II ^dai h6» ~6w -idai j did -SO 00 «daj ~dod -idod ™doi a*S §» S*S §** S** S*S gs§ CO s« PI PI *5 S2s m i— §*t 3 n g»g ?H I*. a»f PI ^1 PI i& 3*3 s~? joooco a*5f 3*f 3«r s*£ S2S E = t |.» s^l sss £*? 8*£ s?£ 5SS CO S H s Sg 2"°3 §2S 8 Eg 5sfif «o CO Oi i-H r-H <© 00 a** r-. CN 3SS *s* 5325 *H 2 2g S2S ESS 22S 228 s! 6,-sW d«m S 6 MOD d-iod d«co d~o6 d-ioi d-oi Focus of Lens. i - 3 CO "<* 5 S 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, Allien, Gelatine, fax, Resin, ana Silver ; AS ALSO Heliographic Engraving, Photolithography, Photozincography, Microphoto- graphy, Celestial Photography, Photography in Natural Colors, Solar Camera Work, Tinting and Coloring of Photographs, Printing in Various Colors ; the Carbon Process, the Card-Pic- ture, the Cabinet-Picture, the Vignette, and Stereography. Br J. TOWLER, M.D., TROFFSSOR OF NATURAL PHILOSOPHY AND CHEMISTRY. EIGHTH EDITION. ENLARGED, IMPROVED, AND ILLUSTRATED WITH NUMEROUS WOODCUTS, And containing matter written by Blanquart Evrard, John W. Draper, M Carey Lea, R. J. Fowler, Valentine Blanc ard, Major Russell B. J. Satce, Dr. Hill Norris, M. Clatjdet, M. Van Monkhoyen, G. Wharton Simpson, Jabez Hughes, Lake Price, and other distinguished writers. •'And God said, Let there be light: and there was light." NEW-YORK: E. & H. T. ANTHONY & Co., Publishers. LONDON : TRUBNER & CO. 1873. Entered, according to Act of Congress, in the year 1873, by E. & H. T. ANTHONY & CO., In the Office of the Librarian of Congress, at Washington. PREFACE TO THE EIGHTH EDITION. New York, June 1, 1873. The increasing popularity of the Silver Sunbeam, and the urgent demand for it everywhere and by all who are interested in Photography, has resulted in the publica- tion of another edition — the Eighth — in which is includ- ed such additional chapters as w T ere found to be desirable and necessary to render the Silver Sunbeam an encyclo- paedia of the art to date. The Eighth Edition contains all and everything of the preceding seven ; and, besides the valuable and interest- ing new matter, it is embellished with a large number of illustrations of photographic apparatus in present use, with brief descriptions of the same. It is a gratification to know that the Silver Sunbeam continues to be the favorite photographic manual with stock dealers, amateurs, beginners, and practising pho- tographers, and that its pages form a comprehensive and intelligible guide in every branch of photography, and for all classes. Some errors may be noticed of trifling importance, but they are such as will be readily detected by any one familiar with the subjects treated of, though they will be of no disadvantage to others. The Publishers. PEEFACE TO THE 'SEVENTH EDITION. New-York, April, 1870. We are again called upon for another edition of The Silver Sun- beam — the seventh. We will say nothing of the great success of the book, or of the fact that it is now universally admitted to be the standard work on the art, and that it contains information and instruction in every branch of Photography. As will be seen, we have added largely to the already large stock of information contained in the previous editions. ' We give several new chapters, each containing a variety of articles of great value : one written by Herr Albert, about his new Mechanical Printing Process ; one on Sarony's new Photo-Crayon Portraits ; one by Gr. Wharton Simpson on Printing with Collodio -Chloride of Silver on Paper and Opal Glass ; Bovy 's new Process for Printing on Painted Can- vas ; an article from Samuel Fry on the Advantages of a Substratum for the Collodion Film ; M. A. De Constant's new Photo-Miniature Process ; a New and Simple Process for Enlarging, by W. H. Davies ; H. Baden Pritchard's Method of Photographing Machinery ; an article from Al- fred Hughes, and many others whose names it is unnecessary to men- tion here. We also give, in one page, the names of over one hundred celebrated writers on photography, whose formulae are given in this work. Suffice it to say, that the additions to the Seventh Edition of The Silver Sunbeam will be considered of great importance by all photo- graphers and amateurs, and be an incentive to many to purchase the Seventh Edition, although they may be in possession of some of the previous ones. We are gratified in being assured by stock-dealers everywhere that The Sunbeam is as salable as ever. For an amateur or beginner, " The Sunbeam " is always recommended as the best authority on the art. As edition after edition comes from the press, the book grows more and more bulky. We can find nothing in the work which we think can be left out with advantage ; and with each edition we add a large amount of new matter. The First Edition was comprised in 350 pages. The present edition embraces 570 pages — an increase of over sixty per cent in the amount of matter ; and we have therefore advanced the price of this edition to three dollars per copy, which is an increase of only twenty per cent, and an increase which we feel fully justified in making. With these few remarks by way of preface to the Seventh Edition, the publisher would once more offer his thanks to the trade, and the public generally, for the warm reception they have heretofore given to The Sunbeam, and he trusts that the present edition will also meet with their approval. PREFACE TO TIE SIXTH EMTIO! The last edition of The Silver Sunbeam having been entirely- exhausted, and the demand for the work still continuing, it becomes our duty as well as pleasure, to issue the Sixth Edition, which largely exceeds all the previous issues both in the quantity and variety of its contents. We have added over one hundred pages of entirely new matter, much of it illustrated with woodcuts, and most of it embracing sub- jects not before treated upon in this work. We have added Nine new Chapters, each chapter embracing a variety of topics. In the first part of the work we have placed eighteen pages devoted to Ele- mentary Photography, adapted especially to the wants of the New Beginner. We publish full details of Mr. Swan's improved Carbon Process, as given by him the past year. The new matter published in the third and fifth editions, was embraced under the head of " Ap- pendix this we have divided up into chapters, with a suitable run- ning head on each page. At the end of chapter forty-seven, we give additional information on the important subject of reducing photographic wastes, illustrated with woodcuts. We give full de- tails, illustrated with woodcuts, of the process of Enlarging by the Solar Camera ; also a chapter devoted to Failures ; their Or%m and Remedies, suitably illustrated by eleven woodcuts. Full details of photographing microscopic objects, photographing on canvas, Cam- arsac's new process of Enameling, or Burning-in; the Serum process for enlarging photographs, and numerous other processes not before published in The Sunbeam, the whole embracing nine chapters and fifty-nine woodcuts. PREFACE. It has been our aim to have in this edition everything new in the Art which is of interest, and which has come to light during the past two years. There is no book published which contains near as much information on the subject of Photography as is embraced in the five hundred and forty-five pages of this book ; and we issue this Sixth Edition in the confident hope and expectation, that it will meet the wants and desires of intelligent Photographers both in this country and in England, where numerous copies have been sold. With this description of the changes and improvements made in the present volume, we offer the work to the operator and amateur, trusting that they will find it interesting and valuable. The Publishes. New York, Jan., 1869. PREFACE TO THE FIFTH EDITION. Four editions of The Sunbeam have been exhausted in the short space of three years ; and on entering the Fifth Edition, the Publisher is of opinion that the writer of this work ought to herald its reap- pearance with some prefatory remarks. This is the most irksome task ever imposed upon the author ; he would rather march twelve hours a day in a tropical climate than launch out eulogistically on his own efforts in this direction. Eulogy of self is the tenor of every preface. The success of those efforts is to be attributed to the want they supply, and not to their intrinsic merit as an original production. The work has acted like the pill of the medical prac- titioner, who is capable of making a correct diagnosis ; but the reader must look upon this expression as laudation. The public knew, every photographer knew, that a practical text-book on the helio- graphic arts was needed on this side the Atlantic : this was the diag- nosis. No more merit could be attached to the definite determina- tion of it than to the remarks of the doctors in reference to the un- fortunate passengers on the steamship England ; " They were suffer- ing for want of food, of pure air, and of more room to stir in and food, pure air, and more room having been administered and assigned to them, and the reputed cholera having vanished, the sanitary directors are regarded as very meritorious and shrewd medical ad- visers. The author of The Sunbeam stands in a similar relation to photo- graphers ; he has thrown more light into their dark-rooms, prescribed numerous recipes for the practical explanation of photography, and defined by common language and with common-sense what before was abstruse and mystical. They feel the benefit of his instructions, and, in gratitude, demand a new edition commensurate with the ad- vances and discoveries of the photographic art and science. In accordance with this request the work has been enlarged by the addition of a totally new appendix ; but the original work has been left unchanged. Changes are odious to authors, who, attached to their productions as to their offspring, prefer the fabrication of new works to the patching up of old ones. Such is the writer's view . and being willing to cater for the public taste and wants, he will edit an entirely new work the moment circumstances require it, and con- sign The Sunbeam to the shade. Geneva Medical College, April 24, 1866. NAMES OF WRITERS. The following are the names mulae are given in this work. ACKLAND. Anthony, Henry T. Blancard, Valentine. Baldus. Bayard. Bertsch. Burnett. Beauregard. Bond. Berry. Becquerel. borlinetto. Britton. Bloede, Victor G. Bartholomew. Bur well, F. W. Bolton. Claudet. Crookes, Champlouis. Chardon. Camarsac, La Fon de. Caron. Castracan. Draper, John W. Draper, Henry. Despratz. Dubosq. Donne. De La Rue. Deville. Duncan, David. Drummond, A. J. EVRARD, BLAITQUART. England, W. Edwards. writers on photography, whose for* Fowler, R. J. Fargier. Fizeau. Forrest. Fox, Thomas. Fink, F. Gage, William. Geoffray. Glover. Garnier. Girard. Hartnup. Hodgson. Haakman. Harrison, William H Herschel, Sir John. Hilaire, David. James, Sir H. JOUBERT. Keene. Lea, M. Carey. Libois. Loewe. Legray. Larpey, James. Molard, Humbert D. Mudd, James. Mayo. Marion. Motileff. Matthiesen. moitessier. Maddox. Meinerth, Carl. NAMES Newton, H. J. Niepce. Neuman. Norms, Dr. Hill. Osborne-Obernetter. Price, Lakh Prichard. POUNCEY. PoiTEVTN. Phipson. Bussell, Major. Sayce, B. J. Salmon. Sutton. Secchi. Schwartz. of writers. Simpson, G-. Wharton. St. Clair. sonstadt. Swan, Joseph W. Selle. Tunny, James GK Taupenot. TlLLARD. Talbot. Towler, John. Verity. Van Monckhoven. Wortley, Lt. Col. Stuart. Wenderoth, F. A. Woodbury, Walter. Willis, William. Woodward. CONTENTS OF " ELEMENTARY PHOTOGRAPHY." We give here the contents of that portion of this work entitled Elementary Photography, which is first published in this edition, and the pages of which are numbered at the bottom from 1 to 18 inclusive. PAGE. Introduction, 1 Apparatus necessary, 3 Chemicals necessary, 4 How to Prepare the Dark-Room, 5 How to Begin Work, . . . .6 How to take Glass Positives, Ferrotypes and Ambrotypes, ... 8 How to take Negatives, 13 How to Varnish the Negative, 18 Positive Printing on Plain and Albumenized Paper, 18 Additional information on the above subjects will be found as follows : PAGE. List of Photographic Outfit, 25 The Glass-House, etc., 27 The Camera and the Lens, 34 The Dark-Room, 46 The Work-Room, 49 Chemicals, 51 to 125 The Collodion Positive Process, 127 The Collodion Negative Process, 144 CONTENTS. CHAPTER I. 1 PAG1 History op Photography, « , 9 CHAPTER H. Preliminary Observations, 21 List of Photographic Outfit, 25 CHAPTER III. Specialties in reference to the Articles in the preceding Chapter — the Glass- house, etc., 27 CHAPTER IV. 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, 3T To find the magnifying power of a Lens or Combination, 37 To find the comparative magnifying power of Lenses or Combinations, 3T 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, 38 How to buy a good Lens, 39 CHAPTER V. Specialties continued— The Camera, 42 CHAPTER VI. Specialties Continued, 46 Dark-Room, 46 Work-Room, 49 CHAPTER VII. Collodion, 51 Preparation of Pyroxyline, 52 Formula, No. 1, for the preparation of Pyroxyline, 53 Formula, No. 2, for the preparation of Pyroxyline, 55 Formula, No. 3, for the preparation of Pyroxyline, 55 Formula, No. 4, for the preparation of Pyroxyline, 55 CHAPTER VIII. Ether and Alcohol, 56 Ethyle Group, 56 Ether, , 53 Alcohol, . 59 Decomposition of Collodion, 61 Preparation of Glycyrrhizine, 63 Preparation of Nitro-glucose, 63 CHAPTER IX. Collodion Sensitizers — Iodides and Bromides, 65 CHAPTER X. Preparation of the Iodides, 69 Iodine, 69 Properties of Iodide, 70 Preparation of Ilydriodic Acid,, 70 Iodide of Barium, 71 Iodide of Calcium, , 72 Iodide of Lithium, 72 Iodide of Potassium 72 Iodide of Sodium and Iodide of Ammonium, , 73 Iodide of Cadmium, 73 Impurities of the Iodides,. » 73 Tests of the purity of the Iodides, 74 X CONTENTS. CHAPTER XI. PAOB Bbomhtb, 75 Preparation of Bromine, Jo Hydrobromic Acid, 76 Bromides, £6 Preparation of the Chlorides, 76 Preparation of Chlorine, 77 Properties of Chlorine, 77 Chloride of Lime— Chlorinetted Lime, etc., 73 CHAPTER XII. Normal or Plain Collodion, Iodized Collodion, Bromo-iodized Collodion, 79 Bromo-iodizing Solutions, SO P( rmula of Lieut.-Col. Stuart Wortley, SO Ommeganck's Formula for Portraits and Landscapes, SI Formulas of Disderi, 81 Formula for copying Collodion, 83 CHAPTER XIII. Silver — Salts of Silver, 84 Properties of the Nitrate of Silver, 8S Photographic properties of the Nitrate of Silver, 88 Preparation of the other Salts of Silver, 90 Hyposulphite of Silver, 90 Iodides of Silver, 90 Iodide of Silver for the Silver Bath, 90 Bromide of Silver, 91 Chloride of Silver, 92 Photographic properties of the Chloride of Silver, . . . .' 93 Other uses of the Chloride of Silver, 93 CHAPTER XIV. Reducing Agents — Developers, 94 Iron Developers, 97 Nitrate of the Protoxide of Iron, 97 Sulphate of the Protoxide of Iron, 9T 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, 103 Formic Acid, „ 104 Photographic uses of Formic Acid, 105 Citric Acid, 105 Citrate of Soda, 106 Photographic uses of Citric Acid, 106 Tartaric Acid, 10T Preparation of Tartaric Acid, 107 CHAPTER XV. The Nitrate of Silver Bath, 109 Preparation of the Sensitizing Solution, „ 110 Formula, No. 1, 110 Formula, No. 2, Ill Formula, No. 3, Ill CHAPTER XVI. 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 Disderi's Developer, 115 Lieut.-Col. Stuart Wortley's Developer, .... 116 BKeynier's Developer, 116 Hockins's Developer*, . 116 Waldack's Formulas, [ 116 CHAPTER XVII. Fixing Solutions, 119 Cyanogen, 118 CONTENTS. xi PAGE Preparation jf Cyanogen, 118 Hydrocyanic Acid — Prussic Acid, 119 Cyanide of Potassium,. , 119 Sulphocyanide of Potassium, 12D Sulpbocyanide 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 Sulphocyanide of Ammonium, 121 CHAPTER XVIII. Intensifies, 122 Preparation of Bichloride of Mercury — Corrosive Sublimate, 125 Preparation of Sulphide of Potassium — Hepar Sulphuret, 125 Preparation of Sulphide of Ammonium, , 125 CHAPTER XIX. Wet Collodion Process, 127 Collodion Positives — The Melainotype — the Ambrotype, 127 Ambrotype, 128 First 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, 132 Sixth Subdivision — Fixing the Image, 133 Remedy for Fogginess, 133 Seventh Operation— Drying the Plate, 135 Formula for subdued Contrasts, 136 Eighth Operation— Coloring the Picture, 136 Ninth Operation — Varnishing the Image, 136 Varnishes, 137 Tenth Operation — Background for Collodion Positives, 138 Black Varnishes, 138 CHAPTER XX. Alabastrine Positives, 140 Alabastrine Solution, 140 CHAPTER XXI. Melainotype — Ferrotype, 142 Operation, 142 CHAPTER XXII. Collodion Negatives, 144 Negative Developers, 145 Formula, No. 1, Iron Developer, 145 Formula, No. 2, Pyrogallic Acid Developer, 146 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, 147 Intensifying Operation, 147 Formula, No. 1^-Nitrate of Silver, 147 Formula, No. 2— Pyrogallic Acid, (Stock,) 148 Formula, No. 3— " " 148 Varnish — Formula fordo., 149 CHAPTER XXIII. Transfer Process of Collodion Positives on Japanned Leather, Linen, Paper, etc. 150 Black Japan, 150 Transfer Paper, 151 CHAPTER XXIV. Collodion Positives on Glass by transmitted Light — Transparent Positiykc,. . . . 153 CHAPTER XXV. Enlargement of Negatives by the Ordinary Camera, 157 Reflectors used as Condensers of Light, 15S xii OOXTENTS. CHAPTER XXVI. PAG1 T&ANSFA PENT POSITIVES BY CONTACT BY TIIE WET PROCESS, 159 CIIAPTER XXVII. Collodion Negatives or Positives copied from Collodion or Paper Positives,... 160 CIIAPTER XXVIII. Stereographic Negatives and Landscape Photography, 164 Instantaneous Stereographs, 166 Instantaneous Process of Lieut.-Col. Stuart Wortley, 16T Valentine Blanchard's Bromo-iodized Collodion, 163 Hockins's Iodized Collodion, 169 Claudet's Developer, 169 Instantaneous Shutters, 169 CHAPTER XXIX. 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, 179 Wet Paper Negative Process of Humbert de Molard, 180 Improved Calotype Process by Prichard, 180 CHAPTER XXX. Printing on Plain Paper, on Albumenized Paper, on Arrow-Root Paper, 182 Description of the Materials tised in Positive Printing,. , 183 Albumen, 184 Gelatine, 185 Amylaceous or Non-Azotized Substances, 186 Starch, 186 Gum- Arabic 187 Chloride of Gold, 187 Nitrate of Uranium, 189 Acetate of Soda, Citrate of Soda, Phosphate of Soda, 190 Carbonate of Soda, 190 Carbonate of Lime, 190 CHAPTER XXXI. Manipulation of Positive Printing, 192 Preparation of Salted Paper, 192 Preparation of the Albumenized Paper, 194 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 Fuminating Process, . 198 CHAPTER XXXII. 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 What to do with the Clippings, 207 Mounting Stereographs,. 20T CHAPTER XXXIII. Bertrand's New Process for Positive Printing, « 209 Glover's Resinized Printing Process, 210 ,» CHAPTER XXXIV. * Printing by Development, - 218 Second Method of Printing by Development, with a Chloride 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 CONTENTS. xiii CHAPTER XXXV. pagi The Card-Picture, , . . . , 218 Lenses for the Card-Picture, , 219 Development, , 219 Fixing, 221 Printing of Card-Pictures, 222 Vignette Printing, , 223 Tuning, Fixing and Mounting, 224 On the Tinting and Coloring or Photographs, 224 Colors used most frequently,, . ... 225 Other indispensable articles. . . , 225 Coloring of a Portrait, 225 Coloring of the Face, 226 Blonde hair, chestnut-coltfred hair, black hair, 227 Gi-ay 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 How to imitate Metals, etc., with colors, 230, 231 CHAPTER XXXVI. Dry Collodion Process — Dry Processes, 232 The Albumen Process, 233 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, 23T Preparation of the Glass Plates, 238 Formula for the Collodion, 238 Sensitizing of the Taupenot Plates, 239 Exposure, 239 Development, 239 Fixing of the Taupenot Plates, 240 Modified Albumen Process, by James Larpey, , 240 Modified Collodio-Albumen Process, by James Mudd, 241 Fothergill Process, 242 CHAPTER XXXVII. 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 CHAPTER XXXVIII. 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, 251 MlCROPHOTOGRAPHY AND MaCROPHOTOGRAPHY, 257 Solar Microscope, . , 257 How to find the point where the Lens is to be placed, 260 MACROPHOTOGRAPHY, OR THE ART OF TAKING ENLARGED PHOTOGRAPHS, 262 The Negative for enlargement, 262 The quality of the Negative, '. 262 CHAPTER XXXIX. Thb 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 xiv CONTENTS. CHAPTER XL. Printing without the Sal^s of Silver, 272 Process with the Salts of Iron, 272 (VAN (TYPE, 273 CRTS TYPE, 273 Process with the Salts oj? Uranium, 273 Pr ioess for Red Pictures, 274 P loi ESS for Green Pictures, 274 Process for Violet Pictures, 274 Process for Blue Pictures, 275 Carbon Process, 275 Poungt^s Process, 277 Podnct's New Carbon Process, 277 Processes of Salmon and Garnier, 278 Fakgier's Process, 280 Carbon Processes with the Salts of Iron, 2S1 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 Process of Fizeau, 287 Process of Talbot, 288 asphalto-type of nlcephore nlepce, 291 Etching on Glass, 296 Negre's Process for Heliographic Engraving, » 296 Copies for the Engraver to work from, 296 Photo-Lithography and Photo-Zincography, 297 asph^lto-pnoto-llthographic process, 297 Bichromo-Photo-Lithographic Processes of Poitevin, 299 Photo-Typographic Process of Poitevin, 300 Photo-Lithographic Process of Newton, 300 Photo-Zincography by Colonel Sir H. James, R. E. ; and Photo-Lithography by Mr. Osborne, 301 Photo-Pap yrogra phy by Colonel Sir H. James, R. E., 308 On the production of Photographs, etc., on Glass in Enamel Colors by Joubert,. . 308 CHAPTER XLI. Stereoscopicity, , 310 Strabonic Stereograph 316 .. 319 CHAPTER XLII. Celestial Photography, 320 CHAPTER XLIII. Heliochromy, or the Art of taking Photographs in Natural Colors, 323 CHAPTER XLIV. Imperfections in Collodion Negatives and Positives and their Remedies. 326 Fogginess, .* 326 Spots and Apertures, 82S Ridges and Undulating Lines, 330 Streaks and Stains, 331 Feebleness of the Image or Deficiency of Contrast, 331 Harshness or Excess of Contrast, 332 Imperfect Definition,.." 332 Solarizration, 332 Tender and Rotten Films, 332 Imperfections in Paper Prints, 333 CHAPTER XLV. Swan's Improved Carbon Process, 337-362 Van Monkhoven's Cuprammonium Process, 342 CHAPTER XLVI. Improvements in the Tannin Process, t # 345 The Alkaline Developer, """"**!" 351 fannin as a Sensitizer, " " " ' ' 353 Cliromo-Photography, m m [ ] * * 35(5 p rocess without the Salts of Silver, 358 Celestial Photography, 860 CONTENTS. XV H CHAPTER XLVII. The Wothlytype, . .' 365 Sutton's Dry Process, * 363 The Raisin Process, 373 A Reliable Tannin Process, 877 Russell's Improved Tannin Process, 382 Modified Fothergill Process, 385 Haakman's Process, 387 The Collodio-Broraide Process,. 389 The Porcelain Picture, or Opal type, 392 The Collodio-Chloride Process, 399 To take an Opal Picture by Contact, : . 402 The Eburneum Process, 4C3 The Eburneum Background, s . . 405 Glazed Collodion Positives, 407 "lazed Photographs, 403- How to take Photographs by Magnesium Light, 412 Magnesium, 413 The Duplex Type, 417 The Hellenotype, 419 The Ivorytype, , 420 Reduction of Wastes and Residues, 421 Collo-Protosulphate of Iron Developer, 425 The Collo- Ferric Developer, 426 Photo-Mezzotint Printing, , 427 Photo-Relief Printing, 429 The Foxtype,., 431 Selle's Intensifying Solution, 432 Photographic Residues, 433 CHAPTER XLVIII. The Solar Camera and Solar Enlargements, 443 CHAPTER XLIX. Failures : The Origin and Remedies, 454 CHAPTER L. Photomicrography, 465 Photographing on Commas, 467 Enameling, or Burning-in Process, 470 Printing on Ivory, 475 Serum, or Whey Process for Enlarging, 47T CHAPTER LI. Copying Engravings, ( 480 Washed Plate Process, 4S2 The Morphine Process, 482 The Coffee Process, / 483 Obtaining Positives in Colors, 484 CHAPTER IH. - Sel Clement, 486 Mezzotint Photographs, 489 The Magic Photograph, 490 Cabinet Portraits, 492 Gage's Improved Photographs, 492 CHAPTER LIII. Newton's Dry Processes, 494 The Tea Process, 494 Newton's Opium-Tannin Process, 496 Description of Apparatus, 497 CHAPTER LIV. Weights and Measures, 499 CHAPTER LV. Comparison of Thermometric Indications in the Principal Thermometers in use,.. 502 CHAPTER LVI. Comparison op Hydrometric Specific Gravity Indications, 504 CHAPTER LVII. Table of the Elements of Matter, with their Symbols and Chemical Equiva- lents, 506 xvi CONTENTS. CHAPTER LVIII. ADDITIONS TO THE SEVENTH EDITION. ITerr Albert's Mechanical Printing Process, 507 Sarony's Photo-Crayon Portraits, 509 Printing with Collodio-Chloride of Silver on Paper and Opal Glass, 510 A new Process for Printing on Painted Canvas, 512 CHAPTER LIX. On the Aptantages of a Substratum for the Collodion Film, ' 514 Chromo-Photography or Photo-Miniature, 515 A Simple Apparatus for Enlargements,. . 