaned and flowed with collodion, as be- 
fore directed. It is sensitized too in the same bath, and then ex- 
posed. Let the time of exposure be from ten to twenty sec- 
onds in the glass-room, probably more ; much depends upon 
the proper adjustment of the light, and its concentration by 
the lenses. The object in view is to obtain much more ac- 
tinic action, not only on the film, but through the film, so as 
to produce a denser metallic reduction for the shades, which 
in the ambrotype are lights. To guard against the liability 
to fogging, a much weaker and more acid developer is used 
than in the positive process. The developing is carried on 
as long as the shades increase in density by transmitted light. 
It is quite an advantage in this process to have a small square 
of orange-colored glass situated lower down than the posi- 
tion of the negative, as you hold it for the operation of de- 
velopment, in order that the light may come from below, and 
thus through the glass. If fogging sets in, or the density 
seems to be stationary, or even to retrograde, the negative 
is developed as far as circumstances in the present instance 
will permit. If the density of the shades is so great as to 
prevent you from distinguishing objects through them, and 
these shades are regularly tempered down through the inter- 
mediate tones to the bright lights, and these lights are still 
clear and transparent, it is very possible that the image is suf- 
ficiently negative, and that you have succeeded in your under- 
taking. It is absolutely necessary that you should know what 


you have to do, before you can depend upon what you do, 
or rely on definite results. A true negative is just what I 
have described. If the lights are not clear and transparent, 
with sufficient detail, of course, intermingled ; if the shades 
are transparent, and not comparatively opaque, so much so 
as to allow the print of a book to be read through them ; or 
if there are no intermediate tints, but your negative is all 
black and white ; then you have not succeeded — your nega- 
tive is faulty. We will suppose, however, that the three 
gradations of shades, middle tones, and lights exist, but 
that the intensity of the shades is not strong enough; there 
is a general weakness in the negative, and your object is to 
push on the development, which is found to be ineffectual 
without producing a haziness or fogginess over the whole 
print ; the conclusion to be drawn from this circumstance is 
that the time of exposure was too short. Another sitting 
may remedy the evil. On the contrary, if when the deve- 
loper is poured on, the reduction on the shades is very ra- 
pid, and this reduction commences, rushes with rapidity into 
the lights before you have time almost to stop it, you may 
fairly conclude that the time was too long. But a develop- 
er sometimes may produce very much the same effect ; for, 
if the proportion of the iron salt, in comparison with the 
acid and the water, be great, fogging and rapid reduction 
will certainly be the result. As before remarked, a much 
weaker developer is required in the preparation of a nega- 
tive than in that of a positive, and a proportionately larger 
quantity of acid to check its action, until the proper density 
of opacity is attained in the shades. (I use the words shades 
and lights in the negative, to represent what they really are, 
and not what they produce on the paper print ; shades are. 
dark and opaque ; lights are thin and transparent.) 

VTe do not aim to obtain brilliant white silver reductions 
on the negative ; for the color, or metallic brilliancy is altoge- 
ther a matter of little consequence ; on this account we use 
no silver solution in our negative developer. Where the 
time of exposure is not necessarily required to be very short, 
a pyrogallic acid developer produces a very pleasing nega- 

V gative Developers. 

Formula No. 1. Iron Developer. 
Sulphate of the protoxide of iron, 4 drachma. 

Rain-water, 8 ounces. 

Acetic acid, H ounces. 

Alcohol, .6 drachma. 



Foiinula No. 2. Pyrogallic Acid Developer. 

Pyrogallic acid, 3 grains. 

Water, 2 ounces. 

• ' Acetic acid, ...."".... 2 drachms. 
Alcohol, 6 drops. 

The negatives which produce the softest prints are those 
which are produced by the first development, where the 
time of exposure and the action of the reducing agents have 
been in such relatively due proportion as to produce the 
three gradations with a proper amount of opacity in the 
shades. This proportion can not always be determined be- 
forehand, because of the variability of the light, and its ac- 
tinic powers, of which we know as yet absolutely so little. 
We can not determine the reason of the widely diverse ac- 
tion of light at six in the morning, and six in the evening, or 
at the vernal equinox, and the autumnal. In consequence ot 
this want of definite knowledge of the prime cause that in- 
stitutes the actino-physical changes in the iodo-sensitized col- 
lodion film, it will frequently happen that the developed 
image is not perfect ; the shades are not endowed with suf- 
ficient opacity. Fortunately in such cases we possess means 
whereby these shades, middle tones, and detail in the lights 
can all be in relative proportion rendered more opaque, and 
as much more opaque as may be desired. The process by 
which this end is attained, is denominated the Intensifying 
or Redeveloping process. 

The image having been developed as far as possible in ac- 
cordance with the rules laid down, the plate is thoroughly 
and carefully washed on both sides, and freed entirely from 
every trace of nitrate or developer. Cyanide of potassium 
in solution, the formula of which is given at the end of the 
positive process, may be employed to remove the undecom- 
posed iodides or bromides, care being taken not to continue 
the action of the solvent too long, nor to apply it in too con- 
centrated a condition, lest the fine markings of detail are dis- 
solved off at the same time. Because, as already mentioned, 
cyanide of potassium is a reducing agent, as well as a fixing 
substance, and giving a silver salt so acted upon a reguline 
appearance, it is regarded as the fixing agent proper for 
collodion positives ; whereas, owing to the properties pos- 
sessed by hyposulphite of soda as a fixer alone, and not a 
reducer, and because its solvent action is not so violent as 
that of the cyanide, it is properly recommended to fix nega- 
tive pictures. 


Fixing Solutions for Negatives. 

Formula Xo. 1. 

Hyposulphite of soda, . . ; . 5 ounces. 

Water, 10 ounces. 

Formula Xo. 2. 
Cyanide of potassium, . . . . 1 drachm. 
Water, 5 ounces. 

In case the image is fixed with the first formula, that is, 
with hyposulphite of soda, the plate requires to be washed 
with the utmost care, for if any of the hyposulphite of silver 
is left in the film, it will become manifest after the drying 
of the film, sometimes at the expiration of months, by the 
formation of a crop of crystals on the surface that complete- 
ly ruins the picture. As soon as washed, the plate is ready 
for operations quite distinct from those in the positive pro- 

Intensifying or Redeveloping Process. 

Formula No. 1. Depositing Fluid. 

Iodine, 1 grain. 

Iodide of potassium, 1 grain. 

Rain-water, 1 ounce. 

Formula Xo. 2. For ilie Stock Bottle of the same material. 

Iodide of potassium, 1 drachm. 

Water, 2 ounces. 

Iodine to saturation. 

Depositing Operation. 
Take from ten to twenty drops of this solution to each 
ounce of water, and flow the developed plate with it. This 
operation can be performed in the diffused light of day. The 
plate must be kept in motion all the while, and the fluid 
poured off and on, in order to obviate all irregular deposi- 
tion. The solution will gradually lose color, whilst the film 
in the mean time assumes a gray or yellowish-gray hue. If 
the negative does not require much additional opacity in the 
shadows, it is not necessary to carry on the depositing oper- 
tion further than the gray film. The plate is now washed 

Intensifying Operation. 

Formula Xo. 1. Xitrate of Silver. 

Nitrate of silver, 30 grains. 

Rain, or distilled water, .... 1 ounce. 

Take three drops of this solution with two drachms of 
water, and cover the plate with the fluid. Pour the fluid off 
and on several times. 


Formula No. 2. Pyrogallic Acid. (Stock) 
Pvroeallic acid, . . 12 grains. ) T - . , , , 
Acetic acid,. . . . 1 ounce. \ Keep in a dark place. 

Formula No. 3. 

Of this take, 1 drachm. ) 

Water, *7 drachms. > For immediate use. 

Alcohol, . . . .10 drops. ) 

To two drachms of Xo. 3, add ten drops of Xo. 1 ; mix inti- 
mately by shaking-, and then pour it upon the plate, and keep 
it in agitation. The shades will soon increase in blackness 
and opacity. The oj^eration is carried on to the greatest ad- 
vantage by holding the negative over a light reflected from 
below, as in the dark-room, or near a doorway receiving its 
light from the sky. Stand sufficiently far back, and side- 
wise of the door, so that the light does not shine upon the 
negative directly from the sky, but is received as it is re- 
flected upward from the floor, etc., below. The shadows 
will grow darker and darker; and the process has to be stop- 
ped as soon as the opacity is sufficiently dense. Experience 
alone can tell you exactly when to stop. The denser the 
background in the negative, if a white screen were used, the 
whiter the print will be ; but the opacity may be so great as 
to require an hour or two for the subsequent printing opera- 
tion, which is very inconveniently long. A certain connec- 
tion exists, therefore, between the negative effect and the 
positive printing effect afterward, which experience has to 
teach; and even if you do not execute your own printing, 
this connection must not be lost sight of. In parts that must 
really appear white in the paper, the opacity must be dense 
enough to prevent you from reading print through them ; 
taking this for your guide, separate such a part in the pic- 
ture ; keep your eye steadfastly upon it as it increases in 
darkness, and when it has arrived at the point indicated, 
pour off the intensifying solution, and wash very thoroughly. 
It sometimes happens that the tilm becomes contracted by 
this operation, or that the fluid gets between the glass and 
the film, and thus the latter becomes loosened, and is liable 
to peel off. Careful experience will teach you how to retain 
the collodion in its place. 

Where many prints have to be taken from a negative, it 
is quite requisite to varnish the film when dry. But almost 
all varnishes have a penetrating effect, like oil of turpentine 
on paper, and thus diminish the opacity of the negative. 
This has to be taken into consideration, and the negative 


must bo intensified in accordance deeper than required when 
without varnish. The property of a varnish, suitable for 
such purposes, must be a sufficient hardness of film, to pre- 
vent scratches, insolubility by the heat of the sun, freedom 
from any liability to cracking by contractility, perfect trans- 
parency, as little penetrating power as possible, and freedom 
from all action upon the film. 

Varnish. Formula. 

White lac, 4 ounces. 

Picked sandarac, 4 drachms. 

Alcohol, (concentrated,) .... 60 ounces. 

Oil of bergamot, 20 drops. 

Dissolve by the aid of a water-bath, and filter. 

To obviate the diminution of opacity by means of the var- 
nish, I frequently flow the plate with a dilute solution of 
gum-arabic or gelatine, which is allowed to dry ; and then 
the plate is varnished. 



Before the preparation of the iron plates, known as Me- 
lainotype etc., the transfer process had more importance. A 
transferred positive has all the beauty of a melainotype, with 
the advantage of being non-inverted, and upon a medium 
that suffers less from being bent. It is especially suitable 
for inclosure in letters to distant friends. Any fine sub- 
stance, as very thin leather, linen, paper, etc., neatly and 
evenly varnished with black Japan, is adapted for the recep- 
tion of the collodion transfer. Such substances can be ob- 
tained from the wholesale dealers in photographic goods ; 
they can also be prepared in the following manner : Take, 
for instance, a piece of fine leather, or oiled silk, and fix it 
on a stretcher, or flat board ; then varnish it on one side with 
the following mixture. 

Blade Japan. 

Chloroform, 8 ounces. 

Asphaltura, 8 ounces. 

Canada balsam, 2 ounces. 

The ingredients when intimately mixed are poured in suffi- 
cient quantity upon the side to be japanned, and allowed to 
dry at a gentle heat. The varnish will soon set, and in a short 
time will be ready for the transfer operation. If metallic 
plates have to be japanned, such as the melainotype, that 
have to be introduced into the silver bath, they must pre- 
viously be coated w T ith common positive or -negative var- 
nish, in order to be prevented from exercising any injurious 
effect upon the silver bath, and afterward they are japanned 
on one side, as just described. These plates are not used in 
the transfer process, but to receive the image instead of glass. 
The collodion on glass, when dry, or after it has been 
dried, adheres to the plate with considerable tenacity. The 
film for transferring, too, must be of the glutinous kind, con- 
taining more ether than alcohol. After the image has been 


fixed, and washed, and whilst the film is still moist, it is 
flowed with the following solution : 

Alcohol, 5 drachms. 

Water, 5 drachms. 

Nitric acid, .... from 12 to 16 drops. 

The solution is immediately poured off, and the plate drained 
of its superfluous fluid. The prepared leather, etc., is now 
cautiously laid upon the film, beginning in the middle, and 
allowing either end to fall gradually upon the collodion, so 
as to exclude all bubbles of air. The leather is next pressed 
w r ith a burnishing tool all over the posterior surface, so as 
to bring it in intimate contact with the film beneath. If the 
operation be performed with dexterity and care, bubbles of 
air may be avoided ; if any are observed, they must be re- 
moved by drawing up the leather gently before adherence 
takes place, and then by letting it down again with more 
caution. Having succeeded in bringing the collodion film 
and the leather in juxtaposition, without a single bubble, the 
plate is warmed gently over an alcohol-lamp, after which the 
leather can be removed, together with the collodion film ad- 
hering to it. The leather is now rinsed in pure water, and 
allowed to dry. 

If it be desired that the collodion picture shall be in the 
form of an oval, circle, or square, etc., we proceed as follows : 
Place a mat with the proper opening upon the collodion pic- 
ture, and with a pointed style go round the picture, cutting it as 
it were from the glass. All the collodion on the outside of 
this line is next removed with a piece of wood, as for instance, 
the end of a match cut to a flattened point, and made moist. 
By using this like a scraper, and keeping it moist, the collo- 
dion will gradually disappear, and the surface will be kept 
clean. The picture is afterward transferred to leather, en- 
amelled cloth, etc., by the method just described. 

Transfer Paper. 

Paper is prepared as follows for receiving the collodion 
positive. Dissolve 

Asphaltum, 3 ounces in 

Turpentine, 6 ounces. 

Boiled oil, S ounces. 

Afterward take — 

India-rubber, (belting,) .... 1 ounce. 
Camphene, 2 ounces. 

Dissolve the latter by a gentle heat, and then add it to the 
first solution. Shake the solutions well together, and then 


allow the mixture to settle for a few days. It is afterward 
decanted iiito a dish. Ordinary unruled fine paper, in pieces 
of the proper size, is floated on this hath, and afterward 
hung up to dry. By repeating the process, the paper finally 
receives a very smooth surface. It will keep for any length 
of time. With a mixture of one ounce of alcohol, and three 
drops of nitric acid, moisten both the collodion film and the 
prepared paper surface, and pour the surplus back again into 
the bottle. Dip the plate and the paper into soft water sev- 
eral times ; then, laying the plate on the table, place the pa- 
per upon the collodion positive in the manner already pre- 
scribed, in order to exclude bubbles ; press them close to- 
gether until the paper is quite smooth. The latter may now 
be raised, and removed from the glass, and dried. 



Transparent JPositivt s. 

This kind of picture is used more especially for stereosco- 
pic slides. Its application to church-windows, etc., for which 

it is so well adapted, has not yet been introduced to any great 
extent. A transparent positive may be produced either by 
means of the camera, or by direct contact of the negative. 
By means of the camera the proceeding is as follows : 

In the first place we require a good orthoscopic lens, or, 
in fact, any lens that will produce with an inserted diaphragm 
a clear, well-defined picture of a page of print, without dis- 
tortion of the marginal lines. Ascertain the length of the equal 
conjugate focus of the lens, that is, half the distance between 
the object and its image, when these are of the same size. 
Then construct a square cylinder of thin Avood, in which the 
camera can slide ; let the inside be blackened with a solution 
of ink, laid on twice. At the end in front of the lens, cut 
out an aperture of the size of the negative, leaving a ledge 
of three sixteenths of an inch all round on which the nega- 
tive can rest. Fix the negative by means of a tack or small 
pin in each corner. It is inverted laterally, that is, the 
sides have changed places, left being right, and right left ; 
and the collodion side is inwards, or facing the lens. This 
compound camera is now pointed either to a white cloud, or 
directly to the sun. Focus the image on the ground idass 
with great accuracy ; it is much more difficult to obtain the 
right focus in such work than in ordinary portraiture, and a 
microscope is invariably required to obtain a sharp and cor- 
rect copy. It facilitates the operation of focussing to find 
some small point, or mark, or wrinkle, and then to slide the 
camera in the cylinder backward and forward, until you 
think you have got the sharpest definition, and afterward to 
make the final adjustment with the microscope. Inasmuch 
as the lens is within the cylinder, all the focussing has to be 
performed by means of the sliding of the camera ; and when 


once the right focus has been found, the cylinder and the cam- 
era are firmly fastened ; and a mark is made by which at 
any time aftei'ward the adjustment can be quickly made, 
"without resorting to an independent system of focussing on 
each occasion when a transparent positive has to be taken. 

With the bright rays of the sun, and an orthoscopic lens, 
probably as much as from one to three minutes' exposure will 
be required ; whereas, with an ordinary well-corrected por- 
trait lens, the time will vary from a quarter of a minute up- 
ward. It is supposed, of course, that a small stop is used, 
so as to obtain a sharp and undistorted picture. With a 
large diaphragm, naturally a much shorter exposure would 
be quite sufficient. All the rest of the operation of collo- 
dionizing, developing, and fixing is the same as that already 
described. The picture is developed near the pane of glass 
which admits light from below. A bright, transparent pic- 
ture is particularly required in this operation ; there must 
be no fogging, and the shades must be pretty deep and dis- 

Such is a general outline of producing transparent posi- 
tives on glass, by means of the lens and camera ; but there 
are specialties that demand our attention. One of these re- 
fers in particular to the nature of the negative. A bright, 
transparent, and clear negative, somewhat less opaque in the 
shadows thanfor the common printing process on paper, is best 
adapted for the purpose in question. If a negative had to 
be specially prepared for producing transparent positives, I 
would recommend its preparation as above described, only 
giving a trifling less exposure, and using a slightly stronger 
developer. The reduction, too, must be stopped the very 
moment there is the slightest tendency to veiling. Finally 
after the negative is fixed, supposing it to be already suffi- 
ciently intense not to require any redevelopment, (which 
is a very desirable condition,) it is flowed with a solution of 
iodine in iodide of potassium for a few moments, taking care 
to keep the fluid in motion ; this operation must be very short 
in duration. Pour off the solution ; wash, and again fix with 
cyanide of potassium. This operation may be appropriately 
termed the Clarifying Operation, for the negative becomes 
quite clear and transparent, from the fact that in those parts 
where there was a tendency to a veil or fog, the reduced sil- 
ver that produced it has been converted into iodide of silver, 
and dissolved by the cyanide in the second fixing. This 
clarifying operation must be employed with extreme care, 
lest the minute details might be carried off at the same time. 


Varnishing, it is true, will also reduce the amount of density 
in the shadows, hut it does not remove any of the fogging, 
and besides this it increases the opacity of the transparent 
parts ; in short, it tends to diminish contrast. On this ac- 
count it is preferable not to varnish the negative. 

By fixing the negative in the holder with the collodion 
side next to the lens, the positive collodion picture will he 
on the right side of the glass, erect and free from lateral in- 
version. If it were fixed otherwise, then the positive would 
he on the under side of the glass, and would not appear so 
brilliant when mounted. 

Another specialty to be observed, refers to the color of 
the positive. The shadows, after reduction w T ith the proto- 
sulphate of iron, are grayish or silver-white. For viewing 
by reflected light, if they were in their proper place, they 
would be endowed with a very pleasing aspect ; but viewed 
by transmitted light, the contrast is by no means agreeable ; 
the shades are too gray. The object, therefore, is to com- 
municate to them a rich black hue. We effect this by pour- 
ing over the film a sufficient quantity of a saturated solution 
of bichloride of mercury free from acidity. As soon as the 
film is black, pour oif the mercury, and wash the plate in 

The next operation is to flow over the plate a saturated 
solution of cyanide of silver in cyanide of potassium. 

Formula No. 1. 
Cyanide of potassium, .... 100 grains. 
Rain-water, 2 ounces. 

Nitrate of silver solution, (50 grains to the ounce,) as long 
as the precipitate is dissolved. 

_ This solution, after filtration, is ready for use. Or a solu- 
tion of cyanide of copper may be substituted for the silver 

Formula JVo. 2. 
Cyanide of potassium, .... 100 grains. 
Rain-water, . • 2 ounces. 

Nitrate of copper solution as long as the precipitate is dis- 
solved by shaking. Filter as before, and use. 

The image when flowed with either of these menstrua as- 
sumes an intense black hue. The solutions can be used over 
and over again until exhausted. 

The plates are now washed carefully and thoroughly, and 
again fixed with solution of hyposulphite' of soda, but not 
with cyanide of potassium, because it reduces the silver to 


a white film again. This mode of blackening the silver film 
may be used also as an intensifier. 

When this operation is complete, the plate is washed and 
dried, also varnished, unless the slide has to be mounted with 
a glass before it, when the varnishing may be omitted. Pre- 
vious to mounting, it may be colored either on the picture 
side or on the back, by which a very rich effect is produced. 
When positives are thus colored, they are mounted with a 
plate of ground glass behind them, and thin transj^arent glass 
in front. 

For the magic lantern, the slides must be preserved as 
transparent as possible ; consequently no ground glass is 
used behind. The coloring, too, must be laid on, either be- 
fore varnishing, or afterward, very lightly and artistically, 
so as to impede the passage of the light as little as possible. 



Haying obtained a sharp transparent positive, it is evident 
that, by a reverse process, a negative may he reproduced, 
and of course as many negatives as may he required. It is 
thus that photographic negatives may he stereotyped. Xot 
only can we thus procure a matrix for the reproduction of a 
valued negative, (a proviso which ought never to be omit- 
ted,) but from such a transparent positive may be obtained 
enlarged negatives. The enlargement depends upon the ca- 
pacity of the lens of the camera. The bellows part of the 
latter admits of greater elongation and correlative lateral ex- 
pansion than that of the ordinary camera. As soon as we 
have found the distance of equal conjugate foci, as before di- 
rected, then by diminishing the distance between the posi- 
tive and the lens, we increase the distance between the lens 
and the new negative. (The transparent positive is placed 
in the opening in front of the lens, where originally the ne- 
gative was placed.) But in the same proportion as this dis- 
tance is increased, in like manner is the new negative en- 
larged. The amount of enlargement* will depend, as soon 
as the camera is arranged, upon the perfection of the lens, 
which, be it ever so good, has to be stopped down to a small 
aperture, in order to overcome spherical aberration, which 
causes distortion, and detracts from the sharpness on the 
peripheral parts. TTith the bright light of the sun there is 
no difficulty in thus obtaining a negative magnified ten times 
diametrically with such a lens, and in a very reasonable 
time. Thus a stereoscopic portrait or view maybe enlarged 
into a cabinet-sized picture or landscape, with but a small 
expenditure of time and expense. Xor is a large lens re- 
quired for this operation. The same lens with which the 
original negative was taken may be applied to the purposes 
of enlargement. In making enlarged negatives, however, we 
require particularly a greater amount or a greater intensity 

* Vide Chapter for the table of distances and niaguitudea. 


of light, so that with a given light the exposure must be so 
much the longer. In such eases, then, where the enlarge- 
ment is as great as before mentioned, it is advisable to con- 
struct a system of reflectors in front of the aperture for the 
reception of the negative or positive. 

directors used as Condensers of Light. 
Let the aperture for the negative, etc., be four inches 
square; then construct a frustum of a pyramid out of four 
pieces of silvered glass, of the following dimensions : The nar- 
row end of each piece is four inches, the broad end is 14-^ 
inches; the length of either side is 21 T i v 6 ?r inches. Fix these 
pieces of glass in a tin frame, with the silvered side inward, 
and attach the frustum to the aperture for the negative. 
When the latter or a transparent positive is in its place, 
turn the camera (which for this purpose must be fixed upon 
a universal joint) toward the sun ; it will be found that the 
intensity of the light has been greatly increased. Such a 
condensing reflector is calculated to condense all the rays 
that Ml upon it, either by one or two reflections, so that 
they all fall upon the negative. But the amount of light 
that impinges directly upon the larger base of the frustum 
is at least thirteen times greater than that which falls upon 
the smaller base; and if there were no loss of actinic power 
by reflection, the light condensed on the negative would be 
thirteen times more than would impinge upon it without the 
aid of the condensers. If then the light be increased by ten 
times in intensity, and the picture be enlarged by ten times, 
the time of exposure would remain the same. 



Ixthis operation, as in the preceding, a very bright, sharp, 
clear negative is required. Transparent positives by direct 
contact are obtained best by dry collodion plates ; they can, 
however, be prepared as follows : Let the negative be var- 
nished and thoroughly dry. Place it in the plate-holder, as 
you would the sensitized collodion plate. Next cut out a 
piece of thin writing-paper of the same size as the negative, 
and then cut out of this an interior piece of the same shape, 
thus leaving a margin all round of about a quarter of an inch 
in width. Place the marginal rectangle upon the negative, 
and see that it lies in contact all round. Now prepare a col- 
lodion plate ; sensitize it, and allow it to drain thoroughly ; 
then place it also in the plate-holder, and in contact with the 
margin of paper, and close the slide and shutter. Previously 
a cylinder of thin wood, blackened with ink within, is pre- 
pared with grooves at one end for the reception of the plate- 
holder, and open at the other extremity for the reception of 
the light. Such a cylinder may be six feet in length. The 
object in view is to obtain only direct and parallel rays of 
light, to counteract the effect arising from the imperfect con- 
tact between the wet plate and the negative. Direct the 
open end of the cylinder to a white cloud, and then draw 
the slide for a moment, that is, a fraction of a second, ami 
close it again. Probably this maybe too much qp>osure, in 
which case it will be well to paste a sheet of white paper 
over the -end of the cylinder, in order to moderate the action 
of light. The plate is afterward taken out, developed, black- 
ened, and fixed, as already described. 

On removing the plate from the holder, the marginal pa- 
per will probably adhere to the wet collodion ; if so, remove 
it carefully, and lay it on a flat surface to dry. It is possi- 
ble too, owing to the inequality of surface, that the negative 
has been wetted by the superincumbent wet plate, in which 
case it must be carefully washed in rain-water, and dried. 
Without the long cylinder, oblique rays would enter from 
all sides, and destroy all the sharpness of the picture by pro- 
ducing thick lines out of thin ones. TVnereas in the man- 
ner prescribed, vertical rays alone are admitted to the bot- 
tom, and entering perpendicularly are not refracted. 



In this chapter will be described the method of copying 
photographic or typographic prints. Three things are abso- 
lutely requisite in order to secure a good copy ; these are, as 
before, a good lens, good light, sharp focussing. 

For the purpose of copying I invariably use the full blaze 
of the sun. Some artists pretend that the system is false. 
They take their ideas from the effects produced on solid ob- 
jects, where the contrasts are so immensely exaggerated ; 
and they do not bear in mind that on a flat surface there can 
be no shadows, because there are no prominences. All the 
contrast that can possibly be obtained in the copy, exists al- 
ready in the original. 

Upon a light built table or board, two inches wider than 
the camera, nail down on either side a ledge of wood, within 
which the camera can slide longitudinally. At one foot's 
distance from one end erect a piece of board of the same 
width as the long board, and a foot high ; let it be fixed per- 
pendicular to the board and to the direction of the ledges, 
by means «*' triangular braces near the end of the long board. 
On the side fronting the camera, construct two beveled 
ledges, one on either side, perpendicular to the base-board, 
of half-inch material ; within this a piece of half inch board, 
six inches wide, is correctly adjusted by planing, so as to 
slide up and down with facility ; on its surface on cither side 
is a similar bevelled ledge running horizontally, in which an- 
other thin piece is made to slide with ease. This last piece 
is the holder of the print to be copied. By the construction it 
will be seen that the holder admits of motion vertically and 
horizontally, and that thus the print can be accurately ad- 
justed in a correct position in front of the lens, so that the 
center of the print and the axis of the lens coincide. The 
print, too, will thus be parallel with the ground glass in the 
camera. Small slips of tin plate are screwed on the surface 


of the holder, in order to clamp down the print, and to pre- 
vent any unevenness on its surface by cockling from the 
heat. Pins or tacks are inadmissible here, because of the 
shadows produced by them on the print to be copied. As 
soon as this mechanical contrivance is complete, slide the 
camera up to the holder, and adjust the latter so as to bring 
its center in front of the cap of the lens, and with a pencil 
draw a circle around the cap and upon the surface of the 
holder. Whilst the slides are in this position, mark the verti- 
cal and the horizontal slide, so that at any time afterward the 
holder can be brought into position with great facility. The 
holder is now taken out, and the print to be copied is fixed, 
so that its center coincides as near as can be with the cen- 
ter of the circle ; it is placed upside down, so that its four 
boundai'ies are vertical and horizontal. Now slide the print- 
holder into its place, and slide back the camera until the pic- 
ture on the ground glass is of an exactly equal size with the 
original. A microscope is required in this operation, in or- 
der to focus with the utmost accuracy. Do not despise the 
microscope, it is almost indispensable. Focus whilst the sun 
is shining upon the picture. Use a very small stop. Let the 
sun shine from one side slightly, with your back turned to- 
ward this orb. The most agreeable time to copy by this 
method is early in the morning ; the light is then clear, and 
by turning the table on one side, the rays illumine the object 
very brilliantly, and without any haze ; turn the table always 
so that no shadow of the camera or lens falls upon the ob- 
ject. As long as the sun shines, you can thus cojw, and copy 
perfectly ; the morning hours being personally more agree- 
able, photographically perhaps not as effective as toward noon. 
The time of exposure will vary according to the power of the 
lens, the size of the diaphragm, and the magnitude of the 
copy. With a lens of three inches focus, of C. C. Harri- 
son's manufacture, with a diaphragmatic aperture of one third 
of an inch, and when the copy is equal to the original, an ex- 
posure of fifteen seconds will produce a rich negative. The 
same conditions remaining, the one fourth orthoscopic lens of 
Voightlaender, whose focus is about twelve inches, will re- 
quire an exposure of between two and three minutes to pro- 
duce the same effect. 

By the first-named lens, an ambrotype or nielainotype will 
require only two or three seconds. 

By adhering cautiously to the rules prescribed, and above 
all things by very accurate focussing, and by taking care that 
the surface of the photograph, plate, or print is perfectly 


smooth, and in a plane parallel with the ground glass, copies 
can be obtained that can scarcely be distinguished from the 
originals. But a very slight undulation on the surface of 
the print, or deviation from parallelism is sensibly observ- 
able when the conjugate foci are equal, and much more so 
when the copy is amplified. The camera, when once ad- 
justed for the day, is strapped down firmly to the board, so 
that the conditions of focussing can not be altered by insert- 
ing the tablet, etc. It is necessary to cover the whole cam- 
era, and especially the posterior opening, with a dark cloth, 
lest a single ray might penetrate into the interior. Close 
the lens always with the cap before you take out or put in 
the slide, because it is easier to move the cap than the slide. 
After the slide has been taken out, wait until all oscillation 
or vibration has ceased, before you remove the cap. Per- 
form all your motions in this operation firmly, but with gen- 
tleness, not roughly and in haste. Whilst the ground glass is 
out, place it where no reflection can interfere with the print 
to be copied. The board on which the camera slides, as also 
all the other parts, had better be stained black, or of some 
neutral tint. 

If the light of the sun could be directed through a long 
cylindrical opening, and then applied directly to the illumin- 
ation of the print, without interference from reflections in all 
directions, the operation would be neater and more effectual. 

Where copying has to be performed by diffused light, this 
light must be small in quantity, proceeding from a single 
pane of glass, as reflected from a white cloud or a white 
sheet, and all reflections must be carefully avoided. The 
management of the light in copying is reduced to very sim-' 
pie conditions — a single light is all that is required — no more 
contrast is required ; see that none is communicated by unne- 
cessary and extraneous shadows from neighboring bodies, 
caused by secondary light. A single light, where there are 
no bodies in its direction to the print, will produce no shadow, 
consequently all shadows must proceed from secondary lights ; 
shut up, therefore, every aperture, excepting the one which 
is to illumine the print or type to be copied. These precau- 
tions will bring with them success ; the neglect of them will 
cause you to quit copying with disgust for want of success. 
With such a contracted light, the "illumination can not by 
any means approach that produced by the direct rays of the 
Sun ; the consequence will be firstly the necessity of using a 
large diaphragm, and of thus diminishing the sharpness of 
the copy ; and, secondly, of increasing the length of the expo- 


sure. The difference of illumination in copying and in di- 
rect portraiture is very distinct ; for the latter purpose a 
single light without reflection will not, can not succeed; 
whereas for copying, more lights than one would be not only 
so much more than sufficient, hut at the same time probably 
in most cases injurious. Do not, therefore, confound the 
two operations, and blame the light for your mismanagement 
of it, for in nine cases out of ten your want of success is to 
be attributed to this mismana cement. 



Hereafter I shall devote a chapter to the stereograph 
and its philosophy ; in this I shall simply give plain instruc- 
tions for taking the stereoscopic negatives by the wet collo- 
dion pi'ocess. For in-door work, and for out-door scenery where 
the objects are close at hand, a camera is required, which is fur- 
nished with two lenses of short focus, and of exactly equal 
power, for the production of stereoscopic negatives. These 
lenses are fixed in the same horizontal line ; and about two 
inches and a half is the distance between their centers. Each 
lens can be attached to a separate slide, so that this distance 
can be slightly increased to two inches and three quarters, 
if found necessary. In the camera there is a vertical septum 
in the middle which divides it into two halves, one for each 
lens. This septum is nearly in contact with the collodion, 
and consequently makes a division line between the two 
images, which are taken on the same glass. The glasses for 
stereoscopic negatives are seven inches long by three and a 
half wide ; I should prefer them eight inches by four, in or- 
der to have room for blunders and mishaps on the edges. 
The operation of focussing is the same here as before, only 
that there are two lenses to be adjusted. Fix upon a cer- 
tain object which is to be the central or most important one, 
and turn the camera so that it is seen in the center of one of 
the picture's of the ground glass. Where architectural ob- 
jects occur in such pictures, the camera must be perfectly 
horizontal, if you intend the vertical lines to be vertical in 
the negative. If it happen that such architectural objects 
can not easily be comprehended in the negative, without tilt- 
ing the camera, use this expedient ; for, after all, the distor- 
tion which it produces on the print can be rectified in some 
measure afterward, by tilting the print in the stereoscope to 
the same amount. If portraits are to be the principal things, 
they must be placed in such a position artistically and photo- 
graphically as to appear well, and at the same time in perfect 


focus; if certain objects are to be preeminent in esteem, di- 
rect your attention upon them when focussing, and regard the 
rest as secondary ; and finally, if the whole landscape is the 
object, divide up the focus, or focus in such a manner that 
the view as a whole is tolerably sharp ; this can easily be 
done by focussing an object at some distance, and by exclud- 
ing all near objects from the print. In such cases, however, 
Ave require long-focussed lenses. For in-door operations the 
portrait combinations are used ; for landscapes a pair of trip- 
lets, or of ordinary view lenses, produce excellent results. 
The globe lens of C. C. Harrison is all that can be desired 
for field work ; it comprehends a larger angle than almost any 
other lens, and produces an irreproachable picture. Ross, Dall- 
meyer, and Grubb manufacture stereoscopic lenses for land- 
scape photography, with which instantaneous pictures can be 
produced, and which in all other respects are highly com- 
mended by the intelligent amateurs of Great Britain. Jamin's 
view-lenses produce very neat results, and are besides lower 
in price than those already alluded to. 

In the ordinary stereoscopic negative, as in every negative, 
the pictures are laterally inverted, and when printed, this in- 
version is corrected only for each picture individually, for 
the right-side picture is still inverted and in the place of the 
left-side picture. In consequence of this, the printed stereo- 
graphs have to be cut apart, and moimted so that the right- 
hand photograph is placed on the right side, and the left- 
hand photograph on the left side. When taking pictures of 
still life, as also others, where the living objects are not in 
motion, it is very easy to manage matters so as to invert the 
photographs on the negative. The method is as follows : 
Take a large-sized camera-stand, allowing sufficient space 
for the camera to slide laterally. Placing the camera in the 
right-hand corner, focus the left-hand lens. Next slide the 
camera gently, or lift it up and place it in the left corner, 
and focus the right-hand lens. The space between the cen- 
ters of the two pictures thus focussed must be about two 
inches and three quarters. Whilst the camera is in this posi- 
tion on the left side, insert the sensitized plate, take out the 
slide, uncover the right-side cap for a second or two, and 
take this picture. Then close up the lens, lift up the camera 
gently and place it on the right side. In this position un- 
cover the left-side lens for the same length of time. In this 
way, and in the space often seconds or so, , the two pictures 
can be taken in a proper condition for printing so as to pro- 
duce a non-inverted stereograph. For such work it would 


be no difficult task to contrive a slide by which a single lens 
would be all-sufficient; that is, when the camera is on the 
left side, the lens must slide to the right side, and vice versa 
on the right side. 

As soon as the negative is thus taken, it has to be devel- 
oped before it gets dry. The development and fixing can 
be performed in a dark tent specially arranged for such pur- 
poses. Various contrivances have been adopted in landscape 
photography for these operations. For my own part I con- 
sider a simple hand-cart, with iron rods from corner to cor- 
ner diagonally, in the form of semi-ellipses, and covered with 
a balloon-shaped tent, a very practical accommodation. But 
each successful photographer is somewhat of a genius, and 
can easily arrange a dark chamber according to his own taste 
and materials on hand. 

Negatives thus taken and fixed are placed carefully away 
in slides where they can not be injured during transport- 
ation home. In the evening, or the next day, or at any con- 
venient time, the negatives are examined; if clear, transpar- 
ent in the lights, and sufficiently intense in the shades, they 
are varnished. On the contrary, if the opacity of the shadows 
is not deep enough, although the appropriate gradation ex- 
ists between the lights and shades, it will then be deemed 
necessary to proceed to intensification. Previously the edges 
of the negatives must be varnished to the depth of one tenth 
of an inch upon the collodion, to prevent its peeling off dur- 
ing the operation. This is effected by dipping the quill end 
of a feather into the varnish, and then running along the 
edge of the collodion and of the glass, with this portion of 
the feather slightly inclined, so that the varnish does not drop 
off, a sufficient quantity is attracted upon the collodion as you 
proceed. After this put the negatives aside, that the varnish 
may become thoroughly dry and hard. As soon as it is dry, 
immerse the plates in rain-water, and allow them to remain 
there for about a quarter of an hour, by which time the col- 
lodion film will have become saturated with this fluid. Now 
you may commence the intensifying process, as before de- 
scribed in the chapter on collodion negatives. 

Instantaneous StereograjyJis. 
There is no branch of photography that has so intensely 
attracted the attention of wealthy and intelligent amateurs 
as that of stereography ; on this account we owe to them 
most of the discoveries in the art ; and the new incitement 
that has arisen hi this department, that of Instantaneous Ac- 


tinsim, has communicated a new impulse from which -we de- 
rive fresh deductions and new results. The co-laborers in ste- 
reographic pursuits in Europe, but more especially in Great 
Britain, beginning with royalty downward to the rural gen- 
try, are very numerous, very intelligent, and, best of all, very 
commtmica&ive. They take out no patents for their discov- 
eries, they make no commerce with secrets, odious things 
which noble minds eschew. It is to such a goodly host of 
fellow-soldiers in the stereographic camp that we must attri- 
bute the riches of our knowledge. That light can act acti- 
nically in the twinkling of an eye is no tax upon cultivated con- 
ceptions ; for in this same wink, which to us is instantaneous, 
Light has run round the earth several times ; in this twink- 
ling, Light has seen more than man in his age can ever see ; 
in this twinkling, millions of fresh portions of light have 
impinged on the model, and have rebounded to the lens and 
through it, and have nestled upon the sensitized film — we 
are justified then in expecting that instantaneity in photo- 
graphy is feasible. The sole questions present themselves : 
What film is sensitive enough to receive it ? What deve- 
loper refined enough to produce the reduction ? The ques- 
tions are answered by facts. Instantaneous stereographs ex- 
ist in great number, and the artists that produced them have 
bequeathed to the public their modus operandi. I can not 
do better than quote a few instantaneous processes. All 
amateurs agree in certain particulars, which conduce to suc- 
cess. The light must be very bright y the atmosphere very 
clear ; the glass very clean y the collodion very ripe ; the de- 
veloper very sensitive, and the lens very well corrected^ and 
capable of producing a sharp picture with a large diaphragm; 
the shorter the focus the better within proper boimds. 

Instantaneous Process of Lieutenant- Colonel Stuart Wbrtley. 


Ether, 1 ounce. 

Alcohol, spec, grav., .802, . . . 2£ ounces. 

Iodide of lithium 15 grains. 

Bromide of lithium, \ grains. 

The pyrovyline is first steeped in the iodo-bromized alcohol, 
and the ether then added. 

Silver Path. 

Re-crystallized nitrate of silver, . 35 grains. 
Distilled water, 1 ounce. 

Iodized by leaving a couple of coated plates in the bath for 
several hours ; acidified at the rate of from two to three 


drops of nitric acid to the ounce of bath. Leave the plate 
in the bath longer than you would if the collodion contained 
only iodine. 


Sulphate of iron, 2 ounces. 

Distilled water, 12 ounces. 


Acetate of lead, 24 grains. 

Water, 2-£ ounces. 

Mix the above solutions, and when the precipitate has all 
settled, decant oft* very carefully, and then add : 

Formic acid, (pure,) 2| ounces. 

Acetic ether, 6 drachms. 

Nitric ether, 6 drachms. 

From this stock-developing solution take as much as is re- 
quired, and add acetic acid, according to the temperature, gen- 
erally in about the same quantity as the formic acid. The 
developer is kept on the plate until the necessary detail is 
brought out ; after which the plate is well washed and fixed 
with a weak solution of cyanide of potassium. 

Pour on a saturated solution of bichloride of mercury ; as 
soon as the proper color is attained, the plate is thoroughly 
washed, and a five-grain solution of iodide of ammonium in 
water is poured on and oft* until the desired depth has been 
attained. (The reader will comprehend the rationale of this 
proceeding by carefully perusing my remarks on this subject 
in a preceding chapter.) After this the following solutions 
are used : 

No. 1. Pyrogallic acid, .... 12 grains. 

Water, 1 ounce. 

No. 2. Citric acid, 50 grains. 

Nitrate of silver, .... 10 grains. 
Water, 1 ounce. 

Pour a few drops of No. 2 into No. 1, and pour on and off , 
until the negative has assumed the required density. After 
which wash the plate thoroughly in several waters, dry and 

Valentine JBlanchard prefers a bromo-iodized collodion, 
although under certain conditions he admits that a simply 
iodized collodion is more rapid, but at the same time there 
is less contrast. The silver bath is composed of re-crystal- 


lized nitrate of silver, forty grains to the ounce of distilled 
water, and saturated with iodide and bromide of silver. It 
is always supposed to be acid, to which is added a small quan- 
tity of moist oxide of silver ; after the solution has been suf- 
ficiently agitated, it is filtered, and then acidified by a weak 
solution of nitric acid, containing three or four drops of acid 
to one hundred of water. This acid solution is added very 
cautiously, until the picture is quite clear and free from fog- 
ging. A bath so prepared is very sensitive whilst new, and 
it is only whilst new that any bath is likely to produce in- 
stantaneous results. 

The developer consists of the sulphate of the protoxide of 
iron, generally thirty, and frequently fifty grains to the ounce 
of distilled water, acidulated with glacial acetic acid, because 
the ordinary acid contains impurities. 

The negatives, when they require it, are intensified with a 
saturated solution of bichloride of mercury in cold water, 
until the film is of a uniform gray color ; they are then washed 
and treated with a solution of iodide of potassium, (one grain 
to the ounce of water,) by pouring it on and off, until the 
film assumes a greenish-slate color. There should be no 
greenish hue on the wrong side of the plate, for this is an in- 
dication that the strengthening has been carried too far. 

Hockins uses simply iodized collodion; his bath contains 
thirty grains of nitrate of silver to. the ounce of distilled 
water, and is iodized by throwing in a proper quantity of 
iodized collodion ; it is then filtered. Two minims of pure 
nitric acid are added to each eight ounces of the bath, which 
is prepared twenty-four hours before using. 

The developer consists of 

Formic acid, (strong,) .... 2 drachms. 

Pyrogallic acid, 20 grains. ; 

Distilled water, 9£ ounces. 

Alcohol, i ounce. 

This is kept on the plate until the operation is complete. 

Claude? s Developer. 

' Pyrogallic acid, 20 grains. 

Distilled water, *7£ ounces. 

Formic acid, 1 ounce. 

Alcohol, 6 drachms. 

Instantaneous Shutters. 
The means by which light is cut off instantaneously, which 
means very quicldy, are various, and many of them are very 
ingenious. Some of these shutters are behind the posterior 


combination in the lens, and are so graduated for other than 
instantaneous purposes as to give a shorter exposure to the 
sky than to the foreground. For my own part I prefer sim- 
plicity, and I use means in which I have been anticipated by 
Wilson and others. My cap is my shutter. Sometimes I 
use a book. With both I have succeeded, and naturally sup- 
pose others can do the same. I do not despise the ingenious 

In very many cases, w T ith all the preparations in a normal 
condition, as we suppose, success does not attend our ma- 
nipulations. There is still, therefore, a yearning for some 
method more reliable. I have frequently succeeded in taking 
instantaneous positives, that could not be intensified into »e- 
spectable negatives. But from a collodion positive we know 
that a collodion negative can very easily be prepared by 
copying. In this way many a well-valued view is obtained, 
which otherwise would have to be sacrificed. On such oc- 
casions, therefore, where there is the least doubt of success, 
it is advisable to develop with the ambrotype developer, con- 
taining nitrate of potassa, nitrate of silver, and free nitric 
acid — the latter, however, in very minute quantity. We shall 
thus probably obtain a good collodion positive on a melaino- 
type or ferrotype plate. This is afterward carefully copied 
into a negative. In several instances I have obtained a tol- 
erable effect by using solution of sulphate of iron without 
any acid. 



These comprehend the Talbotype or Calotype, and the 
Wax-Paper Process of Legray, and its modifications. 

Tlie Talbotype or Calotype Process. 

This process is a negative on paper. Talbot published, six 
months before the discovery of the Daguerreotype, his pro- 
cess with the chloride of silver ; and the year following the 
Calotype, or, as it is now frequently denominated, the Talbo- 
type, was made known. The object is to obtain a deposit or 
film of iodide of silver of a fine and even structure upon the 
surface of paper. The best paper for this purpose is of the 
English manufacture, being sized with gelatine, the foreign 
papers being sized with starch. 

There are two methods of iodizing : 

1st. Float the papers on a solution of iodide of potassium, 
and allow them to dry ; afterward float them on a solution 
of nitrate of silver. By double decomposition, a film of iodide 
of silver is formed on the surface in contact with nitrate of 

2d. Add a solution of iodide of potassium to one of ni- 
trate of silver. Collect the yellow precipitate, and dissolve 
it in a strong solution of iodide of potassium. The paper is 
floated for a moment upon this solution and dried. It is 
then floated upon water which decomposes the salt, and 
precipitates the iodide of silver in a very finely divided state 
on the surface of the paper. The sheets of paper are then 
dried. Their color is a pale yellow, and they are as yet not 
sensitive to light. 

To Sensitize Calotype Paper. 
Float the papers, or rather brush over their surfaces a so- 
lution of nitrate of silver, containing both acetic acid and 
gallic acid. Acetic acid acts here as elsewhere: it diminishes 
the energy of the decomposition ; it preserves the whites of 
the paper. 


The Talbotype process in more definite terms stands as 
follows : 

Float the paper in the following solution for a minute : 

Nitrate of silver, 60 grains. 

Distilled water, 2 ounces. 

Hang up the paper in a dark room to dry. ISText float it in 

Iodide of potassium, 1 drachm. 

Distilled water, 2£ ounces. 

for ten minutes ; afterward it is soaked in water for an hour, 
in order to remove the excess of iodide, and then dried. It 
is sensitized by brushing over it the following solution : 

Nitrate of silver, 25 grains. 

Distilled water, 4 drachms. 

Glacial acetic acid, 1 ounce. 

Saturated solution of gallic acid, . 1^ ounces. 

In a few seconds the excess is allowed to flow off, and, af- 
ter draining, it is placed between folds of blotting paper, 
when it is ready for immediate use. If the sensitized paper 
has to be kept some time, a much weaker solution of gallo- 
aceto-nitrate is used than that just prescribed. To every 
ounce of the above solution add' from thirty to fifty ounces 
of distilled water, according to the temperature of the cli- 
mate and the time it has to be kept. 

An exposure of the paper in the camera whilst still moist 
for a second or two will produce a latent image, which is de- 
veloped in full intensity by washing the paper with a mix- 
ture of four parts of the saturated solution of gallic acid, and 
one part of a solution of nitrate of silver, (50 grains to the 
ounce of water.) The image soon begins to appear, and is 
fully developed in a few minutes. 

Fixing of the Negative. 

Immerse the prints in a solution of bromide of potassium 
often grains to the ounce, or in one of hyposulphite of soda, 
as was afterward indicated by Sir John Herschel, of one 
part of the salt to ten parts of water, until the yellow iodide 
has been completely removed. The prints are finally washed 
in many waters, dried and saturated with white wax, which 
renders them transparent. 

Several distinguished photographers have improved upon 
this calotype process, amongst whom we may mention Blan- 
quart-Evrard, Legray, Baldus, Geoffray, Tillar'd, etc. Amongst 
all these improvements and extensions the wax-paper process 
of Legray is the most extensively employed. For tourists 


it presents undeniable advantages in portability of material, 
and less liability to fracture. The wax, too, is a decided pre- 
servation of organic matter against the action of nitrate of 

Wax-Paper Process of Legray. 

This is the simplest of all the processes for taking negatives 
on paper. It differs from the calotype, inasmuch as the paper 
is first waxed before sensitization in Legray's process, where- 
as in Talbot's the waxing part of the operation is the last. 
The paper suitable for this process must be thin, compact, 
homogeneous, when viewed by transmitted light, and the 
sizing of the paper must have been carefully performed. The 
English papers, although perhaps the finest, are not suitable, 
from the fact that they have been sized with gelatine, which 
presents great difficulty in the waxing. Saxony negative 
paper is considered the best. 

Waxing of the Paper. 
Obtain pure white wax from the bleacher's, or, in case this 
can not be procured, make use of the purest yellow wax that 
can be had. Next prepare a water-bath in which water can 
be kept boiling, either by lamps or a charcoal-fire. On the 
lid of the water bath place a porcelain or metallic plate, and 
when hot, rub the surface with the wax until it is covered 
uniformly with a layer of melted wax. Place upon this a 
piece of paper to be waxed. Rub its surface in like manner, 
until it is uniformly covered and transparent ; and proceed in 
this manner until a pile of eight or ten papers is thus formed. 
If the dish is sufficiently large, place a piece of paper by the 
side of the pile, and then if the uppermost paper on the pile 
is quite transparent with Avax, place it upon the dry paper ; 
upon this place another sheet of unwaxed paper, and then on 
this the second one from the pile, and proceed thus until all 
the waxed papers are interleaved with dry sheets. The in- 
tention of this operation is to get rid of the excess of wax. 
Repeat this operation until the object is effected. Use a pad 
of cotton, and gentle pressure on the top of the pile as you 
proceed, but be very careful not to make a single crease, 
otherwise the sheet in question is utterly spoiled. As soon 
as the paper ceases to shine from the melted wax, it is time 
to stop any further removal of wax. The sheets of paper, 
that have served as interleaves, may be used in the prepara- 
tion of the next batch of waxed papers. The papers thus 
prepared are separated, and when the wax has congealed in 


their fibrous structure, they are put away for future use be- 
tween plates of clean glass. 

Iodizing of the Paper. 

Formula of Legray. 

Rice-water,* 25 ounces. 

Sugar of milk, 1 ounce. 

Iodide of potassium or ammouium, 3 drachms. 
Bromide of potassium, .... 48 grains. 

Mix, dissolve, and filter. It is necessary to be supplied 
with an abundance of this bath, in order that the papers can 
easily be submerged, in which there is considerable difficulty 
by reason of the fatty nature of wax. This bath can be pre- 
served a long time if kept, after using, in well-stoppered bot- 

"When about to use this bath, pour it into one of the deep 
dishes employed in other operations in photography, such as 
for albumenizing or for toning, and let it be two or three inches 
in depth when poured in. 

Take each paper by two opposite diagonal corners, and 
bending it into a hollow curve, immerse first one of the two 
other diagonal corners, and then the other ; move the paper 
backward and forward, so as to get the fluid over it, grad- 
ually lowering the two corners held in the hands. Finally, 
by means of a glass triangle or bent glass rods, press the 
sheet entirely beneath the surface of the liquid, and re- 
move all bubbles. Proceed in like manner with all the 
rest, carefully avoiding all bubbles between the papers. In 
about two hours the papers will be sufficiently impregnat- 
ed with the iodizing solution ; after which they are taken 
out singly by first raising one corner with a glass rod, and 
then seizing this with the left hand, it is removed from the 
liquid and allowed to drain for a moment, and finally hung 
upon varnished hooks to dry; or the papers maybe susijend- 
ed on a line by clamping each upper corner by means of a 
elothes-pin. Great care is required so as not to produce any 
wrinkle or crease in the papers in any of these oj^erations. 
Several iodizing solutions have been proposed ; the following 
with ichey or serum is found to work well. 

* Take seven ounces of rice and bruise it ; then boil it in seven pints of 
rain or distilled water. As soon as the rice yields beneath the fingers, the 
boiling has been carried on far enough. The" water is decanted, and to this 
are added forty-sis grains of isinglass to each pint of rice-water, and the mix- 
ture is again boiled. 


Whey* or serum, 23 ounces. 

Sugar of milk.f 4 drachms. 

Iodide of potassium, . . . . 3 drachms. 
Bromide of potassium, .... 48 grains. 

To the first of the two preceding formulas, containing rice- 
"vrater, which is that of Legray, the author of the process 
was in the habit of adding a small quantity of the cyanide 
and fluoride of potassium, which are regarded now as of 
little or no consequence. 

When removed from the iodizing bath, the papers have 
changed their appearance ; they are now in a spongy condi- 
tion and devoid of transparence ; hut by heat they may be 
restored to their original state. They frequently assume a 
violet color. When dry, the sheets of paper are placed one 
over the other, between pieces of blotting-paper, and packed 
in a well-closed card-board box for future use. 

Sensitization of the Paper. 
The alkaline iodide in the Avaxed paper is converted into 
iodide of silver by immersing the sheets in the following 
aceto-nitrate of silver bath: 

Re-crystallized or pure nitrate of silver, . . . *l drachms. 

Glacial acetic acid, V drachms. 

Distilled water, 12 ounces. 