518 How to Photograph Machinery, 521 CHAPTER LX. How to make Ripe Collodion at once, 523 Stippling Glass in the Studio, 524 An easy and certain Method of Printing on Wood Blocks, 526 The new Calotype Process, 527 Indexes to each Edition, 633 TO THE READER. There have been some complaints that in the previous editions of The Silver Sunbeam, the introductory part was too complicated for the pupil who had no knowledge what- ever of the Art of Sun Drawing; that before coming to the simple details of the Positive Process, or the art of taking an Ambrotype, he was obliged to read through one hun- dred and twenty pages, devoted to the History of the art, the theory of Lenses, how to find the congugate foci of a Lens, etc.; all about the Camera, the dark-room, work-room, etc. Then the pupil must learn the nature of all the Chemicals used in the art : the Iodides and Bro- mides of Barium, Calcium, Lithium, Potassium, etc.; the Chlorides; Salts of Silver; Acids; Developers; Intensifi- es, and many others— all these, although of great import- ance to the photographer, come rather hard and are very discouraging to the new beginner. He does not care for all this information on the start ; he wishes to know what apparatus and chemicals are necessary, and how to use them; he does not care how they are made; he will, how- ever, need all this information after he has learned to take a picture, and he will then read it with a relish, and un- derstandingly. The Publisher, therefore, in order to ac- commodate New Beginners, has thought best to insert, as an introductory chapter, some simple instructions in the Art, much of which is written by Jabez Hughes, of Eng- land, one of the best artists and writers in that country. These instructions are plain, simple and easily compre- hended by the learner. Additional information on the art of taking an Ambro- type, or any kind of Positive Picture, will be found com- mencing on page 127 of this book. There also will be found full directions on the Collodion or Negative Process, and every other process known in the Art. After reading and practicing this preliminary part of the book, the pupil will be better prepared for the remainder. ELEMENTARY PHOTOGRAPHY INTRODUCTION. We propose, in a simple and familiar manner, to intro- duce the reader to the wondrous and fascinating Art of Photography. We take for granted that you are entirely unacquainted with it, and that you are anxious to learn. Before proceeding, however, to the practical portion, we wish to impress on your mind a few of the leading prin- ciples. The word Photography means drawing, engraving, or writing by Light. You are doubtless aware that white light — light from the sun, for instance — is composed of three different colors — Yellow, Red, and Blue: it also possesses three distinct properties — Illuminating, Heating, and Chemical powers. These three powers are singularly connected with the three colors. The Illuminating property exists mainly in the Yellow rays — the Heating property in the Red — and the Chemical in the Blue or Violet rays. With the Illuminating power you are daily familiar; the July sun gives certain proof of its Heating power; and it is your present purpose to learn that all Photography is based on its Chemical power. For the full explanation of these facts we must refer you to Hunt's Besearches on Light ; in that excellent work is detailed in a most satisfactory manner the threefold func- tion of a sunbeam — to illuminate, to heat, and to produce chemical change. That these three properties are distinct 1 INTRODUCTION. from each other is proved by their being separable from each other. Thus, black glass stops the illuminating and the chemical rays, but allows the heating rays to pass through ; dark blue glass arrests the heating and illumin- ating rays, but allows the chemical ones to get through; while yellow or orange glass admits light and heat, but d9nies passage to the chemical rays. Strictly speaking, then, it is not Light — the illuminating agency — that is the cause of photographic action, but an active principle associated with it, and which is connected 23i*incipally by the weakest illuminating and even invisible rays. This Photographing Power, then, that is associated with Light, but which is not Light, is termed Actinism. The daily experience of every photographer proves, that though these two active principles, Light and Actinism, are. constantly associated together, yet that they often exist in very different proportions to each other. There may be a brilliant light with but moderate actinic power, or a dull light and considerable photographic energy. In the au- tumn, when the sun's light and heat are at their maximum, the actinic power is by no means great. In winter, though the light be rather bright, the photographic power is al- ways dull; while in early spring, before the sun has ac- quired his full strength, the actinic influence is relatively the most powerful in the w T hole year. But in photographing from colored objects, these facts will be more strongly impressed on your mind. When brilliantly-lighted yellow objects " come out " dark, and dimly-lighted blue ones will appear bright, you will re- member the reason — that the former reflect abundance of light, and but little actinism ; whereas the latter throw back little light, but much actinism: and that Actinism, not Light, is the real picture-producing power. The general term Photography embraces many proces- ses of producing jnctures, but the particular method we intend teaching you — the Collodion Process — has sup- planted nearly all others, it being not only the most per- fect and comprehensive, but also the most simple. Pictures by this process are taken on glass, and are either Positive or Negative. These terms will be explained hereafter, when the processes are described; and it is only necessary now, before we commence actual operations, to impress on you that photography, from beginning to end, consists of a series of delicate chemical experiments. The successful execution of these depends apparently on many 2 APPARATUS AND CHEMICALS NECESSARY. minute causes, which, if attended to, will produce the de- sired end, but which, if neglected, either from ignorance or carelessness, will as certainly cause failure and disap- pointment. You must be very exact in mixing your solutions, and in using only perfectly clean vessels to put them in. Cultivate the habit of noticing carefully all that you do ; for as there is no such thing as chance in Photography, you must clearly understand that when you fail, you do something different to when you succeed, and that this something causes the failure. As your natural desire will be to avoid failures, you must try to discover these causes, that you may avoid them; and if you proceed in this man- ner you will certainly become a good and intelligent Pho- tographer. APPARATUS AND CHEMICALS NECESSARY. The first thing is to obtain a set of Apparatus. Begin- ners too frequently get a common cheap one, and are sur- rounded with unnecessary difficulties from this cause alone. There is no reason that the apparatus should be very ex- pensive, but each article should be good of its kind. The quantity you will require will depend on the branch to which you devote yourself. A set for producing the usual sized Glass Positives will require the fewest articles. For the production of Negatives and Printing them on paper — a much higher branch of the art — more apparatus will be necessary. Should you wish to be equally well furnished for producing Portraits and Landscapes, a full equipment will be necessary. The following comprises a complete set, equally adapted for all purposes, together with a list of Chemicals, the quantities being calculated for the 8| by 6 J inches, or " whole-plate 93 size. Should there be more articles enumerated than you think you will require, you must consult with some photographic friend, or explain to the person of whom you make your purchase, the descrip- tion and size of pictures you wish to take, and you will be advised what articles to omit. Apparatus. A Lens for Landscape and Architecture. A well-made Bellows Camera-Box for Views. A light, strong, but portable Tripod Stand for ditto. 3 APPABATUS AND CHEMICALS NECESSAKY. A traveling Glass Bath with water-tight top. A portable Dark Tent, for working in the open air. A good Portrait Lens, fitted for a set of Polished Black Glass Diaphragms. A substantial square Camera-Box for in-door work. A strong, well-made Camera-Stand for in-door work. A Jenny Lind Head-Rest for attachment to Chair-Backs. A strong Iron ditto for Standing Figures. Three Plate Boxes, 24 grooves, to suit the sizes of the Camera. Chance's Sheet Glass to fill the above. Set of Scales and "Weights, with Pans. 1 Plate-cleaning Vice. 1 or more Printing-Frames. 1 Pneumatic Plateholder for large Plates. 1 Developing-Stand for ditto. 2 or more Photographic Ware or Porcelain Dishes. 1 ditto, to be used for Hyposulphite of Soda only. 1 large and 1 small Glass Funnel. 1 Gutta-percha Funnel, medium size. 1 each 20 oz., 5 oz., 2 oz., and 60 minim, Graduated Glass Measure. 1 Four oz. tall Graduated Collodion Bottle. 1 Diamond for cutting Glass Plates. 1 Horn and 1 Boxwood Pincers. 1 Hydrometer, for testing the Strength of Silver So« lutions. A few Glass Stirring Bods. 1 yard of Canton Flannel. A few wide and narrow-mouthed Bottles. A black velvet Focusing Cloth, about one yard- square. Chemicals. 1 lb. Bromo-iodized Negative Collodion. 1 lb. Positive Collodion. 5 oz. Becrystalized Nitrate of Silver. 1 oz. Pyrogallic Acid. 1 oz. Citric Acid. 1 lb. Protosulphate of Iron. 1 lb. Hyposulphite of Soda. 15 gr. Chloride of Gold. 4 oz. Kaolin. 4 oz. Cyanide of Potassium. 5 oz. Glacial Acetic Acid. 4 HOW TO 1'REPARE THE DARK-ROOM. 5 oz. Alcohol. 1 bottle Varnisn. 4 oz. Acetate of Soda. 1 oz. Bicarbonate ditto. 1 bottle Rotten Stone. 1 quire Album enized Paper. 1 ditto white Blotting Paper. 3 sheets Litmus Paper. 1 packet of large round Filter Papers. 1 ditto small It is not necessary that you should get the chemicals in exactly the quantities given above, and for sizes below r 8^ by 6^ in. smaller portions will do; yet it is not well to be- gin with too small a stock, as from your inexperience you will be very apt to spill and waste a quantity at first; and if you reside in a country district you may experience a difficulty in obtaining articles sufficiently pure for your use. As a rule, it is better to buy them of stock dealers who supply photographic materials, from whom you will obtain them cheaper and better than from local chemists and druggists. HOW TO PREPARE THE DARK-ROOM. Having selected your Apparatus and Chemicals, the next thing is to prepare a room in which to conduct your prin- cipal operations. This is technically called a dark-room, though, except in a chemical sense, there is no reason that it should be very dark. Many persons imagine that any cupboard, or out of the way corner, will do to prepare plates in : this is a mistake, and if you can select a room sufficiently large in which you can move about freely, it will be much better than being cooped up and crippled in your actions. Moreover, in warm weather, the fumes from the chemicals will be injurious to your health, if the chamber be too small and ill-ventilated. Everything that can be spared should be removed from the room, and nothing allowed to remain that can be injured by chemicals being spilt upon. It should be kept very clean, for dust and dirt are too great enemies to good photography. Oilcloth or bare boards are best for the floor, not carpet. A convenient range of shelves should be made round the room, and some hooks provided for hanging cloths and towels on. 5 HOW TO BEGIN WORK. You will remember we explained that the Actinic force that accompanies Light resides mainly in the blue, and scarcely at all in the yellow rays; and photographers in- geniously take advantage of this fact by illuminating their " dark" rooms with this non-photographic light, and thus see how to prepare their most sensitive plates. Every aper- ture and chink that admits white light must be carefully stopped up. If there be more windows than one, they must be blocked out, and the remaining one covered with three folds of yellow calico; or, better still, have a hinged frame to cover the window, and glaze this frame with dark yellow or orange glass, so that you can have yellow or white light in your room at will. If a window is not obtainable, a gas light, a lamp, or even a candle may be used, if a yellow glass be provided. An ordinary lamp, with a yellow paper screen over it, makes a fair light for the dark-room. Per- sons usually make the room for preparing their plates too dark. This is a mistake; at least sufficient light should be admitted to enable you to see what you do, but it is im- portant that this light be quite yellow. Should you com- mit the error of admitting too much light, you will find, fully illustrated, under the head of " Failures, their Origin and Remedies," near the end of the book, the proper method of proceeding. Near the window or lamp, a strong shelf or table should be placed, on which to place the bottles which you will re- quire ; and close at hand you must have a supply of water. If you can have the water laid on, with regular tap and sink, your arrangements will be perfect; failing this, you may have a cask or other vessel with a tap in it, filling it up with water as you need; or, on an emergency, use a jug, and a pail to receive your slops. Have a towel and soap conveniently placed to wash your hands with. HOW TO BEGIN WORK. Tour room being prepared, you are ready to make a commencement, and your natural desire will doubtless be to take a portrait. But as you are a beginner, you should commence with the easiest thing, and to take a good portrait is one of the most difficult things in photography. The proper pro- ceeding is to set up a plaster cast, engraving, porcelain statuette, or similar still-life object, and practice upon it, 6 HOW TO BEGIN WORK. being prepared for many failures arising from your igno- rance and clumsiness, before you attempt portraiture. You should try picture after picture, noticing carefully the faults you commit in one, so as to avoid them in the next. In this way, by patience, observation and practice, you will speedily gain such experience as will make your new occupation a pleasure. Above all things, do not expect to produce good pictures all at once; and be not discouraged with failures, but try to understand why you fail. In setting up an inanimate object to copy, the risks of failure are less than when you have a person to sit, for it will not move or alter its expression, or make remarks if you do not succeed. "When brother Tom, or friend Harry is called in, the case will be different; they will be full of fun and jokes, will most likely move at the critical mo- ment, and say disparaging things when they find the pic- ture a failure. All this will confuse you, and cause you to omit things you ought to have done, and do abundance of things you ought not to have done, and dishearten you in your early progress. You had better, therefore, set up a plaster cast bust — one painted stone-color will be best — such as those of Shakspeare, which are so abundant, and, using this as a model, work frequently at it until you have sufficient mas- tery of your instrument and materials to produce, with moderate certainty, a passably good picture; then you may proceed to portraiture. Place your object in good light; a glass-house built for the purpose is the best; but this you may not at present be able to obtain. A well-lighted apartment will do, if you use a white screen — a sheet thrown over a clothe's horse — to reflect light upon the shaded side. A background may be formed by hanging some quiet drapery a little dis- tance behind your object. Now get out your portrait lens, and after wiping carefully the surfaces of the glasses with a clean silk handkerchief or chamois leather, screw it on to your portrait camera, and place them both on your heavy camera-stand opposite to your object. The ground-glass of your camera should have the sizes of the glass plates marked on it in squares, corresponding to the holders in your dark slide. Place your stand and camera so that the lens is opposite to about the center of your object, and move the stand and camera backward or forward until the image of the bust is of the 7 HOW TO TAKE GLASS POSITIVES. size, and occupies the place on your ground-glass that you wish the image to do on the plate you are going to use, remarking that the nearer the camera is to the object, the larger the object will be, and vice versa. Lay the focusing- cloth on the camera; put your head under the cloth, and you will more clearly see the image on the ground-glass. Slide in or out the inner body of the camera until the image is seen quite distinctly, then fix the camera with the screw provided. While your head is still under the focus- ing-cloth, pass your hand round to the lens, and move the rack backward and forward till you find the point at which it is most distinct. It is then said to be "in focus/' or " sharp." These instructions for adjusting the focus apply to the common camera. The best kind of camera is provided with an endless screw arrangement, or a rack and pinion, by which the adjustment is made more easily and perfectly. You may now return to your dark-room, and prepare your chemicals for " Glass Positives/' these being the most easily produced photographs. HOW TO TAKE GLASS POSITIVES. The chemicals required are — Positive Collodion. Nitrate of Silver solution. Developing " Fixing " Crystal Varnish. Rotten Stone. Black Glass. The positive collodion you will purchase ready prepared. When required for use, pour three or four ounces into the tall collodion bottle; and when you have done for the day, return what remains back into the stock-bottle, that it may settle. In this manner you can always use from a clear quantity, and avoid these spots and defects which arise from a turbid or unsettled collodion. The nitrate of silver solution is one of the highest im- portance. To know how much solution to mix, fill your bath with water to within an inch of the top, and measure 8 HOW TO TAKE GLASS POSITIVES. how much it holds. Suppose it to contain 25 fluid ounces;* as 35 grains of nitrate of silver to one fluid ounce of dis- tilled water is the proper strength, 2 ounces of the nitrate will be required to form 25 fluid ounces of the necessary solution. Dissolve the silver in 4 ounces of distilled water, or boiled rain-water, then add a quarter of an ounce of positive collodion to it, shake it well for a few minutes, and add 21 ounces more of distilled water. The solution will now be a pale milky color, and will re- quire filtering. Should it not run through quite clear, it must be re-filtered. Add one drop of pure nitric acid to every 3 ounces of nitrate solution, and then it will be ready for use. Developing Solution. Protosulphate of iron - 100 grains. Glacial acetic acid - \ ounce. Water ----- 10 ounces. Nitric acid ----- 5 minims. Alcohol ----- i ounce. Dissolve the crystals, and if the solution be . not quite clear, filter it, then add the alcohol and acids. It will keep good until it is a deep brown color, when it ought to be rejected. Fixing Solution. Cyanide of potassium 60 grains. Water ----- 6 ounces. Dissolve, and it is ready for use. Let each of these solutions be distinctly labeled, and cork the bottles when they are out of use. The fixing so- lution had better be marked " Poison," to prevent any ac- cidents. It should also be particularly kept out of reach of children, as it is a most deadly poison, despite its rather attractive smell. * It is important to notice that in all photographic formulae, where ounces of fluid are named, fluid ounces are meant, and that the glass measures are gradu- ated for the purpose. When solids are named, Apothecaries' weight is meant. But the materials are sold to you by Avoirdupois weight ; and as the ounce of the latter is not so heavy as that of the former, this fact must be carefully re- membered, or disputes with shopkeepers, and errors in mixing your solutions, will arise. The Apothecaries' ounce weighs 480 grains, and the ounce Avoir- dupois but 437£ grains. It is better, therefore, in mixing nitrate of silver solu- tions, to estimate the quantity required in grains, remembering that the pur- chased ounce of nitrate of silver will never contain more than 437£. 9 HOW TO TAKE GLASS POSITIVES. How to Clean the Glass. Certain fixed sizes are used by photographers, and the glasses are sold cut ready for use. The description of glass known as " Polished Black Glass " is well suited for positives, but, before using, it re- quires careful cleaning. The sharp edges should be first removed with a fine file, or by drawing the edge of one piece over the edge of another; then lay the glass on a clean flat surface, or put it in a vice, and dust a little of the prepared rotten stone in the middle. Rub it carefully over every part with a bit of clean soft rag: turn the glass over, and do the other side the same. Then polish each side with a clean cloth, and finish with a soft chamois leather kept expressly for this purpose. Now breathe on the glass; and if the breath deposits evenly, the plate is clean. If the plate, however, shows patches and marks, it must be re-cleaned. Let the edges be carefully wiped, and the plate is ready for use. This amount of cleaning will gen- erally be sufficient for new glasses, but when they have been used they require more labor. They must then be well washed under the tap, to get rid of all collodion and chemicals, and be wiped on cloths kept expressly for the purpose. No soap, only plain soda and water, must be used in washing these cloths. Should the plates have been varnished, they must be soaked for some hours in a satu- rated solution of washing soda, till the varnish and film come freely off. The glasses must then be well washed, and treated as already described. It is a good plan, when working, to have a dish of water at hand, and to place the spoilt pictures in it at once while they are wet, and at the end of the day to wash them all, and put them away clean. By thus not allowing the films to dry on the glasses, they are much easier cleaned, and fewer failures will arise from dirty glasses. Collodion is a good material for cleaning glasses when they are not very dirty. Pour a few drops on the glass, and well rub it with a clean cloth, and you will entirely re- move ali grease. A hint may thus be taken how to use up waste collodion. Pouring on the Collodion. Remove the stopper from the bottle, and wipe from the lip any dust or dry film adhering; and, holding the plate horizontally by one corner with the thumb and finger of the left hand, pour steadily into the middle of the plate as 10 HOW TO TAKE GLASS POSITIVES. much collodion as will half cover it. Then gradually in- cline the plate so that the collodion flows to each corner, not allowing it quite to touch the thumb, nor to flow a second time to any part; then steadily pour back the ex- cess from one corner into the bottle, and while the plate rests on the mouth of the bottle, move the plate backward and forward to prevent the collodion setting in crapy lines. Perform this operation coolly and steadily, and try to avoid spilling any of the collodion. A little practice will make it easy. When the collodion is set — usually in a few seconds - — the plate is ready to be immersed in the nitrate of silver bath. Lift the dipper up, and place the back of your plate on it — it will adhere by capillary attraction — and im- merse plate and dipper into the bath solution with one steady dip, and continue to agitate the plate by moving it about in the bath for a few seconds. Take care it does not slip off the dipper. After agitating the plate, cover it over to keep it from light and dust. If there be the least hesi- tation or stop while the plate is being immersed, there will be a line marked across the plate. To know how long to keep the plate before putting it in the bath, after it is collo- dionized, is a point that you will gain by experience; but it depends on many circumstances, such as the nature of the collodion and the temperature ; but this rule will guide you; if you put the plate in too soon, streaks and marks will be formed, commencing from where it first touched the silver solution. If you do not immerse it soon enough, the part of the plate that has become too dry will be in- sensitive, and will show a transparent mark. By noticing these points, you can judge whether you have made an er- ror in the time of immersion. The plate must remain in the bath in summer time about two minutes, and in winter from five to ten. "While the plate is in the bath, you must get ready your dark slide, and see that there is no dirt in it. When ready to put your plate in the bath, you must shut your door, and see that only yellow light illuminates the room. Lift the plate up and down in the bath several times by means of the dipper, and the agitation of the solution will re move the oily-looking lines on the surface. Allow it to re- main in the bath till all apparent greasiness is removed, and the film has become creamy-looking. Then take it off the dipper, and, handling it as carefully as possible — chiefly by the corner uncollodionized — let it drain for a few seconds on clean blotting-paper, and then lay it, collo- 11 HOW TO TAKE GLASS POSITIVES. dion side downward, into your dark slide, the silver wire corners supporting it by the four corners. Close up your dark slide, and your plate is ready for use. You may now return to your plaster cast, and removing the ground-glass frame from the camera, insert the dark slide in the place. Cover the lens with the cap, raise the shutter of the dark slide, and gently remove the lens cap, so as not to shake the camera : thus the light will be ad- mitted to the sensitive plate. Experience can alone deter- mine the length of the " exposure." The brilliancy of the light, color of object, kind of lens, nature of collodion, time of day, and even the period of the year, are all modifying circumstances. Suppose you allow ten seconds. Count the time ex- actly, and replace the cap on the lens. Next shut down the shutter of the slide, and take it into the dark-room. Close the door, and noticing that no white light is admitted, remove the plate carefully from the dark slide. The ni- trate solution that has accumulated at the bottom drain off with clean blotting-paper. Put about an ounce of de- veloping solution into a clean measure glass, and holding the plate horizontally by the bare corner, collodion side upward, pour steadily but quickly along the bottom edge of the plate sufficient to easily cover it; gently incline the plate to allow the developing solution to flow uniformly backward and forward. Watch the "coming out" of the image. The image will quickly appear; first the parts most strongly lighted will show themselves, next the shaded portions, and when these are fully out, turn off the solution, and wash the plate well, by allowing the water from the tap to flow over it for not less than one minute, or until all the greasy lines disappear. Lay the plate in a shallow photographic ware or porce- lain dish kept for the purpose, and quickly pour over it sufficient of the fixing solution to cover it. Directly the yellow film of iodide of silver is dissolved, the plate must be lifted out and well washed. When the plate goes into the fixing solution, white light may freely be admitted. The fixing solution must be put back into its bottle, and may be used as long as it continues to dissolve the yellow film. If the exposure be correct, and you have developed properly, you will now have a nice picture of your bust.* * If the picture be not perfect, refer to the chapter on " Failures, their Ori- gin and Remedies " for further instructions. 12 HOW TO TAKE NEGATIVES. Tour plate may be dried spontaneously or by heat. The collodion surface now requires varnishing, to protect it from atmospheric action. Remove carefully with a camel's hair brush any dust or dirt on the picture, and pour the varnish over it as you did the collodion. Drain it, and when dry your picture is finished, and ready to be mounted. You have now passed through the various operations, and it only requires practice and observation to make them familiar to you. Having obtained this practice, the bust may be removed, and a friend being placed in its stead, you may, by applying the same manipulations, pro- duce a portrait. Let him sit in an easy, graceful position, and, if necessary, steady his head by the use of the head- rest. Let him look at some dark object, and allow him to wink his eyes freely during the sitting, but caution him to be quite steady in all other respects. HOW TO TAKE NEGATIVES. The pictures produced by the above method have the disadvantage that a separate sitting is required for every- one; this, together with the fragility of the material, has caused the process to be less generally followed than the more complex one, where a negative is first obtained, from which an indefinite number of paper pictures can be pro- duced. The practice, however, you acquire in producing glass positives will be extremely useful in producing nega- tives, as, up to a certain point, the manipulations are similar. You must clearly understand the difference between a Negative and a Glass Positive. Every glass picture, to a certain extent, partakes of the nature of both; but a "glass positive " is a picture done at one operation, and complete in itself; whilst a Negative is not so much a picture as the means of producing one. Glass positives are examined by reflected, negatives by transmitted, light; the one you hold down to look at, the other you hold up to look through; the former are black varnished to make them opaque, if not taken on black glass; the latter clear varnished to give transparency. The one shows natural objects as they are — lights for lights and darks for darks; the other, just the reverse — faces, hands, and linen very dark, and black drapery quite clear. Hold a picture of each kind up to the light and look through them, the positive will appear thin and transpar- HOW TO TAKE NEGATIVES. ent, the negative dense and opaque; turn them down and look at them, the positive is clear and distinct, the nega- tive misty and confused. The two kind of pictures are so different that you must judge each by its own rules; for what is a fault in one, may be a merit in the other. In other w r ords, a negative is a glass picture produced by somewhat similar means to a positive, only that in the de- velopment a much thicker and denser deposit is formed. In fact, the negative is to the photographer what the types are to the printer; and as the latter, you know, are arranged just contrary of the impression that is taken from them, so must the photographer's negatives — his types — be the reverse of his prints. The analogy between the two processes is so considerable,* that the production of paper pictures by the aid of negatives is always termed printing. It will be a great assistance to you, if you can obtain from some photographer a negative that you can keep by you, to compare with your own, until you have acquired experience to know how to judge for yourself. The same apparatus serves for the production of nega- tives as positives, but some of the chemicals are different; those that you require are — Bromo-iodized negative collodion. Nitrate of silver bath solution. Developing " Fixing " Spirit varnish, The Bromo-iodized Negative Collodion is rather differ- ent in its preparation to positive collodion, and is better adapted for giving dense pictures. It is often supplied as plain collodion and iodizing solution. It is made ready for use by mixing three parts by measure of the former to one of the latter. It is better to mix it a few hours before using, so that time be allowed for floating particles to subside. Nitrate of Silver Bath Solution. The same you used for positives will not do for negatives. Eecrystalized nitrate of silver 2 ounces. Distilled or boiled rain-water - - 25 " Dissolve the silver in four ounces of the water; dissolve 14 HOW TO TAKE NEGATIVES. two grains of iodide of potassium in one ounce of the water, and add it to the four ounces of silver solution; agitate till the yellow precipitate formed first is dissolved. Add a few drops of a saturated solution of bicarbonate of soda, agitating well between each addition, until the silver solution becomes rather milky, then add the remaining 20 ounces of distilled water. Filter, and add half a drachm of glacial acetic acid, and your nitrate bath is ready for use. Eill it up from time to time with a plain solution of nitrate of silver, 50 grains to the ounce. Developing Solution for Negatives. Protosulphate of iron - 150 grains. Glacial acetic acid - \ ounce. Alcohol - - - - 1 « Distilled water 10 This solution gradually acquires a sherry color, but its quality remains equally good. It should be filtered before using. Fixing Solution. Hyposulphite of soda 5 ounces. Water - 5 This solution may be used until it loses its power of fixing the negative. It soon becomes discolored, but that is of no consequence. Chance's Sheet or B. P. C. is good glass for negatives, as Crown is not flat enough. It requires the same careful cleaning as for positives. As it is more difficult to produce clean negatives than positives, you had better accustom yourself to use a glass one size larger than you require, so that the defects, which usually occur on the margin of the plate, may not spoil your picture. Pour the collodion on the plate, sensitize, drain, and place it in the dark slide carefully, and according to the directions given for glass positives. The same difficulty occurs with negatives, in giving any rule for the length of exposure, as in positives; the ap- pearance of the plate during development is a useful guide, but they always require at least twice as long time as for positives. Be very careful, when your plate is in the dark slide, to keep it erect, and to handle it gently. Never 15 HOW TO TAKE NEGATIVES. knock it against anything, or it will be covered with abund- ance of spots from particles of dust and dirt falling on it. When in the dark-room, take the plate out as carefully as before, and remove, with clean blotting-paper, the nitrate solution that has accumulated at the bottom; and holding it by the corner, pour over it the developing solution, and in a few seconds the image will appear. After a little ex- perience you will be able to judge, by the manner in which the image makes its appearance, whether you have given the proper exposure in the camera. If it start out at once, directly the developer has flowed over the plate, the exposure has been too long; but if the image comes out slowly and reluctantly, and you have difficulty in making the deepest shades appear, it has not been exposed long enough. The happy medium between these two is the correct time. When this has been given, the image makes its ap- pearance steadily and gradually — first the high lights, next the light shades, and finally the deep shadows. Suppose it a portrait of a gentleman — the shirt-front, face, and hands are first seen; the light folds of the drapery next show themselves ; and lastly, the details in the darkest parts. If it were a positive, you would have poured the developer off before these last were seen; but, being a negative, you must carry it on until the whole of the de- tails are clearly out, then pour the solution off the plate and wash it well. By holding your plate up to the light and looking through it, you will see the image as a nega- tive — the whites all dark, and dark portions nearly trans- parent; and if the picture appear in proper harmony, mak- ing allowance for reversed effects, the lighter portions being nearly opaque, and the darker parts very clear — but the whole picture full of gradations and half-tones, with scarcely any parts entirely opaque, and very few clear glass — then the development is complete; if, however, the pic- ture presents somewhat this appearance, but is deficient in opacity of deposit, or " density," it must be " intensi- fied." To do this, pour over the plate as much as will comfortably cover it of the following: • Negative Intensifying Solution. Pyrogallic acid - 3 grains. Citric acid 1 grain. Glacial acetic acid J drachm. Distilled water - 1 ounce. 16 HOW TO TAKE NEGATIVES. When this solution has thoroughly mixed with the water on the plate, pour it back into the measure-glass, and add a few drops of nitrate of silver solution to it (30 grains to the ounce of water), mix, and pour again over the plate; the image will speedily begin to intensify — that is, the silver will be deposited over the various parts where the light has acted. This intensifying must be continued until the parts of the negative most lighted have the requisite opacity. This solution sometimes becomes turbid and muddy be- fore the picture is dense enough. In such a case, pour it away, and renew with some fresh intensifying solution and silver, and proceed as before. This may be repeated many times, if needed, until the required effect is produced. Here is, perhaps, the most difficult thing you have to learn — to know how far to go, and w T hen to stop ; how to gain intensity enough to produce a vigorous negative, and yet to avoid making it too dense, and losing half-tone. As a rule, beginners over-develop their positives, and under- develop their negatives. But it is possible to intensify too much, and make the picture so dense that you cannot print through it. You must watch the kind of prints that different negatives pro- duce, and when you find one that gives a brilliant yet soft image — for the real test of a negative is the kind of print it produces — study that negative well, observe the degree of opacity it has, and, keeping it as a standard, try and produce all others like it. In this way you can train and educate yourself to produce good negatives. The development and intensifying being finished, wash the plate and lay it in the dish; pour the fixing solution over, and when the yellow iodide is dissolved out, give it a careful and copious washing; for if any of the hyposul- phite of soda* remain in the film, it will crystalize and spoil it. Your picture now being washed, you may calmly examine it. If it appear as a moderately good but over-exposed positive, with a red and green pearly tint, and on looking through it, shows- abundance of half-tones, both in the opaque and transparent parts, you may consider you have a correctly-exposed and well-developed negative, and one from which you may anticipate brilliant prints. If, however, the negative appear as a good positive, with brilliant blacks, but rather chalky whites, and on looking through if these latter are very dense without half-tone, 17 HOW TO VARNISH THE NEGATIVE POSITIVE PRINTING. and the former almost like bare glass, then your picture is defective, and will only produce a hard black and white print; the fault being that it was not long enough exposed in the camera. Should it, however, appear as a very much over-exposed positive, the whole plate having a gray film over it, obscur- ing the image, and on looking through, the details of the shadows are almost as intense as the white linen, and the whole picture is deficient m contrast, then it has been over-exposed. The two instances we have pointed out are extreme ones: it is your object to avoid each; but of the two errors, under-exposure is the worst, for by careful printing you may get a passable proof from an over-exposed negative ; but no dexterity will avail with an under-exposed one, and unfortunately, beginners' negatives, from their great desire to " work quick," have too frequently this latter fault. HOW TO VARNISH THE NEGATIVE. After the plate has been well washed and dried, it is ready to varnish. If only a few prints are wanted, and you do not intend to keep the negative, you may use a cheap varnish. If, however, you value your negative, and purpose producing many prints from it, the cheap varnish will not give sufficient protection, and you must use a spirit varnish which will produce a much harder sur- face. To use this spirit varnish, warm the negative before a fire uniformly all over as hot as the back of the hand will bear, then pour the varnish on like collodion, drain off, and dry it with heat. The proper degree of heat to use will be acquired by a little experience ; if the plate be made too hot, the varnish will not flow uniformly over, but will run and dry into irregular streaks. If it be not hot enough, the surface will dry dull and dead. With the me- dium heat the film will dry with a hard, glossy surface. When cold, your negative is ready to be printed from. POSITIVE PRINTING ON PLAIN AND ALBUMENIZED PAPER. The learner having now got his negative in readiness to print from, will find full details of the manipulations of the printing process commencing on page 192 of this book. 18 PHOTOGRAPHY. CHAPTER I. HISTORY OF PHOTOGRAPHY. 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 discoveiy of some new chemical ingredient, may be 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 the 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 born in London, in the year 1706, and died in 1762. 10 HISTORY OF PHOTOGRAPHY. 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 such mighty instruments for weal and for woe, is so distinctly marked, that admiration and awe have engendered, 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 ways and 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. HISTORY OF PHOTOGRAPHY. 11 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-writing, whilst the word photography signifies light-writing, Not one of these exjDressions 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 potassa, 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. 12 HISTORY OF PHOTOGRAPHY. 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 was made until after the lapse of several years. In 1801 Ritterf 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 experi- 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 ; w r hilst 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. He died on the twenty-first of May, 1786, at Koeping, 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, 1828, in London. HISTORY OF PHOTOGRAPHY. 13 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 Newcastle-under-Lyne, in 1730, and died in the year 1795. f Sir Humphry Davy was born at Penzance, in 1778, and died at Geneva, in 1828. 14 HISTORY OF PHOTOGRAPHY. 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 Avould 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 1833. HISTORY OF PHOTOGRAPHY. 15 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 was 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, Nlepce 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 ISTiepce 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 how Daguerre should hit upon the idea of using this vapor, or that a latent * Daguerre, L. J. M., was born at Cc-raieilles, in 1787, and died in 1851 16 HISTORY OF PHOTOGRAPHY. 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. Niepce, too, is entitled to an .equal share of honor ; for without Niepce, in all probability, sun-drawing would still be a latent property of nature ; as also, without Daguerre, the discoveries of Mepce 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 by Claudet ; 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 Niepce, 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 Niepce 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 HISTORY OF PHOTOGRAPHY. 17 fill 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 Talbotype or Calotype. 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. This 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 Niepce 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 w^as 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 18 HISTORY OF PHOIOGRAPHY. 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 paper 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 impression 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 positions. 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 Niepce 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 flowed 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 HISTORY OF PHOTOGRAPHY. 19 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 ne w era. Le- gray originally suggested that collodion might be 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 of 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 gun-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 forms a very thin, even, and transparent 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- possible 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- velopments. In the year 1838 or 1839, Mr. Mungo Ponton pointed out a very important discovery in reference to bichromate of potassa, 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 coated 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 20 HISTORY OF PHOTOGRAPHY. picture resulting from this treatment is a positive print, in black and Avhite, of which the shades are produced by the carbon of the lampblack. This discovery gave rise to car- bon-printing. 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 press. 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 £rans/er-paper, that is, paper coated with a layer of albumen. A negative is placed m 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 HISTORY OF PHOTOGRAPHY. 21 promises to be the basis of the most successful operations in photo-lithography. Asser, of Amsterdam, invented or used the transfer pro- cess at the same time that Osborne was using it in Aus- tralia. 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 process 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. 22 HISTORY OF PHOTOGRAPHY. 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. CHAPTER II. PRELIMINARY OBSERVATIONS. 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 quantity. 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 24 PRELIMINARY OBSERVATIONS. out most prominently ; the Collodion processes, wet and dry, the Tannin process, and the Albumen process. 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 inrpression 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 positives, 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 PRELIMINARY OBSERVATIONS. 25 tlie 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. LIST OF A PHOTOGRAPHIC OUTFIT. 1. Glass-house, or room in the garret furnished with a sky-light. 2. Dark room, for sensitizing plates or papers. * 3. Operating room, for collodionizing plates, mounting prints, etc. 4. Screens (white, gray, blue, and artistic) for the glass- house. 5. Lenses, (|, £ , etc., stereoscopic and orthoscopic.) 6. Cameras, (for portraits, views, stereographs, and for copying.) V. Ornamental carpets, chairs, stands, curtains, pillars, balustrades, etc. 8. Head-rests, etc., camera-stands, mirrors, brushes, combs, pins, needle, and thread. 9. Washhand-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 acidj 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- 2G PRELIMINARY OBSERVATIONS. phaltuni, 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, wax 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, negative-holder. CHAPTER III. SPECIALTIES IK REFERENCE TO THE ARTICLES IN THE PRE- CEDING CHAPTER THE GLASS-HOUSE, ETC. 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 superintending 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, but he must know what arrangements are the most appropriate. The success of many an artist depends upon the fortuitous advantages of his glass-house ; but 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 28 SPECIALTIES — THE GLASS-HOUSE, ETC. light in reference to his art, whereby nature becomes na+ tural. 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 which 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 day 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. Now 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. SPECIALTIES — THE GLASS-HOUSE, ETC. 29 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. Next construct a water-tight flat roof, beginning at the side and running toward the north about ten feet. Where 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 be about thirty feet. The dark-chamber and 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, and 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 in the space beneath the flat roof, on the southern side, and so far back as to cut off*, as much as pos- 30 SPECIALTIES — THE GLASS-HOUSE, ETC. 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 proposed, 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 distributed. The screens or backgrounds for placing behind the model SPECIALTIES — THE GLASS-HOUSE, ETC. 31 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 lenses, and will tend to communicate to the photograph a vulgar appearance. 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 exuvise, 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 wil l be no better than the painting of Dr. 32 SPECIALTIES THE GLASS-HOUSE, ETC. 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 th6 screen be inclined to the horizon at an angle of forty-five degrees, rays that fall upon it through the sky-light will pass off 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 Becond cause is obviated by preserving a uniform tempera- SPECIALTIES THE GLASS-HOUSE, ETC. 38 ture 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 light, 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 CHAPTEE IV. SPECIALTIES CONTINUED. — THE CAMERA AND LENS. 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. No 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 lens, 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 SPECIALTIES — THE CAMEEA AND LENS. 35 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 flint- glass are combined in accordance with the principles just alluded to. Such a combination corrects partially ; it is 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 lenses, properly constructed, is" an improvement upon the doublet ; and a pair of doublets whose radii and distances are mathe- matically and optically calculated, can be made to produce more correction than it is 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- poses, a pair of compound lenses can be constructed and adjusted so as to be practically perfect. We are indebted to Dolland for the first achromatic combination. Doublets and triplets are decidedly the best arrangements for land* 36 SPECIALTIES — THE CAMERA AND LENS. scape photography ; whereas two pairs of doublets, adjusted at a given distance apart, or at a variable distance apart, are 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 easv 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 like 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 JEqui-distant Conjugate Foci of a Lens or Combination. — Adjust the object, as, for instance, a card- picture, in front of the lens or cohibination in the camera, until the image on the ground-glass is of an exactly equal size with the object w^hen 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. SPECIALTIES THE CAMERA AND LENS. To find the Magnifying Power of a Lens or Combination. — On a sheet of card-board, in the middle, construct a circle one inch in diameter, 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. Now, 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 Power 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 poAver in favor of the lens, whose dis- tance is the shorter. To find a Single Lens equ ivalent in Power to a Compound Lens. — 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 Macrophotography.) 