Filter the bath into the appropriate dish and sensitize one 
sheet at a time, or at least do not place one sheet over an- 
other, and take care to break up all bubbles on the surface 
of the wax-paper. After remaining two or three minutes 
in this bath, each sheet is taken out, immersed in a dish of 
rain-water, well washed, and then immersed in a second. 
Afterward it is taken out, allowed to drain, pressed between 
folds of bibulous paper until it is no longer wet, but simply 

* Whey is obtained by boiling a couple of quarts of skimmed milk, and 
then adding, as soon as it 1 >egins to rise, acetic acid drop by drop until the curd- 
ling or coagulation is complete. The whole is then poured into a muslin bag 
and filtered. When it has cooled down to about 100° or blood heat, the white 
of an egg well beaten is added and stirred up. The liquid is again made to 
boil, and by the coagulation of the albumen, the whey becomes clarified. It 
is filtered a second time, and is then ready for use. 

f Sugar of milk is concentrated whey, or that part which crystallizes when 
whey is evaporated to a syrupy consistence. This sugar of milk, or laetin, 
as it is also called, is purified by animal charcoal and again crystallized. It 
forms white, translucent, four-sided prisms of great hardness. It is solu- 
ble in five or six times its weight of cold water ; its taste is feebly sweet, anil 
feels gritty between the teeth. It enters into combination with the protox- 
ide of lead, and is converted into grape sugar by boiling with dilute mineral 
acids. It can be made to ferment, but does not do so spontaneously. 


moist. In this condition it may be placed between two 
pieces of clean glass and exposed immediately, or it may be 
gummed along the edges, and then pasted upon a sheet of 
card-board and dried for future use. 

De Champlouis has introduced an improvement into this 
part of the process. As soon as the sheets are removed 
from the aceto-nitrate bath, each is placed whilst still moist 
on the glass destined to receive it in the plate-holder ; it is 
then carefully pressed on the surface by means of a small 
piece of sponge, in order to expel any bubble of air which, 
by remaining between the paper and the glass, might pro- 
duce uneven reductions. On the sensitized paper a sheet of 
blotting-paper is in like manner applied by the sponge, and 
afterward a sheet of wax-paper or wax-cloth, which sub- 
serves the purpose of a final pressure. These two sheets 
must be thoroughly moistened with distilled water ; they 
form a sort of cushion, which is pressed together by a second 
glass of the same dimensions as the first. The whole arrange- 
ment may then be placed in the plate-holder, for it is ready 
to receive the view immediately, or at any time within twelve 
days. By this expedient the paper dries very slowly from 
the edges to within. No washing is required before ex- 
posure, which is a great saving of time. 

Iodized wax-paper, whatever may be its color before, 
whether yellow, reddish, or violet, is very quickly bleached 
in the silver bath. 

Exposure to the Vleto, etc. 

The sensitized sheets, however prepared, must be pro- 
tected against all access of light, otherwise they will be 
utterly spoiled. There are changing-boxes to be had for 
the reception of waxed paper sheets as also for dry plates ; 
these are so arranged as to contain a certain number of 
sheets or plates, and to expose one at a time without any 
injury to the rest. "Without such an arrangement, the tour- 
ist will be obliged either to have as many plate-holders as 
plates, or to have a small dark-chamber in which the hands 
can make the requisite changes by feel. The time of ex- 
posure of course is variable, according to temperature and 
the brilliancy of the light. Two or three minutes in a good 
light will in general be sufficient ; in ordinary light on an 
average from ten to fifteen minutes will be required. 

Development of the Image. 
This operation may be performed right away or any time 
within twenty-four hours. In extreme cases the develop- 


raent may be postponed for a week ; but the best results are 
obtained by developing immediately after exposure. The 
image, as a general thing, is not visible when taken from the 
plate-holder, excepting, perhaps, in parts especially where 
the paper has been well washed. The most constant de- 
veloper is that of Crookes. 

Heat in a glass flask twenty fluid ounces of concentrated 
alcohol to near the boiling point, and then add four ounces 
and a half of gallic acid ; Alter this solution into another 
vessel containing seventy-two grains of glacial acetic acid. 
This forms the stock solution of gallic acid which will keep 
for an indefinite time. It has a brownish color, but it is 

When about to develop a picture, measure out two fluid 
ounces of rain-water, to this add half a drachm of the alco- 
holic solution of gallic acid and seven minims of a solution 
of nitrate of silver containing eighty-six grains to the ounce 
of water. 

The. sheets of paper are kept submerged in this bath for 
about half an hour, by means of the glass rod or triangle, 
when the development will be complete, which must be de- 
termined by experience. 

De Champloms develops as follows : 

In the first place the paper is previously passed through 
the silver bath, in order to restore its humidity, if it is al- 
ready dry ; it is next placed on a plate of window-glass and 
floated witli a thin layer of gallic acid solution ; the image 
appears with great rapidity, owing to the quantity of silver 
in the moistened paper; notwithstanding this, the operator 
can easily follow the development. By pursuing this plan, 
.spots and other mishaps are avoided. 

Whichever plan is pursued, the temperature must always 
be at about 80° ; the developing solutions can be used only 
once, and are then accumulated and reduced. Whilst the 
paper is developing, a dirty deposit appears gradually to 
cover its surface ; it need not, however, cause any anxiety. 
The surface, too, becomes spongy and porous after develop- 
ment — a condition which is removed afterward. 

If the exposure has been too short, the image is very slow 
in appearing, unless an excess of aceto-nitrate of silver be 
used, and even then there is a want of vigor, and especially 
of the middle tones. Such a negative will produce only 
blacks and whites in the positives printed from it. 

If, on the contrary, the time has been too long, the surface 
presents a red tint, and the development commences with 

178 :n-egatiyes ox paper. 

great rapidity on every part simultaneously, and soon as- 
sumes a uniform shade which takes away all contrast. For 
this there is no remedy ; so that a short exposure is prefer- 
able, because a certain degree of vigor in the latter case, as 
well as contrast, can in general be obtained. The develop- 
ment is to be observed, as it progresses, by transmitted light, 
otherwise you might be deceived by the gray deposit already 
alluded to, and think the negative spoiled. 

If the time has been about right, the print will appear 
possessed of the right gradations of light and shade, and of 
proper density of shade. As soon as the darkest parts are 
so opaque as to prevent an object from being distinguished 
through them, the development may be considered complete. 
All further action is then stopped by immersing the nega- 
tives in water and washing it well by agitation, or by plac- 
ing it on a plate of glass and then washing it from the tap, 
first on one side and then on the other. 

Fixing of the Image. 
This is effected by allowing the paper to remain for a 
quarter to half an hour in a solution of 

Hyposulphite of soda, 2 ounces. 

Rain-waler, 16 ounces. 

or until all the yellow color on the white parts has disap- 
peared. The print is then well washed as before, and finally 
left in a vessel of water for a number of hours. Finally it is 
taken out, allowed to drain, and dried between folds of blot- 

When dry the papers have lost their brilliancy, they have 
a spongy appearance, and as if covered with an infinite num- 
ber of small protuberances, such as are caused by the iodiz-* 
ing solution. The brilliancy can be restored and the spongy 
appearance be removed by holding the papers over a fire, or 
by placing each between sheets of blotting-paper on a water- 
bath, or finally by running a hot iron over each, so protected 
with bibulous paper. The iron, however, must not be hotter 
than boiling water. The wax-paper negatives are now com- 
plete, and are ready for use ; from them positives on paper 
are obtained as from glass negatives. "When not in use, 
they are preserved in a portfolio. 

Geoffraxfs Process with Cerolein for taking Paper Negatives. 

The author separates the cerolein from the myricin and 
cerin of bees-wax as follows : 

Dissolve five ounces of yellow or white wax in ten ounces 


of alcohol in a retort, by means of heat raised to the boiling 
temperature ; receive the distillate in a cool receiver, until 
the wax is completely dissolved. The melted wax is then 
poured into a vessel to cool ; gradually the myricin and cerin 
solidify, and the cerolein remains alone in solution with the 
alcohol, which is separated by pouring it upon a fine muslin 
sieve, and finally being mixed with the distillate, it is filtered 
through paper. This forms the stock solution of cerolein 
No. 1. 

Secondly, dissolve in three drachms of alcohol (spec, grav., 
.849) four drachms of iodide of ammonium, (or of potas- 
sium,) twelve grains of bromide, either of ammonium or of 
potassium, and twelve grains either of fluoride of ammonium 
or of potassium. 

To twelve grains of freshly prepared iodide of silver add 
drop by drop of a concentrated solution of cyanide of po- 
tassium, until the former is dissolved, and then mix this with 
the alcoholic solution of the iodides, etc. There will be a 
deposit of salts undissolved in this mixture, which is bottle 
No. 2. 

Of these two solutions the author takes, when about to 
use, about twenty drachms of No. 1 and two drachms of 
No. 2, and filters into a porcelain dish. This forms the bath 
in which the papers are immersed for about a quarter of an 
hour, five or six at a time, until the solution is exhausted. 
The papers when dry have a rosy tinge. The operations of 
sensitizing, etc., are the same as in Legray's process. 

Turpentine and Wax Process of Tillard. 
White wax, in small pieces, is digested in the essence of 
turpentine for several days ; the solution is then decanted 
and filtered. To every three ounces of this solution add 
seven grains of iodine, which is immediately dissolved with- 
out discoloration, or if any be produced, expose the mixture 
to the sun. Now add about from forty to forty-five drops of 
castor oil, pure and freshly made, to the above quantity of 
wax and turpentine. This forms the bath when filtered, in 
which the papers have to be immersed for five minutes or 
so. They are then sensitized, when dry, in the following 
bath : 

Nitrate of silver, 1 drachm. 

Nitrate of zinc 2£ drachms. 

Acetic acid, 2£ drachms. 

Water, 3 ounces. 

The paper is then washed carefully and dried. After ex- 
posure, the prints are developed by immersing them in 


Distilled water, 5 ounces. 

Saturated solution of gallic acid, . 5 ounces. 
Acetic acid, 1 ounce. 

To which is added a small quantity of a fresh solution of 
nitrate of silver. This process is said to be very rapid. 

As before mentioned, various improvements have been 
made in the calotype and wax-paper processes, amongst 
which I shall finally give the wet-paper negative process of 
Humbert de Molard, owing to its simplicity and the rapid- 
ity of its action. 

Wet-Paper Negative Process of Humbert de Molard. 
The papers are floated for five minutes on the following 
solution : 

Distilled or rain-water, 6 ounces. 

Iodide of ammonium, 2 drachms. 

They are then taken out, hung up, and dried. This paper 
will not keep long, and must not, therefore, be prepared 
long beforehand. With most papers, that is, those which 
are sized with starch, a violet color is produced by this float- 
ing, owing to the free iodine generally existing in iodide of 

When dry and about to be used, float each sheet on the 
following bath : 

Distilled or rain-water, .... 6 ounces. 

Nitrate of silver, %\ drachms. 

Nitrate of zinc, \\ " 

Acetic acid, . li " 

It is then placed with its moist side downward on a clean 
piece of glass and exposed to the object, taking care to make 
allowance for the thickness of the glass. From three to 
thirty seconds will produce the required result. The paper 
is next floated on the developer, which consists of 

Water saturated with gallic acid, 6 ounces. 

Water saturated with acetate of ammonia, . . from 48 to 60 drops. 

The image appears with great rapidity, and its development 
has to be carefully watched. The washing and fixing are 
performed as usual. When dry, the negative prints are 
waxed, in order to give them the requisite transparence for 
the printing operation. 

Improved Calotype Process by PricJiard. 
Take a sheet of iodized Turner's paper, half an inch wider 
and longer than a plate of glass fitting in the dark slide for 
the dry collodion process ; pin it on to a board in the usual 


way, and, with a glass rod, spread over the paper a solution 
composed of 

Nitrate of silver, 28 grains. 

Distilled water, 1 ounce. 

Glacial acetic acid, 10 drops. 

Allow this to remain on the paper one minute, and then, care- 
fully and evenly, pour one ounce of water over the paper, 
which is easily done by holding the board on which it is 
pinned slantingly, and take care that the lower edge of the 
paper reaches just beyond the corresponding edge of the 
board. Repeat this washing a second and a third time, and 
then pin up the paper to dry, or it may be dried between 
folds of blotting-paper. Noav turn the sensitized surface 
downward on a sheet of white blotting-paper, and placing 
the plate of glass upon the non-sensitized side, with a little 
thick gum attach the overlapped edges of the paper to it. If 
the paper lies even — and it will do so if, when slightly moist, 
it be gummed to the glass, and afterward dried — it may then 
be exposed for a few minutes to the view. The time, of 
course, has to be learned by experience for given intensities 
of the light and the power of the lens. 

After it has been exposed, separate the paper from the 
glass with a penknife, and develop the picture with a solu- 
tion of gallic acid, to which has been added two drops of the 
silver solution to each drachm of the gallic acid solution. 
The picture comes out very quickly, and when it is fairly 
out, the development is completed with the gallic acid solu- 
tion alone. 

Fix with a weak solution of hyposulphite of soda ; wash, 
dry, and wax by means of a hot iron, white wax, and blot- 

The points requiring most care are : 

1. To wash evenly, and so as not to allow any portion of the 
paper to escape washing, as such portion would take no im- 
pression and spoil the picture. 

2. Not to expose before the paper is evenly dry. 

3. To be very careful that the back of the paper is kept 
clean and untouched from any of the chemicals. 



Printing on Plain Paper, on Albumenized Paper, on 
Arrow-Moot Paper. 

The theory and practice of positive printing are second 
only in time, not in importance, to the theory and practice 
of the negative ; it is rare, however, that the same amount of 
care and labor is bestowed upon this department as upon 
that of taking a negative. We run all sorts of risk, make 
every effort, incur immense expenses in order to secure a 
first-rate negative, and then frequently abandon the gem into 
the hands of an indifferent assistant, which is tantamount in 
many instances to leaving the negative to print itself. What 
an analogy exists here between that of planting and culti- 
vating ; that of begetting and of educating ! Do not some 
farmers dibble a hole, insert the seed, and then conclude their 
labor is ended ? Do not some parents almost come to the 
same conclusion ? They both leave the cultivation and edu- 
cation of the young germs to the sun, the wind, and the wea- . 
ther, not to Providence ; for he that believes in Providence, 
puts his shoulder to the wheel and works for Providence. 
In a manner quite analogous, the photographer neglects the 
execution of the printing department, regards the operation 
as secondai'y, concludes that having secured a good negative, 
prints will grow from it like potatoes from the seedling. 
This negligence must be abandoned, and more vigorous ac- 
tion commenced. 

Positive printing is two-fold, consisting in direct printing 
by the rays of the sun, and printing by development or con- 
tinuation • in the former case the image becomes visible dur- 
ing the operation by means of light itself; in the latter case 
the impression made by light is latent, and is rendered visi- 
ble afterward by chemical reduction. The chemical mate- 
rials used in the preparation of the paper for the reception 
of the image are, first, surface materials for communicating 
a more uniform and smooth layer, such as albumen, gelatine^ 


starch and gums • secondly, substances that undergo some phy- 
sical or chemical change by the agency of light, and which are 
mixed with the surface-materials ; these are the chlorides, bro- 
mides and iodides of the various metals. Paper, so prepared, 
is sensitized in the dark-room in a bath of nitrate of silver ; 
the chloridized paper, when sensitized, yields an image by 
the direct operation of light. Paper, prepared with the 
other salts, receives an invisible impression of the image, 
which is made manifest in a bath of gallic acid or some other 
material, according to the circumstances of the case. The 
image obtained by the direct agency of light has a beautiful 
color, but the picture is not permanent, for light continues 
still to act upon the prepared film, and finally obliterates 
the image. The positive thus obtained, therefore, has to be 
fixed in the same manner as the collodion picture, and by one 
of the same fixing solutions, hyposulphite of soda. But the 
color of the image after fixation is far from being bright and 
agreeable ; we have, therefore, to resort to means before fix- 
ing, during fixing or afterward, by which the color can be re- 
stored, or an agreeable color can be communicated. This 
operation is denominated the toning of the picture. The 
chemical substances used m this operation are : chloride of 
gold, and sometimes nitrate of uranium, together with cer- 
tain accessories that modify the action of these two salts, 
such as carbonate of soda, carbonate of lime, phosphate of 
soda, acetate of soda, c/dorinetted lime, citrate of soda, etc. 
Direct positive printing will occupy our attention first. The 
subject is divisible into the following branches; Description 
of the principal materials used; Preparation of the paper; 
Sensitizing of the paper ; Printing by exposure to the sun ; 
Washing of the prints ; Toning of the prints ; Fixing of the 
prints ; Washing of the fixed prints ; Drying of the prints ; 
Cutting and Mounting of the prints. 

Description of the Materials used in Positive Printing. 

Paper, suitable for photographic purposes, must be homo- 
geneous throughout, and of a very fine texture. The surface 
particularly must be uniform and satinized, free from all 
marks or specks, or chemical particles which, by decomposi- 
tion afterward, would spoil the picture. Such paper can be 
had of the different photographic establishments, from the 
various paper-mills of America, England, France, Germany, 
etc. Owing to the different materials employed in the sizing 
of the paper, arises a difference in the tone of the photogra- 
phic picture ; some sizing consists of starch, others of gela- 


This substance derives its name from the tchite of egg, of 
■which it constitutes the greatest quantity. It is found also 
in blood, in the form of serum, (the fluid in which the 
blood corpuscles swim,) in the serum of milk, in all serous 
secretions, etc. It exists in two forms, soluble and insoluble. 
When coagulated, or in the insoluble form, it constitutes a 
portion of most of the solid tissues of the animal frame. 
Solid albumen can be obtained by evaporating either the se- 
rum of blood, (the watery fluid which separates from the clot 
after coagulation,) or the white of an egg to dryness, at a 
temperature not exceeding 120°. The latter substance must 
first be broken up thoroughly, so as to separate the membran- 
ous or fibrous material that holds it together in a compact 
form, and then after subsidence the fluid portion is decanted. 
The dry mass is a yellow, transparent, tough and hard sub- 
stance, consisting of albumen, with a small quantity of the 
saline substances that exist in this material, and which may 
be separated by digestion in alcohol and ethei\ So dried, it 
swells up when put in water and finally dissolves. Before it 
is dissolved, ii may be heated to a higher temperature than 
the boiling point of water before it passes into the insoluble 
condition ; but when dissolved in water and heated to a tem- 
perature between 140° and 150°, it coagulates, and becomes 
quite insoluble in water. Albumen in solution is precipitated 
by alcohol, acids, metallic salts, and several organic bodies, 
such as tannic acid and kreosote. The precipitates of albu- 
men by metallic salts constitute two distinct substances, 
namely, albumen with the acid, and albumen with the oxide, 
of which generally the former is soluble and the latter insol- 
uble. Pure albumen is supposed to be really an insoluble 
substance, but rendered soluble by the alkalies which it con- 
tains ; for if the white of egg, or serum of blood, be dissolved 
in a large quantity of pure water, and the solution be exact- 
ly neutralized by acetic acid, a flocculent precipitate is ob- 
tained which is insoluble in pure water, but easily soluble 
when the latter contains a small quantity of caustic alkali. 
So obtained by precipitation, it has neither color, odor, nor 
taste. Albumen contains in one hundred parts : 

Carbon, 53.5 

Hydrogen, - . . 7.0 

Nitrogen, 15.5 

Oxygen, 22.0 

Phosphorus, 0.4 

Sulphur, 1.6 



Common dried albumen, not obtained by precipitation, eon- 
tains, in addition to common salt, phosphate of soda, and car- 
bonate of soda. It can easily be shown that white of egg 
contains sulphur, by boiling - it in a solution of caustic potas- 
sa and acetate of lead, when a black precipitate of sulphide 
of lead will be formed. The photographic student will also 
observe that albumen contains the elements of ammonia, 
which is generated during the putrefactive decomposition 01 
this material. The salts which it forms with metallic oxides 
are denominated albuminates • and the albuminate of silver, 
which is formed at the same time with the chloride of this 
metal in the albumen film, is instrumental in producing the 
difference that exists between a plain print and an alluunen 


This substance, if it exist in nature, has never yet been ob- 
tained otherwise than by the use of boiling water ; it is sup- 
posed, therefore, by some to be a product of the decomposition 
of albumen or fibrine. All membranes, such as the skin, ten- 
dons, cartilage, hoofs, and bones, yield, when boiled at a high 
temperature, a solution which, on cooling, concretes into a 
semi-transparent tremulous mass. This substance is gelatine 
or its congener chondrin, (from cartilage.) The jelly obtained 
from boiling calves' feet, common size, isinglass, and common 
glue are familiar examples of gelatine. Isinglass (the dried 
swimming bladder of the sturgeon) dissolves in water, and 
yields a very pure form of gelatine. When pure and dry, 
gelatine is colorless and transparent ; it swells and softens in 
cold water, in which it is very sparingly soluble; but in hot 
water it dissolves very easily. Alcohol and ether do not dis- 
solve it ; it is precipitated by alcohol from an aqueous solu- 
tion. When dry it can be preserved for an indefinite time 
without alteration, but in a moi>t state it undergoes decom- 
position, becomes acid, and ceases to gelatinize. Long-con- 
tinued boiling produces the same effect. Some metallic salts 
produce a flocculent precipitate in solution of gelatine, so 
does chlorine; but its most characteristic property is that or 
being precipitated from a very dilute solution by means of 
tannic acid, the only acid by which it is precipitated. Act- 
ing on this principle, skins are converted into leather by the 
process called tanning ; but skins are not boiled hi this pro- 
cess, and hence it is supposed that gelatine, after all, is a na- 
tural product. 

When gelatine is digested in strong sulphuric acid, or in 
caustic potassa the same decomposition is efiected. Ammo- 


nia is invariably one of the products, and among other pro- 
ducts we may count sugar of gelatine or glycocine and leu- 

Dry gelatine is found to contain in one hundred parts : 

Carbon, 50.05 

Hydrogen, 6.47 

Nitrogen, 18.35 

Oxygen, 25.13 

Amylaceous or ITon-Azotized Substances. 

Starch, arrow-root, cellulose, gum-arabic, etc., belong to this 
class of bodies. They are found in the vegetable kingdom 
in a free state, and produce by slight changes in the veg- 
etable organization, a great variety of substances, containing 
no nitrogen, and differing essentially only in the different num- 
ber of equivalents of water with which they are combined, 
or, as for as regards chemical equivalents, sometimes not dif- 
fering at all ; for starch, dextrin, arrow-root, gum-tragacanth, 
cellulose, ami din, all contain the same number of equivalents 
of carbon, hydrogen, and oxygen, and are all resolved into 
saccharine substances by treatment with acids. 

Seeds, roots, tubers, and stems of most plants contain this 
substance in the form of very minute insoluble granules. If 
pumpkins, potatoes, or horse-chestnuts be rasped, and the 
pulp be then well washed on a fine sieve, these granules 
will pass through the meshes, whilst the cellular tissues will 
be retained on the sieve. The powder will finally subside, 
and the fluid above it can be poured off. This substance is 
starch, which has to be washed several times, in order to get 
rid of impurities, and especially the bitter principle peculiar 
to certain seeds and plants. After the white residue has thus 
been thoroughly purified, it is dried at a gentle heat, by which 
it concretes and cracks into the form in which it generally ex- 
ists in commerce. Starch is not only insoluble in water, but 
also in alcohol. When examined in the microscope, these 
granules, of an oblong shape generally, exhibit concentric 
rings by which the starch granule is easily designated from 
other powders, and frequently the granule of one plant can 
be distinguished from that of another, as, for instance, that 
of the potato from that of arrow-root. The latter substance 
is the starch obtained from the roots of the maranta arundi- 
iiacea, growing in the West-Indies. The size of the granule 


varies from ? { ? to ~o parts of an inch in diameter. Each 
grannie is regarded as a cell of concrete and insoluble mate- 
rial, holding within a soluble pulp. When boiled, the cells 
are burst or broken up, and the soluble part mixes with the 
water and forms a thick gelatinous mass, called amidine. If 
the solution of starch be dried at a gentle heat and then di- 
gested in cold water, the fluid portion can be separated from 
the insoluble husks or cells, in a colorless, transparent form. 
A thin solution of starch is precipitated by several bases, as 
lime, baryta, and protoxide of lead ; a large addition of alco- 
hol has the same effect. Infusion of galls causes a yellow 
precipitate which dissolves when the solution is heated. The 
best test of the presence of starch is free iodine, which pro- 
duces a beautiful violet-blue color or precipitate in solution 
of this substance. The blue color disappears on the applica- 
tion of heat, and returns as the solution cools. 

The substance called British gum is simply starch that 
has been heated above 240°, when the latter softens and be- 
comes brown and soluble in cold water. If a solution of 
starch be boiled with a small qtiantity of dilute sulphuric, 
hydrochloric, or, in fact, almost any acid, it soon becomes 
thin and is then called dextrine. The sulphuric acid is after- 
ward removed by adding chalk to saturation, and then by fil- 
tering and evaporating the filtrate to dryness. The substance 
thus obtained resembles gum and is soluble in cold water. 
By continuing the action of sulphuric acid and the boiling, 
dextrine is converted into grape-sugar. This conversion is 
produced also in the act of germination of seeds as in malt- 


This substance is the spontaneous exudation from the bark 
of the acacia vera and the acacia arabica. In its purest and 
finest condition, it is in the form of white or slightly yellow- 
ish concretions, which are soluble in cold water, forming 
thus a viscid, adhesive solution. The pure gummy princi- 
ple, called arabine, is precipitated by alcohol and by basic 
acetate of lead. 

Chloride of Gold. 

Gold does not dissolve directly in hydrochloric acid, but 
it enters into combination very vigorously with moist chlo- 
rine, or with chlorine in the nascent state. The menstruum 
in which it dissolves is nitro-hydrochloric acid. 

Gold. — Symbol, Au. Combining Proportion, 197. Specific Gravity, 19.3. 
Protoxide of Gold. — Symbol, Au 0. Combining Proportion, 205. 
Teroxide of Gold. — Symbol, Au 3 . Combining Proportion, 221. 
Terchloride of Gold. — Symbol, Au Cl 3 . Combining Proportion, 303. 


Gold dissolves in a mixture of one part nitric acid and 
four parts hydrochloric acid. In this mixture the nitric acid 
becomes decomposed, parting with oxygen, which then de- 
composes the hydrochloric acid and combines with its hy- 
drogen to form water, whilst the chlorine in the nascent 
state combines with the gold in the solution. This is after- 
ward evaporated on a water-bath in order to drive off all 
excess of acid. In this way we obtain a red-brown, de- 
liquescent crystalline mass of the terchloride. If the heat 
be too great, the salt is decomposed, chlorine is set at liber- 
ty, and a protochloride or metallic gold is left, according to 
the temperature. The terchloride is very soluble in water, 
ether, and alcohol. The solution has a yellow color and an 
acid reaction ; it stains the skin purple. Ether separates 
this salt from an aqueous solution very effectually by agita- 
tion ; and the mixture ascends and forms a layer on the sur- 
face of the water, which can easily be separated by decanta- 
tion, by a syringe, or by allowing the water solution to flow 
off from a funnel ; after which the ether is expelled and col- 
lected by distillation. 

Most of the deoxidizing agents reduce terchloride of gold, 
such as hydrogen, carbon, carbonic acid, deutoxide of nitro- 
gen, sulphurous acid, phosphorous acid, and their salts, ter- 
chloride of antimony, the proto-salts of iron, many of the me- 
tals, most organic substances, and oxalic acid. 

The crystallized terchloride has a dark reddish-brown color ; 
but if it contains excess of hydrochloric acid, it has a bright 
yellow color ; the solutions partake of the same color ; the 
color, therefore, is a criterion of the purity of this salt. A 
strong solution of the salt has a dark olive-green tinge, 
which becomes yellow by dilution. This salt combines with 
the analogous potassium, sodium, and ammonium salts, giv- 
ing rise to definite compounds of these double salts, which 
are very frequently sold in commerce for the true terchlo- 
ride. The formulas for these three salts are : 

Aurochloride of Potassium. — K CI. Au CI 3 + 5 Aq. 
Aurocliloride of Sodium. — Na CI. Au Cl 3 + 4 Aq. 
Aurochloride of Ammonium. — NH 4 CI. Au Cl 3 + 2 Aq. 

_ All these salts, as well as the double salt of gold and cal- 
cium, are used in toning. They are formed by neutralizing 
the hydrochloric acid in excess in the terchloride by means 
of the respective carbonates of the preceding metals. 

Refuse gold solutions are reduced in general by either 
sulphate of the protoxide of iron or by oxalic acid. The 
brown powder which subsides is well washed, first with 


water, then with boiling hydrochloric acid ; this is pure 
gold in a fine pulverulent form, which can be used for gild- 
ing and enameling, or for making pure terchloride. 

The gold coins of the country are alloyed with either sil- 
ver or copper, which can be separated by various methods. 
Both the silver and copper may be removed at the same 
time by the following means : melt, for instance, a gold dol- 
lar together with ten times its weight of silver (ten five-cent 
pieces) in a crucible ; when melted, pour it out on a clean 
stone, and afterward pass the lump between a pair of rollers 
so as to reduce it to very thin foil. Digest the foil in pure 
nitric acid, which will dissolve the copper and the silver, and 
leave a residue of a bright cinnamon color. Wash this re- 
sidue, which is gold in a very porous or pulverulent condi- 
tion, and then dissolve it, as before directed, in nitro-hydro- 
chloric acid ; evaporate to dryness, dissolve, and rectify by 

Whenever silver is alloyed with gold, it is precipitated 
during the solution in aqua regia as the insoluble chloride, 
which can be removed by decantation of the chloride of gold. 
The copper is afterward precipitated as the green carbonate 
by adding carbonate of soda to the solution as long as effer- 
vescence is produced, which is separated, in like manner, by 

If steel be dipped in an ethereal solution of the terchlo- 
ride of gold, it becomes covered with a film of reduced gold. 
Dry gilding is performed by coating the article with an 
amalgam of gold, submitting the same to heat, so as to drive 
off the mercury, and then burnishing the gilded surface. 
An amalgam of gold consists of a solution of gold foil to 
saturation. The article is first dipped in a solution of 
nitrate of mercury, and then covered with amalgam. 

The gold solution for electro-gilding is made by dissolving 
to saturation the terchloride of gold in a saturated solution 
of cyanide of potassium ; this solution can afterward be di- 
luted ad libitum. 

Nitrate of Uranium. 

Uranium is a metal which is not very abundant ; in com- 
bination it occurs in the mineral pitch blende, as the black 
oxide ; with silica, oxide of lead and oxide of iron, as tiran- 
mica or chalcolite, and as uranite in combination with lime 
and phosphorus. 

Uranium. — Symbol, U. Combining Proportion, 60. 
Sesquioxide of Uranium. — Symbol, U a 3 . Combining Proportion, 144. 
Nitrate of the Sescmioxide of Uranium. — Symbol, U 2 O a , NO 5 . Combining 
Proportion, 198. 


This salt is obtained directly from pitch blende by treat- 
ment with nitric acid. The ore is first pulverized and acted 
upon by nitric acid ; and the solution is then evaporated to 
dryness. The residue is then washed with water, which 
dissolves the nitrate and leaves a quantity of sulphate and 
arseniate of the sesquioxide of iron. The liquid still con- 
tains salts of copper, lead, and arsenic ; these are removed 
by passing a current of hydrosulphuric acid through the so- 
lution, which precipitates all these metals. The solution de- 
canted or filtered from the sulphides of the above metals is 
evaporated to dryness, and the residue is again treated with 
water, which takes up the nitrate and leaves a residue of 
sesquioxide of iron. The solution is now evaporated and 

Nitrate of uranium is a yellow salt, which is very soluble ; 
it contains six equivalents of water, which by heat can be ex- 
pelled, and by greater heat the salt is decomposed. The al- 
kaline carbonates all produce yellow precipitates with the 
salts of the sesquioxide ; whilst ferrocyanide of potassium 
produces a red-brown precipitate. This salt has been lat- 
terly used in the toning-bath along with the terchloride of 

Acetate of Soda — Citrate of Soda — Phosphate of Soda. 
These three salts are easily prepared by adding to each of 
the acids, acetic, citric, and phosphoric, carbonate of soda as 
long as there is any effervescence. The solutions are then 
evaporated and crystallized. 

Acetate of Soda.— Symbol, Na 0, C 4 H 3 3 + 6 HO. 
Citrate of Soda.— Symbol, 3 Na 0, C, a H 5 0,,. 
Phospbate of Soda.— Symbol, 2 Na 0, HO. POs. 

Carbonate of Soda. 
Symbol, Na 0, CO*. 
This salt is now obtained from chloride of sodium or com- 
mon salt. The latter salt is first decomposed into sulphate 
of soda; the sulphate of soda is next roasted with charcoal, 
by which it is converted into sulphide of sodium ; and final- 
ly the latter substance, by roasting with powdered limestone 
and coal, is reduced to carbonate of soda. 

Carbonate of Lime. 
Symbol, Ca 0, C0 2 . Combining Proportion, 50. 
This substance occurs in great abundance, as chalk, marl, 
marble, and limestone. Chalk is sufficiently pure for the pur- 
pose alluded to. When added to the terchloride of gold, car- 


bonic acid is liberated, and chloride of calcium formed, giv- 
ing rise to the double salt, aurochloride of calcium, which is 
to be decanted from the insoluble residue. This salt is 
more easily prepared in a definite condition than any of 
the preceding mirochlorides / and on this account its em- 
ployment in the toning-bath is more reliable and to be re- 

Chloride of Ammonium. — Symbol, N\H 4 CI. Combining Proportion, 52. 
Chloride of Sodium. — Symbol, Xa CI. Combining Proportion, 58. 
Chloride of Potassium. — Symbol, K CI. Combining Proportion, 74. 
Chloride of Barium. — Symbol, Ba CI. Combining Proportion, 104. 
Chloride of Calcium. — Symbol, Ca CI. Combining Proportion, 63. 

All these chlorides can be so easily prepared by saturating 
hydrochloric acid with their respective carbonates as long 
as effervescence is produced, that it*s not necessary to de- 
scribe them separately. There is this to be remarked about 
them in their application to photography, that the same 
quantity of either (a thing -which I need scarcely remark) 
will not produce the same effect. Of those already men- 
tioned, the chloride of ammonium by weight requires to be 
used in the smallest quantity, whilst the chloride of barium, 
when just twice as heavy, is only equally efficacious in pro- 
ducing a given quantity of chloride of silver. 

The iodides and bromides, as also gedlic acid, have been 
already described. We shall, therefore, proceed to the mi- 
nutiae of the manipulation of positive printing by contact. 



Preparation of Salted Paper. 

Foe sensitizing paper and for toning, washing, and fixing, 
we require either porcelain or gutta-percha dishes of an ap- 
propriate size. These can be had of the city dealers, of any 
size that may be needed ; those of gutta-percha are the best 
for large operations. The photographic-ware baths may also 
be used for these purposes, and are to be recommended on 
account of their cheapness. 

There ai*e several kinds of paper in use, such as Saxony 
paper, French paper, and English paper. There is a differ- 
ence in the surface of paper, that is, there is a right side and 
a wrong side. The smooth or right side is the one which 
receives the sensitizing materials ; it can easily be distin- 
guished from its opposite or wrong side. Salted paper may 
be either arrow-root or albumenized paper. 

Plain Salted Paper. 
Make a solution as follows : 

Salting Solution. Formula 2To. 1. 
Chloride of ammonium, .... 100 grains. 
Distilled water, 10 ounces. 

Formula F~o. 2. 

Chloride of ammonium, .... 100 grains. 

Distilled water, 10 ounces. 

Gelatine, 10 grains. 

Formula 2To. 3. 

Chloride of sodium, 40 grains. 

Chloride of ammonium, ... 60 " 

Citrate of soda, 100 " 

Gelatine, 10 " 

Distilled water, 10 ounces. 

Dissolve the gelatine in warm water, then add the solution 
to the chloride and water, and filter into the porcelain or 
gutta-percha dish. The mixture in each formula is filtered 


before use. The object of the citrate is to give a slight rose 
tinge to the middle tones. 

The sheets of paper are now prepared as follows : 
Fold back each corner of the sheet so as to form a lip by 
which to hold it ; these lips are from the smooth or satin 
side backward to the wrong side. Then taking the lip on 
the right-hand farther corner between the first finger and 
the thumb of the right hand, and the lip on the left-hand 
corner between the thumb and the finger of the left hand, 
raise the sheet, bend it into a curve, and lower the middle 
part upon the surface of the salting solution; now lower the 
right hand gradually so that the farther side of the sheet 
rests upon the fluid ; and then lower the left hand in like 
manner, until the whole sheet swims uniformly upon the 
surface. The next thing is to see that there are no bubbles 
beneath the sheet. With a glass rod in the right hand raise 
the farthest right-hand corner with the left hand, and if any 
bubble becomes visible break it up with the glass and moisten 
the paper where the bubble existed, and proceed in this man- 
ner with one half of the sheet. Xext, holding the glass rod 
in the left hand, raise the nearest left-hand corner, by the 
lip, with the right hand, and remove all bubbles from the 
other half. TVhen these are all broken up, and the paper is 
moistened on the parts where they existed, the sheet is low- 
ered on the fluid and left therefor three minutes. The opera- 
tion of removing the bubbles is the work of a moment. You 
have to learn the knack of floating the sheets on the salting 
solution without soiling the back of the sheet, that is, with- 
out getting any of the fluid on this side. If the two sides 
of the paper are equally smooth, that part which is not cov- 
ered with the salting solution is marked in one corner with 
a pencil or stamp-mark. After the expiration of the three 
minutes, each sheet is raised in the following manner. The 
lips will have sunk down on the surface of the fluid ; with the 
glass rod in the left hand raise the nearest right-hand cor- 
ner, seizing this lip with the thumb and linger of the right 
hand, raise the sheet gradually. Laying aside the rod, seize 
now the nearest left-hand lip with the left hand and hold 
the hands apart as far as the paper will permit, and the left 
hand more elevated than the right, allow the sheet to drain 
into the bath. Now letting the right-hand corner go, with 
a pin fix the upper left-hand corner to the wooden partition 
or slip of wood for this special purpose. If the sheets are 
large, pin also the upper right-hand corner in like manner, 
to prevent the sheet from curling upon itself whilst drying. 


Remove the accumulating drops of salting fluid from the 
lowest corner, and then let the sheets dry. After this opera- 
tion the sheets are piled, with the unsalted sides downward, 
one upon another, and a smooth board placed above and be- 
low the pile, and submitted to pressure until required for 

Preparation of Albumenized Paper. 

Albumen can be used either pure or diluted. With pure 
albumen the prints are very brilliant, but the paper is not so 
easily prepared. Take, for instance, the whites of twenty 
eggs, taking care to separate the yolk thoroughly, and place 
them in a graduated measure. Remove all the germs with 
a glass rod, and ascertain the number of ounces. Afterward 
pour the crude albumen into a clean basin, and add for every 
ounce ten grains of chloride of ammonium dissolved in the 
least quantity of distilled water. Beat the mixture into a 
thick, white froth by means of an egg-beater, and allow it to 
stand for ten minutes ; then remove the froth with a fork, 
and throw it upon a clean hair-sieve. Proceed in like man- 
ner with the residual fluid, until it has been completely con- 
verted into froth and strained through the sieve. Now leave 
the albumen to stand for a day or so, well covered up from 
dust ; after which filter through a piece of sponge, and again 
allow the mixture to settle for a couple of days, and then 
pour off the supernatant liquid portion from the settlings 
into the porcelain or gutta-percha dish for use. 

The paper, as usual, must be of the finest quality, and 
marked or stamped on the back, before floating. Much 
more care is required in the successful management of laying 
the paper on the salted albumen than upon the plain salting 
solution, for bubbles are more likely to be formed, and are 
less easily removed than in the former preparation. Besides 
this, if the paper be dry, and the weather also very dry, the 
albumen does not attach itself easily to the paper, and in this 
case, although a sheet has been thoroughly floated, and Avith- 
out bubbles, the upper part of the sheet, when hung up, al- 
lows the albumen to flow off, so that the film on the upper 
part is much thinner than on the lower part, and a number 
of irregular marks and curves are apt to be formed on the 
lower part. To obviate this, the sheet is suspended by its 
broadside, by which the distance between the upper and 
lower side is the least possible. The time of salting in this 
bath is from two minutes and a half to three minutes. Of 
course in all cases the time has to be reckoned from the mo- 


ment the slieet lies uniformly and without bubbles on the 
surface of the solution. 

In every operation of this nature it is well to have sys- 
tematic arrangements. For this purpose I recommend the 
photographer to proceed as follows in the preparation of his 
drying-chamber. On the side of the room, behind the salting 
solution, and at an elevation of the eyes of the individual, 
screw on a slip of wood a couple of inches wide and the 
length of the room. Supposing then the sheets are twenty- 
two inches long, then bore two holes twenty-one inches apart 
through the slip of wood ; into the apertures insert corks, fitting 
firmly, and projecting about half an inch from the surface of 
the wood. Into the center of each of these corks insert the 
eye end of a steel needle inclined slightly upward. The 
sheets when raised by the two interior corners, and after 
draining, are hooked by the two upper corners upon the pro- 
jecting needles, whieh, before their insertion into the corks, 
have to be varnished to prevent rusting and other troubles. 
When several rows of sheets have to be dried consenta- 
neously the uppermost slip of wood must be the thickest, as, 
for instance, three inches, if there are three rows, one over 
the other; the second, two inches ; and the last, one inch thick. 

In proportion as the albumen accumulates on the lower 
border, it is removed with bibulous paper, until the papers 
finally are dry. They are then taken down and planished 
between rollers or otherwise, and piled away. 

Preparation of Arrow-Root Paper. 
Cut out a board a trifle less in length and width than the 
sheet of paper ; fix a sheet at a time by a pin at each cor- 
ner of each edge, folding the edges of the paper down over 
the edges of the board. Then, with a very fine, soft and 
moist sponge cover it over smoothly, longitudinally and lat- 
erally with the following salting mixture : 


Chloride of sodium, (common salt,) 5 drachms. 

Citric acid, 4 grains. 

Distilled water, 19 ounces. 

Dissolve and filter. Then add four drachms of arrow-root, 
rubbed with cold water into a cream, so that all lumps have 
been thoroughly broken up and saturated. Boil the mixture 
in a glass or porcelain dish, taking care to stir it all the 
while. When it is cold, and the scum has been removed, it is 
ready for application with the sponge. By means of a glass 
triangle or glass rod, all ridges or asperities may be removed, 


and the paper is then suspended, as before directed for albu- 
men-paper. Arrow-root paper is well adapted for large por- 
traits, and even for large landscapes; for smaller pictures, 
where more fineness of grain and sharpness are required, al- 
bumenized paper is by far the best. All the papers, pre- 
pared as directed, will keej:>, but they are best when fresh. 

Sensitizing Hath. 
The preparations for sensitizing ai'e divided into two class- 
es, one containing essentially nitrate of silver, and the other 
ammonio-nitrate of silver • these are subdivided by differ- 
ences in the strength. The ammonio-nitrate of silver solu- 
tion is certainly much more sensitive than the plain silver 
bath ; the great drawback has been the blackening of the so- 
lution by use, for which several remedies have been proposed. 
Whichever bath is used, its strength has to be maintained at 
its original point by the addition of fresh silver every time it 
is used, for the bath soon becomes impoverished by the float- 
ing of paper for printing. The sensitizing solution must al- 
ways be slightly acid, in order that the whites may be thor- 
oughly preserved. 

Formula for the Plain Silver Solution. 

Nitrate of silver, 2 ounces. 

Bain-water, 12 ounces. 

Nitric acid, 2 to 3 drops. 

The paper to be sensitized in this bath is prepared exactly 
in the same manner as for floating in the salting solution; 
the corners are turned back, and then, seizing two opposite 
corners and bending the paper into a curve with the middle 
and salted part downward, it is lowered into contact with 
the fluid, while first one end is gradually let down and then the 
other, taking care afterward to remove all bubbles with the 
glass rod, by first raising one corner and then the other. 
Previous to use, the bath ought to be always filtered from in- 
numerable little particles and scum that accumulate on its 
surface. By means of an argentometer the strength of the 
bath can easily be maintained at a given jDoint, namely, at 
about TO grains to the ounce of water ; and by the applica- 
tion of test paper, it can be ascertained whether it be acid or 
alkaline, and thus corrected. I will repeat, the bath must be 

Slightly acid. 

Filtered every time it is used. 

Its strength maintained, at 70 grains to the ounce. 
The papers are floated on the fluid for five minutes, then 


raised, allowed to drain, and hung up on varnished steel 
needles inserted into corks in a line over the gutter alluded 
to in a former part of this work; or if such a contrivance be 
wanting, the silver solution is removed from the pendent cor- 
ners by blotting-paper, which is afterward thrown aside on a 
special heap for reduction. The bath by use will become discol- 
ored; in such a case, throw in a small quantity of solution of 
common salt by degrees and shake well. This will remedy 
the evil after filtration, but it removes also a considerable 
quantity of silver, which has to be replenished. The black 
residue, together with the precipitated, chloride of silver, is 
preserved with all other refuse silver for reduction. 

Formula for the Ammonia- titrate Silver Solution. 

Xitrate of silver, 2 ounces. 

Rain-water, 8 ounces. 

Alcohol, 1 ounce. 

Dissolve the silver in six ounces of water ; then separate 
two ounces of the solution, and add ammonia to it, until the 
precipitate of oxide of silver first formed is redissolved. This 
solution is then mixed with the alcohol, and the remaining 
silver solution and water. By the addition of ammonia de- 
composition takes place, oxide of silver of a brown color is 
thrown down, and nitrate of ammonia is formed ; an addi- 
tional quantity of ammonia then dissolves the oxide, so that 
the solution contains nitrate of ammonia and solution ot 
oxide of silver in ammonia. When this part is thrown into 
the remaining solutions, oxide of silver is again precipitated ; 
the final solution therefore contains free oxide of silver, and 
solution of oxide of silver in nitrate of ammonia and alcohol. 
The alcohol prevents the solution of the albuminous film and 
discoloration probably. 

The papers are floated in this hath not more than a minute ; 
half a minute I find in most cases to be sufficient. But there 
is this caution to be observed : if the papers when removed 
from the bath appear streaked with oil, it is well to rub the 
fluid gently over the whole surface with a tuft of cotton wool. 
The bath can be filtered, but in that case the same filter has 
to be used over and over again, because the oxide of silver 
is gradually taken up and dissolved by the ammonia liberated 
during the operation. I prefer, however, not to filter the 
bath, but after use to keep it in the stock-bottle, together 
with the residue of oxide of silver. When about to use it, 
it is carefully decanted into the dish, and after settling, a 
small sheet of paper is drawn over the surface to remove any 


particles that might ho left. The strength of this bath, like 
any other, has to be kept rip by the addition of crystals of 
nitrate of silver ; fresh alcohol and ammonia are added from 
time to time. The albuminous film is not injured by this 
solution ; the time of floating is much shortened, and although 
the strength of the solution is higher than that of the pre- 
ceding, no more silver is wasted or consumed in the opera- 
tion, because the picture is maintained on the surface of the 
film, owing either to the diminution of the time of floating, 
or to the induration or coagulation of the albumen, or to its 
dryness and consequent impermeability in so short a time. 

Fuminatlng Process. 

The advantages of the ammonio-nitrate sensitizing solution 
are attained by subjecting the sheets of paper, already sensi- 
tized by the plain-nitrate of silver solution, to the fumes of 
ammonia. The modus operandi is as follows : Float the pa- 
pers for four or five minutes in the first bath, containing from 
sixty to seventy grains of nitrate of silver to the ounce of 
water, and allow them to dry as usual. This is the first part 
of the process. 

Xext prepare the fuminatlng box or chamber. Where 
the quantity of work to be done is not very extensive, a box 
three feet long, two feet wide and two feet deep is first con- 
structed. On either side and five inches from the top a piece 
is cut out, leaving the two ends projecting five inches above 
the two sides. Construct next on either side a shallow box 
of the same length as the original one, five inches deep, and 
two feet wide, and having only three sides. These are fast- 
ened by screws to the large and middle box, in such a man- 
ner that the open side fits exactly where the piece has been 
cut out, forming as it Avere two shelves. By means of trian- 
gular supports these shelves are held in a firm and horizon- 
tal position, and give an appearance to the box, when regarded 
from the end, of the letter T. On each end of the deep box, 
as well as on each side, on a level witli the lateral shelves, 
screw on four narrow slips of inch stuff, on which can rest a 
board three feet long and two feet wide ; this board, there- 
fore, in its place covers the middle box like a lid. When it 
is in its place, screw down a small piece of wood on either 
end of one side, so that it can not slide too far. This lid lias 
a sliding motion by means of an iron rod in the middle of one 
side, lying horizontally, and passing through an aperture in 
the side of one of the shelves, so that it maybe made to close 
the top of the box or open it when required. On the top of 


this T-shaped cavity, there are three doors, each three feet 
long and one foot ten inches wide, opening by hinges as fol- 
lows : At a distance of one foot ten inches from either side on 
the top of this cavity screw on a slip of wood two inches 
wide; to these slips the hinges are all fixed, so that each 
lateral door opens toward the middle, and lies when open 
upon the middle door; whereas the middle door opens to- 
ward one side and lies upon the side door. It is intended 
that one door alone is to he opened at a time. The wood of 
which these doors are constructed must he soft, so as to al- 
low the insertion of small tacks or pins. This is the fumin- 
ating apparatus. 

The sensitized dried sheets or pieces of paper are fixed 
npon the inside of each door by sticking a pin obliquely into 
ea<h corner, with the albuinenized surface downward when 
the door is shut. At the bottom of the deep box place a 
plate, containing a drachm or more of ammonia. In winter a 
pan of warm sand may be -introduced, with the plate over 
this in order to increase the evaporation. The sliding door 
all this while is open. AVhen each door is covered with 
sheets, or with as many as are required, close them. It is 
evident that the fumes of the ammonia will soon fill the 
whole of the interior, and will thus come in contact with the 
surface of the silvered paper and produce a decomposition of 
the nitrate of silver into oxide of silver and nitrate of ammo- 
nia. After the paper has been exjiosed for about ten min- 
utes, the sliding door is closed by pushing it forward with 
the iron rod until it juts against the small pieces of wood on 
either end of the opposite shelf. By this means the fumes 
of ammonia in the body of the fuminator are excluded from 
the air, and only that portion escapes which lies on the shelves. 
The fuminated papers are then taken out and pinned by one 
corner on the corks, in order that all superfluous ammonia 
may escape, when they will be ready fur printing. It has 
been asserted that there is a great saying of silver by this 
process ; that the film is much more sensitive to light, and 
consequently the time of printing is shortened, and that the 
tones are more brilliant. 



The operation of printing is performed by the direct rays 
of the sun or by diffused light. Frames of various sizes are 
to be had of the dealers for this special purpose. These are 
oblong dishes, about two inches deep, with a pane of plate 
glass for the bottom, lying upon a ledge loosely. Upon this 
the negative is placed, collodion side upward, and over the 
negative the sensitized paper, albumen side downward. A 
piece of chamois leather, soft cloth or Canton flannel of the 
size of the pane of glass is placed over the paper carefully, so 
as to keep it in its position directly over the negative, and to 
form a sort of cushion when the folding doors, that come 
next, are fixed in their place. There is quite a knack in ad- 
justing the leather so as not to produce any friction upon the 
negative, which would certainly injure if it were not var- 
nished. The negative lies as near the middle of the pres- 
sure frame as can be, and in the same direction as to length. 
The folding doors are two thin flaps of wood joined by hinges 
in the middle, equal in size together, and lying horizontally 
to the pane of glass. This door is adjusted in its place over 
the cloth or leather in the following manner. Whilst the 
outstretched fingers of the left hand are holding the paper 
and cloth in their places, without the slightest friction, the 
nearer flap is put in its place and held down by a gentle 
pressure, whilst the left hand now relinquishes its hold and 
closes down the other flap. By means of strips of wood, an 
inch and a half wide, stretching across the frame and fixed 
on hinges on one side of the printing frame, and supplied 
with metallic springs beneath, each flap is pressed down and 
held in its place by means of a hook on the other side. By 
such an arrangement it is evident that each folding door is 
independent of its neighbor, and by opening it the cloth 
over one half of the negative can be thrown back, the picture 
can be raised and examined, and again replaced without dis- 
turbing the relative position of the paper and negative. So 


arranged, the printing frame is now exposed to the sun, by 
rearing it on a shelf at the outside of the window right in 
front of this orb. The color of the paper will soon begin to 
change, and soon the whole picture will be apparent. Some 
negatives produce the best prints when exposed to a very 
powerful light; others on the contrary require to be printed 
slowly. A negative which is very dense will yield the best 
effect by exposing the frame to diffused light ; whereas a very 
thin negative may be exposed to the full blaze of the sun. in 
order to be printed very quickly. The best prints are ob- 
tained from negatives that are neither too dense nor too thin. 
The frame' is taken into a shaded corner of the room from 
time to time, and one end of the print is examined in order 
to ascertain the progress of the operation. If the lights are 
strll white, and the shades not yet bronzed in the slightest 
degree, the print is not yet finished. As a rule it may be, 
concluded that this operation is complete when either the 
- have become slightly tinged by reduction, or when 
ring is beginning to appear in any part of the shadows. 
In this case, take in the frame, and placing it on a table or 
shelf, remove the folding doors, then the cloth, and finally 
the print. Be careful not to expose the print to a strong 
light, otherwise the whites will be injured. Place it between 
the leaves of a book or in a drawer in the dark-room, until a 
sufficient quantity has accumulated for the next operation. 
An experienced printer will be able to obtain satisfactory re- 
sults as far as circumstances "will permit; but it is utterly im- 
p< ><>ible to force an inferior negative to yield a superior print ; 
a certain relation, a certain happy relation, (a remark that I 
have so many times repeated, but not too often,) must exist 
between lights, middle tones and shades, with a given den- 
sity of the latter in order to secure normal prints; and where 
this exists, it is the fault of the printer if he does not arrive 
at the maximum result of perfection. 

Toning of the Prints. 
In the dark-room, illumined by the yellow light of a lamp, 
or by that which passes through the orange-yellow non-ac- 
tinic lihiss, examine the points separately, rejecting each in 
which there is a decided failure, and cut off all extraneous 
that are certainly not required when mounted, allow- 
ing, of course, always sufficient margin forthe final trimming. 
Next throw each print separately into a pail or tub of water, 
taking care that its surface conies in contact with the water, 
without the intervention of bubbles. Keep the prints in mo- 



tion by turning them over ar\d over again for the space of 
five minutes, and afterward take them out separately and im- 
merse them in another tub of water in the same manner as 
before. The water from the first pail is poured into a large 
barrel or tank kept for this special purpose. Move the prints 
about as before for five minutes, and then proceed to the 
third pail in like manner. The water from the three pails is 
poured into the tank, and a tea-spoonful of common salt is 
added and dissolved by agitation with a wooden stirrer ; af- 
ter the subsidence of the deposit of chloride of silver, the ref- 
use water is allowed to flow off into the sink by a stop-cock 
inserted within a couple of inches from the bottom of the 

Formula JYo 1. For the Toning Solution. 

Chloride of gold, (pure,) 1 grain. 

Distilled water, 8 ounces. 

Carbonate of soda to neutralize the acidity. 
Alcohol, 2 drachms. 

Formula JYo.. 2. 
Double chloride of gold and potassium, 2 grains. 

Distilled water, 3 ounces. 

Carbonate of soda, 3-5 grains. 

Formula JYo. 3. 

Chloride of gold, 1 grain. 

Distilled water, 8 ounces. 

Chalk to neutralize the acidity. 

Chlorinetted lime, 5 grains. 

Alcohol, 2 drachms. 

Formula JYo. 4. Gold and Uranium. 

( Chloride of gold, (pure,) ... 1 grain. ) 

< Distilled water, 4 ounces. V 

( Chalk to neutralize the acidity. l Filter each 

i Nitrate of uranium, .... 1 grain, j and then mis. 

-| Distilled water, 4 ounces. > 

( Chalk to neutralize the acidity. ) 

Formtda JYb. 5. 

Chloride of gold, 2 grains. 

Distilled water, .8 ounces. 

Phosphate of soda, 100 grains. 

Neutralize with chalk. 

Formtda JYo. 0. 

' Chloride of gold, (pure,) . . 2 grains. ") 

Distilled water, 4 ounces. 

Carbonate of soda to neutralize the acidity, | 

Phosphate of soda, .... 2 grains. \- Filter the latter 

Acetate of soda, 2 grains. and mix. 

Nitrate of uranium, .... 2 grains. 

Distilled water, 4 ounces. 

Chalk to neutralize the acidity. 

No. 1. 

No. 2. 

No. 1. 

No. 2. 


The acidity of any of the above solutions is neutralized as fol- 
lows : In the first place throw into the solution a piece of blue 
litmus paper of the size of a ten-cent piece, its color will be 
turned red ; now throw in either carbonate of soda or carbon- 
ate of lime until the blue color is restored. Carbonate of 
lime (chalk) has this advantage over carbonate of soda, it 
can be used without litmus paper, taking care only to throw 
in a superabundance, which does no harm, andean afterward 
be removed by filtration. I prefer preparing the double chlo- 
ride of gold and calcium beforehand, and in quantity in a 
concentrated liquid form. In such a condition a few drops 
can be added to the toning bath in a moment, whenever it 
is found that the toning does not commence or proceed 

Pure chloride of gold is a deliquescent salt, is not easily 
crystallized, and when crystallized is not easily retained in 
this form. Its color is of a deep reddish color. But the 
chloride of gold, sold as such, is of a yellowish color, in a 
dry crystalline condition, and is not deliquescent ; it is there- 
fore not pure ; it is probably in most cases a double chloride, 
either of gold and potassium, or of gold and sodium. These 
double salts are used in toning, as recommended in the above 
formula ; but it must be remembered, that in buying such an 
article, double the quantity will be required, and of course 
you have to pay the price of gold for the soda or potassa in 
the mixture, which is poor economy. 

"With any of the preceding formulas baths may be formed 
which will produce rich tones. Formula Xo. 5 admits the 
substitution of citrate of soda, or acetate of soda for the 
phosphate. The first is the simplest, and I think the most 
rational; probably the third will please many; its tone is 
more of a sepia. The aim of the citrate, acetate, and phos- 
phate is to produce a purple tone. The uranium bath pro- 
duces a rich tone, still I do not think it superior to the sim- 
plest alkaline gold bath. Use the bath slightly warm, that 
is, at a temperature of 90° or 100°. Before the prints are in- 
troduced into the toning bath, pass them separately through 
hot water. Let the bath be sufficiently large to accommo- 
date a number of prints side by side; turn them over contin- 
ually ; keep them in motion. The tone of the prints soon 
begins to change ; before it becomes of a slate blue, take each 
print out, wash in hot water, and immerse in the fixing bath. 

J 7 !. ring Solution. 

Hyposulphite of soda, ... 2 ouuees. ) 

WMer, 12 ounces. -Slightly warm. 

Alcohol 4 drachms. ) 


The first effect of the toning bath is to change the color to 
a reddish hue, and then finally back again. Move the prints 
about in this bath continually, and keep them in until the 
whites are perfectly clear when viewed by transmitted light, 
and the tone has been restored. Where the printing lias 
been well performed, supposing the contrast in the negative 
to be right, the color of the deep shades is but very little 
changed in the fixing solution, and very soon returns to the 
proper tone. If the whites are full of gray spots when the 
prints are placed between the light and the eyes, it is a sign 
that the fixing is incomplete, and probably too that the prints 
during the washing and the toning have been too much ex- 
posed to a strong light. All operations, until the fixing is 
complete, ought to be performed in a room lighted by non- 
actinic rays. When the tone of the picture and the transpar- 
ency of the whites are satisfactory, remove the print from 
the fixing bath and immerse it in a tub of water. Do so with 
all of them, until the fixing operation is complete. The print s 
are now kept in motion for a few minutes in the water, in 
order to remove as much as possible of the fixing solution 
from their surface. They are then taken out and allowed to 
drain, and finally immersed in another tub of clean water, 
Avhere they remain for a number of hours, taking care to 
move them about, and to turn them over frequently. The 
water in the washing operation can not be changed too fre- 
quently ; in fact, it is by far the most desirable plan to have an 
arrangement by which the prints can be subjected to a run- 
ning stream of water, which can easily be made in large cities 
supplied with water works. 

The apparatus for this purpose is adjusted on pivots so as 
to rise and fall like the beam of a pair of scales, and it is put 
in motion by the weight of the water itself. It consists, in 
the first place, of a trough of wood of any given appropriate 
length, as, for instance, three feet ; its breadth may be one 
foot, and its height the same. It is divided into two com- 
partments in the middle, and supported on pivots in the 
middle of the base-board about six inches above the table or 
shelf on which it rests; by this means it has an oscillating 
motion or play of about twelve inches at either end, like a 
see-saw. This trough is placed so that the middle division 
is, when horizontal, immediately below the stop-cock ; but 
when one is down and filled with water, and the other up 
and empty, it is evident that if the stop-cock be open, the 
water will flow into the empty compartment until this sinks, 
which it will do when the other is empty. Each compart- 


tuent is supplied with a syphon, whose arch reaches to a plane 
nearly level with the top ; the calibre of this syphon is some- 
what greater than that of the ingress pipe furnished with the 
stop-cock. Now when either end becomes filled with water, 
the latter will rise higher than the arch of the syphon, which 
will then be filled with water. The longer arm of the syphon 
passes through the end of each compartment and discharges 
the water from its corresponding end quicker than the water 
is supplied to the other end by the stop-cock. By this expe- 
dient one end becomes alternately light and heavy, and thus 
produces a constant oscillation of the whole trough up and 
down. The prints to be washed are placed in these troughs 
as soon as they leave the fixing bath, and are thus kept in 
motion and supplied with freshwater for any length of time. 
Such a machine is called the 

Self-Acting Photographic "Washing -Machine. 
When prints are thus treated an hour's washing will re- 
move every trace of the hyposulphite of soda. They are 
then taken out one by one and pinned by one corner to slips 
of wood, or suspended on varnished hooks inserted into corks, 
as before described in the albumenizing process. 

Mounting of Photographs. 

Photographs may be cut out of the proper size and shape 
either before they are starched or gummed or afterward. 
If before, the following is the mode of proceeding. Place a 
thick plate of glass before you on the table, on which lay the 
photograph, picture side upward. Next place over this a 
heavy mat in such a position as to present the best appear- 
ance the print can receive. Holding the mat firmly in its 
place, by means of the first and second finger stretched far 
apart, with a sharp-pointed penknife cut along the edge of 
the mat through the paper to the glass all the distance from 
the end of the second finger to that of the first. If you stand 
to perform this operation (a position to be preferred to that 
of sitting) move gently round to the left, still holding the 
fingers firmly on the mat. Press upon the mat with the 
right hand, whilst the second finger advances to the position 
of the first, and this one is again stretched asunder to a new 
point along the edge of the mat. Xow make another in- 
cision along the edge in perfect continuity with the first, and 
thus proceed to the termination. This act of cutting out the 
prints requires considerable dexterity in pressing the plate, 
and making the incision so that the terminal cut is a conti- 
nuity of the commencement, and that the edge all round is 


clean and not dentated. "Where the business is extensive, 
it is advisable to fix up a special mounting-table like that 
used by potters for the formation of utensils out of the plas- 
tic clay. Such a table can be turned by the feet on a verti- 
cal pedestal, allowing the operator to sit all the time. A 
whetstone or hone is a very necessary appendage to the 

The prints are now turned over and brushed over with a 
strong solution of gum-arabic, a mixture of gum-arabic and 
gelatine, or what is still better, with a solution of patent 
starch or dextrine, such as is used on the back of post-stamps. 
Where a number of photographs are mounted upon the same 
paper, it is usual to brush them over on the back with the 
solution before they are cut out, and when dry to perform 
the operation just described. The starched surface is then 
made moist by going over it with a moist sponge. The print 
is now adjusted upon an appropriate mount and pressed ac- 
curately clown by placing first a sheet of clean paper over 
the print, so that its edges overlap the latter, and then hold- 
ing the first and second finger far apart and firmly on its 
surface, the print is pressed upon the cardboard by rubbing 
the space between the two fingers with a burnishing tool or 
with the smooth handle of a tooth-brush. The fingers then 
assume different positions, and the burnishing is continued 
until the whole print is smoothly and evenly adherent to the 
mounts beneath. 

Photographs, after they have been starched, or moistened 
after starching, can be mounted much more quickly by first 
adjusting them to their place on the mounts, and then pass- 
ing them beneath the rollers of a glazing or planishing ma- 
chine. The two operations are then performed at one and 
the same time. This planishing is quite an improvement to 
:i print; it is altogether superior to varnishing or glazing. 
The best rolling machines are those furnished with a hori- 
zontal bed, like that in a lithographic press. Still those that 
consist simply of a pair of rollers are very efficacious in pro- 
ducing decided improvements in stereographs or card-pic- 

Great care is required in keeping out all particles of sand 
from the starch or gum, for where these appear they produce 
protuberances on the photographs or apertures when the 
prints are submitted to pressure in the rolling-machines. It 
is therefore always necessary to remove them from the starched 
surface before it is placed on the cardboard, Avherever such 
particles are discovered ; and to obviate the repetition of such 


troubles or diminish their number, it becomes the duty of the 
operator to cover his gum carefully up when it is not in use. 

What to do with the Clippings of Joints. 

Spoiled prints, soiled sensitized paper and the cuttings of 
pictures may as well be preserved as not, for the labor con- 
sists simply in placing them in some corner or box, instead 
of throwing them away. As soon as the stock is very large, 
they may be burnt in a clean stove and the ashes collected. 
These ashes contain silver, oxide of silver and other combin- 
ations of silver, together with the minerals in the paper, as, 
for instance, lime, etc. The ashes so constituted are pr< 
closely and firmly together into a Hessian crucible, then sub- 
mitted to a powerful heat and thus reduced. Or these ashes 
may be mixed with the chloride of silver, obtained by preci- 
pitation of old baths or at the bottom of the tanks containing 
the refuse washing water. The mass is first well dried, then 
intimately mixed with about one half its weight of either car- 
bonate of soda or potassa, and fused. 

In large establishments the refuse silver salts, as well as 
t he cuttings of paper, amount to quite a large quantity an- 
nually, and are sold for reduction to parties who make it 
their business. Where such an opportunity presents itself, it 
i< more advantageous to dispose of the unreduced refuse than 
to perform the operation of reduction one's self. 

Moun ting Stereograph*. 
Stereoscopic negatives taken from nature contain two pho- 
tographs, which, when printed, are inverted, the left picture 
being where the right ought to be. Some photographers 
remedy this defect by cutting the negative in two in the 
middle, and then proceeding from the middle, right and left, 
two inches and three quarters, the residual slips are cut off 
on the ends and thrown aside. The two negatives are now 
placed upon a thin glass stereoscopic slide, perfectly clean, 
and side by Bide in juxtaposition, but inverted, so that the 
right-side negative is placed on the left side. By means of 
gummed or glued ribbon on the upper edges, these negatives 
are held firmly on the slide beneath. The negatives being 
so arranged, the prints will have the right position, and re- 
quire only to be pared at the top and bottom previous to 
mounting. For this purpose a piece of glass, with rectangular 
corners and ground edges, five inches long and two inches and 
a half wide, is placed upon the prints on the mounting-table 
or slab of gla^< ; with a sharp penknife go round the e<3 
taking care to press the glass form firmly on the prints. In 


this way the pair of stereographs will he cut out in one piece 
ready for gumming and mounting. Copies of stereographs 
(if taken with a single orthoscopic lens) do not require the ne- 
gative to he prepared as above described ; the requisite inver- 
sion exists without it. 

But in many instances the negative is not prepared at all 
in this manner for printing, but left in its natural or unaltered 
condition. In this case (and it is probably the easiest method 
of proceeding) the glass form is laid upon the inverted print, 
and the combined prints are cut out ; after which another 
glass form of exactly half the size is laid upon one end of 
the combined prints, which are then cut asunder. The larger 
glass form has a notch on the top and bottom edge in the mid- 
dle ; these notches are placed on the middle line of the print, 
and serve thus to direct its position. If this middle or divid- 
ing line between the two prints has considerable width, which 
is sometimes the case, the glass form must be in proportion 
longer ; but the smaller form retains its size of two inches 
and a half. Stereographs of groups and of architectural ob- 
jects are frequently cut out with rounded corners, sometimes 
on the top only, and sometimes both on the top and bottom. 
For this purpose you must prepare for yourself appropriate 
forms of glass, by grinding down the corners on a grind- 
stone, or you can cut out the requisite shaped mats in brass. 
Those of glass are by far the easiest to construct. 

Mounts for stereographs of various shades of color can be 
had of the dealers ; these, being cut by machinery, are neater 
and cheaper than those you can make yourself from cardboard. 
If you do not possess the power, that is, have not cultivated 
the faculty of seeing stereoscopically without an instrument, 
you must be very careful not to invert the right and left side 
pictures between the cutting and mounting. It is well to be 
provided with two small boxes, one marked left and the other 
right, into which the corresponding prints can be thrown as 
soon as they are prepared for mounting. The mode of past- 
ing, adjusting to position, and passing beneath the roller is 
the same with the stereograph as that with the ordinary pho- 
tograph, which has been already described. 

bertrastd's xew peocess for positive printing. 

Saxoxy paper is the best for this process ; the equality of 
the mass is not absolutely necessary, but that which contains 
iron stains must be rejected. 

The first preparation of the paper is to impregnate it with 
a soluble chloride ; this is effected by plunging it into the 
following bath : 

Alcohol, spec, grav., .842, . . . 100 parts. 

Benzoin, 10 " 

Chloride of cadmium, 5 " 

The paper may be floated on the surface or completely im- 
mersed. The most expeditious means is to take a dozen 
sheets and immerse them one by one in the bath, by means 
of a glass triangle ; when a certain quantity has been im- 
mersed, they are all turned over at once, and then taken out 
one at a time and hung up to dry ; take care to place a piece 
of blotting-paper in contact with the lowest corner of each, 
in order to produce an accumulation of fluid in this place. 

The sheets dry very quickly ; a few minutes are sufficient. 
If necessary, they may be dried by artificial heat. 

The advantage accruing from the use of benzoin is to fill 
up completely all the pores of the paper; air and moisture 
can no longer penetrate into the interior of the print, which 
is thus protected against the greatest, if not the only cause 
of deterioration. Besides this, benzoin oommunicates to pa- 
per the gloss of albumen, but in a less degree. 

The chloridized paper will keep a long time ; in order to 
sensitize it, place it in contact with the following bath : 

Water, 100 parts. 

Nitrate of silver, 15 parts. 

exactly as for albumen-paper. 

If it be required to keep the sensitized paper for some time, 

210 beeteand's new peocess. 

it may be placed in one of Marion's* boxes, where it will 
keep perfectly. 

The exposure beneath the negative is much shorter than 
for albumen-paper ; the picture may be printed deeper than 
required at the end after fixing. If the time has been too 
long, the blacks become deep green, but there is no necessity 
for anxiety about the matter, the toning bath will restore 
them to their original black. 

The prints may be toned either in the Bayard bath : 

"Water, 1000 parts. 

Chloride of gold, 1 part. 

Chloride of ammonium, .... 20 parts. 
Hyposulphite of soda, 4 parts. 

or in the acetate bath : 

Water, 1000 parts. 

Chloride of gold, 1 part. 

Acetate of soda, 30 parts. 

Glover's Kesinized Printing Process. 
Salting Solution. 

Gum thus, 180 grains. 

Gum mastic, 40 grains. 

Chloride of zinc, 200 grains. 

Alcohol, 8 fluid ounces. 

Sulphuric ether, 2 ounces. 

The object of adding the ether is to insure the speedy so- 
lution of the mastic. The paper is to be immersed in the 
above for five minutes, covering the dish with a sheet of 
glass to check evaporation. Take out, drain closely, and 
dry before the fire. Too much stress can not be laid upon 
the necessity of perfect dryness, so that if the salted paper be 
put away for future use, it must again be held some time be- 
fore the fire, previous to floating on the silver bath, or it will 
not take up the solution evenly. The silver bath is composed 
as follows : 

Alcohol, spec, grav., .805, ... 4 ounces. "| 

Gum thus, 80 grains. )■ Dissolve. 

Gum mastic, 10 grains. J 

Nitrate of silver, 960 grains. ) -,-,. , 

Distilled water, 4 ounces. ] ^ lssolve - 

Mix the two solutions ; shake up well ; filter, and add four 

* This box is oblong or square, and constructed of zinc, with a tight-fit- 
ting cover. At the bottom there is a plate for containing fused chloride of 
calcium, above this a shelf of wire-gauze, on which the sensitized sheets are 
placed. When the lid is accurately closed, whatever moisture may be in the 
box, it will be absorbed by the chloride, which is a very deliquescent salt. 

beetea^td's :sew peocess. 211 

drops of nitric acid. "When the paper has been in contact 
with the above solution a few seconds, it has a tendency to 
curl up, which must be checked by breathing upon the edges. 
After it has settled flat on the surface, allow it to remain ten 
seconds ; it is then ready to be removed. Take hold of the 
sheet by one corner, and stroke it with a glass rod, kept for 
this purpose alone, to remove the surplus solution, and dry be- 
fore the fire. It is then ready for fuming over a dish of am- 
monia. This last operation reduces the exposure in the 
printing frame about one third, besides insuring success in 
toning, under almost every condition of the coloring bath. 

On removal from the printing frame, wash in tepid water, 
and tone by any of the alkaline processes. That which an- 
swers best in my hands is composed of acetate of soda, pre- 
pared at least twenty-four hours before use, with the addition 
of a few drops of the usual solution of chloride of gold im- 
mediately before immersing the prints. 

Fix in a nearly saturated solution of hyposulphite of soda, 
containing five per cent of alcohol. 

The subsequent thorough washing must not be neglected 
in this or any other printing process. 

Or in any other bath. 

The print soon assumes a black tone, which is difficult to 
obtain with albumen. 

It is finally fixed in 

"Water, 100 parts. 

Hyposulphite of soda, 20 parts. 

As soon as the print is well washed, it is left to dry, and 
afterward brushed over with a piece of flannel, or a pad of 
cotton, in order to give it a gloss. It is evident that var- 
nishing is useless. 



During the feeble light of winter in high northern or 
southern latitudes, as also in the preparation of enlarged 
views or portraits with the solar camera, printing by devel- 
opment is of very great utility. It is quite analogous to the 
operation of producing a collodion picture by the agency 
of a reducer ; and the same materials in general are em- 
ployed in the two branches. 

Formula for the Salting Solution. 

No. 1. With the Chlorides. 

Chloride of sodium, (common salt,) . . . 100 grains. 

Hydrochloric acid, 6 drops. 

Rain-water, 12 ounces. 

Immerse the papers in this mixture and let them remain in 
it for two or three hours, then take them out and allow them 
to dry. 

Formula for Sensitizing Solution. 

Nitrate of silver, 1 ounce. 

Citric acid, 8 grains. 

Distilled or rain-water, 8 ounces. 

Float the papers on this solution for three minutes, and then 
suspend them on the varnished needles, or on a cord with 
clothes-pins. Remove all the fluid that accumulates on the 
lower side or on the corners. As soon as the papers are 
moderately dry they may be exposed beneath the negative 
or on the screen of the solar camera until a faint image ap- 
pears. Beneath a negative in the rays of the sun, the time 
of exposure will not exceed three or four seconds ; in feeble 
light a minute or more may be required. As soon as the 
print is sufficiently distinct, it is withdrawn and laid upon a 
piece of glass somewhat smaller in dimensions than the pa- 
per, picture side upward ; two opposite edges of the paper 
are folded beneath the glass, and in this position the paper 
and the glass together are placed on the left side of a capa- 
cious gutta-percha developing dish. 


Formula for Developing Solutioyi. 

Pyrogallic acid, 12 grains. 

Citric acid, 6 grains. 

"Water, 6 ounces. 

Of this solution take sufficient to cover the paper. Inclining 
the dish downward to the right side, pour in the solution ; 
then dexterously raising the right side, the fluid will flow or 
may he made to flow over the whole surface without pro- 
ducing any lines of stoppage. This is very important, be- 
cause any stoppage on such paper would be as injurious as 
on collodion prints. The development commences and pro- 
ceeds as rapidly as on a collodion negative, and requires just 
the same amount of vigilance. As soon as the proper con- 
trast has been attained, the further reduction is caused to 
cease by pouring off the developer into the sink or waste- 
tub, and then by washing at the tap. The washing must be 
performed with care and effectually. After this operation 
the prints are fixed in the following solution : 
Formula for the Fixing Solution. 

Hyposulphite of soda, 1 ounce. 

Water, 16 ounces. 

The prints are kept in this solution until the whites are per- 
fectly clear, which will require from ten minutes to half an 
hour. They are then taken out and submitted to the regu- 
lar process of washing, in order to remove every trace of 
the hyposulphites. 

/Second Method with a Chloride and a JBromide. 
Formula for Salting the Paper. 

White of egg, 10 ounces. 

Distilled water, 15 ounces. 

Chloride of sodium, 1 drachm. 

Bromide of potassium, 1 drachm. 

Dissolve the salts in the water and add the solution to the 
albumen, which has to be beaten up into a froth and allowed 
to subside several hours in a cool place. The clear super- 
natant liquid is decanted carefully or filtered from the de- 
posit into the appropriate dish for salting operations. 

The papers are floated in the ordinary way on the surface 
of this bath for three minutes, and then hung up to dry on 
cords and attached by means of clean clothes-pins. After 
this operation the papers are put in a long tin box which is 
inserted in a deep kettle of boiling water, taking care that 
none of the water can get access to the paper, but that the 


paper is submitted through its whole length to the heat of 
steam ; the operation is still more effectual if hot steam could 
come in contact with the albumenized surface ; such an ex- 
pedient is intended to coagulate the albumen. The omission 
of this part of the operation must not deter the operator 
from trying the process ; the results will not materially be 
changed, because the coagulation can be effected in the sen- 
sitizing bath. 

Formula for the Sensitizing Solution. 

Nitrate of silver, 1 ounce. 

Distilled water, 12 ounces. 

Citric acid, 8 drachms. 

Alcohol, 1 ounce. 

The papers are floated on this bath from two to three min- 
utes, and are then allowed to dry as usual. An exposure of 
from eight to ten seconds in the full sun will be sufficient ; 
whilst as many minutes will be required in a weak light. 
The picture must be quite visible, or very nearly so, before 
it can be said that the exposure is long enough. 

Developing Solution. 

Gallic acid, 5 grains. 

Distilled water, 2 ounces. 

The operation of development is best performed in a glass 
or gutta-percha dish ; the print is first moistened and then 
placed on the bottom of the vessel to which it adheres. The 
developing fluid, being poured on the inclined right-hand 
side, is flowed over the print almost instantaneously ; if any 
part remains not covered, a slight, quick motion will easily 
bring the fluid over the part, or a glass triangle will cause 
the difficulty to disappear, dragging along with it sufficient 
of the fluid to cover the part denuded. The reduction is 
very rapid ; and where the exposure has been about right, 
the development of the image will be complete in two or three 
minutes. In very cold weather it is better either to use a 
stronger bath or to warm the bath by floating it in warm 
water. Gallic acid in solution is very apt to become mouldy 
by keeping, and, consequently, a small piece of camphor, or 
a drop of oil of cloves, is mixed with the bath to prevent this 
sort of decomposition. An under-exposed picture develops 
very slowly, and by a long continuance of the action of the 
acid it becomes uniformly dark-colored without any grada- 
tion of tone ; on the contrary, an over-exposed picture is 
developed with great rapidity, and has to be removed from 
the bath quickly to prevent its assuming a dark color over 


the whites. If printed deep enough in the shades, in such a 
case, the lights would in the mean while be completely 
spoiled. The best prints are those in which the gradation 
is all thoroughly and rather slowly brought out in the print- 
ing ; these are afterward carefully washed and fixed in a 
weak solution of hyposulphite of soda, containing as follows : 

Hyposulphite of soda, 1 ounce. 

Water, 20 ounces. 

The prints remain in this solution for a quarter of an hour 
or so, and are again thoroughly washed. After this proceed 
ing, if the tones are not satisfactory, the prints may be im- 
mersed in the gold toning-bath, in order to receive a gold 
deposit, which modifies the color. Any of the gold-toning 
formulas given will answer the purpose. If, in the opera- 
tion of developing, etc., the whites are not clear, an improve- 
ment in this respect is effected by immersing the well-washed 
prints in a bath containing one ounce of chlorinetted lime to 
ten ounces of water. 

Third Method with an Iodide. 

Formula for Salting Solution. 

•»j , ( Xitrate of silver, 44 grains. 

' ' ( Distilled water, 2 ounces. 

Y „ j Iodide of potassium, 7 drachms. 

' | Distilled water, 2 ounces. 

Dissolve the two salts, and then mix the solutions together, 
which will produce a precipitate of the yellow iodide of 
silver. Add to this a concentrated solution of iodide of 
potassium, until the precipitate is dissolved. The fluid is 
then ready for the bath. 

Float the papers on this bath in the usual manner for 
about three minutes, or until they lie flat on the solution. 
They are then taken out and hung up to dry. After this 
proceeding they are floated in a quantity of rain-water, two 
and two together and back to back, for a number of hours, 
taking care to turn them over from time to time. The sur- 
face thus prepared assumes a very uniform but pale yellow 
color. The papers are again taken out and hung up to dry 

Sensitizing Bath. Formida. 

Distilled water, 25 ounces. 

Aceto-nitrate of silver solution, .... 4 drachms. 

The solution of aceto-nitrate of silver is prepared as fol- 
lows : 


Nitrate of silver, 1 ounce. 

Acetic acid, 2 ounces. 

Distilled water, 10 ounces. 

Or the complete formula may stand as follows, where oper- 
ators do not wish to keep a stock of the aceto-nitrate of 
silver : 

Distilled water, 25 ounces. 

Nitrate of silver, 18 grains. 

Acetic acid, 2 scruples. 

The papers are floated on this bath for three minutes, and 
then taken out and hung up to dry. Whilst the surface is 
still somewhat moist, they are exposed beneath a varnished 
negative, or on the screen of the solar camera, for a few 
seconds. The image in this case is quite latent. In dull 
weather, and when the light is very feeble, half a minute's ex- 
posure will suffice. The print is developed by pouring upon 
it, in the manner already indicated, a saturated solution of 
gallic acid containing about one third its quantity of aceto- 
nitrate of silver. If the development is very slow, the ex- 
j)osure has been too short ; on the contrary, the develop- 
ment is quite rapid when the exposure has been too long. 
As soon as the print is completely brought out in all its de- 
tails, it is immersed in water and very thoroughly washed 
in order to remove every trace of gallic acid. 

The prints are then immersed in a solution of hyposulphite 
of soda as follows : 

Hyposulphite of soda, 2 ounces. 

Water 10 ounces. 

Chloride of gold, 2 grains. 

The prints do not change much by immersion in the fix- 
ing solution, if the time of exposure has been sufficiently pro- 
longed ; if the time has been too short, the dark color will be- 
come pale and red. If the tones of the shades do not assume 
a dark color in the developing solution, the cause may be 
attributed to the want of aceto-nitrate of silver in the gallic 
acid; and, as a rule to be observed, the aceto-nitrate is 
gradually added where the development or the intensity 
relax. If the toning in the fixing solution becomes inky, the 
gold may be omitted. 

Method of Sensitizing by Means of Nitrate of Uranium. 
( The Process of JSTiepce de Saint Victor.) 
The paper used in this operation has to be kept in the 
dark-room, or at least excluded from light, for several days 
previous to its employment. It is then floated, without any 
other preparation, on the following bath : 


Sensitizing Bath. 

Nitrate of uranium, 1 ounce. 

Distilled water, 5 ounces. 

After two or three minutes the papers are removed from 
the bath, allowed to drain, and then hung up and dried. 
They will keep a long time when not exposed to light. The 
time of exposure beneath a negative varies with the intensi • 
ty of the light ; from one to ten minutes in the sun, and from 
a quarter of an hour to an hour in a feeble diffused light. 
The image is barely visible. 

Developing Solution. JVb. 1. 

Nitrate of silver, 1 drachm. 

Acetic acid, 1 to 2 drops. 

Distilled water, 2 ounces. 

The development is very rapid. Almost as soon as the 
print is immersed in the fluid, the picture comes out and 
proceeds to its termination with great velocity. As soon as 
the development has advanced far enough, the prints are 
plunged into water, and thus washed and fixed at the same 

Developing Solution. JVb. 2. 

Chloride of gold, 10 grains. 

Hydrochloric acid, 1 drop. 

Distilled water, 12 ounces. 

Prints are developed in this bath with more rapidity than 
in the preceding. 

Another Method. 
Sensitizing Bath. 

Nitrate of uranium, 1 ounce. 

Distilled water, 10 ounces. 

Developing Solution. 

Bichloride of mercury, 5 grains. 

Distilled water, 12 ounces. 

Pass the prints through this solution, and then wash them 
very carefully, after which they are immersed in the follow- 
ing bath : 

Nitrate of silver, 2 drachms. 

Distilled water, . ,. . . . . _ . .12 ounces. 

When the image is intense enough, wash the prints thor- 
oughly and hang them up to dry. 



This picture does not differ from any other photograph in 
the essential parts of its structure or preparation. No pic- 
ture has ever had so wide a sphere of action, has gratified 
taste so long, or has been as productive of gain to the pho- 
tographer as the card-picture. It is the picture of the day, 
and has tended considerably to simplify the photographic es- 
tablishment. A few years past a number of cameras were 
required, ranging from the quarter to the extra four fourth 
tube ; now, a single tube, either a one fourth or a one third 
will be a complete outfit as regards lenses for an ordinary 
practitioner, with which, Deo volente, and the war to boot, a 
fortune may soon be realized. The card-picture generally 
comprehends the whole figure, either sitting, standing, grace- 
fully leaning against a pillar or balustrade, performing some 
natural and easy operation, as playing the piano or guitar, 
trimming a flower in the arbor, or sailing in the yacht ; in fact, 
the photographer, at least the artist, aims to pose his model 
in the midst of nature's charms with ease and grace, and per- 
fectly free from all constraint. 

The size of the card-picture is a distinct characteristic from 
all other pictures. The mounts of cardboard for this picture 
are four inches long by two inches and one third wide ; they 
can be had already prepared, plain or ornamented, with gilt 
edges, or with a gilt border, at any of the photographic 
wholesale establishments in the city. The prints are smaller 
than the mounts, leaving a margin of about one tenth of an 
inch on either side and on the top ; the margin at the bottom 
is larger, being about a quarter of an inch. The paper on 
which such pictures are printed is of the finest quality, and 
very uniformly and highly albumenized. It is impossible to 
obtain the fine, sharp definition on plain paper as on albu- 
men, because of the difference of homogeneity in the two 
surfaces. Tinted albumen paper, too, is now sometimes used 
to meet the wishes of the fanciful, or the cravings after novelty. 


Leyises for the Card-Picture. 
Lenses for the card-picture are prepared with great care, 
so as to produce as little distortion as possible iu the com- 
plete figure. On this account a long-focussed tube is prefer- 
red to one that is shorter ; but of two tubes, if they both pro- 
duce irreproachable pictures in a given room, the one, which 
is the result of the short-focussed instrument, will exhibit 
more roundness, a finer stereoscopic effect than the other. 
Choose therefore the shortest tube that will perform all that 
is required in a card-picture, and at the distance which your 
glass-house will admit of. Where the business in this depart- 
ment is extensive, two tubes, or even four tubes are mounted at 
the requisite distance apart for the taking of two or four photo- 
graphs at the same time. Furthermore, by an arrangement 
of the plate-holder in the camera, by which it is caused to 
slide either horizontally or vertically, or in both directions, 
as many as eight or sixteen photographs can be taken at the 
same sitting. It would be a waste of time to get up such 
cameras one's self; they are manufactured very neatly and 
accurately by city artisans, and are fitted up with the num- 
ber of tubes ordered or required. Each tube is focussed se- 
parately upon the sitter, and then by a shutter the tubes are 
opened and shut cosentaneously at will. After a proper 
number of seconds have expired, the shutter is closed, and 
the plate-holder is moved a fixed distance, so as to expose 
another portion of the collodion plate. In the mean while the 
model remains quite still. The shutter is again opened and 
the plate exposed as before. 

This operation scarcely needs any elucidation ; the proper 
negative effect has to be attained by means of the reducing 
agent and the intensifier as before minutely described. The 
image is by far softer, and in other respects more agreeable, 
if the negative can receive its requisite amount of density by 
the primary development, or nearly so, so that, when inten- 
sified, but little more has to be accomplished, and this little 
can be effected by a weak intensifier. When the strengthen- 
ing solution is very strong, it is apt to engender a pulveru- 
lent deposit on the sm-face of the collodion which detracts 
from softness and sharpness, communicating to the photo- 
graph an appearance of measles or small-pox. In this re- 
spect it is indifferent whatever may be the size of the nega- 
tive, where there is a tendency to this powdery phenomenon, 
whether it arise from the collodion, or, as I have just re- 


marked, from a deposit of the silver, it is always advisable 
to intensify slowly. 

One point in the taking of negatives I have not yet ad- 
verted to. In the wet process, if the sensitized plate has to 
wait long between the time of its removal from the silver 
bath and its development, the silver solution evaporates ra- 
pidly, and the plate becomes dry, or nearly so ; the conse- 
quence of this is supposed to be, that, as the solution thus be- 
comes stronger, it dissolves the iodide of silver in the film, 
and gives rise to the phenomenon of minute apertures. With- 
out attaching much credit to this rationale of a trouble which 
is very annoying, we do know that if the silvered plate be- 
comes dry the development is very irregular. Another cause 
of the minute apertures alluded to is a quantity of insoluble 
bromide in the collodion. It is a recommendation, therefore, 
to dissolve the iodides and bromides in the preparation of 
collodion, first in alcohol, and to filter the solution, after 
standing several hours, before it is added to the plain collo- 
dion. Another reason, and probably a very frequent one, is 
to be traced to the minute insoluble particles in the silver 
bath, which settle upon the tender collodion film, and become 
as it were imbedded in it. These in the subsequent opera- 
tions of dev eloping and fixing produce either opaque pulver- 
ulent black points, or transparent ones, just as they retain a 
fixed position in or on the film, or are washed or dissolved off. 
Both these phenomena are exceedingly annoying. Such a 
cause can be removed by filtration, or by a sort of coagula- 
tion, (if I may use the word here instead of precipitation,) 
by means of a small quantity of a solution of salt, and then 
by filtration. This operation certainly weakens the bath, 
but it makes it at the same time a better solvent of certain im- 
purities that tend to cause the trouble in question. The ten- 
den cy to these homApin-koles is greater when the bath is strong 
than when it is weak ; it would appear, however, that the in- 
soluble iodide of silver in the film can scarcely be a cause of 
the trouble; for being px*esent everywhere in the film, it 
would be uniformly dissolved as the silver solution gradually 
increased in strength, and would thus present a condition for 
actinism the very "best that could be desired. There is cer- 
tainly no doubt that these apertures are caused in the ma- 
jority of cases by an insoluble pulverulent substance, loosely 
attached to the surface of the collodion, and either sensitive 
to the actinic rays or not, (which is quite immaterial to the 
argument ;) these, imbedded on the surface of the collodion 
and opaque, prevent the rays from penetrating to the true 


film beneath, and being afterward brushed off or dissolved 
off by the acids in the developer or by the fixing solution, 
expose parts in which the iodides and bromides have not un- 
dergone the luminous influence, and are hence made trans- 
parent by the hyposulphite of soda, like any other protected 

In fine, no general rule is known by which a priori these 
pin-holes can always be avoided and accounted for. 

The card-negative, next to that which is prepared for the 
solar camera, must be bright and transparent, free from the 
slightest trace of mistiness or fogging, and of such a depth 
of shade as to preserve the whites, whilst at the same time 
the operation of printing is performed quickly. That the 
negative must be sharp is a sine qua non y and in order that 
the negative be sharp and well-defined to the very edge, 
and from top to toe, spare no expense, no trouble in securing 
a reliable lens. With this, and a moderate share of intelli- 
gence, an operator may run his career without impediment 
to success ; whilst his neghbors, with poor lenses, whatever 
their amount of education, will roll down the hill to perdition. 
The lens leads to success or to ruin. 

There is no difference in this department from that which 
will be found in reference to the melainotype, or the ordi- 
nary negative. Either cyanide of potassium or hyposulphite 
of soda is used. The new fixing agent, sulphocyanide of 
ammonium, it appears has no claims of superiority over its 
predecessors; it has, however, a decided disadvantage, and 
that is its expense; this will always exist comparatively, 
because cyanide of potassium can more easily be manufac- 
tured. Like the cyanide, too, it has toxical properties. In 
order to avoid all the poisonous effects that might arise from 
contact of such substances with the broken skin or wounds, 
as well as the discoloration of the skin from the silver salts 
during development, I would recommend a plan which I 
generally adopt. I do not hold the negative in the hand 
when I intensify ; it is placed on a piece of glass cut out 
in the form of the porcelain dipper for the silver bath. At 
one end a small piece of thick glass, one inch in width, and 
as long as the dipper is wide, is cemented by melted lac ; 
over this is cemented a second piece, projecting above the 
first one, so as to form a ledge beneath which the nega- 
tive is kept in its place. At the upper end the negative is 
secured in its place by means of a clothes-pin. In this way the 


negative can be intensified without obscuring the light that 
passes through it from below, and the hand at the same time 
is protected from contact with the pyrogallic acid and silver. 
Stains from nitrate of silver, or from the pyrogallate can be 
removed, it is true, as long as they have not been exposed 
much to light, by washing with cyanide of potassium; but 
this would entail upon the operator the trouble of washing 
after each negative, and might entail upon him incurable ul- 
cers. If he does not wash his hands after each negative has 
been taken, there is no alternative, they must inevitably be- 
come black. The glass dipper will obviate this trouble. An- 
other trouble, but not quite so alarming, arises from the mode 
we practise of turning the prints round with the hands in the 
toning and fixing baths. The health of operators is much 
impaired, and especially in those large printing establish- 
ments, where a number of females are employed in this de- 
partment, who, by this continual manipulation in the two 
fluids, are frequently in a suffering condition Now all this 
can be avoided by a dexterous use of a glass rod, well rounded 
off at either end, and held in either hand. The hands have 
no business in these fluids • and all parties concerned, that is, 
hands, fluids, and prints, will be benefited by following the 
precaution recommended. With a little ingenuity a pair of 
porcelain or glass forceps might be constructed for this spe- 
cial purpose, consisting of porcelain or glass legs fastened 
into a steel spring arch, which would hold them an inch or 
so asunder. Such forceps may be used, too, in holding the 
negative either during development or intensifying. The 
health of the photographer has to be looked to, and means 
adopted for its preservation. 

Printing of Card -Pictures. 
There is nothing peculiar in the printing of card-pictures, 
photographically speaking, as distinct from that in other pic- 
tures on paper, except it be the number of photographs on 
the same plate ; for, as was to be inferred from the manner 
prescribed to take the negative, this plate may contain as 
many as sixteen distinct pictures ; it seldom, however, con- 
tains as many. Condensing reflectors find their application 
here to great advantage when the light is dull. Such an ar- 
rangement of reflectors might be constructed on a movable 
platform, or turn-table, capable of rotating horizontally, 
whilst the frustum itself, lined by the reflectors, and sup- 
ported on vertical pillars, has a vertical motion. By the 
two motions combined, the frustrum can be easily brought 


in front of the direct rays of the sun, whereby a great con- 
densation of light can be effected on any given surf ice. It 
is immaterial how large a surface may be occupied by the 
negative, or the sum of the negatives on the same plate, 
reflectors can be made in accordance, possessing the advan- 
tage of the direct rays that strike the plate, as in ordinary 
printing, together with the extra advantage of the condensed 
light from the rays after one reflection, as well as from those 
after two reflections. The size of each of the reflectors al- 
luded to will be proportionate to that given in a preceding 
chapter. If the negative plate be sixteen inches square, then it 
will be four times as large in its linear dimensions, as in the ex- 
ample given ; consequently, multiplying 14 r \ 8 „- and 21 T 5 g fi o by 
this ratio, that is 4, we obtain 59-Jg-% and 85 , 2 ^ inches for the 
length of the upper or larger base, and 86 T 2 o 4 o inches for the 
length of the side of each plate of glass in the frustum. Such 
a machine, of course, will be expensive, but like a wind-mill 
where no water exists, it will soon pay for its construction 
by economizing time. By such a condensation of the sun's 
rays, a negative will print well in from thirty to sidy seconds. 

'Vignette Printing. 

A vignette is a picture of a portrait, consisting of the head 
and part of the bust, of an oval shape, in the middle of the 
card, surrounded by a sort of halo, or shading off gradually 
into the white background. 

For this sort of printing the operator has to be furnished 
with vignette glasses, which are manufactured specially for 
such operations, and to be had of all respectable dealers. 
The vignette aperture can be had of any size required ; it is 
formed of a piece of glass, stained on one or on either side 
with a metallic oxide, which is burnt into the glass. This 
stain, however, is a mere film, and can easily lie ground away 
of the requisite shape and size by the lapidary, and then pol- 
ished. The external parts being of a red orange color, in- 
tercept or absorb those rays of light whicli would act iq^on 
the sensitized collodion film, whilst through the vignette 
opening all the rays can act almost with their primitive 
vigor. Such a glass, or an appendage of such glasses, is 
placed first on the glass of the printing-frame ; upon this 
comes the negative, and then the paper, as in ordinary print- 
ing arrangements. 

Vignette glasses can be made by the photographer himself 
in the following manner : Take a piece of glass of the proper 
size, and paint either with water or oil colors the vignette 


opening in orange or black, shading off toward the edges ; 
till np the remaining part with white paint, shading the edges 
bordering on the vignette gradually deeper and deeper, until 
the layer becomes uniformly white to the edges of the glass. 
This is the matrix from which an indefinite number of nega- 
tives can be copied, which will be, when varnished, the vig- 
nettes required. 

Toning, Firing, and Mounting. 
No further observations are requisite. Instructions on 
these matters are given in detail in a preceding chapter of 
this work, and on the coloring of the card-picture, of the ste- 
reograph and the photograph in a chapter specially devoted 
to the subject. 

On the Tinting and Coloring of Photographs. 

The colors required to tint or color photographs are the 
same as those employed in miniature painting, and the same 
amount of artistic skill is required in the one as in the other, 
where excellence and perfection are the aim of the photo- 
grapher. "Where very large photographs are to be colored, 
the fineness of miniature painting for hatching or stippling 
is not essential, in fact it would be out of place ; in such a 
case a knowledge of crayon-drawing is brought to bear on 
the subject. Colors for such artistic purposes exist in three 
forms : in cakes, in powders, in liquids, in oil, and in crayons. 

For touching up daguerreotypes, ambrotypes, melainotypes, 
and ferrotypes, colors in very fine powder are employed. 
These are laid on the appropriate parts, shaded off so that 
no sharp edges exist, and afterward the excess is blown off 
with an India-rubber blower, either before the application of 
the varnish or afterward, or both before and afterward, as 
in the alabastrine process, where the color is laid on some- 
times three or four times, until it shows through to the other 

Liquid colors, that is, the new Aniline colors, are spe- 
cially adapted for the tinting and coloring of albumen pic- 
tures ; these colors flow very easily, and the albumen surf ice 
requires no preparation. For the ordinary photographic 
practitioner in card-pictures they are to be highly recom- 

Where the card-picture or photograph is to be colored, 
hatched and stippled to perfection in the form of a miniature 
painting, the artist requires a complete outfit of Newman's 
photographic colors, etc. It is remarkable, however, to see 


with how few colors the real artist can execute the most fin- 
ished work. 

The Colors used most frequent!}/. 

Chinese white, Naples yellow, raw sienna, burnt sienna, 
yellow ochre, yellow lake, ivory black, bistre, gamboge, cobalt 
blue, Prussian blue, indigo, Chinese vermilion, scarlet lake, 
neutral tint, sap green, carmine, rose madder, purple lake, 
Venetian red, pink madder, and sepia. These are in the 
form of cakes. To these may be added a few bottles of 
liquid colors, as of silver white, chrome yellows, greens, etc. 

Other Indispensable Articles. 

Sable, fitch, and camel's hair pencils, prepared ox-gall, 
brushes, shells, stumps, slabs, palettes, varnish, gum-arabic, 
gelatine, penetrating varnish, eraser, basin, tumbler, and 

Coloring of a Portrait. 

In regard to coloring as to photography, I shall treat the 
subject of shading as divisible into three parts : lights, mid- 
dle tones, and shades. An irregular surface has always 
these three gradations, not separated by distinct lines of 
demarkation, but flowing gradually or irregularly into one 
another, according as the undulations of the surface are gra- 
dual or irregular. Difference of distance in a plain surface 
effects what irregularity effects on an undulating surface, 
whose parts are nearly all at the same distance. Supposing 
then a surface of one and the same uniform color gradually 
retires from the eye, it is evident that the nearest parts are 
the most brilliant and light, the middle parts less so, and the 
most distant parts are the darkest and least brilliant. So it 
is also with undulating surfaces, the most prominent parts 
are the lights or the bright parts; the depressions or cavi- 
ties, the shades or darkest parts; and the retiring or interme- 
diate parts are the middle tones. This is the effect of light 
and distance, and we have to imitate this only in color on a 
plane surface, for the gradations of shade are already im- 
pressed in the photograph. The question to be solved then is 
simply this : there are three different degrees of the same color 
in a given space — which is the most appropriate manner of ob- 
taining this collocation or rather gradation of these shades 
of color? Without the slightest pretension to dictate artist- 
ically on a Bubject that takes much genius and incessant la- 
bor to attain to perfection, I recommend to the photographer, 
who aims to ameliorate his photographs somewhat respecta- 
bly with color, to lay on the middle tint first over the whole 


surface, and then the lights and shades afterward, in their 
proper places, when the first is dry. To be enabled to do 
this, select three gradations of the color in question. It some- 
times happens that the white of the paper forms the lights ; 
in this case the dark parts may be laid on and shaded off into 
the lights. 

Coloring the Face. 

Paste the photograph on a piece of cardboard in the first 
place, varnish the surface with Newman's preparation, and 
then proceed as follows : Lay on cobalt blue in small quantity 
in all the shades and depressions of the face with a light hand 
and small pencil, as, for instance, along where the roots of the 
hair commence, about the temples, about the chin, beneath 
the eyebrows, and around the eyelashes, etc. With another 
pencil dipped in water, so as simply to moisten it, spread the 
color so as to dilute it and shade it off, so that it becomes 
more and more transparent, until it finally reaches the bright 
lights and merges into them. You proceed in like manner 
with the interior of the eyes, that is, on the visible parts of 
the sclerotic or white of the eye. The object of this opera- 
tion with cobalt blue is to give more softness to the dark 
shades afterward. The veins of the hand, the borders of the 
coat, waiscoat, etc., and the cuffs of the sleeves where they 
terminate on the linen, have to be treated in like manner, 
beginning with the darkest part and shading off into the 
lightest. Allow this color to dry, and in the mean while pre- 
pare the colors for the face, neck, hands, etc. 

For a person of fresh complexion mix up a little yellow 
ochre, with one third the quantity of vermilion and pink 
lake in water on the palette or slab, and cover the face, 
(with the exception of the eyes,) the arms, the hands, etc., 
with a thin and uniform layer of this mixture ; then tint im- 
mediately the cheek-bones and other prominences with a very 
thin mixture of rose madder and vermilion, in order to give 
more animation to these parts above the rest. If the person 
has a red complexion, these colors are heightened still more ; 
and where the complexion is very pale, less vermilion is used, 
and no color on the cheeks. The upper lip, being in shade, 
must be tinted with a mixture of cobalt blue and lake, whilst 
vermilion is employed for the lower. 

For a sun-burnt complexion, add to the colors indicated a 
small quantity of bistre, and proceed with the general wash 
as before ; follow up with lake and vermilion for cheeks, 
where they are colored, and use nothing where they arc pale. 
Where yellow prevails in the complexion, increase the ochre. 


Where a simply tinted picture is required, the operation may 
stop here ; but where a higher finish is desired, you may pro- 
ceed and stipple in a light tint of lake and vermilion on the 
bright parts of the cheeks, lips, etc., by using a very fine- 
pointed pencil, and filling up the parts with contiguous fine 
dots or points of color ; and by hatching over the shadows on 
the forehead and the retiring parts, the temples and the chin 
with a bluish-gray color, that is, fill up these parts with con- 
tiguous short lines, and then cross them in a similar manner, 
so as to produce a greater depth of shade. Use a little pink 
madder in the corner of the eye next the nose ; stipple the 
lips too, and mix a little Chinese white with the lake and 
vermilion for the high lights. The edge of the eyelids have 
to be treated in a similar way. Stippling and hatching are 
more especially required where the colors have not been 
neatly laid on in the first operations. We now proceed to 
the hair. 

Blonde Hair. 
Wash the entire surface of the hair with a mixture of yel- 
low ochre and bistre in small quantity ; then soften the colors 
down where they border on the temples and the forehead 
with a pencil dipped in water. As soon as this wash is dry, 
take a very fine long pencil and proceed to introduce the 
dark parts with a mixture of ochre containing more bistre. 
The lights are produced by adding either a little white or 
Naples yellow to the original mixture of yellow ochre and 
bistre. Both the lights and shades are introduced by streaks 
of color in the direction of the hair, taking care to avoid the 
wiry eifect produced by making each hair separately. Soften 
down those parts that border on the background, and stipple 
up those parts along the roots of the hair with cobalt blue or 
gray, lest the boundary of the hair should be too marked, 
and give it the appearance of being inlaid. 

Chestnut- Colored Hair. 
Cover the whole with a layer of bistre ; then finish up the 
shades with a mixture of ivory black and bistre, the lights 
with Naples yellow and bistro, and the high lights with a 
little white mixed with cobalt. 

Black Hair. 
The general wash for" such hair is ivory black diluted with 
water ; the dark shades are put in with ivory black of greater 
consistency, and the lights with the same color, mixed with 
white and cobalt if the hair is blue-black, and with Avhitc and 
a little pink madder if the hair is of a pure black. 


Gray Hair. 

Cover the whole with a mixture of equal quantities of bis- 
tre and white ; the dark parts with bistre and a less quantity 
of white ; the lights with bistre and more white than in the 
general wash, and the high lights with cobalt, white, and 
pink madder. 

Red Hair. 

Take yellow ochre and burnt sienna for the general tint ; 
the same and a little bistre for the shades ; white, yellow 
ochre and burnt sienna for the intermediate lights ; white, 
cobalt and lake for the high lights. 

Wliite Hair. 

The general tint is that of the photograph itself; the shades 
are put in with a little black, and a very small portion of 
yellow ochre and cobalt, and the lights with Chinese white. 

The head and face may now be considered nearly finished ; 
all that remains to be done is to put in the deep touches about 
the eyes with sepia and pink madder, worked up with a little 
gum-arabic ; those about the nose are put in with sepia and 
gum-water. Put in the light in the pujfil of the eye with 
Chinese white. All these final touches require great care 
and skill. 

The hand, the neck, the shouldei'S, etc., are retouched with 
the final stipplings or hatchings in the same way, in order to 
give animation to the picture, observing to put in greys or 
cobalt blue in the shades, and pink madder in the bright 


The handsomest drapery is black. The general wash is 
ivory black of the consistency of ink. This is laid on uni- 
formly with a fall pencil, beginning at the top and proceed- 
ing downward to the lowest edge, the picture being inclined 
during this operation. All excess is removed with a dry 
pencil, and the layer is allowed to dry. When dry, the dark 
shades are put in with ivory black, of greater consistency, 
and the lights with ivory black, mixed with Chinese white 
and pink madder. 

In all cases of tinting or coloring with any degree of re- 
finement, it is indispensable for the beginner to be provided 
with two photographs of the model, one to receive the color, 
and the other to serve as guide for the introduction of the 
shades, in case they become obliterated in the general wash. 


Dlue Drapery. 

The general tint consists of Prussian blue, or indigo, aa 
the case may require, mixed with a little black and pink 
madder ; the dark parts are put in with the same mixture, 
containing more black, and the lights with the same, con- 
taining an admixture of white. For light blues, cobalt blue 
may be used ; and the lights may be obtained by proceeding 
with a pencil dipped in water over the parts, so as to remove 
a portion of the color. 

Green Drapery. 

Cover the dress with a mixture of yellow lake and Prus- 
sian blue ; and throw in the shades with the same color, mixed 
with a little black and pink madder. The lights are put in 
with emerald green, and the high lights with this color, mixed 
with a little white. 

Red Drapery. 

The general wash consists of vermilion, mixed with a little 
pink madder diluted with water. Add to this a little bistre 
or black for the dark shades, and Xaples yellow or white in 
place of bistre for the lights. 

Rose - Colored Drapery. 
Pub up pink madder with the requisite quantity of water 
for the general wash ; to this add a little black for the shades, 
and a little white for the lights. 

Drown Drapery. 
Use burnt sienna, with a small portion of black bistre for 
the general tint ; for the shades add a little black, and for 
the lights a little white. 

Pink Drapery. 
Cover the dress with a dilute solution of pink madder ; 
then put in the shades with a mixture of pink madder, black 
and cobalt ; and the lights with pink madder and Chinese 

"White Drapery. 
The general tint is cobalt, much diluted ; yellow ochre, 
cobalt and a little black form the shades, and Chinese white 
is used for the lights. 

Yellow Drapery. 
Any of the yellows, as yellow ochre, yellow lake, gamboge, 
or chrome yellow, diluted with water, may be used for the 
ground color; a little bistre added to the yellow forms the 


dark parts ; and a little white to the yellow is used to pro 
duce the lights. 

Pearl Gray. 
Mix a little cobalt, black and pink madder for the ground 
color ; add to this Chinese white for the lights ; for the 
shades use a mixture of ivory black and cobalt. 

Take equal quantities of Prussian blue and pink madder 
for the general wash ; white and this mixture produce the 
lights ; and neutral tint is used for the shades. 


The background must be secondary in effect to the real 
object in the picture ; as a general ride, it must be lighter 
than the shades of this object, and darker than the lights. 
Avoid the appearance of inlaying the object or portrait in 
the background. This can be done by the appropriate use 
of shadow, which can be made to throw the background far 
into the distance behind. 