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 De perceived that the curvature of the lines will diminish as the aperture diminishes. If with a very small aperture 38 SPECIALTIES — THE CAMERA AND LENS. the lines are still curved, the combination is worthless ; whereas, if the lens or combination can be used without a diaphragm and still produces straight and parallel lines in the images, such a magnifier will be very valuable. To ascertain whether a Lens 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 that 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-defined 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 combination has been either over-corrected, under-cor- rected, or not corrected at all. The actinic rays are on the vio- let side whose refrangibilities 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 be 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. After 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 achromatically 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 cf 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- SPECIALTIES THE CAMERA AND LENS. 39 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 lens, 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 well 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 self-same 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 of decided reputation, who will furnish you 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 40 SPECIALTIES THE CAMERA AND LENS. application to the heliographic 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 to 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 which 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, with 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. Wherever this difference in the size of the picture exists, other things remaining the same, it will be found that the lens which produces the largei 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- SPECIALTIES — THE CAMERA AND LENS. 41 tance. 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 Chimie Photographique, are as follows : Calling the focal distance unity, then the diameter of the lens will be \ of this unity, that of the stop T V> 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 Arms 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 Voightlseiider, etc. 0 CHAPTEE V. SPECIALTIES CONTINUED. — THE CAMERA. The 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 through 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 case, 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. Next 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 1 540. SPECIALTIES CONTINUED THE CAMEBA. 43 requisition. The first thing to be done, where this difficulty exists, is to hunt about upon the original photograph or en- graving for some distinct landmark, as a very minute circle, :>r a couple of lines in apparent juxtaposition, or the open- ing in the letter e or 0, 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 ; care 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 is 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- SPECIALTIES CONTINUED THE CAMERA. graph without inclining the tube upward ; but 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 top, 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 flat 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- SPECIALTIES CONTINUED — THE CAMERA. 45 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 upon 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, which it is required to photograph, is so situated as not to receive the direct light of the sun, as 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, and 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 has 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. CHAPTER VI. SPECIALTIES CONTINUED. DARK-ROOM. The chamber intended for all 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 width of the glass-room — and about ten or twelve feet long. The work-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 below 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 inches 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 it> 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- SPECIALTIES CONTINUED — DARK-ROOM. 4^ 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 hydrosulphuric 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-holders, 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 flat dishes are used with 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 quarter of an inch above the bottom of the dish. Naturally, when the plate is 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 solu« 48 SPECIALTIES CONTINUED — DARK-ROOM. 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 above 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 witfr 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- SPECIALTIES CONTINUED — DAKK-KOOM. 49 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 be 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 be 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. WORK-ROOM. 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 different- sized plate-holders, diaphragms, pliers, scissors, diamonds, 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 mortar, 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, ge- 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 preceding ar- ticles 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 50 SPECIALTIES CONTINUED DARK-ROOM. 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 paper 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 m order to dry them after fixation and washing. The toning and fix- ing dishes are situated on the shelf on the west side ; as are 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. CHAPTER VII. COLLODION". In 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 pyroxyline. 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, or xyloidine, (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 52 COLLODION. 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- oughly 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 COLLODION. 53 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 weak or the temperature too high, whereby a portion of the pyroxyline is dissolved. Such a species of gun-cc,vton 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., 1.843 at 60 Fahr.,. .24 fluid ounces. 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 Commercial nitric acid, Water, Cotton, 1.45T " u 1 ounce. 54 COLLODION. pressed down 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 water 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 plates, 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 has 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. COLLODION. 55 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. No. 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 No. 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 well 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 ISTo. 1. No. 4. Formula for the Preparation of Pyroxyline. DisderVs Pyroxyline. Sulphuric acid, 4000 grains. Pulverized pure nitrate of potassa, 2000 44 Place these in a glass vessel provided with a close-fitting cover, and stir them intimately together with a glass rod. Next add 150 grains of fine cotton-wool, in small flocks at a time, 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 56 COLLODION. that has not been decomposed might be 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 away. CHAPTER VIII. ETHER AND ALCOHOL. 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 w r anting 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, and its frequent want of permanency. Ethyle Group. Ethyle, Symbol Ae, C4 H5. Cyanide of ethyle, Ae Cy. Oxide of ethyle, (ether,) Ae 0. Nitrate of the oxide of ethyle,. .Ae 0, N0 5 . Hydrated oxide of ethyle, (alcohol,). Ae 0, HO. Nitrite of the oxide of ethyle,. .Ae 0, N0.3. Bromide of ethyle, Ae Br. Oxalate of the oxide of ethyle, .Ae 0, C2 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 ether 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. 63 ETHER AND ALCOHOL. ETHER. 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 tube 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 condenser. The product thus obtained contains sulphurous acid, sul- phuric acid, sulphovinic acid, and other impurities. By rectification most of these are removed as follows : 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 ETHER AND ALCOHOL. 59 in a stoppered bottle. After subsidence separate the super natant ethereal solution by means of a syringe, and distill off 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, Alcohol is the rectified spirit of wine of the specific gravi- ty of 0.835, containing eighty-five parts of anhydrous alco- hol and fifteen of water. When pure and anhydrous it is the hydrated oxide of ethyle, (Ae O, HO.) It contains six equivalents of hydrogen, four of carbon, and two of oxygen== H 6 C 4 0 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 60 ETHER AND ALCOHOL. 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 off 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. Now raise the heat gently and distill off seventeen fluid ounces. Alcohol thus obtained will have a density, when the operation is carefully managed, of 0.796. 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 ETHER AND ALCOHOL. 61 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 off 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 pure 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 film 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 62 ETHER AND ALCOHOL. 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 collodion. 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 when developed with the 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. New collodion is colorless, or nearly so ; whereas old collodion sometimes is as deeply red as a strong solution of burnt sugar. Sixthly. New 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 Monckhoven 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- tive. Furthermore Hardwich remarks, that, if these substances be employed to increase the intensity of the shadows in the ETHER AND ALCOHOL. 63 image, they ought to be added cautiously because they de- teriorate from the keeping properties. But nitro-glucose is said to be an impurity in pyroxyline ; it is analogous in several respects to pyroxyline ; and it is prepared with sul- . phuric acid, nitric acid, and sugar / but lignine or cellulose yields sugar when treated with sulphuric or nitric acid , hence in the preparation of pyroxyline grape-sugar is formed at the same time, and by the further action of the acids, nitro-glucose is produced. That there exists a duplex com- pound in collodion may be shown by adding water to it ; a precipitate will be 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 precipitate 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 in water for some time, and adding sulphuric acid to the concentrated syrup. A white precipi- tate is formed, 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 evap orating 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 glass 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. 64 ETHER AND ALCOHOL. 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, and is in fact quite structureless. CHAPTEE IX. COLLODION SENSITIZERS — IODIDES AND BROMIDES. 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 upon that iodide and bromide whose chemical equivalent is the least ; for the less the combining proportion of a given chemical substance, the less the 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 scales, 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; 66 COLLODION SENSITIZERS — IODIDES AND BROMIDES. 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 ef 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 Avhich 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 COLLODION" SENSITIZERS IODIDES AND BROMIDES. 67 the iodized collodion alone possesses all the capacity re- quired. A peculiarity has been discovered in reference to iodized collodion. Some sorts of collodion are suitedfor one iodizer, and sonie 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 glutinosity 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 68 COLLODION SENSITIZERS — IODIDES AND BllOMIDES. 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, ammonium, cadmium, and silver. CHAPTER X. PREPARATION OF THE IODIDES. 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 bases 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. Iodine. Symbol, I. Chemical Equivalent, 127y 7 ; 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 help. 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 five 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 70 PREPARATION OF THE IODIDES. 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. Properties. Iodine resembles plumago or black lead, in ontward 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 reduction 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 a piece of porcelain there be any residue, one or both of the former impurities may be present; the latter impurity is of rare occurrence. 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 Hydriodio Acid. Hydriodic Acid. — Symbol, I H. Combining Proportion, 128yL-. Specific Gravity, 4.43. This substance is a condensable gas ; at a temperature of 5 9°. 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 r 7 o, when it boils at a temperature between 257° and 262°. It is not a stable com- pound ; oxygen from the air is absorbed, and iodine is lib- erated and dissolved by it. Chlorine and bromine decom- pose it. Hydriodic acid may be obtained by several methods. PREPARATION OF THE IODIDES. 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 solution. 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 T %. Barium. — Symbol, Ba. Combining Proportion, 68y 5 7 . 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 12 PREPARATION OF THE IODIDES. a little water of baryta, 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 filtrate, 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 ; they 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 the 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 potass,a 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 with pure carbonate of potassa as long as any pre- cipitate is produced. The insoluble lime is again separated, PREPARATION OF THE IODIDES. IS 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 be 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 74 PREPARATION OF THE IODIDES. De present, too, in the decomposing carbonates and sulphates, so that we may sometimes expect to find them with the otfher impurities. Tests of the Purity of the Iodides. No precipitate is produced in a pure iodide by solution of mloride 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 k 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. CHAPTEE XI. BROMINE. Bromines — Symba, 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-water, 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- mals. 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- 76 BROMINE. bon. The water is removed by a second distillation over recently fused chloride of calcium. Bromine is a brownish- red liquid, which solidifies at — Y 0 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 3 ¥ 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 liquid. Hydrobromic Acid. Symbol, Br H. Combining Proportion, 81. Spec. Gra v., 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. Bromides. These binary combinations can be obtained, as a general thing, 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 BROMINE. 71 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. Preparation. 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. Mix 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. Properties. This substance is a heavy gas of a greenish-yellow color, and exceedingly suffocating odor. Under a pressure of four atmospheres this gas is condensed into a liquid of a bright yellow color, whose 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, as, for example, from ammonia ; still dry chlorine and hydro- 18 BKOMINE. . 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 which it is used both for bleaching and disinfecting. Chloride of Lime, Ghlorinetted 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- ing. CHAPTER XII. NORMAL OR PLAIN" COLLODION", IODIZED COLLODION, BROMO* IODIZED COLODION". 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 gravity, .715 1000 part3 by 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 directed. 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 may be as low as thirty-six or forty parts of the prepared cotton. Normal collodion for present use may be filtered ; but it is far from being as pure by filtration as by subsidence. Filte rs for such 80 NORMAL OR PLAIN COLLODION. 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 film on the glass plate. Bromo-idiozing Solutions for the same. Take of Alcohol, (absolute,) 100 parts. " Iodide of sodium, 8 " u Iodide of cadmium, 8 " " Bromide of cadmium, 4 " Or, Take of Alcohol, (absolute,) 100 parts. " Iodide of lithium, 10 " " Bromide of lithium, 5 " Or, Take of Alcohol, (absolute,) 100 parts. " Iodide of lithium, 6 " " Iodide of cadmium, 6 " " Bromide of cadmium, 2 " Or, Take of Alcohol, (absolute,) 100 parts. " Iodide of cadmium, .... 10 " " Bromide of ammonium, ... 5 " 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- ness. 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 formula?. Formula of Lieut,- Colonel Stuart Worthy. Ether,' 1 ounce. Alcohol, .802, ....... 2i " 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 NORMAL OR PLAIN COLLODION. 81 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. OmmegancUs Formulas for Portraits and Landscapes. For Portraits of short exposure. Ether, 667 parts. Alcohol, 333 " Iodide of ammonium, .... 6 " Iodide of cadmium, .... 6 '* Bromide of cadmium, .... 3 " Pyroxyline, 12 " This collodion is sure to be thick enough ; if too thick, however, it can be rendered more fluid by the addition of an 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, Views, and Direct Transparent Positives. Ether, 667 parts. Alcohol, 333 " Iodide of zinc, 6 " Iodide of cadmium, .... 6 " Bromide of cadmium, .... 3 " Proxy line, 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 alcohol, and dissolve them by frequent shaking ; next add the ether and mix ; finally introduce the pyroxyline in small flocks at a time, and shake until the cotton is dissolved. After the solution is eflected 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. Formulas of Disderi. NO. I. — COLLODION FOR WINTER. First Formula. Alcohol — spec. grav. .813, . 4000 grains. Ether, " " .720, . 6000 " Pyroxyline, 110 " Iodide of ammonium, .... 60 " Iodide of cadmium, .... 40 " Bromide of ammonium, ... 6 " Bromide of cadmium, .... 4 " Iodine, 5 " 82 NORMAL OR PLAIN COLLODION. 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 oi two, and then either decanted or filtered. COLLODION FOR SPRING. Alcohol, (as before,) . . . 5000 parts. Ether, . " 5000 " Pyroxyline, 100 " Iodide of ammonium, . ... 50 " Iodide of cadmium, .... 50 u 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 " COLLODION FOR SUMMER. 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. NORMAL OR PLAIN COLLODION. 83 Formula for Copying Collodion. Alcohol, (absolute,) . . . 5000 grains. Ether, .720, 5000 Iodide of cadmium, .... 100 Pyroxyline, from . . . 75 to 100 Iodine, 2 The collodion film, whether iodized or bromo-iodized, 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-iodizers, and then to sensi- tize the film in a bath as follows : As soon as withdrawn from this bath, the collodion plate is 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 exist — 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 accesso- 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 most of the other silver salts are obtained, and is besides a very costly article, and deserves therefore to be treated with all due respect. Hence the following chapter is devoted to its service chiefly. Distilled water, Alcohol, . . . . Iodide of ammonium, Iodide of cadmium, . Iodide of zinc, . . Bromide of zinc, 100 parts. 25 " 2 " 4 " 2 " 2 " CHAPTBE XIII. SILVER SALTS OF SILVER. Silver.*— Symbol, Ag. Combining Proportion, 108. Spec, gra v., 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. , 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 black 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 quantity. 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 water, 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 off out of SILVER SALTS OF SILVER. 85 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 cupellation, 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 exhibit s 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 laminaB, 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 vessel 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- 86 SILVER SALTS OF SILVER. 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 washed by repeatedly filtering pure hot water over it, until a drop no longer produces a blue tinge with ammonia. The chloride is now dried. Next 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 chlori'de 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 lead 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- ent. Chloride of silver may be reduced, also, by fusing it with SILVER — SALTS OF SILVER. 87 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 ores or residues. Moisten the chloride with dilute hydrochloric acid, and immerse a plate of zinc in the moistened mass for several hours. Decomposition will gradually take place, the silver being deposited, whilst the soluble chloride of zinc is formed. After 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 with 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 jt 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 fine 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 crystallized. In every case where the salt thus obtained is intended for 88 SILVER — SALTS OF SILVER. 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. Properties, 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, 6xygen 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, N0 5 , 2NH 3 , denom- inated ammonio-nitrate of silver, which by evaporation is obtained in the crystalline form. Photographic Properties of the Nitrate 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 SILVER SALTS OF SILVER. 89 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, T3hysico-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 grounds, 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-ba*h 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 bath 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 base, is. in all probability, equally sensitive ; but this sensitiveness is 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 90 SILVER SALTS OF SILVER. many points have to be taken into consideration before normal conditions can be isolated or legitimate deductions drawn. 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 NH 3 in fine transparent crystals. Hyposulphite of Silver. — This combination is obtained by the 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 ; » 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 in solution is added to a solution of iodide of potassium or SILVER — SALTS OF SILVER. 91 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-JBath. — 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 use. 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. 92 SILVER — SALTS OF SILVER. 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 lace, and a dense curdy precipitate falls gradually to the ottom. 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 SILVER SALTS OF SILVER. 93 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 preceding. 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. CHAPTER XIV. REDUCING AGENTS — DEVELOPERS. 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 gas. Heat a mixture of charcoal and oxide of lead REDUCING AGENTS — DEVELOPERS. 95 in a crucrble, 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 sium, 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 bla^k 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 96 REDUCING AGENTS — DEVELOPERS. 