A similar uniform flat tint is laid on as already described 
for the drapery. Where defects exist in the photograph, a 
general wash is first laid on and then pulverized crayon of 
the pi'oper color is rubbed on this, when dry, by means of 
the finger, and in those parts in contiguity with the figure 
with a fine stump. Curtains, pillars, tables, etc., are put in 
precisely in the same way as drapery ; only be very cautious 
not to make these the principal objects of the picture by 
extreme definition and brilliancy of color. They must be 
thrown into the background by less intensity of color, and 
by a general feebleness of outline. 

How to Imitate Jfetals, etc., with Color. 

The artist does not use the metals themselves in miniature 
painting ; it would be an insult to art to request then* use. 
They can all be imitated by color as follows : 

Gold. — Take an equal quantity of yellow lake and yellow 
ochre, and a very small quantity of burnt sienna, and mix 
them together on the slab, and cover the part desired with 
this mixture. As soon as this foundation color is dry, use 
burnt sienna alone for the shades. The lights are formed 
of chrome yellow, and are completed in the high lights with 
a little Chinese yellow. 

Silver. — Mix yellow ochre and cobalt in equal quantities 
together with a small portion of ivory black ; this forms the 


ground-work. The shades are made with a little neutral 
lint or ivory black ; and the lights with Chinese white laid 
on with a firm touch. 

Iron. — The ground-work consists of cobalt blue, with 
small portions of black and yellow ochre. The shades are 
made with neutral tint and a small quantity of ochre ; the 
lights consisting of white, tinted slightly with black. 

Mother of Pearl. — This substance takes light in the pho- 
tograph ; there is no ground-tone ; put in a very light tint 
of cobalt blue, as also of very light pink madder in two or 
three places, taking care they do not come in contact ; the 
shades are then formed of black ochre and cobalt ; and the 
lights with Chinese white. 

Lace, etc. — Lay on a general tint of ivory black somewhat 
deeper than that of the dress ; the meshes are then intro- 
duced with white mixed with a little blue and black. The 
design is finished by indicating it with Chinese white. 

Precious Stones. — Rubies, sapphires, emeralds, etc., receive 
a foundation of neutral tint of considerable consistency ; 
Chinese white is put on the luminous part ; whereas the re- 
flection, which is on the opposite side to the luminous part, 
receives the color of the stone. The diamond alone, owing 
to its nature, has a reflection of a more dead white. 

As soon as the portrait is finished, pass over the eyes, the 
hair, the eye-lashes, the nose, and the mouth, lightly with a 
solution of gum ; do the same also with satin stufls, such as 
collars, waistcoats, and robes. Used in moderation, this so- 
lution communicates a vigor and freshness to the picture 
which are quite satisfactory. 

(The preceding article on tinting and coloring is extracted 
almost entirelv from the small work on this subject by Hilaire 



My instructions hitherto have been limited strictly to the 
chemical and mechanical manipulations that occur in that 
department of photography denominated the Wet Collodion 
Process. This process will ever remain the predominant 
mode of conducting photographic operations in the room ; 
it is preferred, too, by many tourists in the field. The in- 
convenience, however, of dragging along over mountain and 
A-alley, or of stowing away on steamer or on the cars, a com- 
plete miniature operating gallery, has suggested the idea of 
superseding all this trouble by the discovery of a dry 2>rocess. 
Several processes have been discovered which are more or 
less successful, and all very practical ; but it must be con- 
fessed that the same degree of sensitiveness in the dry pro- 
cess has not yet been attained as in the wet process — instan- 
taneous pictures are the result only of the latter. It appears 
natural for us to expect such a result; chemical combina- 
tions and reductions are effected most easily when the mole- 
cules of matter are in such a condition as to have freedom 
of locomotion, by which new molecular arrangements can be 
formed, in accordance with the new electro-chemical attrac- 
tions and repulsions superinduced by the contact of dissimi- 
lar bodies. 

For landscape and especially for architectural photogra- 
phy, for copying, as well as for every case of photography in 
still life, where the time of exposure is not important, dry 
plates are decidedly superior to wet ones because of the uni- 
formity of their condition during the time of their exposure ; 
wet plates, on the contrary, by desiccation are continually 
changing; and one of these changes — the concentration of 
the nitrate of silver during evaporation — is supposed to be 
one of the causes that produce minute apertures in the film, 
and is certainly the cause of an irregularity in the reduction- 
process during development. The aim of a dry plate is to 


attain to a maximum of preservation of the sensitiveness for 
an indefinite time. It has happened hitherto that the ratio 
of this preservation is inversely as the time of exposure, or, 
probably in plainer terms, that the better the plate is pre- 
served so as to retain sensitiveness, the longer the time re- 
quired to be exposed to the actinic influence to produce a 
given effect. The theory, that is, the rational elucidation 
of the action of reduction in a dry plate is still a problem ; 
if the wet plate, after sensitization, be thoroughly washed 
and then exposed, no picture is developed by the reducing 
agent; but in the dry plate the film is very carefully washed 
and then coated with some preservative agent, as it is called, 
such as albumen, tannic acid, gelatine, honey, syrup, infusion 
of malt, glucose, etc., and then when otherwise properly pre- 
pared and dry, it will yield, when exposed and afterward sub- 
jected to the action of a reducing agent, an intense picture. 
I say the rationale of this phenomenon is still a problem. 
Some suppose that the albuminous, collodio-albuminous, gela- 
tinous, etc., film becomes permeable to the developer in the 
dry process ; whilst the collodion film in its simple unpre- 
served condition is not so. Such a supposition is, however, 
the mere admission of our inability to render any satisfactory 
explanation ; it is the admission of little more than the fact 

As yet, also, it is difficult to say which of the dry pro- 
cesses in vogue is absolutely the best ; although perhaps the 
majority would throw the weight of their opinion into the 
scale of the Tannin Process of Major Russell* The dry pro- 
cesses most conspicuously on the carpet are: the Albumen 
Process • the Collodio-Albumen or Taupenot Process ; the 
Gelatine or P>r. Hill N'orris's Process • the Tannin Process 
of JIajor Mussell ; and the Resin Process. 

The Albwnen Process. 
This process was in use several years before that of collo- 
dion ; Kiepce de St. Victor first produced negatives with it. 
It is still employed by some of the most distinguished artists 
in Europe in the production of stereographs, both negative 
and positive, also of photographs of interiors, and in general 
of pictures of still life. Its theory is Very simple ; but its 
manipulation demands great care and skill. 

Formula for Iodized Albumen. 

The white of egg, 10 ounces. 

Iodide of ammonium, 44 grains. 

Distilled water, (sufficient to dissolve the iodide.) 


Dissolve the iodide in the water, then add the solution by 
degrees to the white of egg, entirely freed from the germ 
and yolk, and beat the egg up well with a wooden spatula 
until it is completely converted into froth. This operation 
must be performed in a place as perfectly free from dust as 
possible ; and then the albuminous mixture is covered with 
a clean sheet of paper and put aside to settle for a number 
of hours. After standing the required time, the surface be- 
comes covered with a sort of incrustation, through which an 
aperture is made to allow the iodized albumen to flow out. 
In some formulas for iodizing the albumen, a bromide is 
used and a small quantity of free iodine. 

Formula JYo. 2. 

The white of egg, 10 ounces. 

Iodide of potassium, 44 grains. 

Bromide of potassium, 15 grains. 

Free iodine, 2 grains. 

Distilled water, (sufficient to dissolve the salts.) 

Beat up the white of egg as before. The operation is best 
performed when the temperature of the room is low. A few 
hours previous to the operation of coating the plates, mop 
the floor and wipe all the shelves with a damp cloth — the 
great difficulty in this process is the deposition of dust or 
fibers on the glasses during the time thev are drying. An- 
other trouble (and these are about all the difficulties the 
operator has to contend against) is the flowing of the plate 
with an even £hd uniform film, and its uniform retention on 
the plate until dry. The plates, of course, must \>e perfectly 
clean in this process, as in every other for negative pur- 

Several methods have been proposed by which the plate 
can be covered with albumen, most of which, no doubt, have 
deterred photographers from undertaking this branch. I 
believe the best method is to flow the plate exactly as you 
would cover it with collodion ; and if the albumen ceases to 
flow in certain parts, to use a glass triangle and thus scrape 
it as it were over those parts. It is necessary in all cases to 
pour upon the plate much more albumen than you would 
collodion, in order to cover the plates easily and effectually ; 
most of the superfluous quantity is poured off at the right 
nearest corner ; whilst the residual surplus is made to tra- 
verse the plate diagonally to the farthest left corner and 
then flow off into the receiving vessel. If any surplus still 
remains it is flowed gently toward the middle of the plate 


nnd equalized as much as possible over the whole surface. 
The next operation is the 

Drying Process. 

This operation, in general, has been rendered very tedious 
and inefficient ; the plates were allowed to dry spontaneous- 
ly, which occupied several hours, and in the mean while the 
albumen film became contaminated with the deposition of 
dust, which completely spoiled the plates. By the following 
method they may be dried in a few minutes. Prepare a me- 
tallic table, that is, a plate of iron or other metal supported 
on three legs, sufficiently capacious for the purpose. Be- 
neath this an alcohol lamp is kept burning, by which the 
plate is maintained at any given temperature by the adjust- 
ment of the wick, or its distance from the plate. Next, sup- 
posing that stereoscopic negatives are the objects of manipu- 
lation, prepare a piece of brass or iron longer and wider than 
the stereoscopic plate by a quarter of an inch ; cut out from 
this a piece of the same shape as the negative plate, but 
shorter in its two dimensions by a quarter of an inch. On 
one end rivet a metallic handle, which may be fixed into a 
wooden one. Turn up a ledge on either side, as also on 
either end, (as far as practicable on the nearer end by rea- 
son of the handle,) about one tenth of an inch high. It is 
evident that so constructed, the negative can lie on this 
skeleton plate and within the ledges. Place the plate, al- 
bumenized as above, on this metallic plate, and, taking hold 
of the handle with the right hand, bring it into a horizontal 
position over the heated plate at a proper distance above it ; 
equalize the albumen by inclining the hand as required ; 
and, keeping the hand in continual motion, the film will soon 
dry uniformly, and the plate can then be put away for future 
use. So prepared it will keep for an indefinite time. 

Sensitizirig the Film. 

An oblong flat porcelain or glass dish is preferred to the 
vortical bath for the purpose of sensitizing the film ; and if 
the dish be made twice as long as required, it will answer 
the purpose best. 

Formula for the Sensitizing Solution. 

Nitvatc of silver, 1 ounce. 

Acetic acid, 5 ounces. 

Distilled water, 10 ounces. 

Iodide of potassium • . 2 grains. 


Lay the albumen plate along one side of the glass clish ; then 
raising this side, pour into the inclined side a sufficient 
quantity of the bath ; with a dexterous move raise the in- 
clined side so that the fluid may flow over the albumen film 
in one quick continuous layer. By this contrivance all lines 
or marks of stoppage are avoided. This is a very necessary 
provision here ; for the slightest hesitation or stoppage will 
infallibly show its effect on the negative. About half a min- 
ute will be sufficient to coagulate the albumen, and to sensi- 
tize the film. This operation is performed in the dark-room ; 
whereas that of albumenizing takes place in diffused light. 
After sensitization — which occupies from thirty to fifty 
seconds — the plate is removed from the bath by raising it 
first with a bent silver hook, and then seizing it by one 
corner with the hand. It' is then washed under the tap and 
left to soak in a dish of distilled water until the next plate is 
prepared. Finally, when it is supposed the free nitrate of 
silver has been thoroughly removed, it is used immediately 
or dried for future use. The quantity of acetic acid in the 
above formula may be diminished in many instances ; its ob- 
ject is to prevent fogging, but it diminishes sensitiveness at 
the same time. If with half the quantity no fogginess super- 
venes, this quantity will be quite enough ; by thus beginning 
with a small amount of acetic acid, and gradually increasing 
until fogging ceases, more rapid effects may be obtained in 
the exposure. When the plates are kept long they undergo 
a species of decomposition which induces fogginess ; the 
fresh plates, therefore, are in the best condition for produc- 
ing normal results with the greatest rapidity, because the 
sensitizing bath requires the least amount of acid. 

Blisters are apt to arise in the film by immersion in the 
sensitizing bath, or during the subsequent operations. These 
are frequently owing to the imperfect cleaning of the plates 
or in the clumsy flowing of the albumen. Gummy substances 
are sometimes added to the albumen in order to fender it 
more adherent or less contractile. 

Exposure in the Camera. 
The amount of exposure will depend on the conditions of 
the light, the focal length of the lens, and the sensitiveness 
of the albumen. In the bright light of spring an exposure 
of two or three minutes with a pair of stereoscopic lenses 
will in_ general be amply sufficient. Experience alone can 
determine the amount of time required in a given case. 


Development of the Image. 
The plate is placed in a glass dish, or in one of gutta- 
percha, and the developer is poured upon it by the same 
mode of manipulation as just described to be used in the 
sensitizing operation. 

Formula for the Developing Solution. 

Gallic acid, 8 grains. 

Distilled water, (warm, 90°,) 2 ounces. 

Previous to immersion in the above solution the plates are 
subjected to the softening action of a warm dilute solution 
of gallic acid (one grain to the ounce of distilled water) for 
half an hour. After this the plate is flowed with a sufficient 
quantity of the above solution containing five or six drops 
of a solution of nitrate of silver two per cent strong. The 
image will soon begin to appear, and will proceed until the 
vigor of the print is satisfactory. The development is not 
so soon complete as in collodion operations, the time required 
varying from a few minutes to forty minutes or an hour. 
Any amount of exposure almost can be made to yield a good 
picture by adapting the developing solution in accordance 
with the exposure. If the plate has been xmder-expose'd 
more silver will have to be used ; if over-exposed, less will 
be found to be all that is necessary. Silver from the sensi- 
tizing bath might be used, but in this case it must contain 
more acetic acid. The weak solution above described is to 
be preferred ; and if there is a tendency to fogging, add a 
few drops of acetic acid to counteract the effect. As soon 
as the shades are sufficiently dense, the plate is removed from 
the bath, well washed in many waters, and then the image 
is fixed in a solution of hyposulphite of soda. No varnish- 
ins: is required, because the albumen film is quite hard of 

Taupenot Process — Colloclio- Albumen Process. 

This process was originally proposed by Taupenot. His 
design was to combine the advantages of these two ingre- 
dients, albumen and collodion. The collodion film on the 
o-lass is a much better receptacle of the albumen than the 
Lrlass itself; but the operation is somewhat circuitous, inas- 
much as the plate is sensitized twice. Other methods have 
since been devised, in which the collodio-albuminous film re- 
quires but one sensitization. Some of these are found to be 
very effectual dry processes. 


Preparation of the Glass Plates. 
These are first immersed for a number of hours in the fol- 
lowing solution : 

Salts of tartar, 1 ounce. 

Rain-water, 16 ounces. 

If the plates have been already employed before, soak them 
in water and remove the collodion film with a piece of rag. 
The alkaline solution can be used several times. As soon as 
the plates are removed from this solution, pass them through 
water several times, and then clean and polish them in the 
vice, by means of alcohol and rotten stone, as previously di- 
rected. Immediately before the collodion is flowed upon the 
plate, it is dusted with a silk cloth, and then with the broad 
camel's hair pencil. A collodion that flows well and one 
that adheres forcibly to the glass is to be preferred. 

Formula for the Collodion. 

Ether, (concentrated,) 12 ounces. 

Alcohol, " 3 ounces. 

Pyroxyline, .... 1 drachm. 

Iodide of ammonium, 1 drachm. 

Bromide of ammonium, 15 grains. 

This collodion, containing quite an excess of ether, which 
is very volatile, has to be poured over the plate with great 
dexterity. It is very fluid and admits of this dexterity. The 
plate is then, as soon as the film has sufficiently congealed, 
immersed in the ordinary nitrate of silver bath, containing 
about 35 grains of the nitrate to the ounce of distilled water. 
It is left in this bath for four or five minutes and then taken 
out and allowed to drain. After this proceeding, the plate 
is immersed in a dish of rain-water and well washed by agi- 
tation, or it may be washed at the tap in the ordinary meth- 
od, and then flowed with distilled water several times, and 
again allowed to drain. It is next flowed, while still moist, 
with the following albuminous preparation : 

The white of egg, (free from germs and yolk,) 12 ounces. 

Distilled water, 2 ounces. 

Iodide of ammonium, 44 grains. 

Bromide of ammonium, 16 grains. 

Ammonia, 1 ounce. 

White sugar, 2 drachms. 

These ingredients are intimately mix.ed by an egg-beater 
until the mass is reduced to froth. They are then allowed 
to subside for a day or two. The clear part is separated by 
decantation or by a syringe from the residue below, and from 


the indurated scum on its surface above. With this clear so- 
lution flow the still moist plate as you would with collodion 
almost. Holding the plate by the left-hand nearer corner, 
between the thumb and the first finger, pour the albumen on 
the right-hand further corner, then inclining the plate, let the 
albumen flow to the left-hand further corner. Now allow the 
whole body of the albumen to flow down in one mass, driv- 
ing the water before it until it arrives at the nearest edge. 
Inclining the right-hand nearest corner, allow the water to 
flow off" together with the excess or surplus of the albumen 
into a separate receiver. Kow raise the nearest edge of the 
plate and let the surplus proceed back again to its place of 
starting, and once more to the nearest right-hand corner, 
when all excess is allowed to flow off. The plates are then 
reared away on one corner to dry. * In this state the film is 
not sensitive, and consequently the plates so far can be pre- 
pared beforehand and preserved until wanted. 

Sensitizing of the Taupenot Plates. 

Nitrate of silver, 1 ounce. 

Acetic acid, 1 ounce. 

Nitrate of silver, 12 ounces. 

The plates are immersed in this bath with great care and 
dexterity, in order to avoid all lines of stoppage, etc. In 
thirty seconds the film will be sufficiently sensitized. The 
plate is then taken out and plunged into a dish of water, 
moved about in this, then transferred to another, allowed to 
drain, finally flowed two or three times with distilled water, 
and put away to dry in a perfectly dark place. 

In this condition the film is much more sensitive to light 
than albumen alone, although it is less so than collodion. The 
plates can be preserved sensitive for several months, but the 
sensitiveness gradually deteriorates by age. 

With a portrait combination an exposure of two or three 
seconds will be found to be sufficient to receive a good im- 
pression of an object well illumined by the sun, and as many 
minutes will suffice with a single lense. 

Development of the Image. 
The developing solution is composed as follows : 

Distilled water, 12 ounces. 

Gallic acid, 18 grains. 

Pyrogallic acid, '6 g?ains. 

Alcohol, 2 drachms. 

Acetic acid, \ drachm. 


To every three ounces of this solution add a solution of 
one grain of nitrate of silver, when ahout to use it. A larger 
proportion of pyrogallic acid and nitrate of silver will in- 
crease the intensity of the blacks ; and where the time of ex- 
posure has been too long, the gallic acid may be diminished 
and the acetic acid increased. The horizontal bath is pref- 
erable for this sort of development. The plate, first dipped 
in water, is then lowered dexterously with the collodio-al- 
bumen surface downward into the solution, and the upper 
end is allowed to rest on a piece of glass or porcelain, to pre- 
vent the film from coming in contact with the bottom of the 
vessel. The plate is raised from time to time to watch the 
progress of the development, which may occupy from ten 
minutes to twenty-four hours. When the shades are intense 
enough, the plate is talfcn out, well washed, and then im- 
mersed in the fixing solution. 

Fixation of the Taupenot Plates. 

Hyposulphite of soda, 1 ounce. 

Water, 20 ounces. 

Even a weaker solution will frequently be all that is re- 
quired. The soluble iodides being removed, the plates are 
taken out and thoroughly washed as usual. 

Modified Albumen Process. {By James Parpey.) 

Let the plates be coated with any collodion, iodized or 
non-iodized, and afterward well washed. 

Flow them with the albumenizing solution, which is made 
as follows : 

Formula for Podized Albumen. 

Albumen, 10 ounces. 

Iodide of ammonium, 50 grains. 

Bromide of potassium, 12 grains. 

Water, 2| ounces. 

The mode of flowing is the same as already described for 
the Taupenot process. After draining, dry as before indi- 

Sensitizing Solution. 

Nitrate of silver, 60 grains. 

Acetic acid, 60 minims. 

Water, 1 ounce. 

The time required will be thirty seconds or thereabouts ; 
remove from the bath and wash thoroughly. 



This preparation requires about twice as long an exposure 
as wet collodion. 


Saturated solution of gallic acid and a few drops of a so- 
lution of nitrate of silver, (fifty grains to the ounce of water.) 
By varying the quantity of nitrate, any kind of tone can be 
got. A small quantity yields brown tones ; a larger quantity 
black tones. 


"Wash thoroughly and then fix in the ordinary solution of 
hyposulphite of soda ; finally wash and dry. 

The collodion film in this process facilitates the flowing of 
the albumen, which besides dries much quicker. Its keeping 
properties are very good. 

Modified CoUodio- Albumen Process. [By James Mudd.) 

Coat the plates with collodion, as usual. As soon as the 
film is sufficiently adhesive, immerse in the ordinary bath of 
nitrate of silver. Dilute the collodion with ether if it gives 
a very thick and creamy film. After sensitizing, wash the 
plates thoroughly, and then immerse them in a weak solu- 
tion of iodide of potassium, (one grain to the ounce of water.) 
for two or three minutes, moving them gently all the while. 
AVash again and allow to drain for one minute. 

Formula for Iodized Albumen. 

Albumen, 10 ounces. 

Iodide of potassium, 50 grains. 

Bromide of potassium, 10 grains. 

Ammonia, 100 minims. 

Water, 2^ ounces. 

First dissolve the iodide and bromide in the water, then 
add the ammonia; mix this solution with the albumen, and 
beat the whole into a froth, and then allow it to settle for at 
least twenty-four hours. Decant, as previously directed, be- 
fore use. While the plate is still wet, pour on the albumen. 
Pour it on and off twice. Allow the plate to drain for a few 
minutes ; then dry it rapidly before a clear fire, and make it 
quite hot. 

Sensitizing Solution. 

Nitrate of silver, 40 grains. 

Glacial acetic acid, ^ drachm. 

Distilled water, 1 ounce. 



"Warm the plate slightly, and then immerse it in this solu- 
tion ; drain for a moment, and wash in different dishes of 
pure water, and finally under the tap. Dry the plates by 
artificial heat, or let them dry spontaneously. 

Plates so treated are very sensitive, and possess tolerable 
keeping properties. In summer, however, it is advisable to 
prepare fresh ones every two weeks or so. 

The plate, first moistened and supported on a horizontal 
stand, pour upon it a fresh solution of pyrogallic acid, (three 
grains to the ounce of water.) The image will soon appear, 
but it requires intensity. 


Pyrogallic acid, 2 grains. 

Citric acid, 2 grains. 

Nitrate of silver solution, (20 gr. strong,) 2 or 3 drops. 

Pour a sufficient quantity of the above upon the plate and 
keep it in motion. If the shades do not assume sufficient in- 
tensity, use more silver. The solution may be warm in cold 
weather, or when the picture has been under-exposed. 

Fixing Solution. 

Hyposulphite of soda, 6 ounces. 

Water, 16 ounces. 

Wash the plates well before immersion ; fix as usual, and 
again wash. Cyanide of potassium must not be used for this 

Fothergill Process. 

This process, like the two preceding, is a mere modifica- 
tion of the Taupenot process, the principal difference be- 
tween this and the Taupenot being that the plate is sensi- 
tized only once. The plate is first flowed as usual with any 
ripe bromo-iodized collodion, and then as usual sensitized in 
the common nitrate of silver bath ; after removal from the 
bath, soak the plates in distilled or rain-water, so as to re- 
move all but a mere trace of nitrate of silver. This part of 
the operation is probably the most important and character- 
istic of the operation. Some pursue the plan of soaking the 
plates, as just directed, in a dish of distilled water, keeping 
the water moving over their surface until all apparent oily 
streaks or greasiness have disappeared. Others recommend 
a more definite plan. They use a measured quantity of dis- 
tilled or rain-water for a certain number of square inches of 
surface. For a stereoscopic plate half an ounce of water is 


poured carefully on one corner of the plate, and is made to 
cover the whole quickly, as in the developing process. The 
water is then kept in motion by tilting the plate slightly up 
and down, until the greasiness disappears ; it is then poured 
oft", and the plate is allowed to drain for a moment, and cov- 
ered with the following preservative solution : 

Albumen, 2 ounces. 

Ammonia, 20 minims. 

Water, 6 ounces. 

Mix well by agitation in a large bottle, and filter through a 
sponge immediately before use. 

This solution is poured upon each plate whilst still moist, 
in the same manner as plates are covered with collodion ; the 
residual quantity is poured oft* at one of the near corners. 
Another quantity of the albumen is now poured upon the 
plate and allowed to remain one minute, after which it is 
poured off, and the plate is properly washed, drained, and 
dried either spontaneously or by the application of heat. 

Developing Solution. 
After exposure, the plates are first moistened in distilled 
water, and then covered with the following developer : 

Pyrogallic acid, 3 grains. 

Citric acid 1 grain. 

Water, 2 ounces. 

Alcohol, 10 minims. 

Add to each ounce of the above solution half a drachm of 
a solution of nitrate of silver, containing fifteen grains to the 
ounce of water. Wash thoroughly when the image is per- 

Fixing Solution. 

Fix the impressions in a bath of hyposulphite of soda ; 
wash, dry, and varnish. 



Make use of a non-contractile bromo-iodized collodion, and 
after the film has been sensitized in the ordinary nitrate of 
silver bath, and allowed to drain, pour upon it a solution of 
honey, containing one ounce of honey to two ounces of dis- 
tilled water. The solution must be warmed and filtered 
through filtering paper, previous to its application. This 
solution may be kept in vials, completely filled, for a con- 
siderable time. As soon as the plate has been thoroughly 
covered with the syrup, it is very carefully washed beneath 
the tap, until the washings no longer taste either of honey 
or silver. The plate is next flowed with the following solu- 
tion : 

Preservative Solution. 

Gelatine, 1 drachm. 

Water, (distilled.) 20 ounces. 

Alcohol, ... 4 drachms. 

Soak the gelatine in the water until it has swelled, then ap- 
ply heat to dissolve it. After it is cool, mix with the solution 
the white of an egg»very intimately, then boil the mixture, 
so as to coagulate the albumen. Let it stand for a few mo- 
ments, and then filter whilst still hot through a flannel bag 
before a fire. The first portions of the filtrate, not being 
clear, are poured back again into the funnel and again fil- 
tered. The alcohol is next added to the clear solution, in 
order to communicate to it keeping properties. 

When about to use the gelatine, place the bottle that con- 
tains it in a dish of hot water, in order that the gelatine may 
melt ; a separate vessel used for flowing the mixture is nearly 
filled with the melted gelatine, and rendered still more hot 
and fluid in a hot-water bath. The plate is first heated and 
then flowed with this hot solution, which is allowed to rest 
upon the surface a moment ; fresh gelatine is then poured 
upon the plate, and off again at one corner, until the film is 
quite uniform. Drain the plate and dry. 


The exposure, developing, and fixing are the same as in 
the preceding processes. 

Dr. Hill Norm's theory of this process is as follows : The 
collodion film, as long as it is moist, is a porous material, and 
when it is once dried, it ceases to be porous. Now, by 
the use of honey, gelatine, etc., on the moist surface, it is 
supposed that these substances penetrate the pores, and thus 
prevent the pyroxyline, during induration and drying, from 
closing up apertures which allow the developing solution to 
permeate the film. The special function of the honey, how- 
ever, seems to be the removal of every trace of nitrate of sil- 

Tannin Process of Major Russell. 

This process promises to supersede most of the preceding 
dry methods. The collodion is apt to wrinkle or slide en- 
tirely from the plate, when prepared according to the origin- 
al mode. There are, therefore, two methods of preparing 
the glass for the reception of the collodion film. 

In the first place, and in all cases, file the edges on both 
sides of each plate. Then, if the plate is not first to be covered 
with a solution of gelatine, place it upon a flat surface, as on 
the corner of a table, and laying a flat ruler along either side, 
leaving one eighth of an inch between the edge of the glass 
and the edge of the ruler, abrade the surface of the glass 
along this narrow strip by means of a wet emery or corun- 
dum grindstone, such as is used by dentists. In this wav a 
rough border will be made all round, to which the collodion 
will adhere with great tenacity. 

The plates must be exceedingly well cleaned and free from 
all sorts of reduction from previous use. So prepared, they 
may be manipulated without much risk of undergoing the 
troubles alluded to. But it is the opinion of many good 
amateurs in this department, that the plates work much bet- 
ter when previously covered with a coating of gelatine, which 
acts not alone as a preventive to wrinkles, etc., in the collo- 
dion film, but is supposed in some way to ameliorate the 
photographic results during development, Avith all sorts of 
collodion. Small plates need scarcely to be covered with 

Gelatine Operation. 

To prepare a clear solution of gelatine, proceed as follows : 


Gelatine, 30 grains. 

Acetic acid, (glacial,) 6 minims. 

Water distilled 10 ounces. 


Immerse the gelatine in the cold water, and let it swell for 
two or three hours in a warm room ; after which add the 
acetic acid, and apply a gentle heat until the gelatine is dis- 
solved. To this add the following solution : 

Alcohol, 6 drachms. 

Iodide of cadmium 12 grains. 

Bromide of cadmium, 3 grains. 

Filter the solution two or three times through paper in a 
warm place. So prepared, it will keep a long time, is limpid, 
and has, when warm, about the same consistency as collo- 
dion, but it does not flow over the plate with the same facil- 

Warm the plates and the gelatine solution ; then pour the 
latter upon the surface of the former, and cause it to spread, 
either by breathing forcibly upon it or by means of a glass 
triangle. The surplus quantity is poured off at one corner 
into a separate vessel, and after dripping, the plates are reared 
away against the Avail on the same corner, upon bibulous 
paper, until they are dry. Spontaneous drying in a warm 
room is preferable to drying quickly by artificial heat. The 
plates so prepared can be preserved when dry in grooved 
boxes for an indefinite time. 

Collodion for the Tannin Process. 
A good bromo-iodized collodion, already ripe, and of a 
powdry nature is the best for this process. 

Formula for Collodion. 

Iodide of ammonium, 16 grains. 

Iodide of cadmium, 8 grains. 

Bromide of cadmium, 16 grains. 

Pyroxyline, 48 grains. 

Alcohol, spec, grav., .805, 4 ounces. 

Ether, concentrated, 4 ounces. 

After the plates have been carefully flowed with this col- 
lodion, they are sensitized in a bath of nitrate of silver, made 
slightly acid with acetic acid, that is, with one drop of the 
ordinary acetic acid to each ounce of the neutral nitrate of 
silver bath. For instantaneous work, or, properly sj)eaking 
here, for very short exposures, a neutral bath would be 
the most appropriately calculated to succeed. When the 
color of the collodion film indicates a sufficiency of sensitiza- 
tion, which will be in four or five minutes under ordinary 
circumstances, the plate is taken out and immersed in a dish 
of distilled water, moved about for a short time, and then 
left collodion-film upward in the dish, until a second plate is 


collodionized and sensitized. It is then thoroughly washed 
under the tap with common water, and finally flowed with 
distilled water. 

Preservative Solution of Tannin. 
This solution may vary in strength from ten to thirty grains 
of tannin to one ounce of water, depending xvpon the light 
and the nature of the collodion. 

• Tannin, 15 grains. 

Distilled water, 1 ounce. 

Dissolve and filter through paper hefore use, and then add 
four or five minims of alcohol to the ounce of water, but al- 
ways after filtration. Of this solution pour first a small quan- 
tity upon the plate, so as to remove before it all superfluous 
water ; pour it on and off two or three times, and afterward 
commence with a fresh solution. Allow the plate to drain 
for a minute or two, then rear it up on end upon a piece of 
blotting paper, and afterward dry spontaneously or by ar- 
tificial heat, remote from all light. When perfectly dry, the 
plates will keep in the dark for a long time. 

"When the contrasts of the landscape are very marked, and 
the light brilliant, a less quantity of tannin maybe used ; the 
greater the quantity of tannin, the greater the density of the 
shades. When the plates are dry, the film, if in a right con- 
dition, will be bright and highly polished in its appearance. 

If the tannin plates have not first been covered with a so- 
lution of gelatine, this is the time, before they are put away, 
to proceed round the edges of the film with varnish. This 
operation can be performed best by dipping the quill end of 
a strong feather from a hen's wing into the varnish, and then, 
inclining the feather, begin at one corner of the plate in con- 
tact with the edge and proceed to the other end slowly, so 
that a small quantity of the varnish is attracted by the col- 
lodion film as you advance. The side of the quill is in con- 
tact with the edge, and not the end. As soon as the varnish 
is thoroughly dry, the plates are stored away. It is best to 
use the plates as soon after preparation as possible. 

The time of exposure is three or four times as long as with 
the wet process, but this may be shortened by following the 
plan of development recommended by Dr. Draper. 


No 1 \ Pyrogallic acid, 72 grains. 

| Alcohol, 1 fluid ounce. 

Filter if there is any turbidity, otherwise not. 


! Nitrate of silver, 20 grains. 
Citric acid, 20 grains. 
Distilled water, 1 ounce. 

Filter if there is a white precipitate, otherwise not. With 
No. 1 and No. 2 as stock bottles, proceed as follows : 

Dilute solution of ( Solution Xo. 1, . . . 1 drachm. | y . 

No. 1. ~{ Distilled water, . . . G ounces. J " 

Of this dilute solution of Xo. 1, take out four drachms for a 
stereoscopic slide, and add to it from fifteen to twenty-five 
minims of No. 2. This mixture is made immediately before 
the plate is to be developed. 

Immerse the dry plate for a few seconds in distilled water ; 
then pour on the developer and keep it in motion until the 
image appears. If the picture is slow in making its appear- 
ance, although the sky develops quickly, the time of exposure 
was too short, and the developer must be increased in strength, 
by adding ten or fifteen drops of No. 1. On the contrary, 
where the time has been too long, the development on all 
parts will be simultaneous, and the proper equilibrium of ac- 
tion will have to be maintained by adding a few drops of No. 
2, otherwise the sky will not be opaque enough. 

Dr. Draper's modification consists in immersing the plates 
after exposure in a vessel of hot distilled water, and then 
proceeding as above. The development is very rapid. In 
consequence of this the time of exposure can be reduced al- 
most to instantaneity. 

It is advisable not to postpone the development long after 
the exposure ; during the evening of the day on which the 
pictures were taken is in all respects an appropriate time for 
the development, and although in many instances this opera- 
tion can be put off, it is not advisable. The color of the 
image by the tannin process is rich and warm ; its tone is 
very agreeable. Plates prepared either by this process or 
by the albumen are well adapted for taking transparent pos- 
itives, by direct contact printing, for the magic lantern, or 
for the stereoscope. 

The developed plates are well washed and fixed in a bath 
of hyposulphite of soda, but not of the cyanide, because it is 
apt to loosen the film. They are then carefully washed, so 
as not to disturb the film, dried and varnished. 

Tlie Tannin and Honey Process. 
Several modifications of the Tannin process have been pro- 
posed, more or less successful ; the honey process of Mr. Eng- 
land being one which seems to possess considerable advan- 


tages in sensitiveness. Mr. England's formula for collodion 
is as follows : 

To five parts of ether and three of alcohol, add sufficient 
pvroxyline to give a tolerably thick film. As soon as it has 
well settled, decant the clear supernatant part into another 
bottle, and measure off two portions of ten drachms each ; 
to one add forty grains of bromide of cadmium, and to the 
other thirty grains of iodide of ammonium ; shake till dis- 
solved, and put by to settle. When thoroughly settled, add 
one drachm of each to six parts of plain collodion. 

Sensitize in a neutral bath of nitrate of silver, containing 
forty grains of nitrate of silver to the ounce of water, and 
wash afterward in a dish of distilled water, rendered acid by 
acetic acid. The plate is left in this dish until a second one 
is prepared ; it is then taken out and washed thoroughly be- 
neath the tap, flowed with distilled water, and coated with 
the following solution : 

Tannin, 15 grains. 

Honey, 15 grains. 

Distilled -water, 1 ounce. 

Coat as before directed, wash and dry. Protect the edges of 
the film with varnish. 

After exposure, immerse the plate in a bath of nitrate of 
silver, ten grains to the ounce, as follows : 

Nitrate of silver, 2 drachms. 

Distilled water, 12 ounces. 

Acetic acid, 1 drachm. 

Keep the plate in this bath for one minute, and then develop 
with the pyrogallic acid developer as usual, or according to 
the method in the Tannin process just described. 

Mr. Anthony, of New- York, finds it advantageous to fume 
the Tannin plates for a few seconds with the vapor of am- 
monia, for instance, the evening before their exposure, the 
time of which is said to be shortened by this process. 

JZeshi Process. 
This is the simplest of all dry processes, the discovery of 
Despratz. It consists simply in dissolving in the collodion 
about two and a halt* grains of powdered resin for every 
ounce of collodion. After sensitization the plate is well 
washed and dried. The development and all other manipu- 
lations are the same as in the wet collodion process. Dubosq 
makes use of amber, and Ilardwich of Glycirrhizine for the 
same purpose. 



Sutton 's Rapid Dry Process. 
The operations in this process, as furnished by Sutton, are 
as follows : 

1. Clean the glass plate, dry it thoroughly, and apply to 
it a solution composed of one grain of India-rubber, dissolved 
in an ounce of kerosclene. 

2. Coat the plate thus prepared with bromo-iodized collo- 
dion, containing an equal number of atoms of iodine and bro- 
mine, added in combination with cadmium. There should 
be about five grains of mixed iodide and bromide of cadmium 
to the ounce of collodion. 

3. Excite the film in a bath composed of thirty grains of 
pure recrystallized nitrate of silver, slightly acidified with 
nitric acid. 

4. Wash off all the free nitrate of silver, and pour over the 
film a preservative composed of twenty-five grains of gum- 
arabic freshly dissolved in an ounce of water. Let it dry 
spontaneously, and, before putting the plate into the dark- 
slide, dry it again thoroughly before a hot flat-iron. 

5. Give the same exposure as for wet collodion. 

G. Develop the picture by first wetting it with distilled 
"water, and then pouring over it a developer, consisting of 
one ounce of distilled water, two grains of pyrogallic acid, 
two scruples of glacial acetic acid, and a few drops of a weak 
solution of nitrate of silver. The image appears immediately, 
and very soon acquires the necessary intensity. 

1. Fix the negative in the usual way, with a saturated so- 
lution of the hyposulphite soda or lime, and when dry, var- 
nish it with spirit varnish. 

Keenis Rapid Dry Process. 

This is a modification of the Tannin Process, or Tannin 
and Honey Process. The characteristic difference is this: 
After the plate is sensitized, it is not tcashed, but flowed im- 
mediately with equal parts of a filtered, fifteen grain per 
ounce solution of tannin and gum, the latter consisting of 
four ounces of picked gum-arabic, dissolved in eight ounces 
of rain-water. The collodion plate requires twice the time 
in the nitrate bath of an ordinary collodion plate. When re- 
moved from the bath, drain a few moments and flow it with 
the preservative mixture bountifully, as with collodion, tilt- 
ing the plate, so that the tannin solution flows from the right 
upper corner to the left upper corner, then to the left lower 
corner, and finally to the right lower corner, and then along 


with the excess of water off at this corner. Repeat the opera- 
tion once or twice. The last lot can be used for the first of 
the next plate. The plate is then drained, washed and dried. 
It is said to be almost as sensitive as a wet collodion plate. 
It is soaked in distilled or ram-water before it is developed. 
It is fixed and developed like any other tannin plate. 



Positives on glass, whether for the stereoscope or the magic 
lantern, that is, such as are to be regarded by transmitted 
light, are prepared most easily, most quickly, and most eflect- 
ually by the Dry Process. The first part of the operation 
consists in obtaining a correct negative of the object, either 
by the wet or the dry process, the latter being preferable, 
because the negative so obtained is less liable to be damaged 
in the subsequent manipulations than the ordinary unvar- 
nished collodion negative. The negative in question is re- 
quired to be very sharp in all its parts, moderately dense in 
the deepest shades, though not so much so as for the ordinary 
printing on paper, and transparent in the lights. The film 
must be thin, bright, and free from all deposit of dust arising 
from reduction or impurities. The negative best adapted 
for the printing of glass transparencies is incontestably that 
with albumen ; for it requires no varnish, and is endowed 
with all the requisites above mentioned. The albumenized 
glass, too, is the best for the reception of the transparent image. 
Dry plates by the Tannin Process are the next best ; it is a 
good plan in this instance also to have the negative an 
albumen print, and the transparencies on tannin plates. 

Provided with such a negative, place it in the shield of 
the plate-holder with the image toward you ; on this place 
a sensitized tannin or albumen plate, the film being from you, 
so that the two films lie in intimate juxtaposition ; close the 
door, whose spring retains the plates firmly in contact. In- 
troduce the plate-holder into the grooved receptacle at one 
end of the cylinder, as described in a previous chapter of this 
work, expose the other end to the light of a cloud, etc., and 
draw the slide. An exposure of a few seconds will be all- 
sufficient. The precise time can not be accurately given, but 
is easily ascertained with given materials. Begin with an 
exposure of one second, and proceed until you find the time 
best adapted for the circumstances. With dry plates^ it is 


not absolutely necessary to use the cylinder ; the cylinder, 
however, yields superior results. 

The development of the plate depends upon the nature of 
its constitution; if an albumen plate, develop it accordingly ; 
if a tannin plate, in like manner. These different modes are 
given in detail in the preceding chapters on the subjects in 
question ; as well as every other information referring to the 
completion of the picture after development, such as wash- 
ing, fixing, drying, and varnishing. 

The color of an albumen print is not sufficiently agreeable 
for stereoscopic purposes. This color is improved by im- 
mersing the plate in the first place in a dilute solution of 
bichloride of mercury, and after it has been washed, in a 
solution of sel d'or, (the double hyposulphite of gold and 
of soda,) when the color will be an agreeable sepia tone. 

Chloride of gold alone, in dilute solution, communicates to 
the fixed positive an agreeable purple tone ; naturally the 
prints have to be washed always after such operations. 

To take Copies of any given size. 
Where the required transparency must be of a given size, 
as is the case in the preparation of slides for the magic lan- 
tern, and for other similar exhibitions, or for church win- 
dows, the printing has to be performed in the camera and 
by means of the lens. This process is described in a pre- 
ceding chapter of this work. 

Theoretically a picture can be made as many times larger 
or smaller than the original by an analysis of the well-known 
formula for the conjugate foci of a double convex lens. This 
formula is as follows : 

1 _1 1_ 

<D ~~ f u 

where the thickness of the lens is not taken into consider- 
ation ; but with this consideration, the formula will be : 

v j u ^>\r u ' 

when any two of the preceding terms «, f, and u, are known, 
the third can be found ; f signifies the principal focal dis- 
tance ; u the distance of the object from the nearest surface 
of the lens ; v is the distance of the picture on the ground 
glass from the same surface ; t is the thickness of the lens ; 
r the radius of curvature of the first surface; and p is the 
index of refraction of the transparent medium of which the 
lens i« formed. 


Without going into a minute optical discussion, I will 
analyze the first formula so as to he enabled with a lens of a 
given power, and with a given sized object to show what 
must be the respective distances of the object and image 
from the lens. 

In the first place I will explain a few technical terms, 
such as the axis of a lens, the optical center of a lens, the 
principal focus of a lens, the conjugate foci of a lens, the 
equivalent focus of a combination. 

The axis of a lens is a line perpendicular to all the diam- 
eters drawn from edge to edge. 

TJie optical center of a lens is the point where a line (join- 
ing an impingent and an emergent ray that are parallel to 
each other) crosses the axis ; this center is sometimes within 
the lens, sometimes on its surface, and sometimes external 
to it. 

The principal focus of a lens is the point where parallel 
impingent rays converge and cross after refraction and 
emergence ; it is the burning point of the sun's rays. The 
distance of this point to the optical center is called the prin- 
cipal focal distance. 

The conjugate foci are any point on an object and its cor- 
responding point on the image. The distances of these two 
points to the optic center are denominated conjugate focal 
distances • these distances, however, are generally reckoned 
from the vertex or surface of the lens next to the object. 

The vertex is that point where the axis touches the sur- 
face of the lens nearest the object. 

The equivalent focus is a term that refers to compound 
lenses, such as those used by the photographer ; it is the 
principal focus or the focus of parallel rays of the combin- 
ation. It is called equivalent from being compared with a 
single lens that will produce the same sized picture at the 
same distance of the object. If rays from an object impinge 
upon a lens and on emerging converge, they will cross each 
other, and where they cross they will form a picture of the 

The axis of a radiant point, that is, of any point on an 
object, does not mean the same thing as the axis of the lens ; 
it is a line that is broken at the two surfaces of the lens, 
passing through the optic center, of which the impingent 
and emergent parts are parallel. On this axis the image of 
the object is found. If rays emerge parallel, they will never 
cross, and therefore produce no picture; if they diverge 


after emergence, the image "will be on the same side of the 
lens with the object, and is denominated a virtual image. 

Equidistant conjugate focus refers to an object and its 
image on the ground glass when they are equidistant from 
the optical center, or more intelligibly speaking for the 
photographer, when the image and the object are of the 
same size. The distance of the equidistant conjugate focus 
can be derived from the principal focal distance, or vice 
versa. Thus in the equation : 

J__J_ J_ 

v ~ f u 

let y=12 inches, required the value of v and 21 when they 
are equal, or when the picture and object with the lens in 
question are of the same magnitude ? By transposition 

111a 12 aA . . 

— r-= 1 ss or -T7r= or v=2i inches. 

j v v v 12 v 

Therefore if a given single lens has a principal focus of 
12 inches, the ground glass as well as the object will have 
to be placed respectively at a distance of 24 inches from the 
lens in order to obtain a picture of the same size as the 

The principal focal distance of a single le?is can be found 
with sufficient accuracy for all practical purposes by measur- 
ing the distance of the lens from the burning point, and by 
adding to this distance half the thickness of the lens. 

The principal focal distance of a combination can be 
found with the same degree of accuracy by adjusting the 
camera before a given line so that the image of the line on 
the ground glass is exactly of the same size. One fourth 
of the distance between the object and the image is the 
principal focus required. For instance, let this distance be 
48 inches, then v is 24 and u is 24 inches; by substitution 

J_ 1 1 2 1 

The distance of either the image or the object from the 
optical center bears a direct ratio with the size of the image 
or the object, whether the lens be single or compound. 
Thus then, if Ave know the respective linear magnitudes of 
the image of the same object as obtained by two single 
lenses or by a single lens and a combination, as well as the 
principal focal length of the former, (which can always be 
easily obtained by the sun's rays,) we can by the legitimate 

^4 + ^4 = ~24 = T2' or /= 13 inches 

256 PRrsrrrs"G op transparent positives 

proportion derive the principal focus of the other single 
lens or the equivalent focus of the compound lens. For in- 
stance, let the principal focal length of a single lens be 3 
inches, and the linear magnitude of an image of a given 
object be 2 inches as obtained by this lens ; let also 5 inches 
be the linear magnitude of the image of the same object at 
the same distance when taken by another lens ; required 
the principal focal length of the other lens, (if single,) or 
the equivalent focal length of the combination ? 


By proportion as 2 : 3 : : 5 : 7£ the principal focal length required. 

In the proportion — r-= 1 , let u be n times larger than v ; 

f l J v u ° ' 

required the proportion that/ bears to u? 

Ill nv + v n + 1 
/' v nv ?u' 2 nv 
wo=f (n + 1), but u=nv 
.: u=f(n + l) and 
t =f(n + l) 
■ ' n 

Hence if we multiply the principal focal length of any 
lens by one more than the times the image is linearly greater 
than the object, we shall obtain the distance the screen is to 
be placed from the lens ; and if Ave divide this latter pro- 
duct by the number of times the image is linearly greater 
than the object, we obtain the distance of the object from 
the lens. In these analytical conclusions we suppose the 
lens to be single and very thin. The deductions thus de- 
rived have to be regarded in reference to the center of the 
combination. The following table has been constructed in 
accordance with the preceding principles, and it exhibits 
the distances between the object and the lens, the image 
and the lens, and the object and the image. Any degree of 
reduction and enlargement with a given lens or combination, 
whose equivalent focus is known, can be effectuated with 
great ease by adjusting the object and the ground glass at 
the distances indicated. 

in the following table stands for the distance between 
the object and the center of the combination. 

1 stands for the distance between the image and the center 
of the combination. 

S stands for the distance between the object and the 
image, or the sum of the two preceding. 

















~ I 




„H P 


*- = 





*- = 

«- = 





















| s s 














Is 8 

*. B 


.&£ * 


« e 





:r - 





5s s 

£s s 



: : r~ 



£s s 


**"** ? 


L ~- 

^ = ;; 

{! , T 





1,2 S 




S» B 






-"--"■ f 








: ; 











*- 8 

• " ; 






ls s 






Is ' 



r ; ; : 






S " S 

1* '= 



^ s 

»— f 



* 9 " 
















* P , 



Application of the Preceding Table. 

If the equivalent focus or principal focal length of a com- 
bination be known, it is very easy to arrange the object to 
be photographed, the camera and the screen, so as to produce 
a picture so many times larger or smaller than the object, as 
may be required ; for instance, let the focal length of the 
combination be 4i inches, what must be the conditions of 
the three things, object, combination, and ground glass, so 
as to obtain an image eight times larger than the object ? 

Look for 4| in the first vertical column, and for 8 on the 
first horizontal line ; where these two columns meet will be 
found all that is required. In the first place the object and 
the ground glass must be 45-^ inches apart, the ground glass 
is 40£ inches from the middle of the combination, and the 
object is consequently 5j\ inches from the same point. 

If we wish to diminish the size of the picture eight times, 
then the two latter of the above terms are inverted, the ob- 
ject being 45 T 9 g from the center of the combination, and the 
image only 5 T 'g- inches from the same point. 

The table can be extended as far as desired, by using the 
multiples of the numbers already given. If we required the 
conditions for 15 inches focus, multiply those along column 
5 by 3, the results will be the conditions required. 

Microph olograph)/ and Macroph otograpih y. 

This branch comprehends the mode of taking photographs 
of microscopic or almost invisible objects, as also of amplifi- 
cation by means of the solar camera. In either case means 
are resorted to by which light can be concentrated or con- 
densed on the object or collodion positive to be copied, and 
enlarged or diminished. These means are combinations of 
plane reflectors, concave reflectors, double convex or plano- 
convex lenses. The appendages to the solar camera and 
to the solar microscope are fac-similes of each other ; but 
the solar microscope existed before photography had been 
elicited from chaos ; the solar camera, therefore, is a mere 
imitation of its antecedent ; the patentees of the latter instru- 
ment, then, can make no claim to originality of design ; their 
only claim can be the application of the instrument to pho- 

Solar Microscope. 

The appendages to the solar microscope, that is, the con- 
densing part of the apparatus, consist in the first place of a 
plane mirror in the form of a rectangle, whose width is at 
least equal to the diameter of the plano-convex or double 


convex lens, which condenses the light received from the 
mirror. The length of the mirror must be about four times 
its width. At one end There is a hinge-joint, which allows 
the mirror to swing on the same like a door. The hinge is 
fixed to a circle of brass or other metal, which, by means of 
a dentated periphery, admits of a circular motion. By this 
contrivance it will be seen that the mirror has two motions 
at right angles to each other; for instance, supposing the 
back of the mirror faced the sun at noon, and were perpen- 
dicular to the horizon, then one of the motions mentioned 
would cause the mirror to incline toward the sun, until finally 
it would be flat on the horizon. The other motion permits 
the mirror to move either toward the East or the "West ; so 
that, as it now stands, if moved toward the West, the sil- 
vered surface would face the setting sun. By combining 
these two motions consentaneously, the mirror can always be 
so inclined as to reflect the rays of the sun from rising to 
setting into the axis of the condenser. The two motions in 
question are effected by means of screws and jnuion-wheels, 

The part just described might be a concave mirror admit- 
ting of the same motions ; this would act as a reflector and 
condenser at the same time. The condenser is fixed in the 
brass plate which is attached to the window-shutter, and 
around the condenser the metallic ring moves, to which the 
hinge of the mirror is attached. The object of this part of 
the apparatus is, by refraction, to cause the large bundle of 
parallel rays that impinge upon its surface, to be condensed 
from a cylindrical into a conical form, so that at a given dis- 
tance this converging and condensed light will arrive at its 
apex or focus. 

Xow, at this focus, all the light that has passed through the 
lens will be concentrated ; and at a variable distance, before 
it arrives at this focus, it will cover a variable space, vary- 
ing from a point or zero upward to an amount equal to the 
surface of the lens. 

The amount of condensation will be the ratio between the 
squares of the distances from the focal point ; thus, suppose 
the focal distance be twelve inches, and that we intercept 
the cone of light at three inches from the focus ; then by di- 
viding the square of twelve by the square of three we obtain 
the ratio, which is sixteen, and this indicates that the light 
at this distance is sixteen times more intense than it was 
when it first immerged from the lens. 

The object of the refracting lens, therefore, is to illumine 


the object with light. This is the primary view of the matter, 
but it does more than this ; each ray from the condenser not 
only illumines each point on the transparent object upon 
which it impinges, but on emergence after refraction it passes 
on modified by the medium through which it has penetrated, 
and carries, so to say, this part of the picture with it ; the 
cone of modified light is in fact the picture set in motion, and 
so directed as to strike the surface of the camera-lens which 
is next to it. These rays are convergent, and are each the 
axis of an independent cone of divergent rays from each illu- 
mined point of the transparent negative. Some photogra- 
phers maintain that the axes alone (that is, the rays that con- 
stitute the cone of light from the condenser) are available, 
and that the divergent rays around each axis are of no avail. 
This, however, is a mistake, and is equivalent to saying that, 
if an opaque object Avere illumined by a condenser or reflec- 
toi*, the picture could be taken only by focussing the cone or 
the beam of reflected light ; whereas we know full well in 
copying that the rays that enter the camera through the lens, 
and that go to the formation of the picture, can not be any 
of the reflected rays, because these are perpendicular to the 
surface of the copy, and would indicate that the impingent 
rays were also perpendicular, which is an impossibility, ow- 
ing to the opacity of the camera and its tube, which occlude 
all perpendicular rays. On the contrary, each illumined point 
becomes a new radiant, from which proceeds a divergent pen- 
cil of rays, of which many around the axis are refracted by 
the lens and brought to a focus on the other side. 

If the condensing lens be achromatic, the light will be 
white ; if not achromatic, it will produce spectral colors, of 
which some are useless in photography, whilst others are 
exactly those which are needed. Now the scientific optician 
can arrange his non-achromatic condenser in such a mannei', 
in reference to the lens and the negative, as to make use only 
of the violet light, or the actinic part of the spectrum, for 
the formation of the picture. The focns of the violet or ac- 
tinic light is shorter than that of the luminous or yellow part. 

The next appendage to the solar microscope is the object- 
holder, which has a sliding motion to or from the condenser, 
in the neighborhood of the focus, by which means the object 
can be placed in a condensed part of the cone of light, which 
is just sufficient to cover it and no more, a contrivance by 
which light is economized. 

The remaining part of the instrument is the microscopo 


proper, which contains the corrected objective for magnify- 
ing the object. 

Now the above description is precisely the same as that 
of the condensing part of the solar camera. With such an 
arrangement of mirrors and refractors, the camera and screen 
may remain fixed during the whole time of the operation. 

Another arrangement for concentrating light is accom- 
plished by means of reflectors fixed in the form of a frustum 
of a pyramid. But in the application of this contrivance 
the camera and screens must all move together on a univer- 
sal joint, like a heliostat, by which means the silvered sur- 
faces of the reflectors can always be preserved in front of 
the sun, so as to catch his rays, (as described in a pre- 
vious chapter of this work.) 

The mode of using the solar microscope and the solar cam- 
era is in no wise different, excepting that in the former a 
transparent object is substituted in the holder for the trans- 
parent collodion negative in the latter. Each is placed in 
the cone of condensed light, in order to be brilliantly illu- 
mined, and in such a position, in reference to the objective 
or photographic lens, as to bring the focus of the actinic rays 
immediately on the optical center of the last or front lens of 
the combination. It is by this means alone that the best en- 
larged picture can be obtained. 

Soto to find the point where the Lens is to he placed. 

It appears then that the lens may not be placed in any po- 
sition for maximum eflect ; the true position depends upon the 
power of the condenser, in combination with the power of 
the posterior lens of the tube, where such is used. There 
must be a relative connection between these two powers ; 
but this is not maintained in any of the solar cameras in the 
market, from the fact that tubes are not considered as parts of 
the solar camera ; operators are consecjuently left to apply 
whatever combination they may have on hand ; we must 
therefore avail ourselves of what is next best, and fix the 
combination where the maximum eflect can be obtained with 
given materials. 

Knowing the length of the principal focus of the conden- 
ser and its diameter, as well as that of the compound lens 
from the posterior lens, the mathematician can easily calcu- 
late how much the former focus will be shortened by the in- 
terposition of the tube. Supposing, for instance, the diame- 
ter of the condenser be eight inches, and its focal length be 
twelve inches, then the angle which the side of the cone of 


condensed light makes -with the diameter will be 71° '.23 
Moreover, let the diameter of the posterior lens be two 
inches, and the focal length from the back lens two inches, 
then the angle formed between the side of its cone and 
the diameter will be 63° 45'. That is, if the rays entered 
the combination parallel, they would form a cone, of which 
the outside ray would have this angle with the diameter of 
the back lens. But, being interposed in the cone of condens- 
ed light, of Avhich the rays are convergent, the tendency of 
the combination is to shorten the focal length, by reducing 
the angle 63° 45' to 56° 00', the difference between these 
two angles being the same difference that exists between 71° 
32' and 63° 45'. As the angle diminishes, so will the focal 
length of the cone of condensed light be diminished, and in 
the present instance to the amount of half an inch. 

Besides this, we have to reduce this distance still more, in 
order to find the actinic focus, which the mathematical opti- 
cian can easily find. 

But the generality of photogi'aphers are not supposed to 
be in a condition to deduce the requisite corrections in this 
way ; we must therefore show by practical means how we 
can approximate to the same results. 

Ascertain the focal length of the condenser by finding the 
distance of its burning point from the glass; then, when the 
tube is screwed out to the extent of its play, measure the 
distance from the face-plate, in which the tube is fastened, 
to the front lens ; subtract this distance from the focal length 
of the condenser, the difference will give the distance of the 
condenser to the outside of the camera nearly, or to the part 
upon which the face-plate of the tube is to be screwed. More 
accurately the same result can be obtained by interposing 
the tube in the condensed light, and by moving it backward 
and forward, until the focal or burning point is just on the 
outside of the front lens ; let an assistant measure this dis- 
tance from the outside of the camera, and at this distance 
fix the tube permanently. Whilst doing this the greatest 
care is required to make the axis of the condenser coincide 
with the axis of the tube. 

This is the first rude adjustment. The second adjustment 
consists in bringing the actinic focus so as to coincide with 
the optic center of the front lens. Screw back the sliding 
part of the tube and turn on the sun ; the luminous focus will 
be quite visible in the dark space behind the camera. Now 
insert a piece of deep violet-colored glass between the con- 
denser and the objective, so as to intercept all the colors of 


the luminous cone, excepting the violet, and ascei'tain "where 
the violet cone comes to a focus ; screw the tube out until 
this focus is just in front of the anterior glass ; then, knowing 
the thickness of the front lens, advance the tube until the 
blue focus is in the middle of the front lens, and let this be 
the final and jiermanent adjustment of the tube in reference 
to the condenser. Mark this position by a line on the brass 
work, in order that the tube can be adjusted at a moment's 
notice when required to be used. 

The negative-holder is movable by means of a screw, so 
that it can be brought into focus upon any screen on the 
other side of the tube. Whenever this operation of focus- 
sing is to be performed, insert the violet-colored glass, so as 
to focus in reference to actinism, and not to luminosity. By 
this means the luminous picture on the screen (that is, when 
the violet-colored glass is removed) may not be quite sharp, 
but the printed picture on the paper will be sharp and beau- 
tifully defined. The same mode of proceeding may be fol- 
lowed with the ordinary camera, where there is any doubt 
of the correction of the tube for actinism. Place in front of 
the tube a piece of violet-colored glass every time you focus. 

Macrophotography, or the Art of Talcing Enlarged 

The Negative for Enlargement. 
The size of the negative will have to depend on the diam- 
eter of the condenser ; if this be nine inches, a one-sixth plate 
will be large enough, the object being to get the negative as 
near the apex of the cone of concentrated light as possible, 
and in such a position as to be totally covered by the cone. 

TJie Quality of the Negative. 
The negative suitable for the solar camera must be very 
bright, well defined and quite clear. The glass must be thin, 
perfectly flat, or in the same plane and homogeneous. The 
negative effect need not, in fact, must not be carried on to 
the same extent as for positive printing ; it is but a trifle in 
advance of the ambrotype ; if there should happen to be the 
slightest quantity of fogging, that is, reduction on the trans- 
parent parts, it will be necessary either to take another ne- 
gative or to clear off the fogginess. This is effected by flow- 
ing the phite with a dilute solution of iodine in iodide of 
potassium, until the picture turns slightly cream-colored ; 
the plate is then washed and flowed with a solution of cyan- 
ide of potassium, which dissolves the newly formed iodide 


of silver and thus clarifies the picture. As soon as the latter 
is satisfactory, as to brightness, cleanness, and fine definition, 
wash and dry the plate, but apply no varnish. 

As soon as the negative is in its place, and accurately fo- 
cussed actinically, fix the prepared paper on the screen in its 
place. In order to preserve the paper perfectly flat and 
smooth, sponge the back with a wet sponge, and after it has 
thoroughly expanded, and lies uniformly, and without -undu- 
lations, go round the edge to the amount of half an inch on 
the same surface which has been sponged with a thick solu- 
tion of gum-arabic ; attach the paper so prepared to an even 
plate of glass or drawing-board, of somewhat smaller dimen- 
sions than the paper, and allow it to dry. "When dry, all 
the corrugations and undulations will have disappeared ; the 
paper will be smooth and flat, and ready to receive the image, 
supposing naturally it has already been sensitized in the sil- 
ver bath. If this operation has been neglected or omitted, 
the silver solution can be very expeditiously poured upon 
the surface and spread with a pad or tuft of cotton wool, 
until the film is uniform. The excess of silver is then re- 
moved, and the plate is reared on one corner over a wine- 
glass to receive the drippings. 

When dry it is placed in the focus of the negative, and 
the sun is turned on. By means of the two screws on the 
solar camera, the sun's light is maintained in its position 
during the whole operation. Printing on albumenized pa- 
per by the solar camera is a tedious operation, requiring 
sometimes several hours before it is complete, and some- 
times even a day or two by reason of the cloudiness of the 
sky. Where this sort of printing is practicable, as is the case 
generally in our own country, the results are the best. 
Printing by development, however, is more reliable, because 
it is altogether independent of the condition of the sky, wheth- 
er cloudy or cloudless. 

Several processes for printing by development will be 
found in the chapter in which this subject has been discuss- 
ed. I will insert another in this place, from its applicability 
and reliability. It is the process of Blanquart-Evrard, 
whose prints have been so much admired. 


JBromo-iodizing Bath for Paper. 

"Water, 12 ounces. 

Gelatine, 1 dracbrn. 

Iodide of potassium, 1 drachm. 

Bromide of potassium, 15 grains. 


Immerse the papers in this bath, as many at a time as it 
will contain, and keep them there for two or three hours. 
The bath can be "used over and over again until exhausted. 
The papers are then taken out and hung up to dry. As 
soon as they are dry they may be preserved in a portfolio 
for use. 

Previous to being sensitized they are exposed for a quar- 
ter of an hour to the vapor of hydrochloric acid. This op- 
eration is easily effected by fixing the paper along the sides 
and under the lid of a large nearly air-tight box, by means 
of varnished pins. At the bottom of the box place a saucer 
containing a handful of salt, an ounce or two of sulphuric 
acid, and half as much boiling water. Vapors of hydrochlor- 
ic acid will be generated in abundance, and will thus saturate 
the paper. 

Sensitizing Bath. 

Nitrate of silver, 1 ounce. 

Distilled water, 14 ounces. 

Nitric acid to give it an acid reaction. 

Let the paper float in this bath for ten minutes. By de- 
composition they will now contain the iodide, bromide, and 
chloride of silver. After sensitization they are allowed to 
drain, and then dried either by pressure between folds of 
bibulous paper or by suspension in the dark-room. 

The exposure required will vary from a couple of seconds 
to half a minute beneath a negative, and longer than this on 
the screen of the solar camera. When the image is just 
visible, the printing has been carried on long enough. 

The picture is brought out by immersing it in the ordina- 
ry gallic acid bath, at a temperature of 80 degrees, and by 
keeping it there for a quarter of an hour or more as cir- 
cumstances require. The bath must be large enough for 
many pictures at a time ; these are kept in motion all the 
while. They assume a disagreeable color, and become cov- 
ered with spots which are removed by the operations after- 
ward. As soon as the depth* of shade is sufficiently intense, 
the prints are taken out, laid one by one on a glass plate, and 
sponged on both sides and then immersed in a bath of hypo- 
sulphite of soda for five minutes, in which they are toned. 

Hyposulphite of soda, 1 ounce. 

Rain-water, 20 ounces. 

After this they are removed direct into a second bath of 
hyposulphite of soda of the same strength, and are allowed 


to remain for twenty mhrates, in which they are completely 

The prints are then carefully washed in several waters 
and finally immersed in a hath of dilute hydrochloric acid, 
which removes a yellow deposit and the spots ahove men- 
tioned. A second washing completes the operation, witli 
the exception of drying and exposing to the action of light 
for several weeks, which improves the reddish tone hy chang- 
ing it gradually into purple. 

These prints will keep for an indefinite time, although 
toned with sulphur. 

Jficrophotography, or the Art of taking Diminished Copies 
of Photographs, or Photograplis of Microscopic Objects. 

Diminished Photographs. — It is a much easier operation 
to diminish the size of a photograph or object by photo- 
graphic means than to amplify one ; and the result in genera i 
is more satisfactory, because all the errors of the original 
are diminished in the same ratio as the whole picture is 
diminished. In order to take portraits so invisibly small 
as not to be seen without the aid of a magnifier, we require 
a small camera specially arranged for the purpose. Such 
cameras, furnished with the necessary objective, are manu- 
factured by Bertsch in Paris. The tube requires no focus- 
sing ; the only condition to be observed is to place the pho- 
tograph, object, or print to be copied at or beyond a given 
distance. All lenses have this property of requiring but one 
adjustment, which is permanent when once found, for objects 
beyond a given distance, which varies directly as the focal 
distance or power of the lens. Lenses for the diminutive 
pictures in question are in focus for all distances beyond 
three feet or so. Objectives, such as are sold for microscopic 
purposes, whose focal distances are one inch, half an inch, or 
a quarter of an inch, may easily be arranged in a very small 
camera to take these diminutive portraits. But very little 
ingenuity will suffice to make such a camera out of a small 
telescope, where one tube slides into another. In the end 
of the inner tube the objective is fixed; in the end of the 
outer, the ground glass and the plate-holder. This com- 
pound tube is fixed permanently upon a solid support six 
inches high, on a piece of board four or five feet in length 
or even more. On the opposite end of the board a plane is 
erected at right angles to the former and also to the axis of 
the camera. Find the point on this vertical board where 
the axis cuts the same, and mark it as the center of the pic- 


ture to be copied. The picture is fixed upon this plane by 
means of tacks or pins in an inverted position and so that 
its center coincides as near as possible with the mark just 

The next proceeding is to focus the lens. Take the long 
board and place it so as to receive the sun's rays upon the 
picture. Now move the inner tube of the camera in and 
out until the image is seen on the ground glass by means of 
a powerful magnifier. Focus with the greatest sharpness. 
This operation is very refined and requires a great deal of 
patience. When the utmost definition is thus obtained, 
place before the opening of the tube a piece of very thin 
violet-colored glass and see if the image is still sharp ; if it 
be, fix the two tubes permanently so that their relative posi- 
tion can not be changed. In future this operation of focus- 
sing is no longer required. If, however, the picture is not 
sharp when the violet-colored glass is interposed, focus until 
you get perfect definition, and then fix as just directed. 

The glass to receive the picture is thin and homogeneous ; 
it is flowed also with a very thin collodion and sensitized as 
usual. All the operations are precisely the same as those 
already described in the preparation of the ambrotype. Of 
course a pair of spectacles of very high magnifying power is 
required while developing, fixing, and mounting. With a 
pair of pliers or foi*ceps the small piece of glass can be broken 
down so as to fit into the ring, etc., which is to receive the 

The objectives manufactured by Grunow in New-York for 
microscropes have succeeded quite well with me in the pro- 
duction of almost invisible pictures ; and I have no doubt he 
will be able to fit up a microscopic camera for such as require 
one from the indications here given. Such a camera, requir- 
ing great refinement of workmanship, will of course be more 
likely to be better made by those who are accustomed to 
the refined adjustments of a microscope than by the photo- 
grapher himself. The objectives of Grunow are not only 
unexceptionable, but are endowed with qualities superior to 
those in many of foreign origin. 

Microscopic Objects. — The objectives just alluded to 
are very well suited for taking enlarged photographs of 
microscopic objects, such as the porous structure of wood, 
the siliceous deposit in guano, blood corpuscles, starch 
granules, itch insects, etc. Such an objective is fixed 
to an ordinary bellows camera, so arranged on a sliding 
platform that the axis of the objective coincides witb 


the axis of the cone of concentrated light from the 
condenser of the solar microscope. The latter instrument 
has a special opening between the condenser and the object- 
ive to receive the transparent object whose photograph is to 
be taken of an enlarged size. If the objective is not quite 
achromatic, insert a piece of thin violet-colored glass over 
the object while focussing, and fix the objective so that the 
violet cone of light terminates in the optic center of the 
objective as before described. Focus by means of a pair of 
very powerful spectacles or a compound microscope. In the 
first place make the camera firm on the platform, when the 
objective is once in its place ; then draw out the ground glass 
nearly as far as it will go, and afterward move the micro- 
scopic object nearer or farther off, as the case may be, by 
means of the thumb-screw, until the picture is visible on the 
ground glass ; finally focus with accuracy so as to get perfect 
sharpness. The violet-colored glass may now be withdrawn. 
The prepared collodion plate is inserted in the place of the 
ground glass ; the slide is drawn out, and the sun's light 
turned on for a fraction of a second. It is in many instan- 
ces an advantage to keep the violet-colored glass in its place, 
because it moderates the light ; and the result is even better 
witli it than without it. 

Finish the plate for a positive or negative according to 
rules already prescribed in ordinary photography. 



A photograph on a silver or silvered plate is superior in 
definition and beauty to all other photographs taken on other 
materials. It has, however, its disadvantages ; amongst 
these may be reckoned the lateral inversion of the picture, 
the inability of regarding the image at all angles of reflec- 
tion, and of producing reproductions of the original by 
some quick printing process. 

The Daguerreotype process is divided into six different 

First Operation, or the Cleaning and Polishing of the 
Silvered Plates. 

Copper plates can be purchased already silvered with a 
pure frosted silver surface, of the proper size and ready for 
the polishing. In the first place, with a pair of shears, clip 
off the four corners of the plate, about a quarter of an inch 
from the apex of each angle ; next with the machine for this 
purpose make a ledge all round the plate of one tenth of an 
inch in width from the silver side toward the copper side, 
so as to form a groove such as the tinman makes when 
grooving two edges of tin together. The plate is then fixed 
on a patent plate-holder, which in its turn is next screwed 
tight in the plate-vice. In this condition the silvered surface 
can easily be cleaned. This is effected by means of rotten 
stone, alcohol and Canton flannel, which are used in the same 
manner exactly as in the cleaning of glass plates. As soon 
as the plate is perfectly smooth and free from scratches, it is 
polished with what is called the buff, which consists of a 
piece of wood, about fifteen or eighteen inches long, four 
or five wide, and about three quarters of an inch thick ; 
this piece is slightly curved longitudinally like the rocker 
of a chair, though to a less extent. It is well padded 
on the convex surface and finally covered with chamois 
leather. On the surface scatter a small quantity of jewel- 


er's rouge, (sesquioxide of iron,) and then holding the buff 
by either end in the right and left hand move it backward 
and forward over the smooth silver plate, first in one direc- 
tion and then at right angles to it, until the surface has a 
very uniform rich polish, devoid of lines. The plate is then 
ready for being sensitized. The buffing is more easily and uni- 
formly executed on what is denominated the buffing-wheel. 

Second Operation, or the Sensitizing of the Silver Plate. 

For this purpose two coating-boxes are required, one con- 
taining the vapor of iodine, and the other that of bromine. 
They ai'e so arranged as to allow the introduction of the 
polished plate without any loss of vapor. These boxes must 
be kept at a warm temperature so as to evolve the vapors 
from the materials ; in winter artificial heat is used. One 
coating-box contains at the bottom first a piece of Canton 
flannel, and then about half an ounce or more of iodine in 
crystals ; the other contains a mixture of hydrated lime and 
bromine, well pulverized and mixed. The operation is per- 
formed in the dark-room near the orange-colored pane of 
glass. The polished plate is first inserted in the holder of 
the iodine coating-box, and the lid is then closed. The sur- 
face, if examined closely, assumes various shades of color, 
beginning with light yellow, then deep yellow, reddish, cop- 
per-red, violet, blue, and green. As soon as the plate passes 
from the yellow to the red, it is placed over the bromine 
vapor, and kept there until the reddish color changes into a 
violet or steel color ; it is then put back again over the iodine 
for one third of the time of the first exposure. By this means 
the film receives a very high degree of sensibility. The times 
of these three exposures, as soon as determined by practice, 
are counted in seconds. A more sensitive film may be ob- 
tained by iodizing simply to the light yellow, by bromizing 
to the dark yellow, and then again over the iodine for one 
third of the first exposure. This film, however, is very thin 
and not suitable for portraits, although well adapted for views. 
The plate is now ready for the 

TJtird Operation, or the Jl.iposure to Light. 

It has been observed that the sensitized plates are more 
sensitive to the actinic impression if not exposed for a quar- 
ter of an hour after sensitization ; in general, however, the 
plate is transferred directly from this operation to the plate- 
holder of the camera, and exposed right away. The time of 


exposure is very short ; it is naturally various, as in all other 
and similar cases depending upon the brilliancy of the light, 
the season of the year, the time of the day, and other minor 
circumstances. A few seconds, even in the room, are mostly 
quite sufficient. The exact number is easily learned from the 
conditions of the case ; and then the exposure afterward can 
be regulated by counting. The plate is next withdrawn from 
the plate-holder in the dark-room ; it contains no visible 
image ; this is made to appear by proceeding to the 

Fourth Operation, or Developing by the Vapor of Mercury. 
A cast-iron box is prepared for this purpose, capable of 
being well closed after the plate is introduced. It contains 
mercury at the bottom, which is kept at the temperature of 
from 120° to 150° Fahrenheit, by means of a lamp with a 
small flame capable of graduation, and a thermometer attach- 
ed to the box with the bulb in the mercury. A couple of 
ounces of mercury will be sufficient at once for ordinary 
portraiture. In two or three minutes the development will 
be complete. At intervals the plate maybe examined to see 
the progress of development ; but this examination must be 
made with great care, for the film is easily fogged by expos- 
ure to diffused light. If the time of exposure has been too 
long, the whole image will be fogged and indistinct ; Avhere- 
as if it has been too short, the high lights alone will be de- 
veloped, while the rest will undergo no change whatever. 
Supposing the picture to possess the proper gradation of 
light and shade, it is then ready for the 

Fifth Operation, or the Fixing of the Developed Image. 
The film is still very sensitive, and the picture in a few 
minutes would be irremediably spoiled, unless the sensitive 
character of the film be annihilated. This is effected by 
plunging the plate immediately into the fixing solution, 
which must be preserved in a very clean condition by con- 
tinual filtration after each operation. The fixing solution 
consists of: 

Hyposulphite of soda, 2 drachms. 

Distilled or rain-water, 1\ ounces. 

Agitate the plate in this solution for a few seconds, until 
the iodizing is entirely removed, and then wash the plate in 
distilled water. In all operations of washing and fixing, use 
only filtered materials, for small particles of dust are very 
visible on the dried plates; use, especially, very pure water, 
because ordinary water contains salts, which are left as a 


deposit on the plates when dried. After the fixed plate is 
well washed proceed to the final or 

Sixth Operation, or the Toning with Gold. 
In the first place make a ledge round the plate in the oppo- 
site direction, so as to form a miniature dish with the picture 
at the bottom ; or cut off" the former ledges entirely, and 
holding the plate by one of its corners with a pair of pliers, 
pour upon the surface of the picture, held horizontally, as 
much of the following gold solution as it will hold without 
flowing over the edges : 

Toning Solution. 
■»t 1 ( Chloride of gold, . 1 grain. 

' \ Distilled water, 1 ounce. 

v- 9 j Hyposulphite of soda, 4 grains. 

"' I Distilled water, 1 ounce. 

Dissolve and pour the gold solution into the hyposulphite 
of soda, and mix well together. Next light a spirit-lamp 
with a large wick, and holding the pliers and plate in the 
left hand, play beneath the plate containing the toning solu- 
tion with the flame of the lamp held in the right hand. Do 
not allow the flame to play upon the same spot ; move it 
about, bubbles will soon begin to arise, and the picture will 
soon begin to assume a much more agreeable tone. Take 
care to have an excess of gold solution all the time upon the 
plate, otherwise, if it fails on a certain part during the oper- 
ation of gilding, a stain will be produced that can not be 
removed by any subsequent treatment. Use also a large 
flame, to produce rapid action ; prolonged action fogs the 
picture. When the tone of the picture is satisfactory, im- 
merse the plate at once in a basin of water, and wash well 
at the top ; afterward pour over the plate two or three 
times, distilled water, and then dry the plate ; beginning at 
the upper edge with the application of the flame of the 
lamp, proceed downward, as the film dries, blowing off the 
excess of water as you proceed, or absorbing it with a 
sponge from the pendent edge and corners, until the whole 
surface is dry. 

Daguerreotypes may be touched up with color like any 
other photographs, where desired. It must be confessed, 
however, that a well-toned daguerreotype picture looks best 
unadorned with either color or tinsel. 



These processes comprehend several operations with the 
persalts of iron, chromium, the salts of uranium, and the car- 
bon process. They are very interesting, but have not as yet 
been applied to any useful purpose. The carbon process has 
not arrived at that degree of perfection which is expected 
in such operations.* This expression of its merits is limited 
to direct printing on paper by carbon or other colored media 
in connection with chrome salts, etc. Photo-lithography and 
its congeners, that require the application of carbonaceous 
ink, are properly classified as photo-engraving, and will be 
treated as such. 

Process with the Salts of Iron. 

Sir John Herschel discovered, several years ago, that cer- 
tain of the persalts of iron, when exposed to light in connec- 
tion with organic matter, undergo decomposition, and are 
reduced to the state of proto-salts ; and we are indebted to 
Poitevin for numerous interesting developments in this de- 
partment. For instance, the perchloride, so exposed, becomes 
reduced to the proto-chloride, or, as Van Monckhoven more 
appropriately remarks, to the state of oxy-chloride. For 
this purpose the sesquichloride must be quite neutral. The 
ammonio-tartrate, potassa-tartrate, and the ammonio-citrate 
of iron are much more sensitive to light than the sesqui- 
chloride, and the latter salt the most of all. 

The image formed by means of these salts is much fainter 
than that with the chloride of silver ; but it can be inten- 
sified by the application of other metallic salts. The mode 
of operation consists in floating the paper on the solutions in 
question, in the dark-room, in allowing them to dry and then 
exposing them afterward beneath a negative, as usual, with 
paper prepared with chloride of silver. 

* Pouncy's New Carboa Process seems to give great promise of being 
usefully applied. 


Cyanotype. — Float on a solution of the sesquichloride of 
iron, dry and expose; afterward wash the prints, and then 
immerse them in a hath of ferridcyanide of potassium. The 
picture will appear of a blue color in all those places where 
the sun has acted. Ferridcyanide of potassium has no action 
upon the persalts of iron ; on the protosalts, however, it 
produces prussian blue. 

Crysotype. — If the papers containing the faint image, pro- 
duced on the ammonio-citrate of iron, be floated on a bath 
of a dilute and neutral solution of chloride of gold, the image 
assumes a purple tone, which becomes gradually darker the 
longer it is exposed to the solution. 

Solutions of the other metals, such as those of silver, mer- 
cury, and platinum, also produce images which are of a gray- 
ish color. Bichromate of potash yields a picture by a similar 

Process icitJi the Salts of Uranium. 

The discovery of this process owes its origin to Xiepce de 
St. Victor and to Burnett. The nitrate of the sesquioxide 
of uranium undergoes in connection with organic matter, 
when exposed to the sun, a decomposition analogous to that 
of the sesquichloride of iron. 

The paper, without having undergone any preceding 
preparation, excepting that of having been excluded from 
the light for several days, is floated on a bath of the nitrate 
of uranium, as follows : 

Distilled water, 10 drachms. 

Nitrate of uranium, 2 drachms. 

The paper is left on the bath for lour or five minutes ; it is 
then removed, hung up and dried in the dark-room. So pre- 
pared, it can be kept for a considerable time. 

The exposure beneath a negative varies from one minute 
to several minutes in the rays of the sun, and from a quarter 
of an hour to an hour in diffused light. The image, which 
is thus produced, is not very distinct, but comes out in strong 
contrast when developed by one of the following developers : 

Nitrate of Silver Developer. 

Distilled or rain-water, 2 drachms. 

Nitrate of silver, V grains. 

Acetic acid, a mere trace. 

The development is very rapid in this solution; in about 
half a minute it is complete. As soon as the picture appears 
in perfect contrast, the print is taken out and fixed by im- 
mersion in water, in which it is thoroughly washed. 

274 printing without the salts of silver. 

Chloride of Gold Developer. 

Distilled water, 2 drachms. 

Chloride of gold, 1\ grains. 

Hydrochloric acid, ia drop. 

This is a more rapid developer than the preceding. This 
print is fixed in like manner by water, in which it must he 
well washed, and afterward dried. "When dried by artifi- 
cial heat the vigor of the print is increased. Prints tliat 
have been developed by the solution of nitrate of silver may 
be, immersed in the gold bath, which improves their tone. 

The picture may be developed, also, by first immersing 
the prints in a saturated solution of bichloride of mercury, 
and afterward in one of nitrate of silver. In this case, how- 
ever, the time of exposure is increased. 

Pictures may be obtained also by floating the papers on a 
mixture of equal quantities of nitrate of silver and nitrate of 
uranium, in about six times their weight of water. "When 
dry, they are exposed beneath a negative. In this case the 
image appears as in the positive printing process with chloride 
of silver, being effected by the decomposition of the nitrate 
of uranium, which, reacting on the nitrate of silver, decom- 
poses this salt, and reduces the silver. These prints require 
fixing in the ordinary fixing bath of hyposulphite of soda, 
and then washing as usual. 

Process for Red Pictures. 
Float the papers for four minutes in the preceding bath of 
nitrate of uranium, drain and dry. Xext expose beneath a 
negative for eight or ten minutes, then wash and immerse in 
the following bath : 

Fcrridcyanide of potassium, 30 grains. 

Bain-water, 3 ounces. 

In a few minutes the picture will appear of a red color, 
which is fixed by a thorough washing in water. 

Process for Green Pictures. 
Immerse- the red picture, before it is dry, in the following 
solution : 

Fesquichloride of iron, 30 grains. 

Distilled water, . . . . ' 3 ounces. 

The tone will soon change to a green. Fix in water, and 
dry before the fire. 

Process for Violet Pictures. 

Float the papers in the following bath for three or four 
minutes : 


JVater, 2 ounces. 

Nitrate of uranium, 2 drachms. 

Chloride of gold, 2 grains. 

Afterward take them out and dry. An exposure of ten or 
fifteen minutes will produce the necessary reduction. The 
picture has a beautiful violet color, consisting of metallic 
gold. Wash and dry, as usual. 

Process for Blue Pictures. 

Float the papers for a minute on the following solution : 

Distilled water, 5 ounces. 

Ferridcyanide of potassium, 1 ounce. 

Dry in the dark-room, and then expose beneath a nega- 
tive until the dark shades have assumed a deep blue color ; 
then immerse the print in a solution of: 

Rain-water, 2 ounces. 

Bichloride of mercury, 1 grain. 

Wash the print, and then immerse it in a hot solution of : 

Water, 4 ounces. 

Oxalic acid, 4 drachms. 

Again wash and dry. 

Carbon Process. 

This process aims to produce a picture on paper either 
with lampblack or some other fine, impalpable powder. I 
shall discuss this subject as distinct from photo-engraving or 
photo-lithographic operations, although the two processes 
are based upon the same principle, that of the decomposi- 
tion of the bichromates or the persalts of iron when exposed 
in connection with organic matter to the rays of the sun. 
The chloride of chromium and the other salts of chrome, as 
well as the sesqui-salts of iron, are subject to this mode of 
decomposition. The rationale of the operation appears to be 
this: the chromic acid of the chromate, or the sesquioxide 
in the case of iron is reduced by light into the sesquioxide 
of chromium, or a protosalt of iron, and thus parts with 
oxygen which is communicated to the organic substance with 
which the salts were mixed, such as gelatine, gum-arabic, 
etc., which in their turn become changed in properties as to 
solubility or insolubility, etc. 

Various authors have experimented in this direction ; 
Mungo Ponton first indicated the principle. AVe are indebt- 
ed for the most interesting results in carbon printing to 
Poitevin, Gamier and Salmon, Pouncy and Fargier. In the 
first experiments of Poitevin, a chromate was employed in 


connection with gum, gelatine or albumen. His mode of 
operation, as described in the Traite de V Impression JPhoto- 
graphique sans sels cV Argent is as follows : 

" I apply different colors either liquid or solid to the pa- 
per, fabric, glass or other surfaces, by mixing these colors 
with the solution above mentioned, (bichromate of jDotassa 
and organic matter, etc.) 

" The photographic impression, on this prepared surface, is 
produced by the action of light passing through a photo- 
graphic negative, engraving or suitable object, or finally by 
means of the camera. It is then washed by means of a 
sponge and an abundance of water. The albumen or the 
organic matter becomes insoluble in the parts where the 
lights have acted, and the picture is produced by the color 

A second method is described as follows : 

' ; In the preparation of the papers I cover them with a 
concentrated solution of one of the substances above men- 
tioned (gum, gelatine and the like) in connection with a 
chromate ; after drying I submit them to the direct rays of 
the sun or to diffused light beneath a negative of the object 
to be copied. After an exposure, which varies according to 
circumstances, I apply by means of a pad or a roller a uni- 
form film, either of typographic or lithographic ink, previ- 
ously diluted, and then I immerse the sheets in water. It 
is now that all the parts, which have not been impressed by 
light, give up the greasy substance, while the others retain 
it in proportion to the quantity of light that has passed 
through the negative." 

The principle involved in these two opei'ations is quite 
different, although the result is the same. In one the film ol 
gelatine, etc., where it has been exposed to the sun, has be- 
come insoluble in water, and consequently retains the color- 
ing matter from being carried away in the washing. In the 
other case the film that has received the impression of light, 
has received, a new power, that of adhering to the greasy 
ink applied uniformly to the whole surface, whilst the other 
parts, having no attraction for this ink, allow it to be dis- 
solved off when floated on water. 

All the other carbon j^rocesses, as for instance, that ot 
Testud de Beauregard, of Pouncy, Chardon, Salmon and 
Gamier, Lafon de Camarsac, and of Fargier, are mere modi- 
fications of Poitevin's process, with but little amelioration. 

Testud de Beauregard took out a patent for his process in 
November, 1858. It will be unnecessary to describe this 


process, because it is essentially analogous to Poitevin's 
where he makes use of printing ink. 

Potency's Process, 

Take a drachm of lampblack, reduce it to an impalpable 
powder and pass it through a muslin sieve ; mix it inti- 
mately with half an ounce of a concentrated solution 
of gum-arabic and the same quantity of a similar solu- 
tion of bichromate of potassa. Lay on a uniform layer of 
this mixture upon a piece of a paper fixed on a stretcher, 
by means of a camel's hair pencil ; as soon as it is dry, it 
may be exposed beneath a negative to the sun's rays for a 
number of minutes, (from four to eight.) The print is then 
immersed in water, impression side downward, and left for 
five or six hours in this fluid. Finally it is washed beneath 
the tap. The gum and the coloring matter are retained in 
those parts that have been impressed ; whilst on the others 
they are dissolved or washed off. 

Pouncy's New Carbon Process. 

Take a sheet of tracing paper, made transparent by var- 
nish or oil, and coat it on one side with a solution of gela- 
tine. When dry it is ready to receive a coating of printing 
ink of the consistence of cream. This ink, as far as I have 
been informed, consists of a mixture of lampblack, or some 
similar material, together with asphaltum or bichromate of 
potassa, or with both. The quantity of the latter is very 
small by reason of its insolubility in the other ingredients. 
This ink is brushed over the surface that has been covered 
with gelatine, and is then hung up to dry. This part of the 
operation has to be performed in the dark-room. The paper, 
when dry, may be preserved for months unchanged, if not 
exposed to the light. 

The next operation is to expose the prepared paper be- 
neath a negative to light. Pouncy has availed himself of a 
method of exposure first suggested and used by Fargier, as 
will be seen in one of the following pages. The negative is 
laid in the printing-frame as in the ordinary printing of pos- 
itives ; upon this place the prepared paper, but with the 
white surface upon the film of the negative, and the surface 
covered with gelatine and sensitive ink away from it or on 
the opposite side. 

The light, therefore, has to pass both through the nega- 
tive and the transparent paper before it arrives at the sensi- 
tive film. The time of exposure is about half an hour. 


Wherever the light impinges upon this film, it indurates 
the ink and renders it insoluble in turpentine or benzine. In 
this process the middle tones are produced with great ac- 
curacy and beauty. 

After exposure there is no apparent change in the film ; 
but when the paper is dipped in turpentine the soluble parts 
ai - e all dissolved off. The paper is next placed in a second 
bath of turpentine where the lights are thoroughly cleansed of 

The paper is then taken out and dried. The paper being 
transparent, the picture is seen through it, and then regard- 
ed as a true picture, free from inversion. These prints can 
be used as transparencies, or can be transferred to cardboard 
or stone. In the former case they look like wood-cuts or en- 
gravings, combining at the same time all the beauty of the 

This discovery of Pouncy's has been published without 
the necessary details, just as these sheets are passing through 
the press ; but if the results are as stated by good authori- 
ties, it may be regarded as the great discovery, not only or 
the year, but of the age. Neither silver nor gold is re- 
quired in the process — the prints appear in printing ink 
after developing, fixing, and washing in turpentine. 

Processes of Salmon and Gamier. 

For one of these processes a part of the Luynes second 
prize Avas assigned to the authors in 1858. Their other pro- 
cess was not brought into competition, although it was pa- 
tented. (Poitevin took the first gold prize.) In both pro- 
cesses a transparent positive is employed instead of a nega- 
tive. - 

No. 1. — Dissolve thirty drachms of loaf-sugar in thirty 
drachms of water, then add seven drachms and a half of 
neutral bichromate of ammonia, pulverized and dissolved* 
in a mortar. To this mixture add ten drachms of the 
white of egg previously well beaten up together with 
a few grains of the bichromate. As soon as all these 
ingredients have been very intimately mixed, the solution 
is passed through a linen filter for use. In the mean 
while the paper is fixed on a board by means of tacks, 
and then brushed over with the above mixture. Take care 
to use of the mixture only just enough to cover the surface 
in order thus to obviate streaks and other similar imperfec- 
tions. The paper is then removed and dried before the fire, 
taking care not to bring it too near, and to present the 


posterior side to the heat. This part of the operation is soon 
finished. It is then exposed beneath a positive to the rays of 
the sun for fifteen or twenty minutes. After the expiration 
of this time the image isquitevisible; the paper is again heat- 
ed before the fire, which appears to continue the action of light, 
and thus becomes the means of modifying the intensity of 
the shades. It is now fixed a second time upon the board, 
and fine ivory black is brushed over the surface with a flat, 
moderately soft and flexible camel's hair brush. The film 
of ivory black is afterward uniformly spread by means of a 
soft pad of cotton all over the surface, after which the paper 
is detached from the board and presented for a few seconds 
to the lire. This being done, the [taper is cautiously immersed 
in water, picture-side upward, and left there for a quarter 
of an hour, moving it about gently at intervals. As soon as 
it is supposed that the soluble portions of the bichromate 
have been removed by the water, the paper is withdrawn. 
Finally, in order to improve the whites, the paper is im- 
mersed in a bath containing ten ounces of water and half an 
ounce of concentrated sulphurous acid. Tins operation has 
to be performed, in like manner with the preceding, with 
great care, otherwise the coloring matter is liable to be carried 
off from the parts which are insoluble, for the film does not 
adhere with much tenacity. The object of this final immer- 
sion is to remove a number of yellow and gray patches in 
the lights ; with the greatest care, however, it is very difficult 
to get rid of numerous small particles of charcoal imbedded 
as it were in the porous structure of the paper. After this 
operation the paper is taken and dried. 

Sulphurous acid may be prepared for the preceding oper- 
ation, by heating a mixture of sulphuric acid and small 
fragments of wood, such as chips or matches, in a retort. 
The vapor thus produced is sulphurous acid, which can be 
condensed in cold rain-water to saturation. 

No. 2. — In the second process a thick solution of citrate 
of iron is spread evenly with a soft linen pad over the surface 
of a sheet of satin paper. The paper is then dried in the 
dark-room. It is next exposed beneath a transparent posi- 
tive from ten to thirty minutes to the rays of the sun, by 
which an image is made apparent. This is intensified or 
made more vigorous by the following application. Fix the 
paper on a hoard with tacks and then with a cotton pad dab 
the surface over uniformly with an impalpable powder of 
carbon or any other color. At first no change is apparent, 
but by breathmg upon the surface, those parts that have not 


been impressed by light, being more or lesshygrometric in pro- 
portion to the actinic .action, attract the humidity and at the 
same time the coloring material, which exhibits the image. 
The parts through which light has penetrated, being no 
longer deliquescent, or at least only partially so, reject the 
carbonaceous materials, and these are swept away together 
with the unaltered citrate in the process of washing and 
fixing. The prints are afterward dried and varnished if 
thought necessary. The addition of sugar to the citrate in 
this process is recommended by Poitevin. 

All these processes are more or less defective, producing 
prints devoid of the middle tones. This arises from the 
circumstance that the image is in general a mere surface 
picture, and especially as regards the middle tints. In the 
washing, therefore, these are apt to be annihilated together 
with the soluble film beneath them. This defect had been 
noticed and the cause assigned by Laborde as well as by 
Poitevin ; and it is probable thatFargier eliminated his pro- 
cess on the hints thus published. The difference in his mode 
of manipulating consists essentially in separating the film 
containing the image from the glass upon which it was form- 
ed, and in fixing it on a piece of gelatinized paper the other 
side up. The chemical and actinic part of the operation re- 
mains the same as in Poitevin's. 

Fargier's Process. 

Make a mixture of two drachms of white gelatine dissolv- 
ed in two ounces and a half of water, and fifteen grains of 
lampblack, (previously washed with carbonate of soda, and 
afterward with hydrochloric acid, in oixler to remove all 
fatty or resinous matter ;) to this mixture add a few drops 
of ammonia in order to decompose the alum contained in 
the gelatine and finally fifteen grains of bichromate of 
potassa. The mixture, when the ingredients are thor- 
oughly dissolved, is filtered through a linen cloth, and after 
it is made hot, it is poured upon a properly cleaned glass, 
and the films dried by a gentle heat. 

The glass, thus prepared, is exposed for a few seconds to 
the light, and then beneath a negative to the rays of the sun. 

The first exposition to light for a few seconds is to render 
the whole surface of the gelatine slightly insoluble. The 
second exposure beneath a negative produces an insolubility 
more or less deep according to the luminous intensity and 
its duration. It will be easily conceived that the two sur- 
faces of the gelatine film, that is, the upper surface and the 


one adhering to the glass, are in very different conditions, 
the former being almost totally soluble, excepting here and 
there where the intensity of the rays has penetrated the whole 
substance ; whereas the exterior surface, as before remarked, 
is insoluble. The parts between these surfaces are more or 
less soluble according to the quantity and intensity of the 
light that has passed through the negative. It will be seen, 
therefore, from these conditions of things, that the operation 
if washing, in order to be effectual, ought to be performed 
on the under surface. The film consequently is removed from 
the glass and transferred in the following manner : 

Flow the film on the glass plate with two coats of collodion, 
and then immerse it in a dish of lukewarm water. The col- 
lodion will soon be detached together with the gelatine film, 
which will float in the water. The film is allowed to remain 
until all the soluble parts are dissolved off, together with 
the coloring matter which they contain. By this mode of 
proceeding the most delicate half-tones remain attached to 
the collodion, and the image is brought out very perfectly. 
Whilst in this condition in the water a piece of paper already 
prepared with gelatine i> brought carefully beneath the float- 
ing film and then lifted out of the water and stretched upon 
a board. The film, carefully adjusted on the gelatinized sur- 
face of the paj)er, soon adheres to it, and may thus be dried. 

Carbon Processes with the /Salts of Iron. 
Without recapitulating all the various processes arising 
out of the use of the salts of iron, I may here mention that 
Poitevin has employed the gallate of iron and the sesqui- 
chloride; and that others, following in his steps, have been 
more or less successful in the same domain of experimenta- 
tion. I will give two examples only, and refer the reader 
for more ample information to Poitevin's interesting treatise. 

Nb.l. — Process with Sesquichloride of Iron and Tartaric 


Make two solutions as follows: 

•v-,. , ( Sesqui chloride of iron, . . . . 5i drachms. 

( Water, 15 drachms. 

j- g { Tartaric acid 2 drachms. 

( Water, 15 drachms. 

Filter each solution separately, then mix and add two 
ounces and a half more water. Keep the solution in the 
dark, and use it until exhausted. 

The image with carbon or any other colored and inert 


powder is formed on glass. For this purpose Poitevin re- 
commends such glass as is used for stereoscopic slides, being 
ground on one side. If the glasses have been used before, 
they are cleaned by the ordinary means recommended. 
Each glass is then flowed with the sensitizing solution just 
prepared, in the same way as with collodion or albumen, 
and the excess is poured oif at each corner. They are then 
reared on one corner on pieces of bibulous paper, inclining 
at an angle of 60°, with the sensitized surface downward. 
It is better to dry the plates by rearing them up near 
some heated surface, otherwise the operation of desiccation 
will be very tedious. This operation must be performed in 
the dark-room. The property of the dry plates is this: 
by the influence of light they become hydroscopic. The 
plates so prepared will keep for months in boxes, as was 
to be expected, inasmuch as the persalts of iron have a 
tendency in the dark rather to peroxidize than to be reduced 
to protosalts. 

A plate is exposed beneath an ordinary negative varnished 
with copal dissolved in alcohol ; all other varnishes, such as 
those prepared with benzine, gum, gelatine, etc., would be 
injurious. The film of the prepared glass and of the negative 
are in juxtaposition, and are placed together with great care. 
The time of exposure is about the same as in the common 
printing process. This has to be learned by practice ; it is 
better to give too much time than too little, because the de- 
velopment can be stopped as soon as the image has sufficient- 
ly appeared. When taken from the printing frame the picture 
is already visible, Avhite upon a yellow ground. It is exposed 
in the dark-room to the influence of the air, when it will be 
found that all those parts that have received the luminous 
action will become moist. In a few minutes the filmwill be 
ready to receive the first application of the carbonaceous or 
other inert colored material. — By putting away the plates 
when taken from the printing frame in well-closed boxes, 
the development may be postponed. — The development is 
effectuated by dipping a very soft camel's hair pencil in the 
fine impalpable powder and then dabbing or rubbing it gent- 
ly over the surface of the impressed plates ; the image will 
soon begin to appear, the coloring material adhering only to 
those parts that have become hydroscopic by the action of 
the light, and consequently in proportion to the luminous 
impression. In general the half-tones do not appear by the 
first application of the powder, and it is better when this is 
so ; for if the plate took up the color too quickly, it would 


be a sign that the exposure had been too long. A second 
application of the powder is made, and then a third, and so 
on, until the image is brought out in perfect harmony of 
light and shade. The operation may be stopped midway 
without any injury to the final development, which may be 
completed at any convenient time. It iavery easy to follow 
the progress of development by placing the plate image side 
downward on a sheet of paper, or by regarding it by trans- 
mitted light ; but seen so, it is always more feeble than by 
reflected light. It is also easy to accelerate certain portions 
which are slow in appearing; all that is required is to moist- 
en them with the breath, and then go over the parts with the 
pencil dipped in the carbonaceous powder. As soon as the 
image is perfect, it may be retained on the plate by means 
of a coat of varnish, and thus be used as a transparent posi- 
tive, without any washing or fixing. If instead of lampblack 
or vegetable colors, metallic oxides or enamel powders were 
to be applied to the sensitized glass plate, these coloring sub- 
stances maybe melted in a muffle, which communicates to the 
surface of the glass plate a perfectly unalterable picture, sim- 
ilar to glass-painting; the same mode of operation may he 
applied to plates of porcelain. In case, however, it is required 
to transfer the print to paper, the operation may be perform- 
ed either immediately or a long time afterward. 

To transfer the Carbon Print from Glass to Paper. 

This operation is extremely simple, and presents no diffi- 
culty. Coat the film, containing the picture, with common 
plain collodion, of a consistence suitable for photographic 
purposes, then immerse the plate in water until the oily as- 
pect of the film has disappeared. Xext pour upon the col- 
lodion surface water acidulated with hydrochloric acid ; 
repeat the operation two or three times. The film immedi- 
ately in contact with the glass is rendered soluble in water 
by means of the acid, and the adherence of the collodion to 
the glass is at the same time destroyed. The acid is then 
thoroughly removed by washing in several waters, and then 
a piece of paper, covered with a layer of gelatine on one side 
and previously moistened, is placed upon the collodion and 
brought into contact with it by means of a large, broad and 
soft pencil, which is moved over it in all directions. As soon 
as the contact is complete and all bubbles of air have been 
removed, the whole is left to dry spontaneously. In the act 
of drying the gelatinized paper separates from the glass of 
itself, carrying with it the film of collodion in firm adhesion 


to the picture. All that now remains to he done is to var- 
nish the surface. Copal varnish is suitable for this purpose, 
because it lies upon the surface of the image without pene- 
trating the film of collodion or gelatine, and consequently 
never arrives at the paper beneath. The prints, thus obtain- 
ed, have a very delicate and velvety appearance, the only 
drawback being that of lateral inversion like the negative, 
unless the latter has been specially prepared beforehand. 
But the picture can be produced without any lateral inver- 
sion, not only by having a negative in the right conditions, 
but by the following somewhat complicated manipulation, 
although equally as easy as the preceding. In this ease, 
the collodion is applied as before, the immersion in water 
and the flowing with acidulated water are performed, and 
then a piece of moistened paper, smaller in size than the 
plate, is brought into contact with the collodion film, in the 
same way as the gelatinized paper was made to adhere. 
The border of film all round the paper is now raised and 
folded over the edges of the paper, which when raised with 
caution carries the whole detached film from the glass. A 
piece of paper covered with gelatine and larger than the plate 
is now moistened, upon this the detached print is brought 
into contact, pressed into perfect adhesion by means of the 
soft brush, and then the borders of the film around the edges 
of the first paper are folded back, when, seizing an angle 
of the first paper, it is easily raised from the collodion film. 
The picture now is no longer inverted, and is besides fixed, 
the coloring matter or image proper lying protected between 
two films, one of collodion and the other of gelatine. With 
a tenacious collodion this operation of double transfer is al- 
ways successful ; it takes in fact longer to describe it than to 
perform it ; as to the simple transfer, it always succeeds, 
whatever may be the quality of the collodion. 

This process, after all, is very simple and almost always 
certain ; besides this, it entails but little expense and re- 
quires less delicacy of manipulation than other photographic 

For vitrification or enamel operations, it possesses a great 
advantage arising from the facility of folding the collodion 
film, retaining the picture upon curved as well as upon plain 

Another property of the surfaces prepared with the sesqui- 
chloride of iron and tartaric acid is this : fatty substances, 
such as printing inks, applied after the luminous impression 


through a negative, adhere only to those parts that have not 
been modified by light. 

Almost all vegetable colors may be used in this process ; 
it will be evident therefore that pictures resisting all change 
from the atmosphere or from time, may be obtained of any 
color that may please the fancy. 

Printing directly on Paper by means of the Sesquichloride 
of Iron and Tartaric Acid. 

This is a new process of Poitevin's. Five or six parts of 
gelatine are dissolved in a hundred parts of water ; this so- 
lution is colored with a sufficient quantity of lampblack or 
any othec inert color. Each sheet of paper is floated on this 
solution, which is kept lukewarm on a water-bath. By this 
means a very uniform film of color is communicated to one 
side of the paper, which is afterward placed flat on a hori- 
zontal surface with the colored side uppermost, and allowed 
to dry spontaneously. In this way a large number of sheets 
may be prepared beforehand. 

In order to sensitize them they are immersed in a bath 
containing a solution of sesquichloride of iron and tartaric 
acid in the proportion of ten parts of the sesquichloride or 
iron, one hundred parts of water and three parts of tartaric 
acid. The papers are then allowed to dry in the dark. By 
this treatment the film of gelatine has become completely 
insoluble, even in boiling water. 

These films receive the actinic impressions through a trans- 
parent positive ; and in the parts where the light acts, the 
film becomes soluble in hot water proceeding from the sur- 
face of the film in contact with the transparent positive. 

Alter the paper has been in this way exposed to the sun, 
if the positive is not very intense, (which is preferable in this 
kind of print,) it is immersed in hot water ; then all the 
parts that have undergone the solar influence are dissolved 
in proportion to the quantity of light that has permeated 
the glass positive. In the places which correspond with the 
lights of the positive, the blackened or colored surface is 
dissolved to the surface of the paper, and will leave perfect 
whites ; whereas in the half-tints, only a certain portion of 
the film will disappear, proceeding from the surface, and 
these half-tones will be reproduced by the greater or less 
thickness of the film of gelatine remaining insoluble. Now 
as this part is in immediate contact with the surface of the 
paper, it can not be carried away in washing. As to those 
parts of the positive which are completely black, they will 


be produced by the total thickness of the primitive film. All 
that is required to finish the print is to allow it to dry, and 
then to wash it in acidulated water in order to get rid of the 
salts of iron, afterward to pass it through several waters, 
and finally to allow it to dry spontaneously. 

Photographic Engra v ing. 

It is a curious fact that experiments in photographic en- 
graving gave rise to photography itself. The idea, the most 
prominent in the mind of Nicephore Niepce, when he com- 
menced his indefatigable researches in 1813, was not only to 
fix the image obtained by the camera obscura on a plate of 
metal, but to convert this plate into an engraving from which 
to receive prints by the press. After the partnership con- 
cluded between Niepce and Daguerre, this idea appears to 
have been abandoned ; and an early death removed the 
former, the real originator of much that is valuable in pho- 
tography, before he perfected the process which he left us. 
This process, together with a great deal that is interesting 
in photographic engraving, will be found at length in a small 
pamphlet published by his indefatigable nephew, Niepce de 
Saint- Victor, the Traite Pratique de Gravure Heliograpli- 
ique, in 1856. 

The various ways that have been taken to come to one 
and the same result, that of obtaining a metallic plate, re- 
sembling an engraved plate, from which to receive prints 
exactly in the same way as with the engraved plate, take 
their origin either from the Iodo-mercurio-type or plated cop- 
per of Donne, the bichromotype of Talbot, or the asphalto- 
type of Nicephore Niepce, if I may thus be allowed to create 
new names to represent these three classes. Without adher- 
ing to historical dates, I will singly recount what has been 
accomplished in each class. 

Engraving on the Daguerreotype Plate. 

The first attempts that were made to convert the daguer 
reotype into an engraved plate by an etching liquid, were 
those of Dr. Donne. He first went round the edge of the 
plate with a varnish or wax, making a ledge so as to retain 
the etching fluid. This fluid consisted of aquafortis diluted 
with four parts of water, which, when poured upon the plate 
immediately after the image was fixed, but not gilt, attacked 
the silver parts, without injuring or altering the whites. As 
soon as the etching was supposed to have advanced far 
enough, the plate was well washed, and the varnish or wax 
removed from the edges. It was then ready to print from. 


The specimens obtained by the engraver's press from such 
plates were not very satisfactory ; and the softness of the 
silver film precluded the possibility of printing more than a 
few dozen from the same plate. 

Process of Fizeau. 

This process is similar to that of Donne, but it proceeds 
farther, and thus overcomes two very great imperfections in 
Donne's plates : the want of depth in the parts etched, and 
the extreme softness of the silver film. I will give the pro- 
cess as described by the originator : 

" A mixed acid, composed of nitric, nitrous and hydro- 
chloric, (the last two may be replaced by nitrite of potassa 
and common salt,) is endowed with the requisite properties, 
which is common to a solution of bichloride of copper, but 
in a manner less perfect. 

" If a daguerreotype, whose surface is very pure, be sub- 
mitted to the action of this acid, especially when hot, the 
white parts are not altered, while the blacks are attacked 
with the formation of chloride of silver, which adheres to 
the surface and prevents any further action of the acid by 
reason of its insolubility. 

"Ammonia is then poured upon the plate, which removes 
the film of chloride, and thus presents a fresh surface to the 
action of the acid. By this means the depth of the shades 
can be increased. 

" By operating in this way for several times, the daguerreo- 
type becomes converted into an engraved plate of great 
perfection, but in general not possessed of sufficient depth, 
so that the prints on paper are not vigorous enough. It has 
been found necessary, therefore, to adopt other means of in- 
creasing the depth of the shades. This operation consists in 
gilding the prominent parts or the lights of the engraving, 
and to leave the silver in the etched parts intact ; by which 
means the depth of the etching can be increased afterward 
by a simple solvent of silver. 