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 pure 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 recombine instantaneously and reproduce the vapor of water. Other analogous inversions of chemical af- finity are known to the chemist. REDUCING AGENTS — DEVELOPERS. 97 Iron Developer. Iron. — Symbol, Fe. Combining Proportion, 28. Spec. Grav., 7.8 Protoxide of Iron.— Symbol, FeO. " " 36. Sesquioxide of Iron.— Symbol, Fe2 0 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 up 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, N 0 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, S O3, H 0 + 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 98 REDUCING AGENTS — DEVELOPERS. 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 Avhite 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. Preparation. Take equivalent proportions of sulphate of iron and sul- phate of ammonia, that is, 139 parts of the former to 15 oi 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 acid. 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- drosulphuric acid, which is by far the most valuable reagent in chemistry. Preparation. 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 REDUCING AGENTS — DEVELOPERS. 99 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 be collected or used immediately by 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 tannin; and from its power of combining with metallic bases, and forming precipitates, etc., it is regarded 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, C54H22O34. Gallic Acid.— Symbol, C 14 H fi O ]0 . Pyrogallic Acid. — Symbol, C 6 H 3 0 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 100 REDUCING AGENTS — DEVELOPERS. 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 bitter. It is soluble in water and alcohol, but sparingly soluble in ether. With mineral acids, albumen, gelatine, salts 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 precipitate. 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 chapter. 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 substance. Mix 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- REDUCING AGENTS DEVELOPEKS. 101 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 metagallic acid, being the black shining residue left in the retort. Pyrogal- lic acid, at the proper temperature, is in like manner decom- posed into metagallic' acid and water. 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 102 REDUCING AGENTS DEVELOPERS. 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 Solutions. The solution of protosulphate of iron, or of pyrogallic acid, is frequently much more energetic in reduction 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 proper 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 exposure 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 photograpl lers REDUCING AGENTS — DEVELOPERS. 103 may be 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. Now 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 0 3 HO. Combining Proportion, 60. Specific Gravity, 1.063. 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 nart of the sour liquor 104 REDUCING AGENTS — DEVELOPERS. 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 of lime, 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 liquor, 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 water, 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, C 2 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 ethyl e 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 wood-spirit, a substance very analogous to alco- hol. This acid can be obtained by distilling ants in water. It is an organic acid, however, which 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 REDUCING AGENTS DEVELOPERS. 10£ 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 place. Citric Acid. Symbol, C 12 Ho 0 n + 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. 106 REDUCING AGENTS DEVELOPERS. Preparation. Take ten ounces of expressed lemon-jtiice ; 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 water ; 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 tribasic, 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 impurity in this sub REDUCING AGENTS — DEVELOPERS. 107 Stance is malic acid, and sometimes aconitic acid. Citric acid is recognized by its producing 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 O 10 + 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 wine from which it is deposited dur- ing fermentation. Preparation 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 108 REDUCING AGENTS — DEVELOPERS. 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. CHAPTEE XV. THE NITRATE OF SILVER BATH. Nothing 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 rules 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 oily 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 with 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 110 THE NITRATE OF SILVER BATH. 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 ounce of water, or from 8 to 10 per cent. Formula No. 1. Nitrate of silver, (recrystallized,) . . 3 ounces. Distilled or pure rain-water, 36 ounces. Washed iodide of silver, 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 of 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= THE NITKATE OF SILVER BATH. Ill dions, containing, as they generally do, cadmium salts, the following bath will be found to be quite effective in produc- ing good results : Formula No. 2. Nitrate of silver, (recrystallized,) . . 3 ounces. Distilled or rain-water, 36 ounces. Iodide of silver, (washed,) .... 6 grains. Mix as before, and filter without boiling. For each ounce of nitrate of silver add one drop of nitric acid. This amount will probably be 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 No. 3. Nitrate of silver, (recrystallized,) . . 3 ounces. Distilled, or pure rain-water, . . . .36 ounces. Iodide of silver, (washed,) . . . . . 6 grains. Prepare as before, 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 160 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- tive. In summer the bath need not be so strong in nitrate of sil- ver as given in the preceding formulas. Six or seven grains a>f 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 cold. When 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- 112 THE NITRATE OF SILVER BATH. 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 suck 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 unstable. 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 w T here 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- THE NITEATE OF SILVER BATH. 113 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 glass 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, ^hat the sides and the bottom of the vessel are perfectly clean before the solu- tion is poured back again. A long 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 fluid' is again introduced. This exposure to the rays of the sun, 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 glass eva- porating dish, much of the superfluous ether and alcohol will pass off in vapor, and thus produce a remedy for another evil which an old bath invariably gives rise to, namely, that of causing oily-looking stains and streaks on the surface of the film. Where the trouble of recrystallizing 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 fused mass on a silver or marble plate, as directed in the manufacture of 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. CHAPTER XV L THE DEVELOPING SOLUTIONS. In the ordinary, or wet-collodion process, there are three Developing Solutions, the Protosulphate of Iron Developer, 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. 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 may be 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 Rain-water, Acetic acid, Alcohol, . 4 ounces. 3 drachms. 2 drachms. THE DEVELOPING SOLUTIONS. 115 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 mix as before. A negative requires a longei 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- sition. Formula No. 3. For Negatives. Pyrogallic acid, (pure,) . . ■ . te grains. ) N x g j . Acetic acid, 2 ounces. ) Shake the solution well, and keep in a dark place. Of No. 1 Solution, .... 2 drachms. ) XT now Distilled water, 14 drachms. \ Na 2 Solutlon ' 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. ) Divide into doaes of 2 grains. Citric acid, .... 24 grams. ) ° When 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. DisderVs Developer. Sulphate of the protoxide of iron, ... 4 drachms. Water, 12 ounces. Acetic acid, 4 drachms. 7 116 THE DEVELOPING SOLUTIONS. Lieut.- Colonel Stuart Worthy's Developer. Sulphate of iron, 20 ounces. Distilled water, 120 ounces. Dissolve. Acetate of lead, ounce. Water, 5 ounces. Dissolve. 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, 1-J " 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 W Or the preceding formula may stand as follows : Sulphate of the protoxide of iron, 69 grains. Sulphate of ammonia, 3Y " Water, 24 ounces. Acetic acid, 4 to 8 drachms. Alcohol, 4 drachms. HocJciri's 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 plate. WaldacJc's Formulas for Collodion Positives. Formula No. 1. For Bead -Whites. Sulphate of iron, 3 drachms. Water, . 6£ ounces. Acetic acid, 4 drachms. Alcohol, 3 drachms. Nitrate of potassa, ... 30 grains. THE DEVELOPING SOLUTIONS. 117 Formula No. 2. For Brilliant and Metallic Whites. Sulphate of iron, 85 grains. Water, 6J ounces. Acetic acid, 1 drachm. Alcohol, 1£ drachms. Nitrate of potassa, 30 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. CHAPTEE XVII. FIXING SOLUTIONS. Fixing solutions consist of chemical substances that dis- solve the sensitized salts of silver on plates or paper, on which photographic 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- nium. Cyanogen. Symbol, C 2 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- FIXING SOLUTIONS. 119 composed when exposed to light into a variety of ammonia- cal compounds. By the pressure of four atmospheres it i& 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- les by the superior affinity of the mineral acids for their oases 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 does not precipitate 120 FIXING SOLUTIONS. the chloride of silver, hydrosulphuric acid alone being capa bie 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 iron, 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 Meynier 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. Hyposulpfdte of Soda. . Symbol, N 4 0, S 2 0*. 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 FIXING SOLUTIONS. 121 ^u,te, 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 with 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 No. 1. Fixing Solution with Cyanide of Potassium. Cyanide of potassium, 1 drachm. Rain-water, 4 ounces. Formula No. 2. Fixing Solution with Hyposulphite of Soda. Hyposulphite of soda, 2 ounces. Water, 4 " Formula No. 3. Fixing Solution with Sulphocyanide of Ammonium. Sulphocyanide of ammonium, 1 drachm. Water, 12 ounces. CHAPTER XVIII. INTENSIFIEKS. Intensified 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 ; but 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 with 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 INTENSIFIERS. 123 of action. The iodine thus coming 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; if 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 m the power of the artist ; success, therefore, a\ ill 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- 124 INTENSIFIED. formly higher, until the shadows become endowed with a proper opacity. At the end of this stage fixing solutions have but li /tle 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. AH 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 experiments 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 probably 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 maybe 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. Vol. XV. No. 1. INTENSIFIERS. 125 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 Sublimate. 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 Sulphuris. Symbol, K &. 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 wiiich frequently the metalfl 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 126 INTENSIFIED. 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. CHAPTER XIX, WET COLLODION PROCESS. If the collodionized plate, after sensitization in the silver bath, 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 negatives. Collodion Positives — Tlie Melainotype — The 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 gre&t 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, thereftr e, is limited to portraiture. 128 WET COLLODION PROCESS. Ambrotype. 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-house, 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 chopping-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. Next 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 WET COLLODION PROCESS. 12S 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. ISTow 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 with a 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. A 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 surface is cleaned in like manner. 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, go 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 130 WET COLLODION PROCESS. 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 every 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 £he 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- terials. Third Subdivision. 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 WET COLLODION PROCESS. 133 antil the collodion has a yellowish-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 Subdivision. 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 plate-holder ; raise or remove its 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. Now 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- 132 WET COLLODION PROCESS^ hand corner between the thumb and the finger. In tnis 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 dish, 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 then 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, foi 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 drachms. 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 see, moreover, whether the relative conditions of the collodion and the ;ilver-bath are in good working order, by the mode in whicb WET COLLODION PROCESS. 133 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. — Fixing Solution. Formula. 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, and the picture is offensively black, the 34 WET COLLODION PROCESS. 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 carrying 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 and 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 eyil 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* "WET COLLODION PEOCESS. 135 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 corner, 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- velouer above given. Some tastes are more gratified with a more subdued contrast in which 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 be found practicable. 136 WET COLLODION PROCESS. Formula JVb. 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. Mix intimately, and filter before using. Prepare fresh every day. 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 coloring 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 may be applied carefully, in order to remove the unevenness, or the want of brilliancy. WET COLLODION PROCESS. 137 Varnishes for Collodion Pictures. Formula No. 1. Copal, 1 ounce. Pure benzole, 15 ounces. Dissolve and filter through Swedish or ordinary filtering paper. Formula No. 2. White stick lac, 3 ounces. Picked sandarac, 3 drachms. Alcohol, spec, grav., .815, . . . 40 ounces. Oil of bergarnot, 6 drops. Dissolve the resins in the alcohol by means of a water-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 off the supernatant liquid, which, when clear, is ready for use. The collodion plate must be quite dry and cold when this varnish is applied, and the lat- ter is allowed to dry spontaneously. 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 138 WET COLLODION PROCESS. 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 possible 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 surface 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 JSFo. 1. For Black Varnish. Oil of turpentine, 50 ounces. Asphaltum, 2 ounces. Canada balsam, 4 ounces. Formula N~o. 2. For Black Varnish. Benzole or coal-tar naphtha, . . 50 ounces. Asphaltum, 2 ounces. India-rubber, -J- drachm. Formula No. 3. For Black Varnish. Camphene, 50 ounces. Pulverized bitumen, 10 ounces. White wax, 2 ounces. Lampblack, 1 ounce. Mix these ingredients together, and dissolve by a gentle heat ; afterward filter and preserve in a well-corked bottle. WET COLLODION PROCESS. 139 Varnish with bleached Shell-lac. Formula. 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. For muli. 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 lavender, 3 ounces. Alcohol, . .28 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 place 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. 8 CHAPTER XX. ALABASTRINE POSITIVES. 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 line 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 whites 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. Formula. 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 film 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. ALABASTRINE POSITIVES. 141 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. CHAPTER XXI. MELAINOTYPE EERR OTYPE . The melainotype takes its name from the black background upon which it is taken. Ferrotype from the iron of which it is composed. Very 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 far 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. Operation. 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 ol 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- MELAINOTYPE FERROTYPE. 143 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 olf 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 anibro- 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. i CHAPTER XXIL COLLODION NEGATIVES. A collodion 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 versd. 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 COLLODION NEGATIVES. 145 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 arc dark and opaque ; lights are thin and transparent.) We 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- tive. Negative Developers. Formula No. 1. Iron Developer. Sulphate of the protoxide of iron, 4 drachms. Rain-water, 8 ounces. Acetic acid, . 1^ ounces. Alcohol, .6 drachms. 146 COLLODION NEGATIVES. Formula 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. COLLODION NEGATIVES. 147 Fixing Solutions for Negatives. Formula No. 1. Hyposulphite of soda, .... 5 ounces. Water, 10 ounces. Formula No. 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- cess. Intensifying or Redeveloping Process. Formula No. 1. Depositing Fluid. Iodine, 1 grain. Iodide of potassium, 1 grain. Rain-water, 1 ounce. Formula No. 2. For the 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 again. Intensifying Operation. Formula No. 1. Nitrate 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. 148 COLLODION NEGATIVES. Formula No. 2. Pyrogallic Acid. (Stock) Pyrogallic acid, . . 12 grains. ) ^ . , , , 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 No. 3, add ten drops of No. 1 ; mix iiiti* niately by shaking, and then pour it upon the plate, and keep it in agitation. The shades will soon increase in blackness and opacity. The operation 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 film 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 COLLODION NEGATIVES. 149 must be 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. CHAPTER XXIII. TRANSFER PROCESS OF COLLODION POSITIVES ON JAPANNED LEATHER, LINEN, PAPER, ETC. 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. Black Japan. Chloroform, . 8 ounces. Asphaltum, 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 with 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 TRANSFER PROCESS OP COLLODION POSITIVES. 151 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 with 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, 8 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 152 TRANSFER PROCESS OF COLLODION POSITIVES. allow the mixture to settle for a few days. It is afterward decanted into a dish. Ordinary unruled fine paper, in pieces of the proper size, is floated on this bath, 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. CHAPTER XXIV. COLLODION POSITIVES ON GLASS BY TRANSMITTED LIGHT. Transparetit Positives, 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 wood, 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 glass 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 154 COLLODION POSITIVES BY TRANSMITTED LIGHT. 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 afterward 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 eollo- 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- tinct. 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 shado ws than for 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. COLLODION POSITIVES BY TRANSMITTED LIGHT. 155 Varnishing, it is true, will also reduce the amount of density in the shadows, but 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 be on the right side of the glass, erect and free from lateral in- version. If it were fixed otherwise, then the positive would be 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 with 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 off the mercury, and wash the plate -in rain-water. 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. Kain-water, 2 ounces. Nitrate of silver solution, (50 grains to the ounce,) as it>ng 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 salt. Formula No. 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 tc 156 COLLODION POSITIVES BY TRANSMITTED LIGHT. 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 transparent 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 CHAPTER XXV. ENLARGEMENT OF NEGATIVES BY THE ORDINARY CAMERA. Having obtained a sharp transparent positive, it is evident that, by a reverse process, a negative may be reproduced, and of course as many negatives as may be required. It is thus that photographic negatives may be stereotyped. Not 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. With 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. Nor is ft 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 magnitudes. 158 ENLARGEMENT OF NEGATIVES. of light, so that with a given light the exposure must be so much the longer. In such cases, 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. Reflectors 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 inches; the length of either side is 21 T 5 ^ 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 fall 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. CHAPTER XXVI. TRANSPARENT POSITIVES BY CONTACT BY THE WET PROCESS. In this 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, and close it again. Probably this may be too much exposure, 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. Whereas in the man- ner prescribed, vertical rays alone are admitted to the bot- tom, and entering perpendicularly are not refracted. CHAPTER XXVII. COLLODION" NEGATIVES OR POSITIVES COPIED FROM COLLO- DION OR PAPER POSITIVES. 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 of 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 either 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 COPYING PHOTOGRAPHIC PRINTS. 161 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 boundaries 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 copy, 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 melainotype 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 162 COPYING PHOTOGRAPHIC PRINTS. 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- ple 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 expu- COPYING PHOTOGRAPHIC PRINTS. 163 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, but 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 mismanagement. 9 CHAPTER XXVIII. STE R E 0 GRAPHIC NEGATIVES AND LANDSCAPE PHOTOGRAPHY, 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 process. 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 o the pictures 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 STEEEOGRAPHIC NEGATIVES. 165 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, we 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 mounted 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 of ten 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 166 STERE O GRAPHIC NEGATIVES. 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 Stereographs. 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 in this department, that of Instantaneous Ac- STEREOGRAPHIC NEGATIVES. 167 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 communicative. 