"In order to obtain this result, the plate engraved as just 
described is rubbed over with a drying oil, as for instance 
linseed oil, then wiped in the manner of copper-plate print- 
ers. In this way the oil remains in the cavities alone and 
forms a varnish which soon dries. 

"Gold is next deposited by galvanism upon all the parts of 
the plate excepting those filled with the linseed varnish, 
which is afterward removed by caustic potassa. The result 
of this is that all the prominent parts of the plate are protected 


by a film of gold ; whereas the excavated parts present de- 
nuded silver. 

" It is now easy by means of nitric acid to act upon these 
hollow parts alone, and thus increase the depth ad libitum. 
Previous to this treatment, however, the plate is covered by 
what is denominated by engravers the resin-grain, which 
produces in the metal those numerous inequalities denomi- 
nated aqua-tlnta granulations. 

"From the result of these two operations the daguerreo- 
type plate is transferred into an engraved plate resembling 
the aqua-tlnta plates, which like these is in a condition by 
impression to furnish a number of prints. 

" But since silver is a very soft metal, the number of im- 
pressions would be very limited, if some very simple means 
were not devised to remedy the speedy destruction of the 
photographic plate when submitted to the operations of the 

" This end is attained, previous to handing the plate over 
to the printer, by covering its surface with a film of cop- 
per by the electrolitic process. In this way it is evident 
that the film of copper alone bears the wear and tear pro- 
duced by the labor of the pressman. If this film should 
happen to be damaged to any considerable degree, it may 
be entirely dissolved off by means of a dilute acid, without 
injuring the silver on which it is deposited, when the plate 
may again be covered with copper, and rendered as good 
as new." 

Process of Talbot. 

Plates of copper, steel or zinc are employed in this pro- 
cess. These are first washed over with a dilute solution of 
sulphuric acid in order to remove the film of oxide, then well 
rubbed with a mixture of carbonate of soda, and well dried. 
A solution of bichromate of potassa and gelatine is then 
fl uved over the surface, and dried by the application of heat 
v rlil the film assumes a beautiful yellow color. This opera- 
tion is performed in the dark-room. 

v ■, { Gelatine, 1 drachm. 

\ Water, 2J ounces. 

No. 2. ■{ Saturated solution of bichromate of potassa, . 4 drachms. 

Mix the two solutions and filter. The mixture will keep 
for some time. In summer it is sufficiently fluid ; but in 
winter it requires to be warmed before it is flowed upon the 
plates. It must be preserved in a dark place. The propor- 
tions above given are found to work well, but they may be 


changed, however, -without altering the result. The color 
of the film is pale yellow and generally bordered with nar- 
row fringes of prismatic colors. If the whole surface is 
covered with this prismatic appearance, it indicates that the 
film is very thin, perhaps, if any thing, too much so for suc- 
cessful manipulation. 

The transparent positive or other object is now placed in 
the printing frame and the prepared plate upon it. An al- 
bumen photograph is the best adapted for such operations, 
because the film is the least liable to be damaged. The 
films are in juxtaposition. An exposure of two or three 
minutes to the rays of the sun will produce a picture which 
will appear yellow on a brownish background. A longer 
exposure is required in diffused light ; the amount of which 
will have to be modified by experience. 

The next operation consists in covering the film of the 
plate when removed from the printing-frame with very fne 
copal or resin powder. This part of the work has to be per- 
formed with great care and uniformity. It is frequently ef- 
fected by placing a heap of the finely pulverized material on 
the bottom of the box and then with a pair of bellows to 
make a cloud of the dust in which the plate is placed. The 
object of this operation is to communicate to the plate the 
O'j'Ki-tint'i granulation. If the film of copal or resin be too 
thick, the etching fluid will not be able to penetrate to the 
metallic plate beneath. The plate thus covered with the 
powder is heated over an alcohol lamp in order to melt the 
copal. The fusion is known to be effected by a change in 
the color. The plate is then allowed to cool. The ordinary 
way of producing an aqua-tinta foundation is to project the 
resinous powder on the denuded surface of the metal ; in 
this case it is on the surface of the gmn itself, and it is found 
to act well. 

The etching fluid is prepared as follows : Saturate hydro- 
chloric acid with sesquioxide of iron by means of heat. The 
solution is filtered and evaporated until when cooled it be- 
comes a concrete mass, which is preserved in well-stoppered 
bottles. It is a very deliquescent salt. With this salt pre- 
pare three solutions in the following manner : 

Xo. 1. Saturated solution of sesquichloride of iron in 

Xo. 2. Contains five or six parts of Xo. 1 to one of water. 

Xo. 3. Contains equal portions of Xo. 1 and water. 

The stronger the solution, the less effective in etching; 
the right strength can be learned only by experience. Make 


a trial as follows : Pour a small quantity of Xo. 2 upon the 
plate and spread it with a camel's hair pencil. It is not 
necessary to have an elevated border of Avax around the 
plate, because but a very small quantity of fluid is used, and 
there is no danger of its flowing over the edges of the plate. 
The etching fluid penetrates the gelatine where the light has 
not acted, and this penetration is in proportion to the defi- 
ciency of the luminous action. On this remarkable property 
is founded, in a great measure, the art of photographic en- 
graving. After a minute or so, the engraving begins to show 
itself by turning dark, brown or black ; and soon the effect 
extends over the whole plate. The details of the picture 
appear with great rapidity in each part. This rapidity must 
not be too great, and, where there is a tendency in this di- 
rection, the progress of the etching must be impeded before 
it has acquired a sufficient depth, (which requires an action 
of a few minutes' duration.) If in these preliminary exper- 
iments it be found that this tendency prevails, the solution 
No. 2 has to be modified by the addition of a portion of the 
saturated solution Xo. 1, before Xo. 2 can be employed in 
the etching of a fresh plate ; but if, on the contrary, the 
engraving fails to appear after the lapse of a minute, or 
if it commences but proceeds too slowly, it is a sign that the 
liquid Xo. 2 is too strong or too near its saturation. This 
deficiency is corrected by adding a little water before it is 
employed for a second plate. In making this correction the 
operator must not forget that a small quantity of water often 
produces a great difference and causes the etching to pro- 
ceed very quickly. As soon as the strength of Xo. 2 has 
been appropriately graduated, which in general requires 
three or four experimental trials, it may afterward be em- 
ployed with safety. In this case the plate is flowed as before 
indicated, and the operation proceeds until all the details 
appear and present a satisfactory aspect to the eyes of the 
operator, which takes place generally in two or three minutes, 
the etching liquid being kept moving over the surface all the 
time by a camel's hair pencil. As soon as it appears proba- 
ble that the engraving will not be any better, the operation 
is stopped, by wiping off the fluid with a pad of cotton or 
of wool and" afterward flowing the plate with a sheet of 
cold water. The plate is then wiped with a clean linen 
cloth, and afterward rubbed with soft Spanish white and 
water in order to remove the gelatine. . The engraving is 
now complete. 

Another method by the same author is the following : 


"When the plate is ready for etching pour upon it a small 
quantity of Xo. 1, the saturated solution. This may be left 
on the plate for a minute or two. Xo apparent effect is pro- 
duced by this operation, but it acts beneficially by hardening 
the gelatine. After this it is poured off and a sufficient 
quantity of Xo. 2 takes its place and produces the etching 
already described, which, on its appearing satisfactory, re- 
quires nothing more to be done. 

But it frequently happens that a few. patches of the engrav- 
ing, such as distant mountains or vessels in a landscape, re- 
fuse to appear, and as without these the engraving would 
be incomplete, it is recommended to apply, by means of a 
camel's hair pencil, a little of Xo. 3 to those parts, without 
pouring oft* Xo. 2. This simple means is frequently effective 
in bringing out the details of the picture, and sometimes 
with great rapidity, so that the operator has to be very 
cautious lest this fluid might corrode parts that are to re- 
main white. With proper skill this mode of strengthening 
certain parts will be found of great advantage in bringing 
out portions which probably woidd remain invisible. 

Asphaltotype of Xicephore Xiepce. 

The substance used to produce the image on the plate 
under the influence of light is asphaltum or the bitumen of 
Judea. The process of Xicephore Xiepce has undergone 
various modification-; by his nephew Xiepce de Saint Victor. 
The solution of asphaltum was formerly applied by means 
of a roller covered with leather, or of a pad of cloth or leath- 
er ; it is now applied like collodion. 

Varnish of Xiepce de Saint Victor. 

Anhydrous benzine, 90 parts. 

Essence of citron-peel, 10 parts. 

Pure bitumen of Judea, 2 parts. 

In order to render the benzine more anhydrous, place a 
quantity of freshly prepared chloride of calcium in the vial 
which contains it, and shake the mixture frequently. In 
twenty-four hours it may be used. 

Asphaltum or the bitumen above mentioned dissolves very 
easily in benzine ; it is necessary, however, to shake the 
mixture, and then to allow it to settle for a day or two, after 
which the more liquid part is decanted and filtered in order 
to remove all insoluble particles. The varnish is then very 
fluid, and produces a very thin film. The thinner the film, 
the more sensitive it is to lio-fit. If a thicker film be 


required, it is obtained by removing the stopper of the vial 
for a while, and allowing the varnish to evaporate, or by 
adding three or four parts of asphaltum instead of two. But a 
thick film presents more resistance to the etching fluid, and 
there is a limit to its application, otherwise the half-tones will 
be entirely wanting. The bottle containing the varnish must 
be kept filled and well closed, and be preserved in a dark 
room, if it is to be kept some time. It is better, however, 
to prepare only a small quantity at a time for present use. 

Preparation of the Plate. 

Plates of steel, copper, zinc or of glass may be used in 
this process. The first conditions, naturally, for all such 
operations of contact-printing, are, that they be perfectly 
plane and well-polished. Whether direct from the planirg- 
machine or from previous use where it has failed to succeed, 
the plate of steel, for instance, is cleaned with benzine in 
order to remove all greasy material, then rubbed with a pad 
of cotton dipped in alcohol ninety-five per cent strong, and 
very fine emery powder. By this means the steel can be 
polished as bright as a daguerreotype plate. Copper and zinc 
plates as also those of glass are polished with rotten-stone, 
Immediately before use it is well to cover the steel, etc., plate, 
with a coating of rotten-stone and alcohol, allow the filmto dry 
and then to rub it off; afterward use the broad camel's hair 
pencil, as in the wet collodion process, in order to remove 
all particles of dust. 

Flowing of the Varnish. 

This operation is similar to many others already briefly 
described. Be careful not to shake the varnish before it is 
poured upon the plate, otherwise it will give rise to an in- 
finite number of small bubbles in the film. Pour the varnish 
cither on the middle or the upper right-hand corner of the 
plate, as you would collodion, and as you are accustomed to 
do so with success ; and allow the excess to flow off" at the 
lower right-hand corner. Invert the plate and let it lean 
against the wall on the opposite corner to that from which 
the excess was poured and with the film toward the wall. 
This operation may be performed in a weak diffused light f 
let the plate, however, dry in the dark-room, which will 
take place very rapidly, and use it as soon as dry ; for its 
sensibility is now the greatest. The more uniform and thin 
(to a certain extent) the film may be, the greater the proba- 
bility of a successful issue. 


Exposure of the Plate. 
The printing operation is performed in the printing frame, 
only a transparent positive is used instead of a negative. A 
paper print maybe substituted for the glass positive, first mak- 
ing the paper transparent by a solution of wax in turpentine 
or otherwise. The glass positive is placed upon the glass 
plate of the printing frame ; and then the prepared asphal- 
tum plate lies upon the positive, their two films being in 
contact. In this the frame is exposed to the direct rays of 
the sun or to diffused light. The time of exposure will sel- 
dom exceed a quarter of an hour in the sun or an hour in 
diffused fight ; the right time has to be learned by experience. 

Development of the Image. 
This operation consists in dissolving the parts that have 
not been acted upon by light and thus removing them and 
exposing the plate beneath. 


Rectified oil of naphtha, 4 parts. 

' Ordinary benzine, 1 part. 

This solvent is poured upon small plates in the same way 
as collodion, or the developer, etc. ; but when the plates are 
large, it is necessary to have a porcelain or glass dish, at the 
bottom and the left end of which the plate is placed. The 
solvent is poured upon the inclined right end, and by 
elevating this end the liquid flows uniformly over the whole 
plate. This operation of flowing the plate must be perform- 
ed immediately after the exposure, whether in the camera 
or by contact. 

If the action of the light has been too long, a stronger 
solvent is needed ; the strength of this solution is increased 
either by increasing the quantity of the benzine or diminish- 
ing that of the naphtha. If the whole of the film of asphal- 
tum is dissolved off, the action of the light has not been 
either sufficiently intense or prolonged ; if, on the contrary, 
but little has been dissolved, either the luminous action has 
been too long, or the asphaltum was very sensitive, in which 

rse the image is always foggy. 
If the asphaltum peels off in certain parts of the plate, it 
is an evident sign the plate was moist. It sometimes happens, 
however, that when the film is too thick, the same incon- 
venience takes place. 

The solvent may be used several times in succession, 
taking care to filter it when it becomes too colored. 


Washing of the Plate. 
The picture in general appears very quickly, so that the 
action of the solvent has to he stopped almost immediately 
after its application. If the exposure has heen too long, 
the solvent action of the varnish is not so rapid. In order 
to prevent all further action, the plate is plunged into a 
vessel of water and afterward well washed "beneath the tap 
until every trace of the solvent and all particles of dust are 
removed. The plate is then allowed to dry spontaneously, 
or is dried by artificial heat. 

Fumigation of the Plates. 

The film of asphaltum, unfortunately, is not quite imper- 
meable to the action of the etching fluid used afterward. 
Various means have been resorted to so as to obviate this 
difficulty. Wax is sometimes added in small proportions 
to the varnish to remedy this evil. The best result is ob- 
tained by subjecting the plates after development to the 
vapors of the essence of lavender or spikenard. For this 
purpose an arrangement is required similar to those used 
for iodizing the silver plate in the daguerreotype process. 
At the bottom of this vessel a small porcelain capsule is 
placed containing the pure essential oil not distilled or rec- 
tified, which is heated from below by means of a spirit-lamp 
to the temperature of about from 150° Faln*enheit to 170° at 
the most, lest the oil should be volatilized in too large a quan- 
tity. In the first place let the fumigator be filled with vapor, 
then introduce the plate and keep it there for two or three 
minutes. The same essence may be used a second time, 
but no more. 

The color of the film after fumigation, when successful, 
must be the same as before it has been acted upon by the 
light, bronzed and iridescent. 

The plate is then dried by exposing it a moment to the 
air before the etching fluid is applied, and if the operation 
of fumigation has been properly timed and conducted, the 
film has become quite impermeable. It is necessary to 
guard against carrying the deposition of the essential oil 
too far, otherwise the acids will have no action whateve^ 
upon the metallic plate. 

Application of the Aqva-Tinta Granulation. 
This operation is indispensable for plates obtained direct 
either by contact or in the camera from a photograph, a 
landscape or portrait, etc. ; if the plate be copied from an 


engraving, it is not necessary. Without this expedient the 
plate will not retain the ink. 

The grain is applied in the following manner : Resin re- 
duced to an impalpable powder is placed at the bottom of 
a box made for this purpose, which, by means of a pair of 
bellows, is raised into a cloud, and thus, when it settles on 
the plate, communicates to the latter the granular condi- 
tion denominated aqua-tinta. The plate is then heated, 
whereby the resin becomes melted and forms a sort of net- 
work over the whole surface. This operation gives the 
shades a grain more or less fine, (according to the impal- 
pability of the powder,) which retains the printing ink, and 
thus permits numerous impressions to be taken of the plate 
as soon as the varnish and the resin have been removed by 
the aid of fatty bodies and essential oils or benzine. 

Etching of the Plate. 

It would be useless to attempt to etch a plate where the 
conditions are not appropriate. The film must have a bril- 
liant and iridescent appearance, be sufficiently imperme- 
able to the acid employed, free from fogginess, (that is, the 
metallic plate must be completely denuded in the deep 
shadows and partially so in the half-tones,) and the aqna- 
tinta grain must have been communicated to it. This being 
the case, proceed as follows : 

Raise a border of mastic all round the edge of the plate, 
and varnish those parts that are intended to be quite white 
in the print, as is practised in ordinary etching. Next pour 
upon the film a dilute solution of nitric acid, beginning with 
one per cent of acid, and strengthening it to as high as 
twelve per cent, according to the resistance of the varnish 
and the depth of etching required. The etching fluid has 
to be changed, without increasing the per centage of acid ; 
for it frequently happens that the plate resists the action 
of the fluid for some time, and especially if the film has 
been fumigated with the essential oil of spikenard. Very 
good results may be obtained by pouring hot water over 
the plate before the acid is applied ; but in this case be sure 
to remove every bubble of water from the interstices by 
blowing before you pour on the etching fluid. 

As soon as the etching is supposed to have advanced far 
enough, all further action is suppressed by dipping the plate 
in cold water; this must be done in time, otherwise the 
varnish would be attacked in those parts that ought to be 
preserved, a circumstance that sometimes happens, for which 


unfortunately no definite cause can be ascribed. To obviate 
this difficulty a saturated solution of iodine in water at 60° 
is used as an etching fluid, instead of the aqua-fbrtis. The 
fumigation is omitted ; and the iodine solution is poured 
upon the plate and kept there for ten or fifteen minutes, until 
it becomes nearly colorless ; this operation is repeated two 
or three times, until the etching is regarded as deep enough 
or nearly so ; it is then terminated by employing a dilute so- 
lution of aqua-fortis, which completes the etching without 
attacking the varnish. 

Copper requires a much stronger etching fluid than either 
steel or zinc, and iodine can not be used in this case ; it has 
therefore been recommended to etch the parts by galvanism. 

The plates in general require touching up with the graver, 
especially if copied from photographs; whereas distinct pen 
and ink drawings or plans or maps may be engraved in the 
way prescribed, without requiring the aid of the graver's 

Etching on Glass. 

Etching on glass is performed, when the plates are pre- 
pared, by placing them with the film downward over the 
fumes of hydrofluoric acid. For this purpose a box is con- 
structed of lead, of the size and shape of the plate, and 
about two inches deep. At the bottom of this place a small 
saucer of lead containing pulverized fluor spar and sulphuric 
acid intimately mixed. Cover the box with the inverted and 
prepared plate as a lid, and apply heat to the bottom of the 
leaden box by means of a spirit-lamp ; fumes of hydrofluoric 
acid Avill be set at liberty, and will corrode those parts of the 
glass that have been denuded by the solvent. 

Negress Process for Jleliographic Engraving. 
The plate, prepared either with asphaltum or the bichro- 
mate of potassa and gelatine, is subjected to the luminous 
impression beneath a positive instead of a negative. After 
exposure and washing, the plate is attached to the negative 
pole of a battery and immersed in a solution of gold for 
electrolytic purposes. In this way the lights of the design 
are protected with a film of gold, the middle tones are par- 
tially covered, and the blacks only just sufficient to commu- 
nicate a sort of reticulated structure which forms the ne- 
cessary grain. 

Copies for the Engraver to loork from. 
The metallic plate, the wood, stone or glass is first covered 
on both sides with a varnish quite impermeable to the action 


of acids ; it is then flowed on the prepared surface with 
iodized or bromo-iodized collodion, and treated in every re- 
spect the same as a glass plate for the reception of an ambro- 
tvpe; that is, it is sensitized in the bath of nitrate of silver, 
exposed in the camera, or by contact with an albumen, etc., 
print on glass to the view, etc., developed, fixed, washed 
and dried. Finally, the surface of the picture, thus obtain- 
ed, is covered with a solution of dextrine to preserve it from 
injury. The plate, etc., is now ready for the draughtsman, 
and when prepared by him bymeansof a fine-pointed style, 
it is submitted to the etching fluid, as before directed. 

Photolithography and Photo-zincography. 

These branches have been brought to a high degree of 
success within the last two or three years. They are not 
yet quite perfect ; the want of perfection consists in the in- 
ability to obtain easily and uniformly the middle tones. Draw- 
ings in pen and ink, maps,. plans, pages of letterpress, etc., 
in which there is no intermediate tones between the lights 
and shades, are executed to any amount of reduplication by 
the photo-lithographic process, and very successfully; but 
landscape scenery, architecture and portraiture, where there 
is a regular blending of light into shade, cannot always and 
at will be reproduced satisfactorily by any of the known 
processes of photo-lithography or photo-zincography, al- 
though it must be confessed that the specimens published in 
the work on Photo-zincography by Colonel Sir Henry James 
indisputably prove the possibility of the accomplishment of 
this desideratum. 

The various processes practised in this department of pho- 
tography depend upon the properties of asphaltum, the per- 
saits of iron, and of chrome already frequently alluded to ; 
and the object to be attained consists cither in preparing 
surfaces where the shades are etched out as in the copper- 
plate, or in relief, as in common type. 

In some processes the designs are taken directly upon 
stone or zinc; in others on prepared paper, and afterward 
transferred to stone or zinc. By the latter the picture is ob- 
tained in a direct position; whereas by the former, without 
previous arrangement, the image is inverted. 

Asph alto-ph otolith ograph ic Process. 
This process was originally employed by Nicephore Niepce 
in the production of heliograpbic engravings. The first at- 
tempts in photo-lithography were made at the suggestion of 


Barreswil, in connection with Lemercier, a lithographer, and 
Lerebours, an optician. Davanne, too, co-editor with Bar- 
reswil, of the Chimie Photograpkique, assisted in the pre- 
paration of the specimens published as early as 1853. 

The properties of asphaltum dissolved in ether or in es- 
sential oil, are the following: 

First. It is sensitive to light, and becomes changed in pro- 
portion to the intensity, whereby parts, not acted upon by 
the luminous impression, can be removed by a subsequent 
operation of washing with a solvent. 

Second. It is sufficiently adhesive to the stone and im- 
permeable to the etching liquids to prevent the latter from 
acting upon the stone, excepting on the parts denuded by the 

Third. The parts of asphaltum left on the stone have an 
attraction for the greasy ink used in photo-lithography. 

Now these are the properties required in photo-litho- 
graphy : 

The stone is firstprepared as for lithographic purposes, and 
then placed on a leveling stand and made perfectly hori- 
zontal. Next take a quantity of bitumen, reduce it to a 
powder and dissolve it in ether ; filter as much of the solu- 
tion as may be required to flow the stone. Whilst flowing 
the stone with this preparation be very careful to avoid agi- 
tating the air so as to set the dust in motion, or produce un- 
dulations in the film. The excess of bitumen may be allowed 
to flow off on the sides and corners ; and where there is a 
tendency of the fluid to become stagnant or to flow back 
again upon the stone, this is prevented by the application of 
a glass rod to guide the superfluous fluid over the sides. 
The object is to obtain a thin, uniform film, which beneath a 
magnifying glass presents a reticulated appearance all over 
the stone, communicating to it what is denominated by en- 
gravers a grain. The quantity of asphaltum in ether re- 
quired to produce such a thin and uniform film has to be 
ascertained by practice. 

As soon as the asphaltum is dry, a negative is placed on its 
surface, (the two films being in juxtaposition,) and is held 
down in contact by pressure on the sides and corners by means 
of a pressure-frame. Any negative may be used. The stone 
is now exposed to the light of the sun for a time, which has 
to be learned by experience. This operation being con- 
cluded, the stone is taken into a room feebly lighted, the 
negative is removed and the surface containing the latent 
image is washed with ether. The parts, on which the light 


has acted, have become insoluble ; these, therefore, are not 
disturbed by the solvent ; whereas all the rest of the bitu- 
minous film that has been protected by the shades of the 
negative, is dissolved and washed off. If the time of expo- 
sure has been too short, the image is destitute of all middle 
tones ; it is mere black and white ; if, on the contrary, the 
exposure has been too long, the picture is foggy, that is, the 
fine lines have become heavy and the stone imperfectly de- 
nuded in the lights. In order to be successful, the surface 
must be well washed with ether, otherwise spots will arise 
that can not afterward be removed. 

The film is then dried, and if the image thus formed is satis- 
factory, the stone is then treated in the same maimer as a 
drawing with lithographic crayons ; that is, it is first flowed 
with a weak acid solution containing a little gum, so as to 
preserve the whites and give more transparency to the pic- 
ture ; it is then washed in several waters, and if need be, in oil 
of turpentine ; finally it is inked with lithographic ink. If all 
succeeds well, the image will take the ink with facility as soon 
as the roller is passed over it, and will require no touching 
up. Prints are obtained from stones, prepared in the man- 
ner above described, as with any other lithographic stone ; 
they improve gradually after a number of impressions have 
been taken. The authors, whose process I have copied, as- 
sert that they have prepared a number of stones by this pro- 
cess, that have given great satisfaction and have not been 
worn out quicker than any ordinary lithographic impression. 

BicJiroino-plioto-lithogrcqyhic Processes of jPoitevin. 

The mixture proposed by Talbot of bichromate of potas^a 
and organic matter, such as gelatine, albumen, gum, etc., is 
used by Poitevin in the processes about to be described. 

An ordinary lithographic stone is covered witli a solution 
of albumen and bichromate of potassa, and allowed to dry 
spontaneously. It is then exposed to the light of the sun 
beneath an albumen, tannin, etc., negative, by which the parts 
to which the light has not been able to penetrate through the 
opaque shades of the negative, are preserved in their natural 
and soluble condition, while the parts impressed by the light 
have become insoluble. Tims modified, the latter parts repel 
water, as if the light had produced some greasy substance 
in the film. In this condition these parts easily adhere to 
ordinary lithograpic ink, whilst there is no adherence be- 
tween the ink and those parts that have undergone no actinic 
impression. A roller charged with such ink is then passed 


over the stone ; and the image is made manifest by the ad- 
herence of the ink to the parts impressed and in accordance 
with the intensity of the impression. The excess of ink is 
removed with a wet sponge. The stone is then covered with 
a weak acid which acts upon the parts not imbued with ink, 
and thus presents the image in relief, which is treated after- 
ward like any other ordinary drawing on stone with litho- 
graphic crayons. 

Photo-typographic Process of Poifevin. 

Poitevin has also availed himself of a peculiarity, which 
gelatine in connection with bichromate of potassa possesses, 
of swelling when exposed to cold water and before it has 
been impressed by light. His mode of proceeding is as 
follows : 

A plate of glass is flowed with an even film of a solution 
of gelatine, which is allowed to dry spontaneously. The 
plate is then immersed in a concentrated solution of bichro- 
mate of potassa ; and when the film has become completely 
permeated with the salt, the plate is quickly washed in order 
to remove all excess of the solution, and is put away in the 
dark-room to dry. The plate is then ready for exposure 
beneath a negative, which must be very clear, transpar- 
ent, well-defined and vigorous. After exposure it is im- 
mersed in cold water, by which the parts that have been 
protected beneath the dark shades of the negative, swell. In 
this condition the plate is moulded in plaster. This mould 
is afterward submitted to the electrolytic action of a gal- 
vanic battery, from which a metallic matrix may be obtained 
for printing from by the typographic press. 

The processes above described, whatever the success in 
manipulation, are defective in one essential point: the pic- 
tures are laterally inverted. It is true that negatives may 
be obtained by copying in a condition to produce the proper 

Photo-Uthogropldc Process of Newton. 

A lithographic stone or a plate is covered with a solution 
of one quart of water, four ounces of gum-arabic, one hun- 
dred and sixty grains of sugar, and a certain quantity of bi- 
chromate of potassa. The stone is then put away to dry in 
the dark-room. It is next exposed either in the camera or 
beneath a transparent positive. The gum becomes almost 
insoluble by the action of the light. The stone is then washed 
with a solution of soap, which removes the parts that have 
not been acted upon by light, while the soap is decomposed 


in those parts -where the luminous impression has been made, 
" the action of the soap being inversely proportional to the 
intensity of the light." The stone thus prepared is washed 
with water, and when it is dry it is covered by means of a 
roller with a layer of printer's ink, which, combining with 
the soap, adds new body to the print. When it is desired 
to obtain gradations of light and shade, the stone is submitted 
to the graining process above described; but this is not ne- 
cessary where blacks and whites alone are required. 

It is difficult to observe any fundamental difference be- 
tween this process of Newton and the preceding one of Poi- 
tevin ; it is apparently a mere copy. The remaining pro- 
- to be described are the most important and successful ; 
they are founded upon a discovery of Asser of Amsterdam, 
the transfer-process, although Sutton had remarked that 
printer's ink, put on gelatine paper, would come away, if 
soaked in water, leaving the paper quite clean. 

This process consists in first obtaining a picture on paper 
prepared with bichromate of potassa and organic matter, 
and then in transferring this direct picture on stone or zinc, 
which, being laterally inverted, yields a direct print in the 
press. The process has been much improved in the manipu- 
lations both by Osborne in Australia, as well as by Captain 
Scott and Colonel Sir Henry James, in the Ordnance Office, 
Southampton. Osborne, it appears, made his discoveries and 
improvements independently of Asser's publication, and of 
those from the Government office in Southampton. These 
processes being then essentially the same, it will not be ne- 
cessary to describe more than one in this work. Colonel Sir 
H. James has just published a new edition of his Photo-zin- 
cography, accompanied with very neat specimens of prints 
that can be obtained directly from photographic negatives 
by this process. 

Photo-zincography b>/ Colonel Sir H. James, R.E. ; and 
Phot&Hthography by J/r. Osborne. 
The negatives in this sort of workrequire'above all things 
to be very transparent, without the slightest fogginess in 
the transparent parts; the opaque parts, on the contrary, 
must be exceedingly dense. Such negatives can be obtained 
only by redevelopment or intensifying. The exposure of 
the collodion plate to light is not quite so long as for an 
ordinary negative, nor is the development carried on to the 
same extent in the first instance as for a negative; it is bet- 
ter to stop the action of the iron solution as soon as the pic- 


ture has appeared in full brilliancy as a positive, and then to 
intensify afterward. For copying engravings, pen and ink 
drawings, maps, plans, etc., where the delineations are purely 
black and white, this mode of preparing the negatives is cer- 
tainly to be recommended. Where there is a gradation of 
tone, the time of exposure and of development must be in- 
creased beyond that of a positive or ambrotype, but yet not 
to the same extent as for a negative. 

To intensify the first sort of negative, that is, the one for 
copying engravings, etc., proceed as follows, as soon as it has 
been developed and fixed and is perfectly clear in the trans- 
parent parts : 

While the plate is still moist, flow it with a part of the 
following solution : 

Pyrogallic acid, 3 grains. 

Glacial acetic acid, 48 minims. 

Alcohol, 36 minims. 

Distilled water, 2 ounces. 

After moving the solution backward and forward for a 
minute or so, pour it oif into a wine-glass, and add to it 
about six drops of a solution of nitrate of silver thirty per 
cent strong, if the plate is stereoscopic size, and so on, ac- 
cording to the size; shake the mixture well and then flow 
the plate with it, and keep it in motion, and watch the prog- 
ress of blackening by the light transmitted from below, as 
before directed and described in the article on the negative 
collodion plate. It may be necessary to add more silver, or 
even to repeat the dose of the intensifier, sometimes two or 
three times ; this, however, is a rare occurrence if the time 
of exposure has been right. When the shades are quite 
opaque, the operation is so far complete. Wash thoroughly 
and examine the plate in diffused light. If the lines' have 
become somewhat thickened, or the transparent parts slightly 
fogged, these evils must be remedied by Osborne's clarify- 
ing process. 

Dissolve iodine in a solution of iodide of potassium to 
saturation ; of this solution take ten or twelve drops to four 
drachms of water, (for a stereoscopic plate,) and pour the so- 
lution on the moist plate, and keep it in motion until the sur- 
face of the negative assumes a uniform film of a cream color. 
Wash the plate and flow it with a very dilute solution of 
cyanide of potassium. This will remove the iodide of silver 
and diminish the thickness of the lines and the fogged ap- 
pearance of the transparent parts. 

Sir H. James intensifies with bichloride of mercury, by 


immersing the well- washed plate in a weak solution of this 
salt; as soon as the surface is whitened by the action of 

the mercurial salt, it is washed again* and a dilute solution 
of sulphide of ammonium is poured over it. which changes 
the color to a brown-yellow. If the negative is allowed to 
dry, the bichloride is used, there will be less danger of fill- 
ing up the lines ; but the edges of the film must be varnished 
first, to prevent it from slipping off" when it is washed. 

After the negative has been intensified and is dry, it is 
varnished, and is then ready for nse. 

The following are the formulae for the various solutions 
recommended by Sir II. James : 

For Cleaning the Glass Plate. 

Alcohol, 1 ounce. 

Ammonia, ^ drachm. 

Water, 8 ounces. 

Tripoli powder, sufficient to give it the consistence of cream. 


Pyroxyline, 80 grains. 

Iodide of cadmium, 15 grains. 

Iodide of potassium, 75 grains. 

Alcohol, sp. gr., .812, 10 ounces. 

Ether, sp. gr., .725, 10 ounces. 

Nitrate of Silver Bath. 

Nitrate of silver recrystallized or fused, . . 1 ounce. 
Water, 14 ounces. 

Dissolve and filter, then coat a plate with iodized collo- 
dion, and immerse for twelve hours in order to saturate the 
bath with iodide. If, on exposing the plate, there should be 
any srgn of fogging, add dilute nitric acid, (one of acid to 
ten of water.) drop by drop, until a clear picture is obtain- 
ed.' If at any time the bath should be too acid, it can be 
neutralized by adding a little oxide of silver. 

De v elop in g So bit ion s . 

Iron. PyrogaMc Acid. 

Protosulphate of iron, . 1 ounce. JFyrogallic acid, ... 30 grains. 
Glacial acetic acid, . . G drachms. Glacial acetic acid, . . 1 ounce. 

Alcohol, 6 drachms. Alcohol, 6 drachms. 

Water, distilled, . . . 20 ounces. .Water, distilled, . . 20 ounces. 

Fixing Solution. 

Cyanide of potassium, 15 grains. 

Water, 1 ounce. 


Quality of the Paper used in the Transfer Process. 

The paper suitable^for this purpose must be hard, thin, 
and tough, of even texture, free from wooliness, and but 
slightly sized. Paper made from linen is the best, such as 
that used for bank post paper. If there is too much size in 
the structure, it can be remedied by steeping the paper in 
hot "water a short time before coating it "with the solution. 

Coating of the Paper with the Sensitive Solution. 

This solution must be cpiite fluid at the temperature of 100°. 

tv , ( Bichromate of potassa, 2A ounces. / VT - 

Dissolve •< tt . . . * v '•„ A \ ,~- >-No. 1. 

I Hot water, ram or distilled,) ... 10 ounces. ) 

tv , ( Gelatine, (the finest,) 3 ounces. ) -.- n 

Dissolve • „ t , M , . ."» .„ ,-Xo. 2. 

( Hot water, (rain, etc.,) 40 ounces. J 

Mix the two solutions and filter "while warm. When abcut 
to be used let it be poured into a large flat dish, and main- 
tained at a temperature of 100° by placing this dish in an- 
other containing warm water. 

Float the paper on this solution with the right side down- 
ward for three minutes, taking care to break up all bubbles ; 
the operation is performed in the dark-room. Drain the 
paper and hang it up to dry in the manner already described 
in the positive printing process. When dry, the paper is 
floated a second time and hung up to dry by an opposite 

The surface is afterward smoothed by passing it through 
a copperplate press on a hot steel plate — the rolling press 
with a flat plate is also quite suitable for this purpose. 

Exposure under the Negative. 
The amount of exposure is regulated by the appearance 
of the print. When the lines appear distinctly marked, and 
of a dark brownish-green, the operation is complete. The 
time will vary with each negative, and with the light, from 
one minute in the sun to twenty minutes in dull weather. If 
the printing is incomplete, the lines will break beneath the 
sponge in the washing ; and where the exposure has been 
too long, the ink (to be afterward applied) will adhere to the 
ground of the print. 

The Inking of the Bichromate Print. 
Formula for the Ink. 

Chalk lithographic ink, 2 pounds. 

Middle linseed oil varnish, 1 pound. 

Burgundy pitch, 4 ounces. 

Palm oil, 2 ounces. 

White wax, 2 ounces. 


Melt the three latter in an iron pot until they begin to 
burn, stirring the ingredients all the time; finally, add the 
varnish and the ink, and mix intimately. 

When about to use this ink, the necessary quantity is 
melted with a proportion of turpentine, so as to reduce it, 
when cold, to the consistence of thick molasses. A small 
quantity is laid on the printing roller, which is then worked 
on a stone in the usual manner, till the coating is perfectly 

The closer and finer the lines of the print are, the thinner 
should be the coating of ink. 

A zinc plate is inked with the printing roller, and the bi- 
chromate print is laid face downward on it, and passed 
through a lithographic press ; by this means it receives a 
very even coating of ink. 

The Cleaning of the Surface of the Print. 

After the operation of inking the print is floated on water 
at 90°, back downward, for five minutes ; it is then placed 
face upward on a porcelain or marble slab, and the .surface 
is gently rubbed with a new soft sponge dipped in gum- 
water. If all the previous operations have been well per- 
formed, the ink will readily leave the ground of the print 
remaining on the lines. 

The less friction is used the better ; if the ink does not 
easily leave the paper where it ought to do so, the print 
must be floated once more on the warm water, face down- 
ward, for a few minutes. 

As soon as the ground of the print is quite cleared of ink, 
and the whites appear in the closest parts where they show 
on the original, the paper is thoroughly washed in tepid 
water to remove all the gum from the surface, so that no 
trace remains. It is then dried and is ready for transferring 
to zinc or stone. 

Transference of the Print to Zinc or Stone. 
The plates of zinc are first scraped until all inequalities 
are removed. A piece of a saw-blade makes a good scraper. 
Let it be four inches long and three wide, in the form of a 
rectangle. Grind the long sides quite flat on a grindstone, 
so that these surfaces present two sharp edges for scraping. 
Use the scraper as in veneering. When the surface of the 
zinc is thus made free from blisters, scratches, etc., grind it 
down flat with a pumice-stone, and smooth it with snake- 
stone. Finally it is grained with a disk of zinc four inches 
in diameter, half an inch thick, and fixed to a handle, by 


rubbing the disk with a circular movement over the surface 
with fine sand and water. The sand is passed through a 
wire sieve containing from eighty to one hundred and twenty 
meshes in a square inch. As soon as this operation is com- 
plete, the plate is thoroughly washed and dried, and then 
used immediately. 

Old plates are first cleaned with turpentine, then with an 
alkali, and finally with a mixture of equal parts of sulphuric 
and hydrochloric acid to twelve parts of water. The grain- 
ing, too, is repeated. 

The bichromate print is first moistened between sheets of 
damp paper for a few minutes, then placed face downward 
on the zinc plate, with two or three sheets of paj>er over it, 
and passed through the press. 

If the transfer print is not more than three or four davs 
old, it will be sufficient to pass it through once ; but an old 
print, on which the print has had time to harden, will re- 
quire to pass through the press two or three times. 

The sheets of paper covering the transfer are then re- 
moved, and the latter is damped with a wet sponge for two 
or three minutes ; this causes the gelatine in the lines to 
swell, and makes the ink leave them more readily. 

The print is then pulled carefully from the plate ; and near- 
ly the whole of the ink should remain on the zinc. 

Etching of the Zinc. 

The etching liquid is prepared as follows : 

■^ , j Aleppo galls, 4 ounces. 

XS0 - - { Water, 3 quarts. 

Bruise the galls in a mortar and steep them in the water 
for twenty-four hours; after which the mixture is made to 
boil over the fire, and then filtered. 

fGurn water of the consistence of cream, . 3 quarts. 
Decoction of galls, 1 quart. 
Phosphoric acid, 3 ounces. 

The phosphoric acid is prepared in the following manner : 
Take a bottle, three quarters full when holding a pint of 
water, and insert sticks of phosphorus in the water, so that 
parts of them are exposed to the air above the fluid. An 
incision is cut in the cork to let in air. The phosphorus 
thus becomes oxidized, and the phosphoric acid is dissolved 
by the water below. In a few days the solution is suffi- 
ciently strong for use. 

The etching liquid is poured on the plate, and spread over 


the surface with a sponge or camel's hair brush. For fine 
work twenty seconds will he sufficient ; whereas strong lines 
would hear the action of a minute without injury. The 
etching solution is next removed entirely with a cloth dipped 
in water. 

Finally, the transfer ink is cleared from the plate with tur- 
pentine, or if the design is weak, with turpentine mixed with 
olive oil and gum-water. The plate is then rolled up with 
printing ink, the roller being very thinly and evenly coated 
with it. Impressions can then he printed in the usual man- 
ner; fifteen hundred is not an unusual number for the plate 
to stand without sensible deterioration. 

The bichromate print can be transferred to a lithographic 
stone in a similar manner. 

When the subject admits of it, paper, enameled with zinc- 
white, should be used, as the impressions produced are more 

Formula for Zinc Enamel. 

-y- 1 \ Russian glue, 4 ounces. 

° - \ Water, 3 quarts. 

Soak for several hours, and then dissolve by heat : 

No. 2. -[ Zinc white, (oxide of zinc,) . . . . H pounds. 

Grind with water on a slab, mix gradually with the solu- 
tion of glue, and pass through a hair-sieve. 

This enamel is communicated to the paper with a broad 
brush, and the streaks are obliterated with a flat camel's 
hair pencil. A second coating is applied in a similar man- 
ner, when the paper is hung up to dry. 

Sir II. James remarks that, since the publication of the 
first edition of the process above copied from his work, he 
has discovered that the paper coated with the bichromate of 
potassa and gelatine, after exposure in the printing frame as 
already described, can be made to produce transfers with 
halftone or gradation of s/iadehj using the following com- 
position for the ink, and washing with a soft sponge moist- 
ened with tepid water without gum, and by using a very 
gentle hand in the manipulation. 

Formula for Transfer Ink. 

Lithographic printing ink, S ounces. 

Middle lithographic varnish, 4 ounces. 

Burgundy pitch, 4 ounces. 

Palm oil, 4 drachms. 

White wax, 4 drachms. 


Photo-papyrography by Colonel Sir II. James, R.JE. 

This is a method of obtaining a single copy, or a copy 
or two of some manuscript, plan or document, etc., on 
paper, without incurring all the trouble of preparing either 
a stone or a plate of zinc. For this purpose a nega- 
tive has to be prepared, by copying according to plans al- 
ready minutely described, in which the parts are not later- 
ally inverted. This can be effected too by simply presenting 
the glass surface (not the collodion surface) to the view, etc., 
in the camera. 

With such a negative and with paper already prepared 
with the film of gelatine and bichromate of potassa, a posi- 
tive picture can be obtained in carbon ink, laterally inverted. 
The image is brought out precisely as described in the pro- 
cess of photo-zincography. It is then placed face downward 
on a sheet of paper and passed through a lithographic jiress. 
A sharp and clean impression is thus obtained. 

Colonel Sir H. James prepares negatives on paper covered 
or flowed with the wet collodion process. The sensitive- 
ness is superior to that of collodion on glass, and the nega- 
tives, when waxed, give excellent results. 

On the production of Photographs, etc., on Glass in Enamel 
Colors by Joubert. 
A piece of crown or plate glass is selected for receiving 
the photograph; this glass must be as free as possible from 
all flaws. It is cleaned as usual, and flowed with the fol- 
lowing solution: 

Saturated solution of bichromate of ammonia, . 5 drachms. 

Iloney, 3 drachms. 

Albumen, 3 drachms. 

Distilled water, 20 to 30 drachms. 

Mix intimately and filter in the dark-room. As soon as 
the plate is dry by means of artificial heat from a stove or 
otherwise, it is placed in contact with a transparent positive 
in the printing-frame. An exposure of a few seconds to the 
sun will show, on removal from the frame, a faintly indicat- 
ed negative picture. To bring it out, an enamel color, in a 
very impalpable state, is gently rubbed over with a soft 
brush until the whole composition or subject appears in a 
perfect positive form. It is then fixed by alcohol, in which 
a, small quantity of acid, either nitric or acetic, has been 
mixed. This mixture is poured over the whole surface, and 
drained off at one corner. 


TVlien the alcohol has completely evaporated, the glass is 
immersed gently and horizontally in a large dish of clean water, 
and left until the chromic solution is dissolved, and nothing 
remains but the enamel color on the glass ; it is then allowed 
to dry spontaneously near a heated stove. "When dry it is 
ready for the kiln. 

Enamel of any color may he used, so that by a careful 
registering a variety of colors can be printed one after the 
other, so as to obtain a perfect imitation of a picture; also 
the borders of any description can be subsequently added, 
and the plate again submitted to the fire. 

Naturally ceramic productions can be thus coated with 
the bichromate photograph, and afterward submitted to the 
fire to vitrify the image. 

IV/rite enamel is glass rendered milky by fusion with 
oxide of tin; it forms the basis of many of the colored 
enamels, which receive their tinge from the metallic oxides. 
Thus the purple of Cassias (gold) imparts a fine ruby tint. 
The oxide or phosphate of silver gives a yellow color. The 
oxides of iron communicate blue, green, yellow and brown, 
according to quantity or state of oxidizement. The oxides 
of copper produce a rich green, and, when mixed with tai*- 
tar,' a red color. Antimony yields a rich yellow. The black 
oxide of manganese in excess forms black glass ; in smaller 
quantities, various shades of purple. The oxide of cobalt 
imparts beautiful blues of various shades, and with the yel- 
low of antimony or lead it produces green. Chrome yields 
greens and reds according to the state of oxidizement. 



The property of seeing objects in relief has occupied the 
attention of philosophers from the earliest periods ; and 
various reasons have been given for its existence. I have 
no hesitation in pronouncing them all false, excepting the 
one which I have published myself. The fact exists : we 
see objects in relief — what is the meaning of this expression ? 
.Simply this : we can see at long and short distances at the 
same time. But the eye is a veritable lens, a corrected lens, 
and is subject to the ordinary laws of optics ; the conjugate 
foci of objects at different distances are not on the same 
plane but at different distances ; the retina, therefore, is 
not a surface, it is a substance having depth, and in this 
depth are found those conjugate foci of the different objects, 
producing thus in the sensitive and transparent substance a 
miniature solid picture. This is the simplest means to meet 
the end in A'iew ; and the Almighty makes use of the sim- 
plest means, and these means I think I have understood and 
analyzed. To see long and short distances at the same time, 
that is, to see objects in relief, requires the possession of a retina 
of the depth of about T £ T of an inch in sensitiveness — now 
this is all that is required — the action of the ciliary nerve, the 
motion of the ciliary muscle, the layer-like structure of the 
crystalline lens, the action of the various straight and oblique 
muscles of the eye, the effect of the will, of the optic arteries, 
and numerous other contrivances, all these are not required 
in the production of this happy effect. 

Euclid, it appears, though I know not where, attributes 
this phenomenon to the simultaneous impression of two dis- 
similar images of the same object in either eye of the observer. 

Arago writes that when we see an entire object, the phe 
nomenon is attributable to the rapidity of the action of the 
eye passing in quick succession from one part to another. 

Pouillet's theory is this : he says that the crystalline lens, 
consists of ellipsoidal layers superposed one over the other, 


endowed with the property of acting, that is, of refracting 
light independently of each other, or simultaneously. 

Some authors maintain that the crystalline lens is moved 
by the ciliary muscle from or toward the retina with great 
rapidity during the action of the perception of relief. 

Some maintain that the cornea is made to change its form 
by the instrumentality of some muscular action and thus to 
accommodate itself to different distances, or to compensate 
for the change. 

Others again entertain the hypothesis that the eye-ball is 
either elongated or compressed by some muscular action, 
just as the distance is shorter or longer. 

As I said, all these hypotheses seem to be false, because the 
minutest investigations have not yet discovered that the eye 
is elongated or compressed, that the crystalline lens is ad- 
vanced or drawn back, that the crystalline lens is endowed"* 
with independent optical layers, that the ciliary muscle acts 
as described, that the cornea is in any way changed during 
the act of any perception. On the contrary, it is known to 
be a positive fact, that a single eye has a correct perception of 
relief- — that many animals, such as ducks, fish, etc., have 
their eyes located in such a position as not to allow the 
simultaneous action of either eye on all occasions ; it is sup- 
posed, however, they see as perfectly as human beings. It 
is a well-known fact that we can see near and distant objects, 
as for instance, the moon, a cloud, a church steeple, and the 
branches of a tree close by, without any change of the eye, 
and without any effort. It has been furthermore ascertained 
by microscopical examinations that the retina has thickness, 
transparency throngh this thickness, and is constituted of a 
conical or stick-like juxta-collocation of nervous material 
from before backward, which we have a right to suppose 
sensitive to the impressions of light throughout. With such 
a constitution of nerves the problem of long and short dis- 
tance, or the problem of seeing in relief, is solved. 

The problem of seeing pictures in relief, depends primari- 
ly upon the property which the eye possesses of seeing 
objects in relief; for if the eye were not endowed with this 
power, pictures as well as objects would be seen, as it were, 
projected flat on the ground glass of the camera. This de- 
pends secondarily on the combined action of two eyes ; for 
a single eye can by no contrivance see any picture optically 
in relief. 

It appears that Leonardo da Vinci has touched upon the 
subject of binocular vision in one of his manuscripts. This 


distinguished painter and scholar was born in 1452. There 
is nothing positive in any thing he has left us about the pow- 
er and rationale of seeing pictures in relief. 

The same may be said also of Giovanni Battista Delia 
Porta and of Francis Aguillon, who both seem to have had 
some knowledge of binocular perception. 

The first definite and positive acquaintance with this pe- 
culiar property is of modern date and is mentioned in ls:i2 
in the third edition of Mayo's Outlines of Human Physiolo- 
gy. AVheatstone's reflecting stereoscope appeared in 1838; 
it appears from the evidence of Newmann, of Regent street, 
London, that Wheatstone was acquainted with a refracting 
prism that would produce the same effect. Brewster's refract- 
ing stereoscope appeared in 1850. Since its discoveiy by 
Brewster and its manufacture originally by the celebrated 
opticians, Soleil and Dubosc in Paris, stereoscopicity has oc- 
cupied the attention of philosophers and amused the public as 
much as photography itself, which has been the means, in 
its turn, of rendering the stereoscopes so popular. Without 
photography the stereoscope would be, like the kaleidoscope, 
a mere philosophical toy. 

The way in which photography has extended the influence 
of stereography is attributable to the facility it gives of ob- 
taining consentaneously two dissimilar pictures of the same 
object in the exact conditions as they would be depicted by 
either eye of the spectator ; for it is a well-known fact now 
that these pictures are endowed with differences depending 
upon the parallax of the object on the base line between the 
two eyes ; the greater the parallactic angle, the greater the 
angular displacement of either picture in reference to the 

For example, let a spectator stand before a pane of glass 
looking upon a church for instance. At the distance of 
distinct vision from the glass fix a metallic plate containing 
two small apertures, separated by a distance equal to that 
between the two eyes. Let the observer now, by means of 
a style dipped in thick printer's ink, trace the outline of the 
church on the glass as seen through the aperture of the right 
eye; in like manner, let him do the same through the aper- 
ture of the left eye. He will find that, instead of one church, 
two sketches will appear on the glass side by side, endowed 
witli the following property as characteristically distinct 
from two engravings of the same object from the same plate. 
With a pair of compasses measure the distance between 
two corresponding points on the church which are nearest 


to the observer ; measure also the distance between two cor- 
responding points that are the most distant from the observ- 
er, it will be found that the latter measurement will exceed 
in length that of the former ; and that this result will 
always be obtained ; that is, the greater the distance of 
certain parts of the objects comprehended in a picture from 
the point of observation, the greater the difference of dis- 
tance between two corresponding points in the foreground 
and two in the distant background. It will be found, more- 
over, that the distance between two corresponding points 
which are very remote from the eyes, or properly speaking 
at an infinite distance, is equal exactly to the distance 
between the eyes of the observer. 

The parallactic angle is that angle which is comprehended 
between the axes of the eyes converging to a given point ; 
and the distances between any two corresponding points is 
equal to twice the versed sine of the parallactic angle ; but 
the versed sine of an angle is complementary to the sine, 
and the sine varies as the angle ; thus, therefore, as the 
sine decreases, the versed sine increases ; and in like man- 
ner the distances between corresponding points from ante- 
rior to remoter positions in the background will gradually 
increase. Such are the properties inherent in the two 
pictures of the same object as depicted on the retina of 
either eye, or on the ground glass of a binocular camera. 
Two photographs or pictures taken as thus described, side 
by side, are the mere interception of rays on a flat surface 
as they proceed from the object. It is natural therefore to 
suppose that these pictures, when beheld by the eyes, ought 
to give an impression of the reality in relief. By a minute 
investigation of the subject it is ascertained that conditions 
arise for the effectuation of this result, which at the first 
sight are not anticipated. One condition is to obtain the 
same convergence of the axes of the eyes as existed when 
the pictures were taken. To obtain this convergence is an 
effort for the eyes ; and on this account there are but few 
persons who possess such perfect command of their eyes 
as to secure the right convergence for given pictures. It 
is far from being absolutely necessary that the convergence 
should be exactly the same as existed originally when the 
photographs were taken ; there are, however, certain limits 
on either side, that is, it may be a little either greater or 
less than that of the parallactic angle. 

The object of this convergence is a very essential point in 
binocular perception producing relief; and the rationale of 


this perception of relief is not lucid on other grounds than 
that which admits of the production of a virtual solid image 
in space, either at a distance beyond the pictures or in front 
of them. Such solid images are formed in space by the 
intersection of the rays that proceed from the corresponding 
points in either picture ; for these rays, when they pass the 
optic centers of the eyes, form different parallactic angles, 
according as the distances apart are different, and thus in- 
tersect at variable distances corresponding with the points 
in the real object from which the pictures were taken. 

Some eyes have a very great facility of converging their 
axes ; in which case the rays from corresponding points in- 
tersect in front of the pictures and very nearly, if not exactly, 
at a distance half-way between the pictures and the eyes ; 
in this case, (as may be seen on referring to this subject 
discussed at large, page 73, etc., Vol. XIV. of Humphrey's 
Journal) the effect of relief is inverted, the most distant 
points being projected forward, whilst the anterior points 
are seen in the extreme background. This is the natural 
consequence of the intersection of lines at angles that depend 
upon the peculiar distance apart of the corresponding points 
in the pictures. 

Where eyes do not possess this great degree or facility 
of convergence, the intersections will, with the same degree 
of geometrical consequence, take place beyond the pictures 
and at variable distances beyond. The solid picture in this 
case will not be inverted ; but it will vary in magnitude ac- 
cording as the intersections occur nearer to the pictures or 
farther from them. Persons, therefore, endowed with this 
less degree of convergence, have the pleasure of beholding 
a magnified solid picture, of which the magnitude is some- 
times very great ; whereas, those whose optical axes can 
easily converge, see a solid image uniformly of half the size 
of the pictures, but which is on this account very sharp and 

All eyes can be tutored with very little difficulty to re- 
ceive this impression of relief from two photographs pos- 
sessing the conditions required. 

In order that the solid picture in the latter case shall be 
direct, that is, not pseudoscopic, the pictures must be invert- 
ed, the left being pasted upon the right side ; and the right 
on the left side. Two photographs, so mounted, I have de- 
nominated a Strabonic Stereograph, to distinguish it from 
the ordinary stereograph. 

Another condition, in order to see pictures in relief, by 


the binocular perception, is tb.3 cosentaneous independent 
action of either eye. From this circumstance either eye 
beholds the two images ; but the two interior ones intersect, 
are therefore superimposed and form thus only one image, 
which is the solid image ; the two outside images are flat, 
and do not attract the attention to any great extent, by rea- 
son of the superior brilliancy of the middle picture. The 
rationale of this delightful phenomenon, as hitherto given in 
all our text-books on the subject, is so far erroneous, from 
the fact that it is asserted that each eye sees its correspond- 
ing picture as the object was seen when the pictures were 
taken. If this were true, we ought to see only the solid 
image, and not the two outside flat pictures. 

All the instruments, called stereoscopes, are mere optical 
contrivances whereby in the first place the requisite con- 
vergence is obtained with facility ; secondly, they magnify 
the image in relief; and thirdly, they shut off the two out- 
side flat pictures. They are not essential at all to the per- 
ception of relief furthermore than as accessories. The phi- 
losophy of stereoscopicity is very simple, it is founded solely 
on the production of intersections of rays from corresponding- 
points of two pictures, the distance of which points must be 
endowed with the requisite differences ; from these intersec- 
tions or Buperimpositions a virtual solid image is formed 
which is then regarded as a real object, which produces the 
perception of relief in either eye, because the conjugate pic- 
ture in the retina is also solid. 

It is evident, then, that a single eye can never see a flat 
picture in relief, because the requisite intersections can not 
take place ; but we are by no means allowed to argue from 
this that a single eye can not appreciate, relief or distance 
in real objects, or that relief is the result of binocular per- 
ception. This is an absurdity into which many investiga- 
tors of nature have fallen ; they have not comprehended the 
true origin of this perception, which depends upon the sen- 
sitiveness of the retinal film through a certain thickness, and 
not alone on a surface. 

Eyes may be tutored to see two photographs in relief by 
the following expedients, and without the aid of stereoscopes. 

All persons accustomed to close reading or writing, or 
to the use of magnifying spectacles are more inclined to see 
strabonically than otherwise. They can, in plain language, 
easily squint inwardly and see the end of the nose. 


Strabonic Stereograph. 

In the first place, therefore, prepare a number of strabonic 
stereographs of architectural structures, as follows : " Take 
the ordinary stereographs of the views in question and 
throw them into a pail of water until the photographs easily 
separate from the mounts. Remove the photographs, and 
passing over the backs with a sponge dipped in starch paste, 
transpose them upon the original mounts or upon new ones ; 
that is, fix the right-hand photograph on the left side, and vice 
versa. The student next has to learn to see double. This is 
effected by holding up the thumb before the eyes, so as to see 
two thumbs ; when he is expert at this, let him next hold up 
in front of his eyes, at the regular reading distance, both his 
thumbs, and try if he can see four thumbs. As soon as this 
is effected, then, by bringing the thumbs closer together, so 
that their distance apart is about two inches and a half, the 
two middle ones can be made to overlap each other, where- 
by three thumbs will appear. The difficulty is now over- 
come ; for the eyes, when well-practised in this strabonic 
exploit, are prepared for regarding a stereograph which is 
mounted as abore described, when, with a little patience, 
three photograph* will appear, of which the middle one 
will be very distinct, finely defined, and in full and natural 
relief, exhibiting all the solidity of reality. 

The two outside pictures are indistinct, and the eyes will 
soon learn to neglect them ; or they may be entirely removed 
from the field of view by the use of a frustum of a pyramid 
formed of cardboard, whose height is equal to half the dis- 
tance of distinct vision, that is, half the reading distance; 
the side of its upper base one inch and a quarter, and that 
of the lower three inches. By placing the lower base next 
the eyes and looking through it, the stereoscopic picture will 
appear alone and distinct. 

The second method is founded on a reverse principle, that 
is, by excluding the rays of light from the middle of the 
field of view, comprehending a space of one inch and a quar- 
ter square. This is effected by placing a piece of cardboard 
of this width in the middle, half-way between the eyes and 
the photographs, of which the latter are fixed at the regular 
reading distance ; or the same object can be effected as fol- 
lows : Take a slip of wood about two feet long, two inches 
wide and one inch thick; take secondly, a piece of card- 
board of the size of a stereograph, and bisect the two par- 
allel sides and the two parallel ends, and join the points of 


bisection. Where these lines meet we have the center of 
the cardboard. From this poiut right .and left on the 
larger line, mark off a space one inch and a quarter in length, 
and at either extremity thus marked off draw a circle half 
an inch in diameter. Lay the slip of wood on its flat sur- 
face on a table, and tack the piece of cardboard to one end 
of the slip at right angles to the table, Avith an ecpial portion 
of cardboard projecting at either end. Previously, however, 
the wide surface of the slip must be divided longitudinally 
into two halves, by running a saw from end to end so as to 
form a groove about a quarter of an inch deep ; and at a 
distance from the cardboard, at the end, equal to the reading 
distance, another groove is sawed at right angles to the for- 
mer and of the same depth ; in the latter groove an ordinary 
stereograph is placed, and along the longitudinal groove a 
piece of cardboard at right angles to it. Xow let the ob- 
server look through the two apertures at the stereograph; 
it is evident that the right eye can see only the right photo- 
graph, whilst the left eye is restricted in like manner to the 
left. By concentrating the individual attention of each eye 
to its respective picture, by pressing the external parts of 
the ball of either eye with the fingers, or by compressing 
the eyes as in frowning, the two pictures may be caused to 
overlap each other, when a new picture will appear jnossess- 
ed of the full stereoscopic effect, apparently of a larger size 
than the originals. The magnitude in this case will vary 
with the angle of convergence ; if this should happen to be 
the same as that formed by the axes of the eyes or the 
lenses when the pictures were taken, the solid picture will 
be of the same size as the apparent size of the object from 
which the photographs were taken ; at all other degrees 
of convergence the magnitude will vary. 

Xow the solid picture, produced by either process, can be 
magnified ad libitum by means of eye-lenses or spectacles ; 
and when these eye-glasses are fixed in proper receptacles, 
they are then denominated refracting stereoscopes ; but it 
will be seen that they are far from being indispensable ; they 
are, in fact, mere accessories. 

The differences of distance between the corresponding 
points on two photographs taken stereographically, being 
functions of the parallactic angle, can be easily calculat- 
ed, and consequently artificial stereographs can be deline- 
ated geometrically. The results drawn from such calculations 
furnish means for detecting the inherent properties of stereo- 
scopicity or their total absence in any given photographs or 


designs. In this way it was conclusively determined that 
the drawings of Chimenti were not stereoscopic. Pages of 
print can be set stereoscopically, so that one line alternately 
stands above the other, or in any way whatever. The fol- 
lowing is a typographic stereograph. It is formed by set- 
ting the alternate lines at different distances from one anoth- 
er ; that is, the distance from T to T in the first lines is 
greater by about one sixteenth of an inch than the distance 
from H to II in the second lines ; and all the rest are set ac- 
cordingly. Viewed by the stereoscope the odd lines will be 
seen standing far back behind the even lines ; an increase of 
difference will throw the odd lines still further back into the 
background. An irregularity of difference produces an ir- 
regularity in the relief. 



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TVithix the last few years the importance of the applica- 
cation of photography to astronomical investigations, as 
well as to meteorology, has been recognized by natural phi- 
losophers as a definite help-mate in the prosecution of these 
studies. This application consists, when referred to astron- 
omy, in obtaining photographs and stereogi-aphs of the moon 
in its various phases, of the sun, of the planets, and of the 
comets ; and, when referred to meteorology, in obtaining 
photographic delineations of the different classes of clouds ; 
of the aurora- borealis in its various configurations, of me- 
teors, halos, water-spouts, paraselenes, etc. 

For this purpose the various forms of telescopes, both re- 
flecting and refracting, may be employed, which are used in 
observatories. Refracting telescopes, from the fact of their 
objectives being corrected for the luminous part of the spec- 
trum, are far from being corrected for photographic purposes ; 
and the ground glass has sometimes to be moved as much as 
an inch from the position of the luminous focus before the ac- 
tinic focus is arrived at. Reflecting telescopes, on the con- 
trary, not decomposing light, have to undergo no correction 
for actinism. For amateur astronomical photographers sil- 
vered glass mirrors, as recommended by Steinheil, are most 
easily constructed, are comparatively cheap, and from their 
lightness very manageable. These, when properly mounted, 
will give a picture of the moon, etc., of a magnitude vary- 
ing with the focal length of the mirror. The ground glass 
is placed in the principal focus of the objective or reflector, 
and has a motion by which it can be adjusted to accuracy. 
In such cases the eye-pieces are removed. When the opera- 
tion is not instantaneous, the telescopes have to be furnished 
with clock-work, by means of which the axis of the body 
photographed can always be made to coincide with the axis 
of the telescope, during the time of exposure. 

We are indebted to Messrs. Bond of Cambridge, Crookes, 


De la Rue, Hartnup, Forrest, Edwards, Berry, Hodgson, 
Secchi, etc., for interesting information and photographs of 
celestial objects. 

The moon naturally claimed the first attention ; the Bonds 
were the first to obtain a daguerreotype of this satellite; 
Messrs. Hartnup, Forrest, Berry, and Edwards obtained 
very beautiful photographs on collodion of the moon in 
1854, of an inch and one third in diameter, which they after- 
ward magnified a few diameters on another collodion plate, 
and then exhibited the photographic representation on a 
large screen sixty feet in diameter, the picture having been 
magnified to this extent by means of a magic lantern. 

At the same time Mr. Hartnup suggested a plan of taking 
a stereograph of the moon, by first taking a photograph of 
this luminary twelve hours before full, and then twelve hours 
after full, thus changing the shadows from one side to the 
other. The stereograph was successful, and exhibited the 
moon in relief. From the fact that the moon revolves on 
her axis in the same period that she revolves in her 
orbit, it is difficult to obtain a degree of parallax by 
which more of one side can be seen at one time than at 
another ; but the axis of the moon, that is, the moon itself 
in the direction of its axis, has a sort of libration, which 
brings to light alternately more of the northern parts than 
of the southern. By taking photographs at these different 
periods a sufficient amount of parallactic angle has been 
obtained, and pei'fect stereographs have been the result. 
The moon has been photographed and stereographed in 
all her phases ; the shadows of the mountains are so well 
delineated in these different phases as to admit an accurate 
measurement of the height and diameter of those mountains. 

A few seconds' exposure with a good equatorial will, in 
general, give a tolerable negative. It is not absolutely ne- 
cessary to be furnished with a telescope in order to get a 
photograph of the moon ; the photographer will be glad to 
learn that a long-focussed view-tube will permit him to ob- 
tain a copy of this bright luminary, of about half an inch in 
diameter, which can afterward be magnified to any size de- 
sired. The only difficulty is to keep the moon in exactly 
the same position of the ground glass for a number of 

The sun is easily photographed, because the operation is 
instantaneous. The act of focussing is performed by placing 
a piece of violet-colored glass over the opening of the ob- 
jective, which is retained there during the exposure. In 


this way eclipses of the sun can be photographed without 
that immense trouble and risk which have been so often re- 
ferred to in celestial photography. 

The stars have a high degree of photogenic power, and 
can be photographed in accordance with the intensity of their 
light. Mr. Bond has endeavored to base upon this power a 
means of classifying the stars into magnitudes, which at 
present are quite arbitrary. 

The planets, jDOSsessing much less photogenic power than 
the fixed stars, are in consequence not so easily photograph- 
ed ; but by means of well-regulated clock-work, De la Hue 
has succeeded in obtaining very excellent photographs of 
Jupiter and his bands, Saturn and his rings, as also a stereo- 
graph of Mars, by taking two photographs at an interval of 
two hours, and others of Saturn at an interval of three years 
and a half. 

It is supposed there are planets nearer to the sun than 
Mercury, which have not been discovered by reason of their 
proximity to the solar orb : it is hoped, however, by means 
of photography to settle this supposition ; for if at any time 
in any of the numerous photographs which are taken of the 
sun, a small, round black speck should be discovered, the 
conclusion of the existence of another inferior planet would 
soon be drawn. 

De la Rue is prosecuting this branch of photography and 
astronomy with great zeal and success ; his labors, too, are 
highly appreciated. The Astronomical Society of London 
have conferred upon him their annual large medal as a token 
of their high appreciation of his merits and the results of 
his labors. 



Sir John Herschel observed in 1840, that paper, prepared 
with chloride of silver and blackened in the sun, when ex- 
posed beneath red or blue glass, assumed the respective color 
of the glass; and Edmond Becquerel in 1847 and 1848 pro- 
duced all the colors of the spectrum on a prepared silver 
plate, which were permanent as long as the plate was kept 
in the dark. The surface was sensitized by immersing the 
plate either in a solution of a bichloride, or in chlorine water. 

Niepce de St. Victor, following in the steps of Becquerel, 
is obstinately persevering in his attempts to fix the colors 
which can already be obtained. The production of colors is 
a fact ; the fixation of colors is still a problem xuxsolved. 

The plate for heliochromic purposes is best prepared in the 
following manner : A common daguerreotype plate is var- 
nished on the copper side. In one corner a hole is bored in 
order that the plate can be suspended on a silvered copper 
wire, which is the positive pole of a galvanic battery. A 
small plate of platinum soldered to a copper wire forms the 
negative or zinc pole. xVs soon as the battery is in working 
condition, insert the two poles at the proper distance in a 
vessel containing a mixture of one part of hydrochloric arid 
and eight parts of water. By the electrolytic decomposition 
hydrogen affects the negative pole and is given off there, 
whereas chlorine goes to the silvered plate, combines with 
the silver, and forms a chloride. The operation is best per- 
formed in the dark-room. The amount of deposition is re- 
cognized by the different shades of color which the plate as- 
sumes. The thinner the film, the more sensitive it is. 

Xiepce de St. Victor has recommended the production of 
this sensitive film by immersing the plate in soluble bichlo- 
rides, or in chlorides in combination with copper salts. 

In whichever way prepared, the plate is dried over the 
flame of a spirit-lamp, and the surface is gently brushed over 


mth a tuft of cotton, in order to remove a downy substance 
arising from impurities. 

If this plate be exposed to a diffused light, the film assumes 
a grayish violet tinge ; but if it be exposed to a well-defined 
and very luminous spectrum, it receives an impression of the 
various colors of this spectrum, but not with the same facil- 
ity. The orange, the yellow, and the red are the first colors 
that appear, and the first to darken and to become gray by 
a continued action. Beyond the red a rosy hue is made 
manifest, but this darkens the first of all. The blue, the 
green, and the violet are the most vivid. Beyond the ter- 
mination of the violet part of the spectrum there is a decom- 
2>osition of a gray color. 

By keeping the prepared plates exposed to a temperature 
of about 100° for forty-eight hours in a stove, or to the rays 
of the sun beneath a piece of red glass, the film becomes 
much more sensitive, and not only reproduces the spectrum 
but receives an impression from white light. 

If, when the plate leaves the electrolytic bath, it be sim- 
ply dried, without raising the temperature to such a degree 
as to change the color of the film, and after this the plate 
be exposed beneath a colored engraving, a reproduction of 
these colors will soon be effected ; some of these^are some- 
times latent, whilst others are brilliantly manifest. Those 
which are latent can be developed by simply rubbing the 
surface gently with a tuft of cotton impregnated with am- 
monia, which has been previously used for cleaning a plate. 
It is hence evident that a colored image is already produced, 
which may be partially manifest and partially latent. 

Two very important problems remain to be solved : to 
find means of developing the whole of the image at once in 
all its colors, and of fixing it Avhen developed. Some colors 
can be always reproduced, whilst others ai'e but partially 
obtained. None of the colors as yet can be rendered per- 
manent in diffused light. This branch of photography, 
therefore, is still quite imperfect. It is difficult to form an 
opinion as to the possibility of the solution of this interest- 
ing problem ; because as yet no clue, no rational hypothesis 
can be given of the cause of the reproduction of the colors 
in question. In the ordinary positive printing on the chlo- 
ride of silver, the cause of the decomposition is probably just 
as little understood ; but we are satisfied with almost any 
theory as long as the manipulation is definite in its manage- 
ment, and within our power to continue or restrain. In the 
reproduction of colors these characters are wanting, and we 


are hence tempted to disbelieve in the possibility of the 
effectuation of so desirable a discovery. On the other hand, 
the very tact that colors can be once reproduced, engenders 
faith in the realization of the great object ; and because a 
similar and apparently equally as difficult case of fixation 
of a fugitive image has already been overcome, hope still 
points to the goal of final success. 

Our knowledge of the image-impressions by contact, by 
the influence of heat and of electricity, is limited simply to 
the recorded facts, for which as yet no satisfactory rationale 
has been assigned. Probably all the pictorial representation-, 
of objects in photography, and its congene branches, develop- 
ed either by mercury, pyrogallic acid, the protosalts of iron, 
the breath, impalpable powders, etc., may be classified in one 
and the same category, of which the cause may either be a 
molecular or polar change — that is, either an absolute change 
of position of the ultimate atoms in the aggregated material, 
or simply a change in the attractions of these atoms. The 
hypothesis thus expressed is founded upon the circumstance 
that every latent image is developed by means of matter 
applied to the film, which is attracted to certain parts after 
exposure by apparent predispositions in these parts, which 
have been superinduced by this exposure ; the resulting 
pictures are combinations of the new and applied material 
with the original matter in the film. By an extended course 
of definite experiments applied understandingly in reference 
strictly to cause and effect, we have a right, in the course of 
time, to expect a definite solution of these wonderful manifes- 
tations of the presence of an Omniscient Intelligence. 



The knowledge of an imperfection or an error is half the 
correction. We must, therefore, first know what the fail- 
ures in collodion negatives and positives are. Their enu- 
meration is as follows : 

Fogginess / Spots and Apertures ; Ridges and Undulating 
Lines • Streaks and Stains ; Feebleness of the Image, or 
Deficiency of Contrast / Harshness, or Excess of Contrast; 
Imperfect Definition ; Solar ization ; Tender and Rotten 

Fogginess. — This is a mist or veil-like appearance that 
covers the whole negative ; it gives it a foggy or clouded 
appearance. This imperfection may be the result of many 
and various causes, as for instance : Diffused light in the 
camera through holes or chinks ; reflections from white or 
unblackened surfaces in the camera ; diffused light through 
apertures or chinks in the door behind the plate in the plate- 
holder ; direct rays of the sun through the objective or lens ; 
an alkaline, neutral, impoverished or contaminated state of the 
nitrate of silver bath ; a similar condition of the collodion ; 
certain iodizers in the collodion and at certain stages of 
ripening ; diffused light in the dark-room ; too intense arti- 
ficial light in the dark-room ; too intense a development ; 
fumes of ammonia, of turpentine, of tobacco, of hydrosul- 
phuric acid, and probably almost of any other volatile 
chemical substance in the developing-room ; imperfect 
cleanness of a glass plate that has been used before ; 
the use of gutta-percha baths and dippers. 

Diffused light in the camera, either in front of the plate 
or behind it • Reflections frotn white or unblackened sur- 
faces in the camera. — This is a certain cause of fogging, and 
can easily be remedied. Examine the camera carefully for 
all chinks and holes. Some photographers are very care- 


less ; they screw on the flanges of various-sized tubes on the 
end of the camera, and neglect filling the apertures left by 
the screws when withdrawn. Chinks occur invariably in 
cameras made of green wood ; and the bellows part, by 
frequent adjustment, sometimes cracks. The plate-holder 
has also its imperfections ; the slide sometimes allows the 
entrance of light ; the apertures at the bottom, for the pas- 
sage of accumulating nitrate of silver, are frequently left 
open and not filled with sponge, so that light penetrates in 
this way. The door behind may close inaccurately ; and 
the plate-bolder may slide irregularly and not fill the groove 
calculated to receive it. All these are errors or defects of 
workmanship, which must and can lie avoided or remedied. 
Look, therefore, to your camera first in the search of chinks, 
cracks, and apertures ; secondly, if the inside surfaces of 
the camera are not of a dead black, cover them with uu- 
glazed black woolen or cotton cloth, or wash them over 
with a thick solution of ink or lampblack. 

Direct rays of the sua through the axis of the lens. — 
Avoid this evil ; like many other troubles, to know it, is its 
total remedy. " 

An alkaline, neutral, impoverished or contaminated state 
of the nitrate of silver bath. — Immerse apiece of reddened 
litmus paper in the bath, and see whether it changes coloi', 
after a while, to a blue — if so, the batli is alkaline. 

First remedy. — Make a mixture of six drops of acetic 
acid in a drachm of water, if you are taking negatives, and 
of the same quantity of nitric acid and water, if you are 
taking positives ; add ten drops at a time of either solution 
until the fogging disappears. Sometimes even more acid 
may be required. 

Second remedy . — Instead of adding acid to the bath, add 
an old collodion or tincture of iodine to your collodion in 
present use ; this frequently is the safest plan of action. 

If the bath is impoverished, it will at the same time be 
contaminated. The remedy is to boil it some time in a 
glass flask in order to get rid of the ether, alcohol, and the 
volatile substances produced by decomposition, as also to 
coagulate organic matter; then allow the bath to cool, and 
filter. To the filtrate add more nitrate of silver if required. 
Placing an old bath in the sun for several days is also of 
great assistance, but it is far from being equal to boiling or 

Certain iodizers in the collodion and at certain stages of 
ripening. — Iodide of cadmium alone frequently produces 


fogginess ; almost any new and limpid collodion has the 
same effect. Add iodide of ammonium in the first ease, and 
an old collodion or tinctuVe of iodine in the second case ; 
the sensitiveness will be thereby probably diminished, whilst 
the condition to fog will be removed. 

Diffused light in the dark-room, or too intense an artificial 
light. — Place the artificial light behind a piece of ground 
glass, and do not bring it near the negative until the latter 
is thoroughly fixed. Diffused light must be locked out of 
the room. 

Too intense a developer. — In summer less of the devel- 
oper, whether of iron or pyrogallic acid, or more of the 
acid is required than in winter, otherwise fogging will be 
the consequence — the property of acid is to restrain the ac- 
tion of the developer ; use your judgment, therefore, and 
do not always keep to the same amount of protosulphate of 
iron, or pyrogallic acid to the ounce of water in all seasons ; 
nor restrict yourself unconditionally to the same amount of 
acid in the developer. 

lUtmes of ammonia, ct<\ — Keep your dark-room solely for 
its legitimate purposes. Keep it rigidly clean ; perform no 
chemical experiments in it ; abjure smoking in this sanc- 
tum ; do not sensitize your papers or fuminate with ammo- 
nia in this room ; make no manner of fumes therein. 

Imperfect cleanness of the plate, etc. — Wash the old plates 
with a solution of salts of tartar and water ; if this does not 
remove the adhering dirt, wash it with dilute nitric acid, 
and afterward with salts of tartar, and finally clean and 
polish the plate with rotten-stone and alcohol. Some old 
plates that have lain long in water in which the old develop- 
ing solutions have been thrown I have never succeeded in 
cleaning so as to prevent fogging ; they are contaminated to 
the backbone. 

The use of guttapercha haths, etc. — Instead of these, use 
glass, porcelain or photographic ware baths — the latter are 
very highly recommended ; I prefer glass to every other 

Spots and Apertures. 

Opaque and transparent specks are the most troublesome 
annoyances in the collodion negative process, and occur to 
every photographer more or less. These can be attributed 
to various causes, but seldom for the time being to the right 
cause ; that is, we know in general what will cause them, 
but seldom what did cause them. 


The opaque spots may be caused in the first place by dust 
on the surface of the glass before the collodion is poured on. 
The remedy is simple : brush off the dust with a broad, flat 
camel's hair pencil just before the collodion is applied. 

Secondly. — Opaque spots maybe caused by dust on the 
surface of the collodion ; this dust may be deposited either 
from the bath itself, previous to immersion in the bath, or 
in the camera during exposure. That which is deposited 
either before or after immersion, are the organic substances 
in a state of very minute division floating about in the at- 
mosphere or set in motion within the camera by the agita- 
tion produced with the plate-holder. This is perhaps the 
most fruitful source of trouble, which is of two kinds, opaque 
and transparent spots. The particles of dust attach them- 
selves to the collodion with different degrees of .tenacity ; 
where the tenacity is small, the dust is washed oft* in the 
different manipulations of developing and fixing, and the 
consequence is the production of transparent specks ; on 
the contrary, where the tenacity is great, opaque spots are 
the result ; for the particles remain imbedded after the final 
washing. If the dust be deposited from the bath itself, it 
may arise either from organic materials, in the atmos- 
phere or from an excess of iodide of silver in the bath, in 
the form of the violet-colored deposit found at the bottom 
or on the walls of the bath. The remedy is, in the first case, 
to keep your room-floors moist, and your camera perfectly 
free from this enemy by dusting and sponging. In the sec- 
ond place, the insoluble deposit in the bath is separated by 
filtration ; the bath, too, is thoroughly cleaned by a sponge 
tied to the end of a rod, which can be made to enter into the 
angular spares in which the dust is deposited. 

Third!)/. — Another source of this trouble with opaque 
spots is to be found in the collodion, which contains some- 
times undissolved pyroxyline in the form both of dust and 
fibres, or in fine organic dust from impure sources of mani- 
pulation. To remedy the evil, allow the collodion to settle 
thoroughly and use only the clear supernatant part. 

Transparent /Spots. 

These are of much more frequent occurrence than opaque 
spots. They may arise, in the first place, from undissolved 
particles of the iodides in the ether and alcohol of the col- 
lodion ; this is particularly the case with iodide of potassium 
in anhydrous alcohol ; these afterward become dissolved in 


the subsequent operations. The remedy is a drop or two of 
water, or of diluted alcohol, or of bromide of ammonium. 

As remarked in reference to opaque spots, particles of 
dust in the camera or of the insoluble iodide of silver in the 
bath, adhering to the surface of the collodion, produce sj^ecks, 
both opaque and transparent. The transparent ones result 
from the fact that, during exposure, and the dust particle* 
being opaque, they prevent the rays of light from acting 
actinically on the collodion film beneath, and then, beinrc 
washed olf in the subsequent manipulations of development, 
fixing, intensifying, and washing, they leave the collodion in 
those parts to the mercy of the fixing solutions, which ren- 
der them quite transparent. The remedy is to keep the cam- 
era and the room free from dust, and the bath from insoluble 
particles of the iodide of silver or organic materials. If the 
bath is the cause, the trouble may be avoided by keeping the 
plate in motion during sensitization. 

Another cause of transparent spots, and probably a very 
frequent one, is to be attributed to a crystalline deposit of 
iodo-nitrate of silver, which, as the bath becomes weaker, is 
precipitated in a crystalline form on the surface of the collo- 
dion film. This form of deposit occurs with an old bath. 
Its remedy is to precipitate it out of the bath by adding 
water, and then by filtration. Then for every ounce of water 
thus added pour in after filtration the same amount of a ni- 
trate of silver solution to take its place. 

When the bath is the cause of transparent spots, a small 
quantity of a solution of chloride of sodium (common salt) 
thrown in is found to be of great benefit. Chloride of silver 
and nitrate of soda are formed by double decomposition ; 
the insoluble chloride probably carries down with it the dust 
or particles which are the cause of the trouble, or the nitrate 
of soda dissolves them. I am not able to say what is the 
true explanation. After filtration the bath is raised to the 
proper strength, when it will be found to be free from the evil. 

Hidges and Undulating Lines. 
These are caused by the too great consistency of the col- 
lodion, and are found in the direction of the current of the 
collodion. The remedy is to add sufficient ether to cause 
the collodion to flow smoothly, easily, and uniformly over 
the plate. The mottled appearance sometimes apparent on 
a collodion film, as if covered with flocks of wool, is owing 
also to the thickness of the collodion, and the evil ijgjtemedied 
in the same manner as the ridsres. JT • 


Streaks and Stains. 

Streaks may arise from an irregularity in the immersion 
of the plate in the silver bath, or in withdrawing it; the 
plate has to he immersed or withdrawn without any stop- 
ping. Streaks and stains are produced, too, by the film of 
dust swimming on the surface of the vertical bath, which is 
carried down on the collodion when the plate is immersed. 

They arise, secondly, from the irregular flowing of the 
developing solution ; the remedy is to use the gutta-percha 
developing dish already recommended for such purposes. 
Another remedy may be a proper quantity of alcohol added 
to the developer, if there happen to be a sort of greasiness 
or repulsion in the collodion film to the developing solution 
as it flows along. 

The part upon which the developer first comes in contact 
with the collodion film almost invariably exhibits a streak 
around a denuded part, as if the developer had swept off the 
latent image in that part. The remedy is the developing 
dish, by which the developer acts with little or no moment- 
um greater at one part than at another. 

A sort of fortification system of stains and streaks arises 
from the want of cleanness of the corners of the plate-shield, 
from an inferior quality of collodion, from the unequal dry- 
ness of the film before immersion in the silver bath, as well 
as from a too great and irregular dryness of the film after 
exposure and before development. The remedies are self- 
apparent; avoid the causes. 

Stains of a blue color arise from imperfect washing be- 
tween developing and fixing. 

Feebleness of the Image, or deficiency of Contrast. 

A nexc collodion will very frequently be one cause of this 
trouble — the materials are not yet ripe. As a remedy, add 
old collodion, or wait for a few days, until the collodion is 
sufficiently decomposed. 

Over-exposure is another and very frequent cause of a 
feeble contrast in the picture. All the parts are developed 
simultaneously, and too much deposit of reduced silver is 
the result all over the picture. A shorter exposure is the 

Too intense a developer, or a developer continued too long, 
fogs the picture and weakens the contrast. 

Imperfect lighting is a third cause, in which the light is 
either small in quantity, or diminished in intensity by reason 
of peculiarities in the atmosphere. 


Harshness, or Excess of Contrast. 
Tinder-exposure, a too acid bath, a too acid developer, un- 
der-development, an old and insensitive collodion : all these 
will produce pictures of mere black and white ; the interme- 
diate tones are totally wanting. The remedy is apparent ; 
use it as the case may be. 

Imperfect Definition. 

This may be caused by the want of coincidence in the chemi- 
cal and luminous focus. See that the surface of the ground 
glass and that of the inserted plate have exactly the same dis- 
tance from the back lens, and correct this evil according to 
rules already laid down. 

The want of sharpness may arise from careless focussing, 
from the mbbility of the sitter during exposure, from a change 
of position in the camera when inserting the sensitized plate, 
or, in fine, from a bad lens. The remedy in every one of these 
cases is obvious, excepting perhaps in the last ; for the pho- 
tographer may not always be in a condition to get a better 
lens. The only and most advisable remedy in this case is to 
close his gallery and feign sickness, until the return of the 
Express from the city, rather than lose his reputation or gain 
a bad one. In many cases a microscope is employed in very 
refined focussing, especially in copying. 


This trouble does not occur very frequently; it is made 
manifest by the redness which the high-lights are wont to 
assume during development, when the exposure has been 
either too long or the light too brilliant, as in the copying 
process by the direct rays of the sun. This evil can be 
remedied by avoiding the causes, or by the use of a bromo- 
iodized collodion, or of citric acid in the developer. 

Tender and liotten Films. 

These occur generally in collodion of a certain make, 
owing to the peculiar nature of the pyroxyline, or the relative 
quantity of alcohol- and ether. The defect may arise, how- 
ever, by immersing the plate too quickly into the silver bath 
before the film has set ; also by immersing the plate when 
the film is too dry, in which case it cracks and splits up in 
the development. 

There is no remedy for a rotten film ; but a tender or 
structureless film can be retained on the glass by first filing 
the edges as recommended, and then by careful manipula- 
tions in the various operations of developing, fixing, and 

imperfections and their remedies. 333 

Imperfections in Paper Prints. 

These are to be attributed to defects in the paper ; to im- 
perfect albumenizing and salting • to defective sensitizing ; 
to defects in, the printing or 'in the negative; to imperfect 
washing previous to toning; to defective toning ; to defect- 
ive fixing; to stains of various kinds; mealiness on the 

Defects in the Paper. 

A defective piece of paper must always be rejected at 
once. By regarding the paper by transmitted light, very 
frequently imperfections in the substance of the material can 
be descried, which otherwise would escape observation. Par- 
ticles of inorganic matter, such as lime, the oxide of iron, etc., 
may be found in the substance, which in the various stages 
of the printing operation become manifest by decomposi- 
tion. In choosing paper, where you can make the selection, 
examine each sheet separately for mechanical defects both of 
structure and of contamination, and reject whatever is in 
any way defective. 

Imperfect Albumenizing and Salting. 
The albumenizing and salting require careful and neat 
management. If the albumen is not very thoroughly broken 
up, it will assuredly produce irregularities in the albumeniz- 
ing. The salting materials must be mixed lip at the same 
time with the albumen, but after solution in a small quantity 
of water ; otherwise particles of the salt will remain undis- 
solved and give a spotted appearance in the printing. Use 
the albumen while fresh. See that the surface is not com- 
posed of bubbles ; where these exist you will have a marbled 
or oolitic appearance on your print. If the paper exhibits 
such minute bubbles when removed from the salting solu- 
tion, break these bubbles all up with a clean feather or soft 
sponge, and float the paper again until the film is uniform. 
The amount of salting ought to bear a relation of equiva- 
lents with the silver solution used subsequently. 

Defective /Sensitizing. 
Filter the silver solution before use, or at least remove all 
particles of dust or oxide from its surface, otherwise your 
prints will be spotted and frequently covered with fortifica- 
tions. A marbled appearance is caused by a weak silver so- 
lution, or too short a time of floating. It may arise from 
defects in the albumenizing, as just referred to. In quick 
floating the solution must be very strong. In some cases the 


solution seems to be rejected from the surface of the albu- 
men ; rub over the solution with a tuft of cotton ; float again, 
and the trouble will be overcome. 

Defects in the Printing or in the Negative. 

A weak negative will inevitably produce a weak print. 
Weak prints, too, are the result of too dilute a silver solu- 
tion. Bronzing arises frequently from a want of true rela- 
tion between the lights and shades in the negative. An in- 
tensified ambrotype used as a negative will produce a bronzed 
picture. Thus under-exposure and over-development are the 
causes of bronzing. 

A harsh print proceeds also from under-eoqiosnre and over- 
d, velopment in the negative ; there is a want of middle-tone — 
the picture is all black and white. 

31 any prints are spoiled in the act of printing by extreme 
carelessness. Watch the operation ; the two guides of suc- 
cess are : -Print as long as the high-lights are perfectly tchlte, 
and bronzing has not yet commenced. The impression of a 
perspiring finger on the sensitive film, as well as many other 
similar organic contaminations, also give rise to bronzing. 

Imperfect Washing previous to Toning. 

The print, when removed from the printing-frame, contains 
nitrate of silver and nitrate of the alkalies used in the salt- 
ing solutions, albuminate of silver, chloride of silver ; the 
latter salt has been partly acted upon by light so as to form 
the picture, and another part has not been changed. The 
nitrates must all be removed by careful washing in several 
waters before the toning is commenced, otherwise the toning 
will be sloio and imperfect. 

The operation of washing must take place soon after 
printing and immediately before toning, in order to secure 
a good and quick tone. 

Defective Toning. 

This imperfection may arise from contaminations intro- 
duced into the toning solution by imperfectly washed prints ; 
the gold solution becomes thereby decomposed and incapable 
of toning the printed film. The defect may arise from im- 
pure chloride of gold ; from an acid condition of the toning 
solution ; from bad paper ; from the lowness of the temper- 
ature ; from an excess of elevation of temperature. The 
imperfections of toning are : 

A red tone after fixing ; this is owing to an insufficiency 
of toning. 


A blue tone after fixing ; this is owing to an excess of ton- 
ing ; or to an acid toning solution. 

A yellow tone in the whites after fixing ; this may be ow- 
ing to imperfect washing, imperfect toning, imperfect fixing, 
dirty fingers, introduction of hyposulphite of soda into the 
toning solution, or upon the prints. The defect in question 
may arise also from the decomposition of the gold in pathces, 
for want of uniform mixture before the prints are introduced. 

Defective Fixing. 
A dark mottled appearance in the body of the paper in- 
dicates imperfect fixing combined with the action of the light 
on the unaltered chloride during fixing. An exhausted hy- 
posulphite bath may also give rise to this defect. A bath 
containing hydrosulphuric acid, or a free acid, which will pro- 
duce the former, gives rise to this dark-gray mottled defect. 

A^yelloiD tone in the ichites arises very frequently from sid- 
phurized hyposulphite stains of various kinds. 

These are owing to irregular and careless manipulations. 
The introduction of the fingers into the various baths, and 
indiscriminately from one bath into another, is the cause of 
a number of stains on the prints, as well as of abnormal ac- 
tion of the baths themselves. 

Make rules for yourself, such as the following, and observe 
them minutely : 

1. Print just to bronzing, or until the wdiites begin to be 

2. Wash soon after printing in clean water and clean pails. 

3. Move the prints about in the washing ; repeat the wash- 
ing three times ; two or three minutes' duration for each is 
enough. Long washing is injurious. 

4. The chloride of gold must be pure ; the solution must 
be neutralized with alkalies or lime. 

5. The toning solution must be warm — about 100° — and 
well mixed — and clean. 

6. Wash after toning quickly — in warm or hot water pref- 
erable — take care to introduce no gold solution into the fix- 
ing solution, and vice-versA. 

7. Move the prints about in all the solutions, so as to avoid 
bubbles and uneven action. 

8. Tone to purple or incipient violet. 

9. Use fresh toning for a fresh batch of prints. 

10. Add fresh hyposulphite every time to the old bath, 
or use a fresh fixiug-bath every time ; let the bath be warm. 


11. Alcohol is an advantage in all the solutions beginning 
Avith the nitrate of silver to the hyposulphite of soda. 

12. Wash very thoroughly after fixing. 

Mealiness on the Print. 

Some authors speak of this defect in albumen prints. It 
is said to proceed from paper that has been long albumen- 
ized, or from the paper itself. The remedy is to immerse 
the prints in a solution of two ounces of water and eighteen 
grains of acetate of soda, and to keep them in this liquid 
for about ten minutes. 

Prints frequently appear as if covered iclth snoic, but the 
surface is quite smooth and the whites clear ; this defect is 
attributable to the negative, which has been strengthened by 
pyrogallic acid containing too much nitrate of silver. The 
surface of the negative becomes thereby covered with a pul- 
verulent deposit. There is no remedy for such a negative ; 
there is a remedy, however, to such a mode of intensifying. 
In the first place, the negative must contain the middle tones 
before you begin to intensify; secondly, intensify slowly, 
which is effected by adding only three or four drops of silver 
at a time to the pyrogallic acid, and shaking well before use. 



"Weights and capacities in England and France are esti- 
mated from certain standard linear measurements. In Eng- 
land, a pendulum vibrating seconds of time in a vacuum, at 
the latitude of London, and at the level of the sea, is assum- 
ed as the standard of linear dimensions; it is 39.1393 inches. 
This is the standard, too, of all our measurement of length, 
capacity, and weight in the United States. But, like the 
English, we retain all the old and arbitrary systems of 
weights and measures ; whereas the French have assumed a 
decimal system in all their measurements that merits the 
highest praise and imitation. The linear standard of the 
French, from which they derive all other measurements, is 
called a metre. It is the ten-millionth part of a quarter of 
the earth's meridian, and measures 39.371 inches. The metre 
is divisible decimally in both directions. 

The connecting link between the English linear unit and 
their measures of capacity and weight are as follows : 

A cubic inch of distilled Avater weighed in air with brass 
weights at a temperature of 62° Fahr., the barometer stand- 
ing at 30 inches, is equal to two hundred and fifty-two grains 
and four hundred ami fifty-eight one thousandth parts of a 
grain ; of such grains 5760 are required to make the inipe- 
-rial standard troy or apothecaries' pound ; and 7000 of such 
grains make the commercial or avoirdupois pound. The 
imperial gallon has a capacity of 277.274 cubic inches ; and 
a gallon of distilled water, as above, weighs 10 pounds 
avoirdupois, or 70,000 grains. 

The connecting link between the French linear unit and 
their measures of weight and capacity, arc as follows : 

A cubic centimetre of distilled water, at its maximum 
density, at the temperature of 39.5° Fahrenheit, is the unit 
of weights and is failed a gramme, which is divided deci- 
mally above and below. 

A cubic decimetre is called a Eire, which is the unit of tho 
measures of capacity, and divisible decimally. 



Comparison of Weights and Jfeasures. 

Apothecaries' Weight. 

20 grains 

60 grains 

480 grains 

5760 grains 

3 scruples = 

8 drachms = 

12 ounces = 


French gramme. 

1 grain = 0.0647 
1 scruple = 1.295 
1 drachm = 8.885 
1 ounce = 31.08 
1 pound = 372.96 

I '-rain = gr. Scruple = 3 . Drachm = 3 . Ounce 

Tomid = lb 

Apothecaries' Measure of Capacity. (United States.) 

60 minims = 1 fluid drachm. 

480 minims = S fluid drachms = 1 fluid ounce. 

7680 minims =16 fluid ounces = 1 pint. 

61,440 minims = 8 pints = 1 gallon. 

Avoirdupois Weight. 

16 drachms 
16 ounces 
112 pounds 
20 hundred weight 

French gramme. 
1 drachm = i.77 
1 ounce = 2S.328 

1 pound = 453.25 

1 hundred weight 
1 ton 

Apothecaries' grains. 

= 27.34375 

= 437.5 

1 drachm 

1 ounce 

1 pound = 7000. 

1 hundred weight = 7S4000. 

1 ton = 156S0000. 

Apothecaries' ounce 
Avoirdupois ounce 
United States pint 
Imperial or British pint 
United States gallon 
Imperial or British gallon 

480 grains. 
437.5 grains. 

16 fluid ounces. 

20 fluid ounces. 
128 fluid ounces. = ' 8 pounds avoirdupois. 
160 fluid ounces = 10 " " 

Weight of Water at 62° and Capacity of : 

1 gallon (Imperial) 
1 gallon (U. S.) 
1 quart (Imperial) 
1 quart (TJ. S.) 
1 pint (Imperial) 
1 pint (U. S.) 
16 fluid ounces 
1 fluid ounce 
1 fluid drachm 
1 minim 

Cubic inches. Grains. 









1 37.B 



French Measures of Length. 

English inches. 
Millimetre = " .03937 

Centimetre = .39371 

Decimetre = 3.93708 

Metre = 39.37079 

Decametre = 393.70788 
Hectometre = 3937.0788 
Kilometre = 39370.788 
Myriametre = 393707.88 

French Weights. 

Equivalents in Grains. 

Milligramme, .0154 

Centigramme, . . .... .1543 

Decigramme, 1.5434 

Gramme, 15.434 

Decagramme, ...... 154.340 

Hectogramme, 1543.402 

Kilogramme, 15434.023 

Myriogramme 154340.234 

A gramme of water — 1 cubic centimetre = 15.43 grains = 17 minims. 
1000 grammes of water = 1 litre = 1 kilogramme = 15434.023 grains = 
2 lb. 3.27 oz. 

French Liquid Jfeasures. United States Liquid Measures. 
Cubic inches. 

Millilitre, .... .0610 16.2318 minims. 

Centilitre, . . . .6103 2.7052 fl. drachms. 

Decilitre, .... 6.1028 3.3816 fl. ounces. 

Litre, 61.028 2.1135 pints. 

Decalitre, .... 610.2S0 2.6419 gallons. 

Hectolitre, . . . 6102.80 26.4190 " 

Kilolitre, .... 61028.0 264.1900 " 

Myrialitre, . . . 610280 2641.9000 " 



Thermometers are instruments for ascertaining the tem- 
perature of bodies, whether liquid, solid, or gaseous. The 
principal thermometers in use are : the Centigrade, wh?eh 
is used principally in France ; Reaumur's thermometer, of 
more especial use in Germany ; and Fahrenheit's thermome- 
ter, used more especially in Great Britain and the United 

The temperature of boiling water is 
100° on the Centigrade scale. 

80° on Reaumur's scale. 
212° on Fahrenheit's scale. 

The freezing point of water is indicated by 
0° on the Centigrade scale. 
0° on Reaumur's scale. 
82° on Fahrenheit's scale. 

The number of degrees between the freezing point and the boiling point is 
100° on the Centigrade scale. 

80° on Reaumur's scale. 
180° on Fahrenheit's scale. 

To reduce Centigrade degrees to those of Reaumur. 

Rule : Multiply by 4 and divide by 5. 

To reduce Reau?nur' l s degrees to those of the Centigrade. 

Rule : Multiply by 5 and divide by 4. 

To reduce Centigrade degrees to those of Fahrenheit. 

Rule : Multiply by 9, divide by 5, and add 32 to the quotient. 

To reduce Fahrenheit'' 's degrees to those of the Centigrade. 

Rule : Subtract 32, multiply the difference by 5, and divide by 9. 

To reduce Reaumur's degrees to those of Fahrenheit. 

Rule : Multiply by 9, divide by 4, and add 32 to the quotient. 

To reduce Fahrenheit's degrees to those of. Reaumur. 

Rule : Subtract 32, multiply the difference by 4, and divide by 9. 


Table of the corresponding degrees on the Scales of Fahren- 
/teit, JReaumur^ and the Centigrade. 




Boiling point, 212 































































— 5 

















— 2S 





All the intermediate indications can be obtained by the 
nse of the preceding rules. 



The specific gravity of a body is the comparison of the 
weight of a given bulk of the said substance with that of an 
equal bulk of distilled water at 62° Fahrenheit. Gases are 
compared either with air as the standard or with distilled 

The specific gravity of a body is taken by special instru- 
ments for this purpose ; some of these instruments are de- 
nominated Hydrometers, and give arbitrary indications, 
which have to be reduced afterward in terms of specific 

Baume's Hydrometers are in extensive use in France, and 
Twaddell's Hydrometer in England. Baurne has two Hy- 
drometers : one for liquids heavier than water, and one for 
liquids lighter than water. 

For Liquids Heavier than Water. Baume. 


Sp. Grav. 

6 ... 

. 1.000 

1 ... 

. 1.007 

2 .. 

. 1.013 

S .. 

. 1.020 

4 .. 

. 1.027 

5 .. 

. 1.034 

6 .. 

. 1.041 


. 1.048 

8 .. 

. 1.056 

9 .. 

. 1.063 

10 .. 

. 1.070 

11 .. 

. 1.078 

12 .. 

. 1.085 

13 .. 

. 1.094 

14 .. 

. . 1.101 

15 .. 

. . 1.109 

16 .. 

.. 1.118 

17 .. 

. . 1.126 

18 .. 

. . 1.134 

19 .. 

.. 1.143 


Sp. Grav. 


Sp. Grav. 


Sp. Grav. 

20 . 

... 1.152 

40 . 

. . . 1.357 

60 . 

... 1.652 

21 . 

. .. 1.160 

41 . 

. .. 1.369 

61 . 

. .. 1.670 


. .. 1.169 

42 . 

. . . 1.381 

62 . 

. .. 1.689 

23 . 

. .. 1.178 

43 . 

. .. 1.395 

63 . 

. . . 1.708 

24 . 

... 1.188 

44 . 

. . . 1.407 

64 . 

... 1.727 

25 . 

. .. 1.197 

45 . 

. .. 1.420 

65 . 

. . . 1.747 

26 . 

. .. 1.206 

46 . 

. . . 1.434 

66 . 

... 1.767 

27 . 

. .. 1.216 

47 . 

. . . 1.448 

67 . 

. .. 1.788 

28 . 

. . . 1.225 

48 . 

. . . 1.462 

68 . 

. . . 1.809 

29 . 

. . . 1.235 

49 . 

. . . 1.476 

69 . 

. .. 1.831 

30 . 

. .. 1.245 

50 . 

. . . 1.490 

70 . 

. .. 1.854 

31 . 

. .. 1.256 

51 . 

... 1.505 

71 . 

. . . 1.877 

32 . 

... 1.267 

52 . 

. . . 1.520 

72 . 

. .. 1.900 

33 . 

. .. 1.277 

53 . 

... 1.535 

73 . 

... 1.924 

34 . 

... 1.288 

54 . 

... 1.551 

74 . 

. . . 1.949 

35 . 

... 1.299 

55 . 

... 1.567 

75 . 

. . . 1.974 

36 . 

... 1.310 

56 . 

... 1.583 

76 . 

. . . 2.000 

37 . 

. .. 1.321 

57 . 

. . . 1.600 

38 . 

... 1.333 

58 . 

... 1.617 

39 . 

... 1.345 

59 . 

. . . 1.634 



For Liquids Lighter than Water. Baume. 


10 ., 

11 ., 

12 .. 

13 .. 

14 ., 

15 ., 

16 ., 

17 ., 

18 ., 

19 .. 

20 , , 

21 ., 

22 ., 


.. 1 
. . 0. 
. . 0. 
. . 0. 
. . 0. 
. . 0. 
. . 0. 
. . 0. 

.. o. 

. . 0. 
. . 0. 
. . 0. 
.. 0. 
















23 . 

24 . 

25 . 

26 . 

27 . 

28 . 

29 . 

30 . 

31 . 

32 . 

33 . 

34 . 

35 . 

Sp. Grav. 


. 0.918 

36 .. 

'. 0.913 

37 .. 

. 0.907 

38 .. 

. 0.901 

39 .. 

. 0.896 

40 .. 

. 0.890 

41 .. 

. 0.885 

42 .. 

. . 0.880 

43 .. 

. 0.874 

44 .. 

. 0.869 

45 .. 

. 0.864 

46 .. 

. 0.859 

47 .. 

. . 0.854 

48 .. 

Sp. Grav. 


Sp. Grav 

. . 0.849 

49 . 

... 0.789 

. . 0.844 

50 . 

. . . 0.785 

.. 0.839 

51 . 

. .. 0.781 

. . 0.834 

52 . 

. .. 0.777 

. . 0.830 

53 . 

... 0.773 

.. 0.825 

54 . 

. . . 0.768 

.. 0.820 

55 . 

. . . 0.764 

.. 0.816 

56 . 

. . . 0.760 

.. 0.811 

57 . 

. .. 0.757 

. . 0.807 

58 . 

. . . 0.753 

. . 0.802 

59 . 

. . . 0.749 

.. 0.798 

60 . 

. . . 0.745 

. . 0.794 

61 . 

. . . 0.741 

TwaddeWs Hydrometer. 

The degi*ees on Twaddell are converted into equivalent 
specific gravities by multiplying them by 5 and adding 
1000 ; then mark ofi" three figures as decimals. 


Sp. Grav. 


Sp. Grav. 

Leg. Sp. Grav. 


Sp. Grav. 

1 . 

. . . 1.005 

8 .. 

. 1.040 

15 ... 


22 . 

... 1.110 

2 . 

. .. 1.010 

9 .. 

. 1.045 

16 ... 

. 1.080 

23 . 

... 1.115 

3 . 

. .. 1.015 

10 .. 

. 1.050 

17 ... 

. 1.085 

24 . 

... 1.120 

4 . 

. . . 1.020 

11 .. 

. 1.055 

18 ... 

. 1.090 

25 . 

... 1.125 

5 . 

. .. 1.025 

12 .. 

. 1.060 

19 ... 

. 1.095 

26 . 

... 1.130 

6 . 

. . . 1.030 

13 .. 

. 1.065 

20 ... 

. 1.100 

27 . 

. .. 1.135 

1 . 

. . . 1.035 

14 .. 

. 1.070 

21 ... 

. 1.105 

28 . 

... 1.140 



;Elements. Symbol. |^wToJ Elements. Symbol. £^ c \ 

Aluminum, Al. 14 Molybdenum, Mo. 38 

Antimony, (Stibium,) Sb. 129 Nickel, Ni. 30 

Arsenic, As. *75 

Barium, Ba. CD Nitrogen, N. 

Bismuth, Bi. 213 

Boron, B. 11 Osmium, Os. 100 

Bromine, Br. 78 Oxygen, 0. 8 

Cadmium, Cd. 56 ! Palladium, Pd. 54 

Caesium, Ca3. 123 

Calcium, Ca. 20 

Carbon, C. 6 

Cerium, Ce. 46 

ine, CI. 36 

Chromium, Cr. 26 

Cobalt, Co. 30 

Columbium, (Tantalum,). .Ta. 1S4 

Copper, (Cuprum,) Cu. 32 

Didymium, Di. 4s 

Erbium, Er. ? 

Fluorine, F. 19 

Glucinum, G. 1 

Gold, (Aurum,) Au. 197 

Hydrogen, H. 1 

llmcnium, II. 

Iodine, I. 126 

Iridium, Ir. 99 

Iron, (Ferrum,) Fe. 28 

Lanthanum, La. 44 

Lead, (Plumbum,) Pb. 104 

Lithium, Li. V 

Magnesium, Mg. 12 

Manganese, Mn. 28 

Mercury, (Hydrargyrum,) Hg. lOOl 

The Elements printed in italics are the Metalloids; the 
rest are the Metals. 

Elements. Symbol. 

Molybdenum, Mo. 

Nickel, Ni. 

Niobium, Nb. 

Nitrogen, N. 

Norium, No. 

Osmium, Os. 

Oxygen, O. 

Palladium, Pd. 

Pelopium, Pe. 

Plwsphorus, P. 

Platinum, Pt. 

Potassium, (Kaliurn,). . . .K. 

Khodium, Ro. 

Rubidium, Rb. 

Ruthenium, Ru. 

Selt nium, Se. 

Silicon, Si. 

Silver, (Argentum,) Ag. 

Sodium, (Natrium,) Na. 

Strontium, Sr. ] 

Sulphur, S. 

Tellurium, Te. 

Terbium, Tb. 

Thorium, Th. 

Tin, (Stannum,) Sn. 

Titanium, Ti. 

Tungsten (Wolfram,) W. 

Uranium, IT. 

Vanadium, V. 

Yttrium, Y. 

Zinc, Zn. 

Zirconium, Zr. 




Aberration, chromatic, 34 ; spherical, 34. 

Aberration, to ascertain whether corrected 
for chromatic, 37, 3S, 39. 

Aberration, to ascertain whether corrected 
for spherical. :!7. 

Acetate of silver, 112. 

Acetate of soda, 104, 111, 112, 190; pro- 
duces rigorous pictures, 111. 

Aceto-nitrate of silver, (formula for,) 235, 
239, 240, 241. 

Achromatic lenses, 40. 

Acid, acetic, 103, 111 ; glacial, 104 ; checks 
reduction, 104 ; gives sensitiveness, 104. 

Acid, citric, preparation of, 105, 106 ; uses 
of, 1U7. 

Acids, in developing solutions, 102 ; as re- 
tarders of development, 102, 1" ■'•. 

Acid, formic, a reducing agent, 95 ; prepar- 
ation of, 104 ; photographic uses of, 
105 ; used as developer, 169. 

Acid, gallic, a reducing agent, 95 ; symbol 
of, 99 ; preparation of, 100 ; a devel- 
oper, '2=37, 239. 