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 ; the atmosphere very clear / the glass very clean / 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 bounds. Instantaneous Process of Lieutenant- Colonel Stuart Wbrtley. The pyxoxyline is first steeped in the iodo-bromized alcohol, and the ether then added. Iodized by leaving a couple of coated plates in the bath for several hours ; acidified at the rate of from two to three Collodion. Ether, Alcohol, spec, grav., .802, Iodide of lithium, . . . Bromide of lithium, . . 1 ounce. . 2£ ounces. 15 grains. . 6£ grains. Silver Bath. Re-crystallized nitrate of silver, . 35 grains. Distilled water, 1 ounce. 168 STEREO GRAPHIC NEGATIVES, 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. Develope? Sulphate of iron, 2 ounces. Distilled water, 12 ounces. Dissolve, Acetate of lead, 24 grains Water, 2£ ounces Dissolve. Mix the above solutions, and when the precipitate has all settled, decant off 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. Intensijier. 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 off 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 varnish. 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- STEREOGRAPHIC NEGATIVES. 169 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 3 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 ro 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, 9J- ounces. Alcohol, i ounce. This is kept on the plate until the operation is complete, Claudets Developer. Pyrogallic acid, 20 grams. Distilled water, *l\ ounces. Formic acid, 1 ounce. Alcohol, 6 drachms. Instantaneous Shutters. The means by which light is cut off instantaneously, which means very quickly, are various, and many of them are very ingenious. Some of these shutters are behind the posterior 170 STEREOGRAPHIC NEGATIVES. 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 shutter. In very many cases, with 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 re- 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. CHAPTER XXIX. NEGATIVES ON PAPER. These comprehend the Talbotype or Calotype, and the Wax-Paper Process of Legray, and its modifications. The 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 potassa. 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. 112 NEGATIVES ON 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. Next float it in Iodide of potassium, ..... I drachm. Distilled water, 2-J- 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-J 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 th.e 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 JVec/ative. Immerse the prints in a solution of bromide of potassium of ten 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, Tillard, etc. Amongst all these improvements and extensions the wax-paper process of Legray is the most extensively employed. For tourists NEGATIVES ON PAPER. 11S 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 silver. 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 wax, 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, maybe 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 174 NEGATIVES ON PAPER. 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 ammonium, 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- tles. 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 may be suspend- ed on a line by clamping each upper corner by means of a clothes-pin. Great care is required so as not to produce any wrinkle or crease in the papers in any of these operations. Several iodizing solutions have been proposed; the folic wing with whey 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-six grains of isinglass to each pint of rice-water, and the mix- ture is again boiled. NEGATIVES ON PAPER, 175 Whey* or serum, . . Sugar of milk,f . . Iodide of potassium, . Bromide of potassium, 25 ounces. 4 drachms. 3 drachms. 48 grains. To the first of the two preceding formulas, containing rice- water, 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 ; but 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 waxed 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, ... 7 drachms. Glacial acetic acid, 7 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 begins 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 lactin, 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, and 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. 176 NEGATIVES ON PAPER. moist. In this condition it may be placed between twc 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 View, 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 hour** In extreme cases the develop- NEGATIVES ON PAPER. Ill ment 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 ; filter 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 clear. 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. Th6 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 Champlouis 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 with 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 NEGATIVES ON PAPER. great rapidity on every part simultaneously, and soon as- sumes a uniform shade which takes away all contrast. For this there is n ? 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. Kain-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- ting-paper. 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. Geoffray^s Process with Cerolein for taking Paper Negatives. The author separates the cerolein from the myricin and serin of bees-wax as follows : Dissolve five ounces of yellow or white wax in ten ounces NEGATIVES ON PAPEE. 179 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 foi; five minutes or so. They are then sensitized, when dry, in the following bath : Nitrate of silver, 1 drachm. Nitrate of zinc, 2-J 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 180 NEGATIVES ON PAPER. 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 ammonium. When dry and about to be used, float each sheet on the following bath : Distilled or rain-water, .... 6 ounces. Nitrate of silver, 3-J- drachms. Nitrate of zinc, . H " Acetic acid, . " 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 Prichard. 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 NEGATIVES ON PAPER. 181 way, and, with a glass rod, spread over the paper a solution composed of 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. Now 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- ting-paper. 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. Nitrate of silver, Distilled water, Glacial acetic acid, 28 grains. 1 ounce. 10 drops. CHAPTER XXX. POSITIVE PRINTING. Printing on Plain Paper, on Albumenized Paper, on Arrow-Root 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 secondary, 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, POSITIVE PRINTING. 183 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, chlorinetted 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- tine. 184 POSITIVE PRINTING. Albumen. This substance derives its name from the white 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 ether. So dried, it swells up when put in water and finally dissolves. Before it is dissolved, it 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, Hydrogen, 53.5 1.0 15.5 22.0 0.4 1.6 Nitrogen, Oxygen, Phosphorus, Sulphur, . , 100.0 POSITIVE PRINTING. 185 Common dried albumen, not obtained by precipitation, con- 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 albumen print. Gelatine. 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 moist 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 ot being j>recipitated 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 in 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 effected. Ammo* 186 POSITIVE PRINTING. nia is iv variably one of the products, and among other pro- ducts wa may count sugar of gelatine or glycocine and leu- cine. Dry gelatine is found to contain in one hundred parts : Carbon, 50.05 Hydrogen, 6.47 Nitrogen, 18.35 Oxygen, 25.13 100.00 Amylaceous or Non-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 far as regards chemical equivalents, sometimes not dif- fering at all ; for starch, dextrin, arrow-root, gum-tragacanth, cellulose ; amidin, all contain the same number of equivalents of carbon, hydrogen, and oxygen, and are all resolved into saccharine substances by treatment with acids. Starch. 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* nacea, growing in the West-Indies. The size of the granule P0SIT1VJE PRINTING. 187 varies from w ^ to -^jo parts of an inch in diameter. Each granule 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 quantity 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- ing. Gum- Arabic. 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 O 3 . Combining Proportion, 221. Terchloride of Gold. — Symbol, Au Cl 3 . Combining Proportion, 303. 10 188 POSITIVE PRINTING. 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 Cl 3 + 5 Aq. Aurochloride of Sodium. — Na CI. Au CI3 + 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 POSITIVE PRINTING. 189 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 ether. 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 decantation. 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 uran- mica or chalcolite, and as uranite in combination with lime and phosphorus. Uranium.— Symbol, U. Combining Proportion, 60. Sesquioxide of Uranium. — Symbol, U 2 0 3 . Combining Proportion, 144. Nitrate of the Sesquioxide of Uranium. — Symbol, U 2 0 3 , NO 5 . Combining Proportion, 198. 190 POSITIVE PRINTING. 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 crystallized. 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 ter chloride of gold. 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 0 3 + 6 HO. Citrate of Soda.— Symbol, 3 Na 0, C 12 H 5 On. Phosphate of Soda.— Symbol, 2 Na 0, HO. P0 5 . Carbonate of Soda. Symbol, Na 0, C0 2 . 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- POSITIVE PRINTING. 191 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 aurochlorides ; and on this account its em- ployment in the toning-bath is more reliable and to be re- commended. Chloride of Ammonium. — Symbol, NH 4 CI. Combining Proportion, 52. Chloride of Sodium. — Symbol, Na 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 is 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 gallic acid, have been already described. We shall, therefore, proceed to the mi- nutiae of the manipulation of positive printing by contact* CHAPTEE XXXI. MANIPULATION OF POSITIVE PRINTING. Preparation of Salted Paper. For 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 are 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 No. 1. Chloride of ammonium, .... 100 grains. Distilled water, 10 ounces. Formula No. 2. Chloride of ammonium, .... 100 grains. Distilled water, 10 ounces. Gelatine, 10 grains. Formula No. 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 MANIPULATION OF POSITIVE PRINTING. 193 before use. The object of the citrate is to give a slight i*osq 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. Next, 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. When 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 there for 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 sidea 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 finger 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. 194 MANIPULATION OF POSITIVE PRINTING. 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 use. 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 nlbumen does not attach itself easily to the paper, and in this case, although a sheet has been thoroughly floated, and with- 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- MANIPULATION OP POSITIVE PRINTING. 195 ment the sheet lies uniformly and without bubbles on tho 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, which, 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 : Formula. 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, 196 MANIPULATION OF POSITIVE PRINTING. 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 keep, but they are best when fresh. Sensitizing JBath. The preparations for sensitizing are divided into two class- es, one containing essentially nitrate of silver, ^nd 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. Rain-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 point, namely, at about 70 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 20 grains to the ounce. The papers are floated on the fluid for five minutes, then MANIPULATION OF POSITIVE PRINTING. 197 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 Ammonio- Nitrate Silver Solution, 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 bath 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 Nitrate of silver, Rain-water, . Alcohol, . . 2 ounces. 8 ounces. 1 ounce. 198 MANIPULATION OF POSITIVE PRINTING. particles that might be left. The strength of this bath, like any other, has to be kept up 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. Fuminating 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. Next prepare the fuminating 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 were 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 with the lateral shelves, screw on four narrow slips of inch stuff, on which can rest a board three feet long and two feet w^ide ; 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 has 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 may be made to close the top of the box or open it when required. On the top of MANIPULATION OF POSITIVE PRINTING. 199 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 be opened at a time. The wood of which these doors are constructed must be 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 upon the inside of each door by sticking a pin obliquely into each corner, with the albumenized 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. When 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 exposed 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 for printing. It lias been asserted that there is a great saving 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. CHAPTEE XXXIL THE PRINTING OF SENSITIZED PAPER. 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 THE PRINTING OF SENSITIZED PAPER. 201 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 still 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 lights have become slightly tinged by reduction, or when bronzing 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- possible 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 glass, examine the points separately, rejecting each in which there is a decided failure, and cut off all extraneous parts that are certainly not required when mounted, allow- ing, of course, always sufficient margin for the final trimming. Next throw each print separately into a pail or tub of water, taking care that its surface comes in contact with the water, without the intervention of bubbles. Keep the prints in mo- 202 THE PRINTING OF SENSITIZED PAPER. tion by turning them over and 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 w T ater 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 tank. Formula No 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 No. 2. Double chloride of gold and potassium, 2 grains. Distilled water, 3 ounces. Carbonate of soda, 3-5 grains. Formula No. 3. Chloride of gold, 1 grain. Distilled water, 8 ounces. Chalk to neutralize the acidity. Chlorinetted lime, 5 grains. Alcohol, 2 drachms. Formula No. 4. Gold and TTranium. ( Chloride of gold, (pure,) ... 1 grain. No. 1. •< Distilled water, 4 ounces. ' ( Chalk to neutralize the acidity. S Filter each ( Nitrate of uranium, .... 1 grain. ) and then mix. No. 2. •< Distilled water, 4 ounces. ( Chalk to neutralize the acidity. Formula No. 5. Chloride of gold, .2 grains. Distilled water, 8 ounces. Phosphate of soda, 100 grains. Neutralize with chalk. Formula No. 6. 'Chloride of gold, (pure,) . . 2 grains. Distilled water, 4 ounces. No. 1. < Carbonate of soda to neutralize the acidity, Phosphate of soda, .... 2 grains. Acetate of soda, 2 grains. ( Nitrate of uranium, .... 2 grains. No. 2. < Distilled water, 4 ounces. ( Chalk to neutralize the acidity. Filter the latter and mix. THE PRINTING OP SENSITIZED PAPER 20S 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 carbc n- 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, and can 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 satisfactorily. 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 formulae ; 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 No. 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. Fixing Solution. Hyposulphite of soda, Water, Alcohol, .... 2 ounces. ) 12 ounces. > Slightly warm. 4 drachms. ) 204 THE PRINTING OF SENSITIZED PAPER. 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 has 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 prints 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, where 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- THE PRINTING OF SENSITIZED PAPER. 205 liient 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 fresh water 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. Now 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 206 THE PRINTING OF SENSITIZED PAPER. 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 mounting-table. 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 down 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 w^ith 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 a 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- tures. 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, wherever such particles are discovered ; and to obviate the repetition of such THE PRINTING OF SENSITIZED PAPER. 207 troubles or dimmish 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 Prints. 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 pressed 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 Jie 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 is more advantageous to dispose of the unreduced refuse than to perform the operation of reduction one's self. Mounting Stereographs. 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 side 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 glass ; with a sharp penknife go round the edges, taking care to press the glass form firmly on the prints. In 208 THE PRINTING OF SENSITIZED PAPER. this way the pair of stereographs will be 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 be 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 fbr 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. CHAPTER XXXIII. bertrand's new process for positive printing. Saxony 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 *s thus protected against the greatest, if not the only cause of deterioration. Besides this, benzoin communicates 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 bertrand's new process. 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 pari 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 Pesinized 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, y Dissolve. Gum mastic, 10 grains. J Nitrate of silver, 960 grains. ) Distilled water, 4 ounces. J 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. bertkand's new process. 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. 11 CHAPTER XXXIV. PRINTING BY DEVELOPMENT. 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. JSFo. 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. PRINTING BY DEVELOPMENT. 213 Formula for Developing Solution. 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 be 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 Bromide. 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 214 PRINTING BY DEVELOPMENT. 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, 3 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, 6 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 PRINTING BY DEVELOPMENT. 215 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. i Nitrate of silver, ........ 44 grains. Distilled water, 2 ounces. {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. Formula. Distilled water, 25 ounces. Aceto-nitrate of silver solution, .... 4 drachms. The solution of aceto-nitrate of silver is prepared as fol- lows 216 PRINTING BY DEVELOPMENT. Nitrate of silver, Acetic acid, . , Distilled water, 1 ounce. 2 ounces. 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 : The papers are floated on this bath for three minutes, and Jien 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- posure 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. 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 JSfiepce 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 : Distilled water, Nitrate of silver, Acetic acid, . 25 ounces. 18 grains. 2 scruples. Chloride of gold, 2 grains. PRINTING BY DEVELOPMENT. 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. JVo. 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 time. Developing Solution. JSTo. 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 JBath. 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 drv„ CHAPTEE XXXV. THE CARD-PICTURE. 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. THE CARD-PICTURE. 219 Lenses for the Card-Picture. Lenses for the card-picture are prepared with great care, so as to produce as little distortion as possible in 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. Development. 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 surface 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- 220 THE CAED-PICTURE. 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 developing 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- dency to these horrid£>m-Aofes 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 present 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 THE CARD-PICTURE. 221 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 part. In fine, no general rule is known by which a priori these pin-holes can always he 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. Fixing. 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 b^ath. 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 222 THE CARD-PICTURE. 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 THE CARD-PICTURE. 223 in front of the direct rays of the sun, whereby a great con- densation of light can be effected on any given surface. 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// T an ^ ^IfW DV this ratio, that is 4, we obtain 59^^ and 85 inches for the length of the upper or larger base, and 86 T \ 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 sixty 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 be 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 which would act upon 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 6ize, and paint either with water or oil colors the vignette 224 THE CARD-PICTURE. opening in orange or black, shading off toward the edges ; fill up the remaining part with white paint, shading the edges bordering on the vignette gradually deeper and deeper, unti) 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, Fixing, 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 side. 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 surface requires no preparation. For the ordinary photographic practitioner in card-pictures they are to be highly recom- mended. 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 THE CARD-PICTURE. 225 with how few colors the real artist can execute the most fin- ished work. The Colors used most frequently. 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 sponge. 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 tile photograph. The question to be solved then is simply this : there are three differen t 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 subject 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 226 THE CARD-PICTURE. 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 j3i*e- 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 w T ith 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. THE CARD-PICTURE. 227 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 effect 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 bistre, 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 white and a little pink madder if the hair is of a pure black. - 228 THE CARD-PICTURE. Gray Hair. Cover tlie whole with a mixture of equal quantities of bis- tre and white ; the dark parts w^ith 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. White 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 pupil of the eye with Chinese white. All these final touches require great care and skill. The hand, the neck, the shoulders, 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 lights. Drapery. The handsomest drapery is black. The general wash is ivory black of the consistency of ink. This is laid on uni- formly with a full 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. THE CARD-PICTURE. 229 Blue Drapery. The general tint consists of Prussian blue, or indigo, as 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 Naples yellow or white in place of bistre for the lights. Rose - Colored Drapery. Rub 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. 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. Yelloio 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 230 THE CARD-PICTURE. dark p.xrts ; 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. Violet. 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. Background. The background must ux$ secondary in effect to the real object in the picture ; as a general rule, 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 proper 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 Metals, etc., with Color. The artist does not use the metals themselves in miniature painting ; it would be an insult to art to request their 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 THE CARD-PICTURE. 231 ground-work. The shades are made with a little neutral tint 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 stuffs, 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 entirely from the small work on this subject by Hilaire David.) CHAPTBE XXXVI. DRY COLLODION PROCESS DRY PROCESSES. 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 valley, 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 process. 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 DRY COLLODION PROCESS. 233 attain to a maximum of preservation of the sensitiveness for an indefinite time. It lias 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 itself. 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 Dr. Hill JVbrris's Process ; the Tannin Process of Major Pussell / and the Resin Process. The Albumen Process. This process was in use several years before that of collo- dion ; Niepce 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.) 234 DRY COLLODION PROCESS. 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. 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 they 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 and uniform film, and its uniform retention on the plate until dry. The plates, of course, must be perfectly clean in this process, as in every other for negative pur- poses. 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 Formula No. 2. The white of egg, Iodide of potassium, Bromide of potassium, Free iodine, . . . 10 ounces. 44 grains. 15 grains. 2 grains. DRY COLLODION PROCESS. 285 and 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. Pre'pare 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. Sensitizing the Film. An oblong flat porcelain or glass dish is preferred to the vertical 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. Nitrate of silver, 1 ounce. Acetic acid, 5 ounces. Distilled water, 10 ounces. Iodide of potassium 2 grains. 12 236 DRY COLLODION PROCESS. Lay the albumen plate along one side of the glass dish ; 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 w r ill 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 render 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. DRY COLLODION PROCESS. 237 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 under-exposed 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 Aveak 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- ing is required, because the albumen film is quite hard of itself. Taupenot Process — Collodio- 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 glass is a much better receptacle of the albumen than the glass 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-albvminous film re- quires but one sensitization. Some of these are found to be very effectual dry processes. 238 DRY COLLODION PROCESS. Preparation of the Glass Plates. These are first immersed for a number of hours in the fol- lowing solution : Salts of tartar, . 1 ounce. Kain-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 w^ith 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 batfr> 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 mixed 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 DRY COLLODION PROCESS. 239 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. Now 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 w r ater, 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. Exposure. 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 grains. Alcohol, 2 drachms. Acetic acid, \ drachm. 240 DRY COLLODION PKOOESS. To every three ounces of this solution add a solution of one grain of nitrate of silver, when about 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 taken 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 w r eaker 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 Larpey.) 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 Iodized 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- cated. Sensitizing Solution. Nitrate of silver, 60 grains. Acetic acid, 60 minims. Water, 1 ounce. The time required will be thirty seconds or thereabouts ; emove from the bath and wash thoroughly. DRY COLLODION PROCESS. 241 Exposure. This preparation requires about twice as long an exposure as wet collodion. Developer. 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. Fixing. 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 Collodio- 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. Wash again and allow to drain for one minute. Formida 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. 242 DRY COLLODION PROCESS. 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. Development. 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. Intensifying. 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 purpose. 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 b DRY COLLODION PROCESS. 243 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 off*, 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 off 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. 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 Solutior,. Fix the impressions in a bath of hyposulphite of soda ; wash, dry, and varnish. Citric acid, Water, . , Alcohol, . 1 grain. 2 ounces. 10 minims. feet. CHAPTER XXXVII. DR. HILL MORRIS'S PROCESS — GELATINE PROCESS. Make use of a non-contractile bromo-iodjized 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. Waiter, (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. DR. HILL NORRIS'S PROCESS. 245 The exposure, developing, and fixing are the same as in the preceding processes. Dr. Hill Norris'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- ver. 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 tnis way 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, with all sorts of collodion. Small plates need scarcely to be covered with gelatine. Gelatine Operation. To prepare a clear solution of gelatine, proceed as follows : Formula. Gelatine, 30 grains. Acetic acid, (glacial,) 6 minims. Water distilled, 10 ounces. 246 DR. HILL NORRIS'S PROCESS 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- ity. 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 wall 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. Alqphol, 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 speaking 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 DR. HILL NORRIS'S PROCESS. 247 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 upon the light and the nature of the collodion. Tannin, 15 grains. Distilled water, 1 ounce. Dissolve and filter through paper before 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 may be 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. Development. « , ( Pyrogallic acid, 72 grains. * 0, * ( Alcohol, 1 fluid ounce. Filter if there is any turbidity, otherwise not. 248 DR. HILL KOBRIS'S PROCESS. - ( Nitrate of silver, 20 grains. No. 2. -j Citric acid, 20 grains. ( Distilled water, 1 ounce. Filter if there is a white precipitate, otherwise not. Witfc No. 1 and No. 2 as stock bottles, proceed as follows : Dilute solution of ( Solution No. 1, . . . 1 drachm. ) ^ No. 1. \ Distilled water, . . . C ounces. \ For P resent use ' Of this dilute solution of No. 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. The 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- DR. HILL NORRIS'S PROCESS. 249 tages in sensitiveness. Mr. England's fornmia for collodion is as follows : To five parts of ether and three of alcohol, add sufficient pyroxyline 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- 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. This is the simplest of all dry processes, the discovery of Despratz. It consists simply in dissolving in the collodion about two and a half 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 Hardwich of Glycirrhizine for the same purpose. When thoroughly settled, add Resin Process. 250 DR. HILL NORRIS'S PROCESS. Sutton's Rapid Pry Process. The operations in this process, as furnished by Sutton, aro 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 keroselene. 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. 6. 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. 7. 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. Keends 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 washed, 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 DR. HILL NORRIS'S PROCESS. 251 with the excess of water off at this corner. Repeat the opera- tion once or twice. The last lot can be nsed 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 rain-water before it is developed. It is fixed and developed like any other tannin plate. CHAPTER XXXVIH. PRINTING OF TRANSPARENT POSITIVES BY THE DRY PROCESS. 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 effect- 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 PRINTING BY THE DRY PROCESS. 253 not absolutely necessary to use the cylinder ; the cylinder, nowever, 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 J_ v ~ 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 w, 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 is formed. 254 PRINTING OF TRANSPARENT POSITIVES Without going into a minute optical discussion, I will analyze the first formula so as to be 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. The 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 wall cross each other, and where they cross they will form a picture of the object. 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 BY THE DRY PROCESS. 255 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___l 1_ v ~ f ~~ u let f=12 inches, required the value of v and u when they are equal, or when the picture and object with the lens in question are of the same magnitude ? By transposition 1112 12 . —r= 1 — or -r7r== or a =24 inches. f 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 object. The principal focal distance of a single lens 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 1 1 1 2 1 * - ft • . 7"= 24 = ^4 = T2' ° r /==12 mcheS ' 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 we 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 256 PRINTING 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 ? L.M. P.F. L.M. INCHES. By proportion as 2 : 3 : : 5 : 7i the principal focal length required. In the proportion -i-rr— - -f -i, let u be n times larger than % ; required the proportion that f bears to u t 1 1 1 nv + v n + 1 f ~ v nv ~ ntf nv ° Y nv=f (n + l\ but u=nv u=f(n+l) and v =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 we 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. 0 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 tho image, or the sum of the two preceding. BY THE DRY PROCESS, 257 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 4^ 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 \\ 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 T 9 g inches apart, the ground glass is 40^- inches from the middle of the combination, and the object is consequently 5-^ 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-^ from the center of the combination, and the image only 5 T ^ 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. Microphotograpliy and Macropliotography. 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 flic-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- tography. 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 258 PRINTING OF TRANSPARENT POSITIVES 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 finaMy 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 pinion- wheels, etcetera. 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. Now, 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, supj>ose 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 BY THE DRY PROCESS. 259 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 were illumined by a condenser or reflec- tor, the picture could be taken only by focussing the cone or the beam of reflected light ; whereas we know full w^ell 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 manner, 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 focus 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 microscope I'd 260 PRINTING OF TRANSPARENT POSITIVES 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. How to find the point where the Lens is to be placed. It appears then that the lens may not be placed in any po- sition for maximum effect ; 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 consequently 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 effect can be obtained witli 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 BY THE DRY PROCESS. 2G1 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 which 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 photographers 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 t)f 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 r 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 262 PRINTING OF TRANSPARENT POSITIVES the luminous cone, excepting the violet, and ascertain when? the violet cone conies 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 permanent adjustment of the tube in reference to the condenser. Mark thb 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 Taking Enlarged Photographs. 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. The 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 plate 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 THE DRY PROCESS. 263 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 drachm. Iodide of potassium, 1 drachm. Bromide of potassium, 15 grains. 264 PRINTING OF TRANSPARENT POSITIVES 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. Development. 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 BY THE DRY PROCESS. 265 to remain for twenty minutes, in which they are completely fixed. The prints are then carefully washed in several waters and finally immersed in a bath of dilute hydrochloric acid, which removes a yellow deposit and the spots above men- tioned. A second washing completes the operation, with the exception of drying and exposing to the action of light for several weeks, which improves the reddish tone by chang- ing it gradually into purple. These prints will keep for an indefinite time, although toned with sulphur. Microphotography , or the Art of taking Diminished Copies of Photographs, or Photographs 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 general 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- 266 PRINTING OP TRANSPARENT POSITIVES 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 made. 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 forceps the small piece of glass can be broken down so as to fit into the ring, etc., which is to receive the picture. 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 with BY THE DRY PROCESS. 267 the axis of the cone of concentrated light from the condensBr 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 with it than without it. Finish the plate for a positive or negative according to rules already prescribed in ordinary photography. CHAPTER XXXIX. THE DAGUERREOTYPE. 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 operations. 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 THE DAGUERREOTYPE. 269 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 are 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 Third Operation, or the Exposure 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 210 THE DAGUERREOTYPE. 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 ; where- 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, 2£ 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 THE DAGUEKREOTYPE. 211 deposit on the plates when dried. After the fixed plate is well washed proceed to the final or Sixth Operation, or the Toning vmh 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 he J ding 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. w j ( Chloride of gold, .1 grain. * * i Distilled water, 1 ounce. v- * j Hyposulphite of soda, ..... 4 grains. °* ' ( 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. CHAPTER XL. PRINTING WITHOUT THE SALTS OF SILVER. 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, arc 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 Carbon Process seems to give great promise of being usefully applied. PRINTING WITHOUT THE SALTS OF SILVER. 273 Cyanotype. — Float on a solution of the sesquichloride of iron, dry and expose ; afterward wash the prints, and then immerse them in a bath 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 decomposition. Process with the Salts of Uranium. The discovery. of this process owes its origin to Niepce 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, 7 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, 2-J- grains. Hydrochloric acid, ......... \ a drop. This is a more rapid developer than the preceding. This print is fixed in like manner by water, in which it must be well washed, and afterward dried. When dried by artifi- cial heat the vigor of the print is increased. Prints that 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 Bed Pictures. Float the papers for four minutes in the preceding bath of nitrate of uranium, drain and dry. Next expose beneath a negative for eight or ten minutes, then wash and immerse in the following bath : Ferridcyanide of potassium, 30 grains. Rain-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 : Sesquichloride 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 fowi minutes : PRINTING WITHOUT THE SALTS OF SILVER. 275 Water, .... Nitrate of uranium, Chloride of gold, 2 ounces. 2 drachms. 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 : 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. We 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 Water, .... Oxalic acid, . . . Again wash and dry. Carbon Process. 4 ounces. 4 drachms. 2 76 PRINTING WITHOUT THE SALTS OF SILVER. connection with gum, gelatine or albumen. His mode of operation, as described in the Traite de V Impression Photo* graphique sans sels 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 potassa 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 employed." 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 hi proportion to the quantity of light that has passed through the negative." The principle involved in these two operations is quite different, although the result is the same. In one the film of 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 processes, as for instance, that ot Testud de Beauregard, of Pouncy, Chardon, Salmon and Garnier, 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 thi3 PRINTING WITHOUT THE SALTS OF SILVER. 277 process, because it is essentially analogous to Poitevin's where he makes use of printing ink. Pouncxfs 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. Pouncxfs 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 jmges. 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. 278 PRINTING WITHOUT THE SALTS OF SILVER. 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 are all dissolved off. The paper is next placed in a second bath of turpentine where the lights are thoroughly cleansed of ink. 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 photograph. 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 01 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 was 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 Irachms 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 PRINTING WITHOUT THE SALTS OF SILVER. 279 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 is quite visible ; the paper is again heat- ed befor 3 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 fiat, 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 fire. This being done, the paper 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. This 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 car. 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 board 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 breathing upon the surface, those parts that have not 280 PRINTING WITHOUT THE SALTS OF SIL^R. been impressed by light, beingmore or lesshygrometricin 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 that Fargier 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 1 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 order to remove all fatty or resinous matter ;) to this mixture add few drops ef 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 rendei 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- iaces of the gelatine film, that is, the upper s urface anect of the film has disappeared. Next pour upon the col- odion 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 gelntine 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 14 284 FEINTING WITHOUT THE SALTS OF SILVER. to the picture. All that now remains to be 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 case, 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 processes. 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 surfaces. 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 PRINTING WITHOUT THE SALTS 01 SILVER. 285 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. JPri?iting 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 other 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 01 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. After 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 immersSd 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 completelv black, they will 286 PRINTING WITHOUT THE SALTS OF SILVER. 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 Engraving. 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 Heliograph- 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 simply recount what has been accomplished in each class. • Engraving on the Daguerreotype Plate. The first attempts that were made to convert the daguer veotype into an engraved plate by an etching liquid, were tnose 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. PRINTING WITHOUT THE SALTS OF SILVER. 287 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 further, 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 sivfficient 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 288 PKIJSTTTN G WITHOUT THE SALTS OF SILVER. 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-tinta granulations. "From the result of these two operations the daguerreo- type plate is transferred into an engraved plate resembling the aqua-tinta 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 press. " 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 Ah wed over the surface, and dried by the application of heat i) :/til the film assumes a beautiful yellow color. This opera- lion is performed in the dark-room. ^ 1 j Gelatine, 1 drachm. JN0 * 1, \ Water, 2 J 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 PRINTING WITHOUT THE SALTS OF SILVER. 289 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 i» 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 two 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 fine 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 aqua-tinta 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 gum 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 : No. 1. Saturated solution of sesquichloride of iron in water. * No. 2. Contains five or six parts of No. 1 to one of water. No. 3. Contains equal portions of No. 1 and water. The stronger the solution, the less effective in etching ; the right strength can be learned only by experience. Make 290 PRINTING WITHOUT THE SALTS OF SILVER. a trial as follows : Pour a small quantity of No. 2 upon the plate and spread it with a camel's hair pencil. It is not necessary to have an elevated border of wax 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 No. 1, before No. 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 No. 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 No. 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 : PRINTING WITHOUT THE SALTS OF SILVER. 291 When the plate is ready for etching pour upon it a small quantity of No. 1, the saturated solution. This may be left on the plate for a minute or two. No 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 No. 2 takes its place and produces the etching already described, which, on its aj)pearing 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 No. 3 to those parts, without pouring off No. 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 would remain invisible. Asphaltotype of JVicephore JViepce. 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 Nicephore Niepce has undergone various modifications by his nephew Niepce 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 Niepce 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 light. If a thicker film bo 292 PRINTING WITHOUT THE SALTS OF SILVER. 