Acid, hydriodic, preparation of, 70. 

Acid, hydrobromic, preparation of, 76. 

Acid, hvdrocyanic, (prussic,) preparation 
of, 119. 

Acid, hvdrosulphocyanic, preparation of, 

Acid, metagallic, 101. 

Acid, nitric, a reducing agent, 95. 

Acid, phosphoric, 306. 

Acid, pyrogallic, a reducing agent, 95 ; 
symbol of, 99 ; preparation of, 101 ; 
a developer, 146 ; an intensifier, 148. 

Acid, tannic, a reducing agent, 95 ; prepar- 
ation of, 99 ; uses of, 100 ; vide Tannin 
Process, 245 ; a developer, 247, 249. 

Acid, tartaric, preparation of, 107 ; a re- 
tarder of reduction, 103 ; printing with, 
2 -5. 

Actinic focus, coincidence with luminous, 

Affinity of metals, 95. 
Aguillon, Francis, 312. 

Alabastrine positives, 140; alabastrine so- 
lutions, 14ii. 

Albumen, preparation of, 194; formulas for 
iodized albumen. . .'.•>, 241, 

243 ; albumen-process, 23S ; collodio- 
albumen-process, 237, 241 ; and bi- 
chromate of potassa, 299 ; and bichro- 
mate of ammonia, 

Albumenized paper, preparation of, 194 

Alcohol, hydrated oxide of ethyle, 56 ; pre- 
paration of ether from, 56 ; prepara- 
tion of, 59, 60. 

Alcoholic collodion, 19. 

Aldehyde, 111. 

Amber varnish, with chloroform, 137 ; with 
benzole, 137. 

Ambrotype, 23 ; how to make, 123 to 140. 

Ammonia, 197 ; bichromate of, 

Ammonium, symbol and combining propor- 
tion, 71 ; chloride of, 191 ; iodide of, 
73 ; sulphide of, 125. 

Ammoni-nitrate of silver, formula for bath, 
197 ; albuminous film not injured by, 

Angle, parallactic, 313. 

Aperture angular, defined, 40. 

Aperture, (of diaphragm,) relation between, 
and opening of the lens, 41. 

Apertures in the collodion film, 112 ; cause 
and remedy, 32S, 329. 

Apothecary's weight, 339. 

Aplanatic lenses, 40. 

Aqua-tinta granulation. 259 ; application 
of, 294, 295. 

Arago, report of, to the Chamber of Depu- 
ties, 13. 

Arcken, first application of gun-cotton by, 
19 ; and Fry published a detailed ac- 
count of gun-cotton, 51. 

Arrowroot papers, preparation of, 195. 

Asser, used transfer proce'ss, 21. 

Asphaltum in chloroform, 21 ; for black var- 
nish, 188; dissolves in benzine, 291 ; 
properties of, 298. 

Asphaltotype of Nicephore Niepce, 291. 

Asphalto-photolithographic process, 297. 

Astronomical photographers. 

confer medal on De la Rue, ... 

Axis, convergence of, 314. 

Avoidupois weight, 83s. 

Background, illustration of, 30 ; various 
plain, graduated, pictorial, 31; color- 
ing of, 230. 

Bath, vertical, horizontal, 109, 110; glass, 
porcelain photographic ware, 109 ; pre- 
paration of the sensitizing solutions for 
collodion pictures, 110, 111 ; with ace- 
tate of soda and acetic acid, 111 ; for 
summer, 111 ; how to restore when 
weak. 111 ; how to treat the bath when 
acid or alkaline; 112, 113 ; the necessity 



of filtering, 118; to add tincture of 
iodine to the collodion in order to pro- 
duce acidity in, 112 ; take care that no 
actinic rays get to,130 ; for paper, 196 ; 
ammonio-nitrate, 197 ; for toning, 202. 

Barium, symbol and equivalent, 71 ; iodide 
of, 71; chloride of, 191. 

Barreswil, attempts photolithography first, 

Beauregard, Testud de, process, 276. 

Beaume. 342. 

Becquerel on heliochromy, 323. 

Benzine, how to render anhydrous, 291, 293. 

Benzoin, 209. 

Berard's experiments with the spectrum, 12. 

Berry, 821. 

Bertrand's new process for positive print- 
ing, 209. 

Biology, 10. 

Bichromate of potassa, 11, 270, 277, 230 ; 
bichromate of ammonia, -'. 

Bichromo-photo-lithograptuc processes, 299. 

Bichloride of mercury, as developer, 275 ; 
as intensifier, 169; preparation of, 125. 

Bitumen of Judea, first used by Niepce, 14. 

Blanchard's (Valentine) instantaneous pro- 
cess, 109; prefers bromo-iodlzed collo- 
dion, 108 ; strengthened with bichlo- 
ride of mercury, 109. 

Blanquart Evrard's intensifying process 
by a second exposure to li.'ht, 124; 
bromo-iodizing solutions for printing by 
development, 268; sensitizing bath and 
development, 204. 

Blonde hair, coloring of, 22T. 

Black hair, coloring of, 227. 

Blue drapery, coloring of, 227. 

Blue-tone, owing to excess of toning, or to 
acid toning, 335. 

Boiled oil, in transfer varnish, 151. 

Bond, Messrs., 320. 

Brewster, refracting stereoscope, 312. 

Bromides, 65; bromide of silver sensitive 
to certain colors, 00; bromide of sil- 
ver, 91. 

Bromine, 7.5 ; preparation of, 75. 

Bromo-iodized collodion, greater capacity 
for colors, 06, 67. 

Bromo-iodizing solution for printing by de- 
velopment, 203. 

Bronzing, 334. 

Cadmium, symbol, combining proportions, 
specific gravity, 71 ; iodide of, 07, 7:!. 

Calcium, symbol, combining properties, 
specific gravity, 71; iodide of, 72. 

Calotype, discovery of, 17, 18; how to scn- 
Bitize, 171; Pilchard's process, 180; 
Geoffray's process, 17S ; Tillard's pro- 
cess, ISO. (Vide Talbotype.) 

Camera, 34,42; invention of, 42 ; must be 
horizontal for architectural purposes, 
43 ; stereoscopic, 104 , if tilted, how to 
rectify the error, 104; where to place, 
105; camera stand, 105. 

Camarsac, Lafon de, 270. 

Camel's-hair pencil. 225. 

Camphene, ia transfer paper, 151. 

Canada balsam, in varnish, 150; for black 
varnish, 133. 

Cap, used as an instantaneous shutter, 170. 

Carbon, reducing agent, 94 ; lampblack in 
black varnish, 188; in Fargier's pro- 
cess, 280; in Poitevin's, 281 ; as ivory 
black in Salmon and Garnier's process, 
279; in Pouncy's process, 277; print- 
ing, 20; process, 275; processes with 
the salts of iron, 251 ; print, how to 
transfer, 283. 

Carbonate of lime, preparation of, 190 ; in 
toning formulas, (chalk.) 202. 

Carbonate of soda, preparation of, 190; in 
toning formulas, 202. 

Card-picture, 21S; coloring of, 221. 

Celestial photography, 320. 

Cerolein, 178, 179. 

Centigrade scale, 340, 341. 

Chaldeans, 10. 

Champlouis, (De,) improvement in the wax- 
paper process, HO. 

Chardon, 270. 

Chemical equivalents, table of, 344. 

Chestnut-colored hair, 227. 

Chimenti's drawings not stereoscopic, 3 1 8. 

Chinese vermilion, 225; Chinese white, 225. 

Chlorides, 70; of lime, 78; chlorinetted 
lime, 7S; of gold, 1S7, 203; of silver, 
photographic properties of, 93; of sil- 
ver used for dry-plating and galvano- 
plasty, 93 ; of silver, 12, 17. 

Chloroform, solvent of varnish, 137, 139 ; in 
black japan, 150. 


citrate of iron, 270; of soda, 100, 190. 

Citric acid, 105; uses of, 106. 

Clarifying operation of negatives, 154. 
t's developer, 109. 

Cleaning and polishing the silver plate, (Da- 
guerreotype,) 268; the surface of the 
photo-lithographic print. 

Clippings of prints, 207. 

Coating the glass, (wet process.) 129; the 
paper with the sensitive solution photo- 
lithography, 304. 

Collodion, 19; decomposition of, 01, 02; 
hast stable, 04; most permanent, 01 ; 
sensitizers, 05; for tannin plates, 246; 
plain or normal, 79 ; iodized, 79 ; bro- 
mo-iodized, 79, SO; Wortley's, Lieut. - 
Col. Stuart, formula of, SO ; Omme- 
ganck's formula of, SI; Disderi's for- 
mulas of, 31,62,88; wet process, 127 ; 
positives, 127, 186 ; negatives, 144 ; pos- 
itives on glass, 153; dry-process, 232 ; 
collodio-albumen process, 237, 241 ; for 
Taupenot plates, 23S ; formula of Col. 
Sir H. James, 303 ; imperfections of nega- 
tives, 320 ; remedies of, 320, etc. 

Coloring, of collodion positives, 186; of a 
card-picture, 224; of 0, portrait, 225; 
of the face, 226, 228, 229. 

Colors, not rendered permanent in helio- 
chromy, 323. 

Comparison of hydrometric indications, 
842; of weights and measures, 337 ; of 
thermometric indications, 340, 341. 

Condensers, 157. 

Contrast of light and shade, 127; excess 
of, cause of, 322 ; deficiency of, 321. 

Copal, solt varnish, 157; with benz 

Copies, for the engraver to work from, 296. 

Copying of collodion negatives or posi- 



fives, ICO, 1G1, 102 ; of any given size, 

Copernicus, 10. 

Copper, requires a strong etching fluid, 

Corrosive sublimate, 125. 

Crook. - 

CrysotJ ; 

Crystalline lens, moved by ciliary muscle, 

' 811 
Cyanide of potassium, 119, 120, 155 ; a re- 
ducing a'jent, 1-1. 
Cyanogen, 11-; preparation cf, 11?. 
Cyanotype, -73. 


David Hilaire, 281 

rre, 18, 14. 15, 10. 

Daguerreotype, 268 ; latent image brought 
out by mercury. 15, 270. 

Dark-room, 46, 47 ; what it contains. 47. 48. 
-. iu the printing of 
in the paper, 333; defective sensitiz- 
ing, 333 ; defective toning, 334 ; defec- 
tive fixing, 335. 

Deficiencv of contrast in the negative, cause 
of. 831. 

Definition, imperfect, cause of, 332. 

Develop r native, 14.", 146; sul- 

phate of iron. 114, 115; Diaderi' 
ldeut,-Col. Stuart Wortley's, 1 
Mewler's, 116; I 
Waldack's, 116, 117: Claudet's 
Crookes's, 177 ; De Cha 
too intense, cause oi 

Developing, solutions. 114. 218; the pic- 
ture, twet process.) 131, 132 ; Fother- 
gillV. . Sir II. James's, 3u3; 

of the silver plate, 270. 

Development, of the card-picture, 219 ; of 
the albumen film, 237 ; of the Taupe- 
not plates, 239; of the tannin plates, 
247. . 

Diffused litrht, in the camera, cause of fog- 
in the dark-room, etc., cause 


Direct rays of the sun through t! 
the lens, cause of . 

Dist;m:- : een at the same 

tim>-. tout, 311; dif- 

ferences of. 818. 

Distillation of the nitrate-bath, 112. 

. id. from too great contrast of light, 

Dolland, 9. 

Doobli • 

Donne, 287. 

Draper, Dr., use of hot water in the tannin 

Drying the positive plate, (w 

Drying process, of albumen films. 2 


photographed, 322. 

' H, 10. 
Eleoti ing agent, 95. 

Litiii'.uta of matter, table of, 344. 

Enamels, how to mal:-. 

England, formula for collodion for the tan- 
nin i 

Engraving, ph- t _ 5 ; heliographic, 

on the daguerreotype pi.. 

Etching, fluid, 289, 290; f the plate, 295; 
on glass, - I c, 306. 

Ether, 55 ; how to prepare, 5i ; property of, 
on collodion, 61. 

Ethyle group. 55. 

Eureka plate. 14 '. 

Excelsior plate, 140. 

Exposing the glass, (wet process), 131. 

Exposure of the silver plate, (Daguerreo- 
type, 293 ; un- 
der the negative, (photo-lithography,) 

Eye, its philosophy, 311 ; single eye cogni- 
zant of relief, 311. 


Fahrenheit, scale, 340, 341. 

Feebleness of the negative imasre, cause of, 

Ferrier, 119. 

I e plates, apt to blister in the dry- 
ing, 14a 

Field photography, rules to be observed, 44. 

Films, tender and rotten, cause of, 

Fixing, solutions, US, 121 ; the picture, 

(positive — 

tions for ne I ; solutions for 

prints, 203; of t!.e card-picture, 221; 

of the image, (Daguerreotype.) 270. 
Fizeau, 10. 
Flowing the varnish, in photo-engraving, 

Focus, of a lens, (how to find,) 86, 43, +4; 

equidistant conjugate, ! 

principal, 254 ; equivalent, 254 ; actinic 

and luminous, (coincidence of.) 39. 
Foggioess, remedy for, 134, I . 27 i 

:. 111. 
Formic acic, a reducing agent, 95. 

Formula for zinc enan: 
Fothergill pr c --. 242. 
French government. 
Fumes of ammonia, cause I 

the asphaltum film, . 
Eliminating, apparatus, 199 ; 


Gallic acid, a reducing agent, 95; prepara- 
tion of, 100. 

Gallo-nirrate of silver, 17. 
. 306. 

Gamier. 275. 

Gelatine, 1n5; operation, (tannin-process.) 
245; process, 214. 

GeoEray, process with cerolein, 17-. 

: house, 
28,29 parati ui f< r Taupe- 

not 228; how 

to clean, 803. 



Globe lens, 165. 

Glover's resinized printing process, 210. 

Glycvrrhizine, makes collodion sensitive. 

Gold, deposited by galvanism, 2S7 ; chlo- 
ride of, 1S7, 203 ; gold and uranium 
toning, 202. 

Grain, engravers, 293. 

Gramme, 337. 

Granulation, Aqua-tinta, (how made,) 2S9 ; 
application of, 294. 

Grape-sugar, makes collodion sensitive, 63. 

Gray hair, how to color, 223. 

Green drapery, 229. 

Gum, arabic, 187 ; guaicum, 12 ; mastic, 
210; thus, 210; sandarac, varnish for 
cold plate, 139. 

Gutta-percha baths, cause of fogging, 328. 


Hardwick's views about the decomposition 
of collodion, 62, 63. 

Harshness, or excess of contrast, cause of, 

Harrison, C. C, 41 ; Globe lens, 165. 

Hartnup, 821. 

Heat, a reducing agent, 95. 

Heliochromy, 22 ; or the art of taking pho- 
tographs in their natural colors, 323. 

Heliograph?, 11, 14; heliographic engrav- 
ing, Xegre's process, 296. 

Herschel, Sir John, 15, IS, 323. 

Hipparchus, 10. 

History of photography, 9. 

Hockins, Developer, 116, 169. 

Hodgson, 321. 

HofTmeister, 131. 

Holmes, Booth and Hayden's, 41. 

Honey, 308. 

Horn silver, 92. 

Uow to improve the color of transparent 
positives, 253. 

How to take diminished copies of photo- 
graphs, 265. 

How to take enlarged copies of photographs, 

How to transfer the carbon print from glass 
to paper, 283. 

nydriodic acid, 70. 

Hydrobromic acid, 76. 

Hydrocyanic acid, 119. 

Hydrogen, a reducing agent, 94. 

Hydrometers, 342. 

Hydrosulphocyanic acid, 120. 

Hyposulphite of soda, 120, 121. 

Illumination, for copying different from 
that in portraiture, 162, 163. 

Image, imperfections, theory of, 325. 

Image, solid, 314, 315. 

Imperfections, in collodion negatives and 
their remedies, 326, etc. ; fogginess, 326, 
in paper prints, 333 ; in albumenizing 
and salting, 333; washing previous to 
toning, 884, 

India rubber for black varnish, 138. 

Inking, of the bichromate print, 304. 

Instantaneous process of Lieut.-Col. Stu- 
art Wortley, 167 ; shutters, 169 ; stere- 
ographs, 166. 

Intensifies, 122, 147, 16S, 242; Sir H. 
James's, 302. 

Intensifying, first method, 147, 148, 123 ; 
second and third do., 124. 

Iodides, 65 ; alkaline all soluble, 65 ; tests 
of purity, 74 ; preparation of, 69 ; im- 
purities of, 73. 

Iodide, of potassium, not very soluble, 65 ; 
of ammonium, easily decomposed, 65 ; 
of silver, sensitive to certain colors, 
65 ; of cadmium, glutinizes collodion, 
67 ; alkaline, liquefies collodion, 67 ; 
of barium, 71 ; of calcium, 72 ; of lith- 
ium, 72; of potassium, 72; of sodium, 
73 ; of ammonium, 73. 

Iodine, 69 ; of cadmium, 73 ; of silver, pre- 
paration of, 90; properties and tests 
of, 70. 

Iodizers, certain ones, cause of fogging, 327. 

Iodized albumen, 233, 234, 240, 241. 

Iodizing for gelatine, tannin process 246 ; 
of wax paper, 174. 

Iron, developer for negatives, 145, 146 ; sul- 
phide of, 98 ; protosalts and persalts of, 
97, 98. 

James, Col. Sir Henry, 21, 301, 30S. 

Japan, black, 150. 

Joubert's process for taking photographs on 

glass in enamel colors, 308. 
Jupiter and his bands photographed, 322. 

Keene's Rapid dry process, 250. 
Kaiserstuhl, 11. 

Lace, how to imitate in colors, 231. 

Lampblack, for black varnish, 13S. 

Landscape, photography, 164. 

Lavender, oil of, 11. 

Legray, wax-paper process, 173; first sug- 
gested the use of gun-cotton, 51. 

Lens, 34 ; crossed, 34 ; how to buy a goo.l one, 
39 ; single equivalent to a compound, 37 ; 
axis of, 254; optical centre of, 2.">4 ; 
principal focus of, 254 ; conjugate foci 
of, 254 ; equivalent focus of, 254 ; equi- 
distant conjugate focus, 224 ; vertex of, 
254; how to find the principal focal 
distance of, 254 ; how to find where the 
^ lens is to be placed in the solar micro- 
scope, 260. 

Lenses, for the card-picture, 219 ; compara- 
tive value, 36; magnifying power, 87; 
Harrison's, Ross's, Dallmeyer's,Gruhb's, 
JaminSs, Holmes's, Booth and Hayden's, 
A r oightlaender's, 41. 

Lerebours, 298. 

Light, action of, 96 ; a reducing agent, 95 ; 
single, 162 ; velocity of, 102 ; must enter 
from the north. 

Lime, carbonate of, 190. 



Linseed oil, rubbed into an engTaved plate, 

List of a photographic outfit, 23, 26. 
Lithium. 71 ; iodide of, 72. 
Litre, 33T. 
Lunar caustic, SS. 


Macrophotography, 257, 262. 

Manipulation, of positive printing, 192. 

Marbled appearances in the paper, 333. 

Marion's, Preserving box, 210. 

Mars, photographed, 322. 

Mats, 139. 

Matter for the reception of the image, 23. 

Materials. used in positive printing, 1S3. 

Mayo's Outlines of Human Physiology, 312. 

Mealiness, on the print, 33G. 

Melainotype, 23 ; plate, apt to blister in the 
drying, 148. 

Mercury, bichloride of, 125; vapor of a de- 
veloper, 15, 270 ; preparation of, bichlo- 
ride of, 125 ; bichloride of, an intensi- 
fier, 169 ; developer, 275. 

Metals, how to imitate in colors, 230. 

Metre, 337. 

Modified albumen process, 240. 

Modified collodio-albumen process, (James 
Mudd's,) 241. 

Monckhoven, (Van,) 272 ; his views about 
the decomposition of collodion, 61, 62. 

Moon, photographed, 321 ; stereographed, 

Negatives, for enlargement, 262 ; for card- 
pictures, 221; collodion, 144; enlarge- 
ment by the camera, 157 ; on paper, 
171 ; definition of, 24 ; developer for, 
145, 140. 

Negre's process, 296. 

New tor/fl, photo-lithographic process, 300. 

Nicephore Niepce, asphaltotype, 291, 297. 

Niepce, 14, 15, 16. 

Niepce, Isidore, 10. 

Niepce de St. Victor, IS, 22, 233 ; on helio- 
chomy, 323. 

Nitrate of silver, photographic properties 
38, S9; bath, 109, 110, 111; cause 
of fngginess, 827. . 

Nitric acid, a reducing a<rent, 95. 

Nitro-glucose, preparation of, 63. 

Non-asotized substances, 1S6. 

Norris, Dr. Hill, process, 244. 

Oil, of bergamot, in varnish, 149 ; of laven- 
der, 21. 
Ommeganck's formula for collodion, 81. 
Osborne, 20. 

Ounce. avoirdupois, 100; Troy, 100. 
Overdevelopment, cause of fogging, 834. 
Oxide of silver, how to prepare, 110. 

Paper, albumenized, 194 ; arrowroot, 195 ; 

for transfer-process in photo-litho- 
graphy, 304. 

Pearl-)jTay, color, 230. 

Pension, 16. 

Persalts of iron, 97, 93. 

Phosgene gas, 13. 

Phosphate of soda, 190. 

Photographic-ware baths, 110. 

Photography, 11; Celestial, 320; photo- 
graphic engraving. 286. 

Photographs, mounting of, 205. 206 ; photo- 
graphic properties of chloride of silver, 

Photo-lithography, 297 ; asphalto- photo-lith- 
ographic process, 297 ; photo-zinco- 
graphy, 297 ; first attempts at, 297 ; 
Newton's process, 300 ; Osborne's, 301 ; 
Col. Sir H. James's, 301 ; photo-typo- 
grapliic process, 300; photo-lithograph- 
ic ink, 304 ; photo-papyrography, 30S. 

Physiology, 10. 

Pink drapery, 229. 

Pictures, red, green, violet, blue, 274, 275. 

Ponton Mungo, 19. 

Poitevin, 20, 21, 270, 299. 300. 

Porta. 42 ; Giovanni Battista Delia, 312. 

Positive, printing on paper, 1S2 ; transpar- 
ent by contact, 159. 

Positives, collodion, 127 ; alabastrine, 140 ; 

Potassium, 71 ; cyanide of, 119 ; sulpho- 
cyanide of, 120 ; sulpliide of, 125 ; iodide 
of, 72. 

Preliminary observations, 23. 

Preparation, of salted paper, 192 ; of the 
plates of steel, etc., for photo-engrav- 
ing ; of the glass ; wet collodion process, 
128, 129. 

Preservers, 139 ; preservative, solution. Dr. 
Hill Norria, 244 ; tannin plates, 247. 

Printing, of sensitized paper, 200 ; without 
the salts of silver, 272 ; with the chlo- 
ride of silver, 191 ; by development, 
212 ; directly on paper by means of 
the sesqui-chloride of iron and tartaric 
acid,2S5; of card-pictures, 222 ; direct, 
1S2; transparent by contact. 159; 
transparent by the dry-process, 252. 

Process, Pouncy's carbon, 277 ; Salmon and 
Garnier's carbon, 275 ; Fargier's carbon, 
275, 2S0; carbon with the salts of iron, 
281 ; for colored pictures, 274, 275 ; 
albumen, 233 ; dry collodion. 2 12 ; 
Humbert de Molar.], 180; Pilchard's 
Calotype, ISO; Talbotypc, 172; wax- 
paper, 173; Geoffrav's, 175; Tillard's, 
179; Niepce de St. Victor, 216; Fumi- 
nating, 195; Resin, 24'. i ; Hani! dry, 
250; Bertrand's, 209; Glover's, 210; 
drving of albumen films, 285; Fother- 
gill's, 242; Taupenot's, 237; Dr. Hill 
Norris's, 244 ; Tannin, 245; Tannin and 
Honey, 248; Fizeau's, (similar I 

of Donne,) 2^7 ; Xcgre's, 290 ; asphalt i- 
photo-lithographic, 297 ; bichromo-pho- 
to -lithographic, 299 ; photo-typographic, 
300; Newton's, (photo-lithographic,) 
300 ; Joubert's (colored enamel, 30S. 

Prussic aeid, 119. 

Pyrogallic acid, a reducing agent, 95 ; pre- 
paration of, 101 ; developers, 115, 140. 

Pyroxyllne, 5i : preparation of, 52, 53 ; for- 
mulas for making, 53, 54, 55. 




Quality of the paper used in the transfer 


Radiant, axis of, 254. 

Rapid dry process, 250. 

Rays, direct and parallel, 159. 

Reaumur's scale. 340, 341. 

Red, hair, (coloring of,) 227 ; tone owing to 
defective toning, 334; drapery, (color- 
ing of,) 229. 

Redeveloping process, 14T. 

Reflections within the camera, cause of fog- 
ging, 326. 

Reflectors, used as condensers, 157. 

Resin process, 249. 

Retina of the eye, not a surface, 310. 

Rice water, 174. 

Ridges and undulating lines in the negative, 

Ritter, 12. 

Rose-colored drapery, (coloring of,) 229. 

Roulette. '.'. 

Roval Society, 15, 16. 

Rue, (De la,) 321, 3J2. 

Russell, (Major,) 245. 


Salmon, 275 ; Salmon and Garnier's carbon 
process, 278t. 

Salted paper, (formulas for,) 192. 

Salting solutions, (for printing by develop- 
ment,) 212, 213. 

Salts of iron, (printing with,) 273 ; in carbon 
processes, 2S1 ; of uranium, printing 
with, 273. 

Saturn and his rings, photographed, 322. 

Scale, thermometric, 340, 341. 

Scheele, 12. 

Scott, Captain, improvements in photo-litho- 
graphy, 301. 

Screens. 31 ; with graduated tints, 31 ; pic- 
torial, 31. 

Seebeek, 12. 

Self-acting washing machine, 205. 

Sensitizing, solution, (James Mudd's.) 241 ; 
solution, (James Larpey's,) 240; of 
Taupenot's plates, 239 ; of the albumen- 
film, 235 ; substances, 24; (nitrate of 
silver,) 110, 111 ; the collodion film, (wet 
process,) 130 ; (nitrate of uranium.) 
216, 217; defective, 333; plain silver 
bath, 196; ammonio-nitrate bath, 197; 
far development, 214, 215, 216; the 
daguerreotype plate, 269 ; of wax- 
paper, 175. 

Sesquichloride of iron, 255 ; formula of, in 
carbon process, 2S1. 

Side-light, 29. 

Silver, oxide of 110; iodide of, 90, 110; 
chloride of, 92, 191 ; salts, 84; reduc- 
tion of, 85, bi>, s>7 ; nitrate of, 88 ; pho- 
tographic properties of the nitrate of, 
SS, 89; hyposulphite of, 90; sulphate 
of, 90 ; bromide of, 91 ; tests of the chlor- 
ide of, 93 ; photographic properties of 
the chluride, 93. 

Sir Humphry Davy. IS. 

Soda, citrate of, 106, 190 ; hyposulphite of, 
120 ; acetate of, 190 ; phosphate of, 190. 

Sodium, 71 ; chloride of, 191 ; iodide of, 73. 

Solarization, cause of. 332. 

Soleil and Dubosc, 312. 

Solution for transfer paper, 151. 

Solvent, of the asphaltum film, 293. 

Specialties, 27. 

Specific gravity, comparison of, 342. 

Spectrum, 12. 

Spots and apertures in the negative, 328, 
329 ; opaque, 329 ; transparent, 329, 330. 

Starch, 186. 

Steam-engine, 10. 

Stereograph, instantaneous, 116, 167; stereo- 
graphic negatives, 164; strabonic, 314, 
315 ; how to see strabonic stereographs, 
316,317; Towler's, 319. 

Stereoscope, Wheatstone's, 312 ; mere optical 
contrivance, 315. 

Stereoscopicity, theory of, 310. 

Stone, for photo-engraving, 298, 299. 

Streaks and stains, cause and remedy, 331. 

Sugar of milk, Legray's formula, 174. 

Suitable rooms, 27. 

Sulphate (double) of ammonia and iron, 98 ; 
sulphate of silver. 90. 

Sulphide of iron,9S ; of potassium, (prepara- 
tion of,) 125 ; of ammonium, 125. 

Sulphocyanide of potassium, 12U; of .ammo- 
nium, 120. 

Sulphovinic acid, 58. 

Sulphurous acid, 58. 

Sulphuric acid, 58. 

Sun, easily photographed, 321. 

Suttnn, 19 ; rapid dry process, 250. 

Symbols of elementary bodies, 344. 

Table for increasing or diminishing the size 
of a picture, 256. 

Talbot Fox, 16, 17, 21. 

Talbotype, 17, 171 ; process, 172. 

Tannic acid, a reducing agent, 95 ; prepara- 
tion of, 99. 

Tannin process, 245; and honey process, 
■J4> ; preservative, 249. 

Tartaric acid, preparation of, 107 ; printing 
with, 2S5. 

Taupenot process, 237. 

Temperature modifies development, 103. 

Telescopes, reflecting and refracting, 320. 

Tillard, turpentine and wax process, 1 79. 

Toning of prints, 201 ; formulas, ! 

card-pictures, 224 ; first effect of, 204 ; 
of the silver plate, (daguerreotype,) 271. 

Transfer paper, 20, 151 ; process, of collo- 
dion pictures, 150 ; ink, 307 ; solutii>n, 
151 ; of carbon print from glass to 
pa] er, 283. 

Transference of the print to zinc or stone, 

Transparent positives, 153, 159, 285, 289; 
by the dry process, 252. 

Triplet. 35. 

Turpentine, in transfer solution, 151. 

Twaddell's hvdrometer, 342, 343. 

Tyrolese Alps, 11. 



Cnder-exposure, the cause of fogging 1 , 334. 
Unit, English linear, French linear, 337. 
Undulating lines on the negative, 330. 
Uranium, printing with, '273 ; and gold ton- 
ing, 202 ; nitrate of, 1S9. 

Tarnish of Niepce de St. Victor, 291 ; for 
collodion pictures, 137, 139 ; black, 13j, 
139 ; applied cold, 139. 

Varnishing of collodion positives, 136. 

Vergennes, formula of, 256. 

Vicar of Wakefield. 82. 

Vignette-printing, 223. 

Vinci, Leonardo da, on binocular vision, 311. 

Violet color, 230 ; colored glass for focussing 
actinically, 39. 

Virtual solid image. 314. 

Vision, binocular, 312. 


Waldack's developers, 116, 117. 
Washing machine, (self-acting.) 205 ; of the 
solvent, (asphaltotype,) 294 

Watt, 9. 

Wax-paper process, 173. 

Wedgwood, 13, 14. 

Weight of water, 62, 33S. 

Weights, apothecaries and avoirdupois, 333 ; 
and measures, 337, 339 ; comparison of, 

Wet-paper process. Molard's, ISO. 

Wheatstone's reflecting stereoscope, 312. 

Whey, (serum.) 174, 175. 

White hair, (coloring of,) 228 ; drapery, (co- 
loring of,) 229; wax in black varnish, 

Wollaston, 12. 

Work-room, what it contains, 49, 50. 

Wortley's (Lieut.-Colonel Stuart) collodion 
formulas, SO, 167; developer, 116, 168 ; 
intensifier, 168. 

Wood-spirit, 104. 

Yellow drapery, (coloring of,) 229. 
Yellow tone in the whites, its cause, 335. 

Zinc enamel, 307 ; white, 307. 





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Fortrait Cameras, Printing Frames, 

Yiew Cameras, Stereoscopic Boxes, 

Carte de Visite Cameras, Columns, 

Camera Stands, Pedestals, 

Patent Elevating Camera Stands, Glass-cleaning Vices, 

Lewis's Patent Camera Stands, Photographic Roller Presses for Cartes 

Lewis's Patent Glass Baths, de Yisite. 

Lewis's Patent Yice, Photographic Roller Presses for 8x10 

Lewis's Patent Solid Glass-corner pictures ; also larger sizes made to 

Holders, order. 
Plate Holders, 

And every thing in the line of Apparatus used in the business ; also 




Chemicals, Lewis and Holt's Yarnish, 

Tubes and Lenses, Iron Plates, 

Oval Frames, Card Mounts, 

Cases, Glass, all sizes. 

Hats, Albumen and other Paper used for 

Preservers, Photographic purposes. 

Lewis and Holt's Collodion. 

P. S.— Operators and Amateurs in city or country are invited to 
call before purchasing elsewhere. Goods sent to all parts of the 
world. TERMS: CASH. 


(Formerly JAMES WILCOX,) 




Manufacturers and General Agents in the Supply of 

|^0t0jwjrkk §§teteriafe, 








GILT and other FEAMES, 



Prompt attention given to all orders received by mail. 
USF* The best quality of materials always given, unless 
specially instructed to the contrary. 





Still retains its reputation as being a superior article over any other 
manufacture. This is proved by its constant use by the following 
artists, (the principal ones of New-York City :) 

J. ttUKNKX & SON, Broadway. T. FARIS, Broadway. 

R. ANSON, Broadway. A. BOGARDCS, Broadway. 

GEORGE G. ROCKWOOD, Broadway. R. A. LEWIS, Chatham Street. 

R. A. LORD, Chatham Street. GEO. W. HOLT, Broadway. 

Wl£€eg'S " £&<£&£" ££&■££§, 

Equal to any, and sold at the following low rates : 

£ Size Box of 4 Doz., $2.25 } Size Box of 8 Doz., $1.00 
i " " 8 " 2.00 i " " 8 " Vo 


ow evenly, do not affect the surface of the paper, give a strong an 
right result, and can be used by any body. 

Price per Box of Eight Large Bottles, $1.50. 





Arb all Standard Articles with those who have tried them. 

10 SPRING STREET, New- York City. 

■ »-•-• 




With a printed Formula accompanying each bottle. Being among the first 
in this country to make Collodion Pictures, they can warrant it to be one of 
the best in use ; also their 


For Ambrotypes, Negatives and Melainotypes. 

This Varnish, when applied to Negatives, dries in a few seconds perfectly 
bard, and does not lower the intensity, or soften by the heat of the sun, in 
Printing. It gives a beautiful gloss and brilliancy to Ambrotypes. For 
sale by Stock Dealers generally. 




113 "Washington Street, (First Floor,) Boston, 


*>H0TO0Sm?mo $T00JC 




Black "Walnut, Rosewood, French Polish, and Gilt, manufactured by our- 
selves. French Ovals, with and without Passe-partout. The best and 

In America ; the best Steel Presses for Cards and Photographs ; Apparatus 
of all kinds.; Chemicals, Glass, Cases, Photographic Ware Baths and Dishes, 
and every article which the Photographer may need. 

The Trade is respectfully invited to call or send their orders. 
All Goods warranted to give perfect satisfaction. 




H>T E "W-"5T ORK, 

Bog leave to call the attention of Amateurs and the profession generally to their new 
patented and improved Camera Boxes, which consist of the following : the 


Fpr taking Pictures both in the Gallery and in the Field. 

*n : . 

For all kinds of work — single pictures, four on one plate, and- for copying 



For copying ; adapted for field and gallery use. 


Double and single, with the Patent Dry Plate Box ; together with their adjustable 


This Table is the most useful and convenient article ever offered to the public, and is much 
admired by all first-class Artists. J. S. i Co. would especially introduce to your notice 
their Patent Glass Bath, universally adopted, and celebrated in every particular as 
the tested, perfect, and only reliable Glass Bath in the market. They would also call your 
particular attention to their new Patent 


This Box and Camera has been thoroughly tested, and is admitted by those who are compe 

tent to judge, to be the best arrangement for field work ever introduced. They have also 

just patented an entirely new instrument, 


Differing from any thing heretofore known. The Camera is folding, 
with Baths attached, for taking pictures in the field or drawing-room 
in direct sunlight, without the use of a tent or dark room. This 
instrument will not occupy more than six square inches when 
•he apparatus but the tripod. It is indispensa- 
ble for taking instantaneous views or portraits of deceased pen 
J. 8. A Co. would also inform their friends and patrons that they 
continue to manufacture 

Every style of Instrument used in 

At the shortest notice, and every article is warranted. 





Camera Boxes, Plate Holders, Camera Stands, and 

Printing Frames made in the Best and 

Cheapest Manner. 



PATENTED JUNE 24, 1862. 

Has an ingenious arrangement for elevating the Camera to any required 
height. Is in use in all the leading Galleries in this city and elsewhere. 
No operator can afford to be without one of these Stands. 





With two or four Tubes for Stereoscopic and Card Pictures ; all with the 
latest improvements ; cheap for Cash. 


Rooiri 23, New-Haven Freight Depot, 



All orders thankfully received and promptly attended to. 


The undersigned would hereby call the attention of 


To the Newly-invented and Patented Printing Frame of Mr. J. E. "Whitney, 
of St. Paul, Minnesota, an Operator of twenty years' experience and prac- 
tice. There have been two or three styles of printing frames in the market, 
but none which gave perfect satisfaction. It took much time to open them ; 
first, you open one side, and then the other, occupying 
a minute at least ; but this frame can be opened in 
one second. It will be noticed, by the accompany- 
ing cut, that the cross-bars are separated in the cen- 
tre by a semi-circular spring. By taking hold with 
the thumb and forefinger of each hand, and slightly 
pressing these springs, the cover is instantly re- 

moved. The edge of the lid is beveled, causing the ends of the bolts to 
operate as springs, which gives an even and constant graduated pressure, 
adjusting itself to the thickness as well as to all unevenness in glass. There 
is no possibility of breaking negatives in this frame as in the old kinds. All 
who have seen this Frame have bestowed upon it the highest encomiums. 
It is universally pronounced to be £ 


ever introduced, and must have an extensive sale. Arrangements are now 
being completed to manufacture them on a large scale. Parties wishing 


will please send their orders to the undersigned, who have been appointed 

for the Inventor and Patentee. All persons are hereby cautioned against 
infringing on this patent in any manner, as the Agents are determined to 
protect the rights of the Inventor. 

%W All orders -will be filled in rotation. JgJ 





WOW 3F6. IE -A. X3 "ST , 


For 1864, 

Being an Annual Appendix to " Humphrey's Journal of Photography." 

This is the largest and most complete Photographic Almanac ever issued in this or 
any other country. It has a full and complete calendar for every month in the year, cal- 
culated for New-York, Washington, and Geneva. It is a 12mo book, 160 pages, printed on 
fine white paper, in leaded type, bound in handsome style, and got up in the best possible 
manner. It contains an immense amount of new and valuable PHOTOGRAPHIC IN- 
FORMATION, such as can be obtained in no other form. Every thing in this Almanac is 
CONCISE and practical. It contains the most valuable formulas for all kinds of SUN- 
DRAWINGr, and will be found invaluable for the Photographer and Ambrotypist. It con- 
tains a full and succinct account of all the important events and discoveries in the Photo- 
graphic world for the past year, and is a book which every artist will want. 

Notwithstanding the greatly enhanced cost of book publishing at the present time the 
publisher has determined to sell the Photographic Almanac at the old price of ONE 
DOLLAR PER COPT ! Copies sent by mail, post-paid, on receipt of price. 

Remember, this Almanac contains twelve calendar pages, one for each month, giving 
as full and complete astronomical information as can be found in the best almanac ever 
published. The astronomical observations, the calculations as to the sun, moon, etc., are 
all made expressly for it, and there is also a DIARY connected with the work, to enable 
artists to make memorandums for each day in the year 1S64. All orders filled in ro- 
tation. Parties wishing the Almanac, will please inclose ONE DOLLAR, and address, 

JOSEPH H. LADD, Publisher, 

No. 60 "WHITE STREET, N. Y. 


Office, 458 BROADWAY, N. Y. 

The undersigned is now manufacturing, in addition to the C. C. Harrison Camera 
Tubes, the 


(Patented in the United States, England, and the Continent.) 

These Globe Lenses are especially adapted to the wants of those making either 
Views or Copies, as they have an angle of vision twice as comprehensive as the old View 
or Orthoscopic Lens, and will, therefore, with a very short focus, cover a large-sized 
plate. Their depth of focus is so great that objects near by and distant are equally sharp, 
no matter on which the focus is drawn. For copying they are far superior to the Ortho- 
scopic, as they will give copies of Drawings, Maps, etc., mathematically correct. They 
can be obtained of various sizes from 

2| inches Focal Length for Stereoscopic Plates to 
17 " " " 24x24 " 

Our C. C. Harrison Cameras, manufactured under Mr. C. C. Harrison's direction, 
are now made in every respect perfect, and are guaranteed superior to those of the mobt 
celebrated foreign manufacturers. 

For the Carte de Visile, we have just introduced a one-third size Camera expressly 
adapted to that style of pictures. 

The C. C. Harrison Cameras and the C. C. Harrison and I. Schnitzer 
Patented Globe Lenses, can be purchased from all Stock Dealers. Orders should 

^NELSON WRIGHT, 458 Broadway, New-York. 

Photographic Publications 




The Card Photograph, an Appendix to the Third 

Editiou of a Treatise on Photography. By Charles Waldack. Price, Fifty 

Hardwieh's Photographic Chemistry. Manual of Photo- 
graphic Chemistry, including the practice of the Collodion Process. By 
T. F. Hardwich, Lecturer on Photography in King's College, London. 
300 large 12mo pages, with numerous illustrations. Price, One Dollar and 
Twenty-five Cents. 

Waldack's Treatise on Photography, containing complete 

Directions for making Solar Camera and Stereoscopic Pictures, Views, etc., 
including also the New Toning Processes, the Dry Collodion Processes, and 
all the most recent Improvements. By Charles Waldack. Third Edition. 
Price, One Dollar and Twenty-five Cents. 

Theoretical and Practical Photography on Glass 

and Paper, with positive Rules for obtaining intense Negatives with certainty, 
By F. B. Gage. Price, Fifty Cents. 

The Photograph Manual : A Practical Treatise, containing the 
Cartes de Visite Process, and the method of taking Stereoscopic Pictures, 
and the Tannin Process. Eighth Edition. 260 pages. Price, One Dollar 
and Twenty-five Cents. 

Practical Manual of the Collodion Process, giving in 
detail a method for producing Positive and Negative Pictures on Glass and 
Paper, Photographs, Ambrotypes, Printing Process, etc. By S. D. Hum- 
phrey. Price, Twenty-five Cents. 

Thornthwaite's Guide to Photography, containing simple 
and concise Directions for obtaining Views, Portraits, etc., by the chemical 
agency of Light. By W. II. Thornthwaite. 88 12mo pages. Price, Thirty 
Cents, prepaid. 

Humphrey's Daguerreotype Process, giving the most 
approved and convenient methods for preparing the Chemicals, and the 
combinations used in the Art. By S. D. Humphrey. Fifth Edition. 216 
12mo pages, bound in red cloth. Price, Fifty Cents per copy. 

Humphrey's Photographic Operator, giving the whole 
process of making Photographs, Ambrotypes, etc. Single copies, Fifty 
Cents — -just one half the original price. 

Photography: A Treatise on the Chemical Changes produced by 
Solar Badiation, and the production of Pictures from Nature, by the 
Daguerreotype, Calotype, etc. By Robert Huut. 200 large 12uio pages, 
bound in red cloth. Price, Fifty Cents per copy. 





And all articles and apparatus appertaining 
to Sun-Pictures, 




French, German, and American 



Of all sizes, in great variety. 


Agent for the Sale of 




The Photographic Ware Baths having had such a continued popularity 
ever since their first introduction to the public some years since, the 
manufacturers, in order to oblige numerous customers, who have long 
been inquiring for DISHES to be made of the same materials as the Baths, 
have now the pleasure of offering their new style of 

Since their first introduction, a year since, the demand for these popular 
Dishes has been indeed unprecedented. They are driving out of the 
market all other kinds. In fact, many of the dealers neither offer nor 
recommend any other kind, for the very good reason that none others give 
satisfaction. Their advantages are patent. They will not crack or check 
»s a porcelain dish is sure to do, nor will they drop to pieces, as we have 
seen the rubber dishes do, and they are entirely impervious to oil acid 
solutions. They are very strong, and will last an operator as long as he 
continues in business. Do not fail to order the Photographic Ware 
Dishes, if you want to get the full value of your money. They can be had 


5by7 $0 50 

7by9 75 

8byl0 1 00 

10byl2 $1 50 

12 by 16 2 75 

and other sizes will soon be furnished. 

Thomas Sutton, Esq., Editor of the London Photographic XoUs, says, 
" The Photographic Ware answers the purpose for Baths and Dishes 
admirably," and he ought to know something about them. 

For Sale by all Stock-Dealers. 

New-York, September 1, 1863. 



The Greatest Photographic Discovery of the Age. 




IHjofocjrapbw anb ^mbrohipiiicr, 



They can be had with or -without the overflow, as maybe preferred. They 
are also made to be used as field-baths, for out-door practice, and can be 
fitted with a cover, so as to be perfectly air-tight. They are found to possess 
every qualification that can be called for, besides innumerable advantages 
over any other in use. They hold the least quantity of solution, being made 
very thin. They will not burst and let out the silver solution like the gutta- 
percha bath. They will not turn the solution black, as will the rubber'bath. 
They will not check like the porcelain, nor crack from changes of tempera- 
ture, like the glass baths. They are entirely impervious to all acids, will 
withstand all atmospheric changes, are made by a scientific man on strictly 
scientific principles, and will last a lifetime. Is anything more required of 
a bath I 

»-<y • 


There are no arguments like these. "Where persons have used the Photo- 
graphic Ware Baths and indorse them thoroughly, their testimony convinces 
the most incredulous. Read the following : 

From New-York City Operators. 

" I would say — for the benefit of the Photographic and Ambrotype profession generally — 
that for over three years past I have used, and at the present time am using, in my three 
establishments in New-York City, no other kind of Bath than the one described above, and 
believe it to be the best and only reliable article now in use. I have tried all others, and 
none, except the Photographic Ware, was without objection. I feel confident that all who 
may give them a trial will never have cause to regret it. I have now seven in daily use, 
which any one so disposed can see by calling at my establishments. 

" J. H. YOUNG, 145 and 19$ Eighth Avenue, N. Y." 

" 371 Broadway, New- York. 
" ITavingused the Photographic Ware Bath since its first introduction, I have the utmost 
confidence in its utility, and consider it by far the best article now in use for holding the 
solutions required in the practice of the photographic art. I find it perfectly safe and free 
from all liability to crack or check like the common porcelain in market, and it will not 
cause any stain or destroy the silvering solution, which so often occurs when the gutta- 
percha or India-rubber Baths are used. I can not recommend the Photographic Ware Baths 
too strongly to the favorable consideration of a'l who wish a safe, reliable, and perfect article 

" C. W. GRAY." 

From a Southern Operator. 

" I have been using the Photographic Ware Baths in my establishment ever since their 
Introduction, having been the purchaser of the very first one sold. Time has shown that 
these Baths are perfectly unexceptionable. I consider them to be every thing that the 
Photographer can desire. For no consideration would I be without, them, or return to the 
-utta-percha or porcelain — having seen enough trouble with them before the intro- 
duction of the Photographic Ware. P. P. PAGE, Proprietor of Plumb Gallery, 

•Washington, D. C." 

"As Operator for Mr. Page, I have daily witnessed the advantages and superiority 

of the Photographic Ware Baths, and cheerfully indorse the above. JOHN GOLDIN." 

From "Western Operators. 

" , Illinois, June 11. 

• " Tou ask how I got along with the Photographic Ware Baths. They 
sell first-rate. I have some orders for No. 8, field, without the overflow. I sell six of the 
Photographic Ware Baths to one of any other kind. Yours truly, P. JOHNSON." 

'* , Ohio, Oct. 5. 

" Don't fail to send me a lot more of those Photographic Ware Baths 

with the next goods you ship. My customers have got a taste for them, and nothing else 
will go down. One Operator says he has saved over fifty dollars by their use already ; 
he is not afraid of bursting and letting out the silver, as his old gutta-percha one did. 
And then they are so cheap ! I shall want one dozen each of Nos. 1, 2, and 3, and six of 
No. 4. JOHN H. FISHER." 

" I have just been witnessing the use of the Photographic Ware Baths, which I can not 
do without ; send one of No. 4, and I'll make you a present of my Porcelain Bath — that 
is, if you will pay express charges on it to your city. L. B. BARNES." 

Extract from the London, Dictionary of Photography, (by Thomas Sutton, Esq., 
the Editor of Photographic Notes,) page 131 : 

• " Porcelain Baths are very objectionable, as nitrate of silver acts on 
the glaze. There is a substance used in America for baths and dishes called PHOTO- 
GRAPHIC WARE!, which resembles AVedgewood Ware, and has no glaze; this answers 
the purpose admirably." 

Extract from Humphrey's Journal, Ho. 5, Vol. XL. 

" The Photographic Ware Baths were first made by George Mathiot, Esq., of the United 
States Ooast Survey Office, Washington, for his own use. A friend of his, an artist, was 
struck witli their neatness, durability, and cheapness, and also their special adaptation to 
the use to which they were put. He advised Mr. M. to take out a patent for them at once, 
which he did, and now the whole Photographic fraternity have the benefit of them at about 
one half the price of any other kind of bath. Those who have tried them once will never 
again return to glass, porcelain, or gutta-percha, each of which is objectionable, besides 
costing twice as much." 


1-4 $0 75 

1-2 1 00 

4-4 2 00 

9byll $3 00 

11 by 15 5 00 

They can be had of all Stock-Dealers in the United States, and in New- 
York of the following houses : 


New- York, September 15, 1S63. 


Journal of Photography. 


Published Semi-monthly, and containing annually 3S4 pages of Original 
and Selected Matter, prepared with the greatest care. This Journal is 
devoted to the interests of the Operator, and has for years past been widely 
Known as the best and most valuable publication treating on the Helio- 
graphic Arts. It was established November 1, 1850, and is consequently the 
oldest Photographic Journal in the world. It has always been considered 
a most reliable medium for obtaining information on every thing relating to 
the art of Sun-drawing, and no pains or expense will be spared to enable it, 
for the future, to maintain its high and commanding position. 

The present Editor holds an eminent position as a scientific writer and 
a practical photographer, and he is one who can reach and interest Operators 
in a way that few writers in this country are able to do. He will aim to 
extricate Photographers from their numerous troubles and perplexities, and 
especially so through the medium of ''Answers to Correspondents," whica 
department of our Journal will be found full, complete, and satisfactory. 


"We insert here a few of the many commendatory notices of Humphrey 1 s 
Journal given by the Press of the United States and England : 

the heliographic arts and sciences, to take 
a ccpy of the work." — Sentinel. 
" It is indicative of talent worthy of the 

" We have received a copy of a valuable 
Journal (Humphrey's) published in New- 
York, which has reached the ISth No. of 

Vol. XI We now have the 

pleasure of quoting from our transatlantic 
coadjutor." — Liverpool Photo. Journal. 

" Humphrey's Journal is practical as 
well as scientific in charater." — American. 
Journal of Science and Arts. 

"It treats the subject knowingly and 
with force." — New-York. Tribune. 

" It is both a popular and interesting 
publication."— Mechanics' Magazine. 

" It is highly useful to all who practice 
' shadow-catching.' " — Ohio Slate Jour. 

"The work is neatly gotten up, and con- 
tains many interesting varieties in this new 
field of science." — Times. 

" It should be hailed and encouraged, 
not only by photographers themselves, but 
by every lover of science and art." — The 

" We can not too strongly urge all artists, 
and those persons who feel an interest in 

important art it is designed to elevate." — 

" This art is entitled to its own organ, 
which could not have fallen into better 
hands than those of the Editor of Hum- 
phrey's Journal." — Transcript. 

" It is a scientific work of interest and 
usefulness." — Star of the North. 

" It is rich with interest."— North Am. 

" It contains all the ' improvements.' " — 

" It teaches us how to take our own 
portraits." — Bee. 

" It will cultivate a taste for photo- 
graphs." — Commercial Advertiser. 

" It should be in the hands of ail." — 

" It is the photographer's friend." — Lon- 
don News. 

" It should be found in every library."— 
Evening Journal. 

If paid in advance. Single Copies 12 Cents. 

Complete copies of Volumes 4, 5, 6, 7, 8, 9, 10, 11, and 12 for One Dollar 
each. Volumes 13 and 14, Two Dollars each. 

ADVERTISEMENTS will be inserted at the rate of One 
Hundred and Fifty Dollars per page per year. 

Published by 





^^.TEZSTTEID J-TJJLTX- etla, 1S62. 

According to experiments made in this country and Europe, analyzing 
Negatives and Photographs, it is found that only a minute portion of the 
Silver used enters into the picture, nine tenths or more being wasted during 
the various manipulations. The Editor of one of the leading British jour- 
nals, (the Photographic News,) in an article upon the subject, takes occasion 
to remark that not one tenth part of the Silver used enters into the picture, 
while Prof. Seely, Editor of the American Journal of Photography, states 
the amount at less than one hundredth part. A very large proportion of 
this waste Silver can be saved by using this Apparatus, and I think, judging 
from present results, that I am fully justified in estimating that from one 
half to three quarters of every pound of Nitrate of Silver used can be saved. 

Mr. J. Shaw, the inventor, having placed the entire management of 
the business in my hands, I now make the following very 


I will furnish the most important part of the Apparatus free, with 
full instructions, so that every operator can fit up the Apparatus ready to 
connect with the waste-pipe, at a cost which should not exceed two dollars, 
and when making returns from the first refining, I will refund this two 
dollars over and above the operator's share of the refinement, thus prac- 
tically furnishing the Apparatus free. If I refine only such waste as 
the Apparatus saves from developing Ambrotvpes and Negatives, (hitherto 
a dead loss,) I will return half the proceeds of the same ; but if the operator, 
in addition to the above, will save and forward to me all the other waste, 
(the instructions for saving which shall be simple, and the cost merely nom- 
inal,) I will refine all without cost, and return three fourths the proceeds of 
the refinement, retaining one fourth for rent of Apparatus and refining. 

Mr. M. B. Brady, of this city, and other eminent Photographers in the 
country, are fully satisfied it is what every operator should have in his 
chemical room, also with my responsibility to carry out the provisions herein 


"With Scovill Manufacturing Company, 




The uniform good quality of the Paper albumenized by us has gained for it a high 
reputation. Large dealers have assured us that they find it the only reliable Paper 
they can obtain. It is always the same, whether bought now or a year hence. 


(E. A.,) stamped in one corner. We mention this because our name has been used to 
sell inferior paper. 


A Large Stock always on hand, both of Thick and Thin. 


Vum ttoamsa for Negatives 


Best and Safest Varnish to Protect a Good Negative. 


Attempts have been made to introduce inferior Varnishes, by putting them up in 
similar bottles ; but as photographers put the Varnish, and not the bottle, on their nega- 
tives, they soon discover the difference, and buy none that has not the signature of 
"E. Anthony." 






Some of the best Photographers use what we call our Dry Collodion altogether for 
their Negatives as a Wet Collodion, and say they can find nothing equal to it. 

E. & H. T. ANTHONY & CO., 

501 Broadway, New-York. 

See our Advertisement on first page. 


s-Y 1 ™