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 planing- 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 film to 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 either 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 fiim toward the wall. This operation may be performed in a weak diffused light ; 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. PRINTING WITHOUT THE SALTS OF SILVEE. 293 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 light ; 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. Solvent. 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 case 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. 294 PRINTING WITHOUT THE SALTS OF SILVER. Washing of the Plate. The picture in general appears very quickly, so that the action of the solvent has to be stopped almost immediately after its application. If the exposure has been 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° Fahrenheit 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 N 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 whatever upon the metallic plate. Application of the Aqua-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 PRINTING WITHOUT THE SALTS OF SILVER. 295 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 aqua- 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 296 PRINTING WITHOUT THE SALTS OF SILVER. unfortunately no definite cause can be ascribed. To obviate this difficulty a saturated solution of iodine in water at 6CT is used as an etching fluid, instead of the aqua-fortis. 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 tool. 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 will be set at liberty, and will corrode those parts of the glass that have been denuded by the solvent. Negress Process for Heliographic 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 work from. The metallic plate, the wood, stone or glass is first covered on both sides with a varnish quite impermeable to the action PRINTING WITHOUT THE SALTS OF SILVER. 297 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- type ; 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 by means of a fine-pointed style, it is submitted to the etching fluid, as before directed. Photo-lithography 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 letter press, 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, can not 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- salts of iron, and of chrome already frequently alluded to ; and the object to be attained consists either 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. Asphalto-photolithographic Process. This process was originally employed by Nicephore Niepce in the production of heliographic engravings. The first at- tempts in photolithography were made at the suggestion of 298 PRINTING WITHOUT THE SALTS OF SILVER. Barresvvil, in connection with Lernercier, a lithographer, and Lerebours, an optician. Davanne, too, co-editor with Bar- reswil, of the Chimie Photographiqae^ assisted in the pre- paration of the specimens published as early as 1853. The properties of asphaltnm 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 solvent. 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 first prepared 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 rvpon 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 PRINTING WITHOUT THE SALTS OF SILVER. 299 lias 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 manner 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. Bicliromo-plioto-litlxogvaphic Processes of Poitemn. The mixture proposed by Talbot of bichromate of potassa 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 with 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. Thus 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 300 PRINTING WITHOUT THE SALTS OF SILVER. 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 Poitevin. 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 effect. Photo-lithographic 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 PRINTING WITHOUT THE SALTS OF SILVER. 301 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- cesses 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 by Colonel Sir H. James, P.JE. / and Photo-lithography by Mr. Osborne. The negatives in this sort of work require above all things to be very transparent, without the slightest fogginess in the transparent parts ; the opaque j3arts, 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- 302 PKINTING WITHOUT THE SALTS OF SILVER. 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. After moving the solution backward and forward for a minute or so, pour it off 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 ihe 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 Glacial acetic acid, Alcohol, . . . Distilled water, . 48 minims. 36 minims. 2 ounces. PRINTING WITHOUT THE SALTS OF SILVER. 303 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 use. The following are the formulae for the various solutions recommended by Sir H. James : For Cleaning the Glass Plate. Alcohol, 1 ounce. Ammonia, J drachm. Water, 8 ounces. Tripoli powder, sufficient to give it the consistence of cream. Collodion. 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 sign 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. Developing Solutions. Iron. Protosulphate of iron, . 1 ounce. Glacial acetic acid, . . 6 drachms. Alcohol, 6 drachms. "Water, distilled, . . .20 ounces. Pyrogallic Acid. Pyrogallic acid, , . . 30 grains. Glacial acetic acid, . . 1 ounce. Alcohol, 6 drachms Water, distilled, . . 20 ounces. Fixing Solution. Cyanide of potassium, 15 grains. Water, 1 ounce. 304 PRINTING WITHOUT THE SALTS OF SILVER. 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 a^ 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 quite fluid at the temperature of 100°. Dissolve | bichromate of potassa . . jounces.? ( Hot water, ram or distilled,) ... 10 ounces. ) Dissolve j £ el t at:n t e > (*e .finest,) 3 ounces. ) N ( Hot water, (rain, etc.,) 40 ounces. J Mix the two solutions and filter while warm. When about 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 ojDeration 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 corner. 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 Inlcing of the Bichromate Print. For inula for the Info Chalk lithographic ink, 2 pounds. Middle linseed oil varnish, 1 pound. Burgundy pitch, 4 ounces. Palm oil, 2 ounces. White wax, 2 ounces. PRINTING WITHOUT THE SALTS OF SILVER. 305 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 even. 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 306 PEINTING WITHOUT THE SALTS OF SILVER. rubbing the disk with a circular movement over the surfaco 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- jDlete, 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 paper over it, and passed through the press. If the transfer print is not more than three or four days 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* ]y the whole of the ink should remain on the zinc. 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. 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 Etching of the Zinc. The etching liquid is prepared as follows : No. 1. 1 4 ounces. 3 quarts. ( Gum water of the consistence of cream, No. 2. < Decoction of galls, ( Phosphoric acid, 3 quarts. 1 quart. 3 ounces. PEINTING WITHOUT THE SALTS OF SILVER. 307 the surface with a sponge or camel's hair brush. For fine work twenty seconds will be sufficient ; whereas strong lines would bear 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 be 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 perfect. Formula for Zinc Enamel. -, ( Russian glue, 4 ounces. i>0, 1 ( Water, 3 quarts. Soak for several hours, and then dissolve by heat : No. 2. ■{ Zinc white, (oxide of zinc,) . . . . 1£ 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 H. 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 half tone or gradation of shade by 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, 8 ounces. Middle lithographic varnish, 4 ounces. Burgundy pitch, 4 ounces. Palm oil, 4 drachms. White wax, 4 drachms. 15 308 PRINTING WITHOUT THE SALTS OF SILVER, Photo-papyrography by Colonel Sir II. James, R.E. 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 press. 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 JEnameo 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. Honey, 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. PRINTING WITHOUT THE SALTS OF SILVER. 309 When 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 be 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. White 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 Cassius (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 tar- 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. CHAPTER XLI. STEBEOSCOPICITY. 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 view ; 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 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, STEEEOSCOPICITY. 311 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 >y 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 through 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 312 STEREOSCOPICITY. distinguished painter and scholar was born in 1452. There is nothing positive in anything 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 1832 in the third edition of Mayo' s Outlines of Human Physiolo- gy. Wheatstone'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 discovery 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 other. 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 dij^ped 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 with 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 STEREOSCOPICITY. 313 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 314 STEREOSCOPICITY. 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 pleasing. 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 STERJEOSCOPICITY. 315 the binocular perception, is the 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 superimpositions 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. 316 STEEEOSCOPICITY. Strdbonic 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 w r ith 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 w 7 ill 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 above described, when, with a little patience, three photographs 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. A 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 STEREOSCOPICITY. 317 bisection. Where these lines meet we have the center of the cardboard. From this point 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, with an equal 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. ISTow 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 possess- 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. Now 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 fir 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 ot stereo- tjcopicity or their total absence in any given photographs or 318 STEREOSCOPICITY. 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 H 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. SIBEEOSCOPIOITT. 319 s I i o | O €8 I I +> o -d s 3 d a b •° 0 S te to _ &, > ^5 o oo « £ i, a i 3 t i . *T3 he 7i fl Si ea - ^ w> a " t» o> g , 1 *2 1 5 S S | 2 O " c3 r8 8 2 .2 o | ^ O r| O ft * s a 5 a g "S o 5 0 ** «H4 CI fl s I s .s § 2 ► o fl O d — p ture and put ( Carbonate of iron, . . 6 " ) aside for 20 days. ( Citric acid, 1 drachm. ) Stir the mixture No. 2. •< Distilled water, ... 6 " >• and put aside ( Carbonate of iron, . . 3 " ) also for 20 days. After this time decant the two solutions, and measure out as follows : Of No. 1, 1 drachm. Of No! 2, 3 minims. Shake the mixture and apply it to the surface of paper by a tuft of cotton wool in the dark-room. The paper soon dries, and is ready for printing. In direct sunlight the ex- posure is shorter than that required for a silver print ; in diffused light it is longer. Developer. Alcohol, 15 drachms. Nitrate of silver, 30 grains. The picture brought out by this developer is of a splendid black, which is well washed and dried. It is then placed in a ten per cent solution of citric acid, and kept in continual motion, in order to preserve an equality of tone. The print is afterward washed in several changes of water, and then immersed for two minutes in a weak solution of ammonia. Finally the pictures are again carefully washed and dried. Process without the Salts of Silver. By this process prints can be obtained of a variety of tones, some of which resemble those produced by the salts of silver on albumen paper. It has been elaborated by an indefat- igable German, Mr. Obernetter, engaged in one of the most reliable laboratories in Munich. PROCESS WITHOUT THE SALTS OF SILVER. 359 Take common unsalted photographic paper and float it in the following solution : Sensitizing Solution. Water, 12| ounces. Solution of sesqui-chloride of iron, sp. gr. 1.53 to 1.6, . 78 grains. Chloride of copper, crystallized, 600 grains. Hydro-chloric acid, pure and concentrated, . . . . 72 grains. The paper is allowed to remain in this solution for about two minutes. It is then removed and hung up to dry. It is not absolutely necessary to perform the operation in the dark-room, but is probably to be recommended. Paper thus prepared is endowed with remarkable properties. Age does not seem to make any change in its sensitiveness, which is about one third greater than with albumen paper. Exposure. The paper is placed upon the negative as in the common printing process, and exposed to the direct rays of the sun, or to diffused light. The length of time has to be learned by experience. After exposure the picture is either latent, or at the most, of a faint yellow color. It has to be devel- oped immediately, as the image impairs gradually, until finally no vestige is left, and the paper may be exposed a second time without any further preparation. Fixing Solution. Water, 12£ ounces. Sulpho-cyanide of potassium, . . 48 to 72 grains. Concentrated sulphuric acid, 6 grains. Sensitizing solution, 60 to 120 grains. As soon as the paper is removed from the printing frame, it is floated on the fixing solution, picture side downward, for three or four minutes, taking care to agitate the fluid as little as possible ; it is then immersed, and another print is floated in the same manner, and thus you proceed until all the prints are fixed, or the vessel is full. Fresh solution is gradually added in order to keep up its strength. The bath improves by age. By this process cyanide of copper is precipitated upon all those parts upon which light has acted. The time of im- mersion in the fixing solution depends upon the method to be afterward adopted ; it ranges from five minutes to half an hour. If the print be allowed to remain for twenty-four hours, the deposition is so great as to exhibit the picture in relief. On removal from this solution, the prints are placed in 360 CELESTIAL PHOTOGRAPHY. water for about an hour, during which time the water is changed several times. They are then taken out and dried. In this condition they may be stored away, or toned imme- diately. Toning of the Prints. It happens frequently that the image disappears in the washing ; this need not excite any alarm, for the nucleus is still in the paper, and the image appears with great vigor and beauty when toned. In the first place immerse the prints in the following solution : Water, 6 ounces. Ferrid-cyanide of potassium, . from 180 to 300 grains. In this solution the pictures become red, which gradually increases in intensity, until they finally assume a splendid velvety deep red. In order to obtain the requisite tone, which in the final operation resembles that obtained by the silver printing process, an hour's immersion will be quite sufficient. The prints are then removed and washed in sev- eral changes of water until the latter ceases to be tinged yellow. A quarter of an hour is sufficient for this opera- tion. The next step consists in immersing the prints in the following solution : Water, 20 to 30 drachms. Proto-sulphate of iron, 10 " Sesqui-chloride of iron, .... 4 " Hydrochloric acid, 8 " In this solution they undergo the following gradation of color: First red, then reddish violet, blue-violet, black, and greenish black. The most beautiful purple-violet tones are obtained by leaving them in the iron solution until they be- come green-black. They are then gently washed and flow- ed for a moment with a dilute solution of sub-acetate of lead. After drying, the prints are floated on albumen, and then hung up to dry. In this state they resemble albumen pictures. Celestial Photography. In this department of Natural Science, it gives us infinite pleasure to record the progress made by one of our own countrymen. The advance alluded to is the photographic delineation of the Moon by means of a Reflecting Telescope, constructed by Dr. Henry Draper, Professor in the Univer- sity of New-York. CELESTIAL PHOTOGRAPHY. 361 Since the invention of the Telescope in the seventeenth century, an ardent desire arose among astronomers to tran- scribe to paper an accurate representation of this our near- est companion among the stellar host. Even to the naked eye the concave part of the moon in crescentic form exhib- ited an irregular curve, which, by the telescope, became con- verted into illuminated protuberances and dark indentations, which were soon recognized as the pinnacles of vast moun- tains, and the declivities between mountain ranges. Several selenographical observers have furnished the sci- entific inquirer with very accurate charts both of the moon when full and when crescentic, of which perhaps those of Baer and Maedler are the most to be relied upon. Their map of the full moon is thirty-seven inches in diameter, and is a masterpiece of patient and faithful delineation. But as soon as Photography took its position as a branch of Natural Science, it became recognized at an early period as one of the most unerring helpmates to astronomical in- vestigations. In fact, it is now known that the prepared aim of collodion is sensitive to impressions from objects whose light had given no intelligence of their presence when viewed by the telescope ; in short, that certain protuber- ances or mountains on the sun's disk were made visible by actinism on iodized collodion, which were invisible in the telescope. It is no wonder, then, that to photograph the moon's disk has always been a favorite branch of the Heli- graphic art with the student in science. As early as 1840, Professor J. W. Draper produced pictures of our satellite, of one inch in diameter, which were presented to the New- York Lyceum of Natural History. Since then his son has constructed a very superior reflecting instrument, the largest in America, by which he has succeeded in obtain- ing very large photographs of the moon. The instrument is located at Hastings, near New- York. The Observatory is twenty feet square and twenty-two feet high, and is fur- nished besides with other appropriate buildings for photo- graphic manipulations. All the arrangements are very ingeniously made. The silvered mirror, by which the image of the moon is obtain- ed, is the work of the Professor himself. A full description of the Observatory, the telescope, and the purposes for which they are designed, is being publish- ed at Washington by the Smithsonian Institute. 362 swan's carbon process. New Carbon Process, by Mr. Swan. * This process is pronounced by reliable judges to be superior to its predecessors. Prints obtained by it are endowed with all the complete detail of the best silver pic- tures, and, in many instances, surpass them. It is immaterial, in a great measure, what coloring matter is employed, as long as it is in the form of the most impalpable powder. The process is patented ; but the details of the conditions which will permit photographers to practise it have not yet been published. It is to be hoped, and we believe it is Mr. Swan's liberal intention, that amateurs be allowed to use the process and prosecute further researches, as long as no pecuniary advantage is derived from such a favor. If the carbon prints by this process shall represent nature, the first step consists in obtaining an inverted negative. Any experienced photographer is acquainted with the method pursued in the preparation of such a negative. This, however, is not absolutely necessary, because Mr. Swan has devised an expedient by which the same end can be attained. The next step is then to prepare the flexible film for the reception of the image. A plate of smooth glass is coated with plain or uniodized collodion of good body, and put aside to dry. In this way several plates are coated and preserved for use. Sensitizing Solution. Gelatine, 4 ounces. Water, 16 * Soak the gelatine for half an hour in cold water, and then apply a gentle heat, which will soon dissolve it. When nearly cool, add the white of one egg already well beaten, and stir up the mixture intimately. The more intimate the mixture, the more effectually will the impurities be removed when it is heated to a boiling temperature ; for the albumen coagulating carries them down, and leaves the solution quite clear, which is separated whilst warm by filtration through a moist filter. Next, dissolve two ounces of loaf sugar in a sufficient quantity of water so as to make up the loss by coagulation and filtration, and add the mixture to the gelatine. This solution is now colored with any desired pigment. Take, for instance, Chinese ink, and rub it down on a pallet * For full details of Swan's Carbon Process, as published by him in 1868, see page 337. SWAN'S CAKBON PROCESS. 363 until the proper quantity has been obtained. Mix it with a little water and filter ; then add this to the gelatine. Now prepare the following solution : Bichromate of ammonia, 1 ounce. Water, 3 ounces. Take the gelatine solution already colored and the bi- chromate solution, at this stage, into the dark-room for the subsequent manipulations, and prepare the following mix- ture : Gelatine solution, from 8 to 10 ounces. Bichromate solution, 1 ounce. This mixture is now sensitive and is ready for use. It is best to apply it always recently made. Take one of the collodion-coated plates, warm it gently, as also the sensitive mixture, and pour the latter in a uniform film upon the collodion, and put the plate on a levelling stand in a warm corner of the dark-room to dry. In a few hours the film will be thoroughly desiccated, and, by cutting along the edges with a sharp knife, it may be stripped off from the glass as a translucent pellicle. Printing Operation. Place the negative in the common printing frame and the translucent pellicle upon it with the collodion films in con- tact. Lay upon the gelatine film a piece of soft cloth, and apply the pressure board as usual. Expose for about five minutes. Development of the Picture, Returning to the dark-room, the film is now pasted upon a piece of paper by means of starch or india-rubber cement, the collodion side being next to the paper. When dry, the latter is placed in warm water at a temperature of about 100°. By this operation the parts that have not been im- pressed by light are dissolved, whilst the remaining parts which form the picture, having become insoluble in water, adhere to the paper. The reader will observe here that Swan has availed him- self of the expedient made use of by Fargier, (vide page 281,) and first discovered by Mr. Burnett. Several changes of water are required before the picture is quite clear. It is better to let the prints soak for an hour or two, after which they are dried and thus completed. If the prints are obtained from an inverted negative, they will be true representations of the objects depicted ; if 364 swan's carbon process. otherwise, they will be laterally inverted. In such cases, the author of the process uses india-rubber cement in the first place, and now covers the surface of the print with starch- paste and applies a fresh piece of paper. When dry, the first paper is easily detached by lifting it from the film. Since the preceding remarks on the Carbon Process were written, Mr. Swan has brought his Process to a great de- gree of perfection, and we publish, commencing at Chapter XL V., page 337, a full account of all the manipulations in Swan's Perfected Carbon Process, as published by him in 1868. This Chapter XLV. was, in our previous editions, devoted to the subject of Weights and Measures, which we have now placed at the end of the book. CHAPTER XLVII. THE WOTHLYTYPE — SUTTON'S DRY PROCESS — THE RAISES" PROCESS THE PORCELAIN PICTURE — ANILINE PRINTING PROCESS — COLLODIO-CHLORIDE PROCESS — EBURNEUM PRO- CESS — GLAZED PHOTOGRAPHS — MAGNESIUM DUPLEX TYPE REDUCTION OP WASTES THE IVORYTYPE PHOTO-RELIEF printing — the foxtype, etc. The Wothlytype; A PROCESS FOR PRINTING ON PAPER WITHOUT EMPLOYING EITHER THE CHLO- RIDE, IODIDE, OR BROMIDE OP SILYER, AND WITHOUT DEYELOPMENT. Prints can be obtained by this process, which, for soft- ness, tone, and brilliancy, can scarcely be surpassed by silver prints ; the tone is quite characteristic and charming. Paper is coated with a sensitive collodion, and when dry is submitted beneath a negative to the influence of light in the usual manner. When the intensity of the shades is suf- ficiently deep, the print is fixed in an acid-bath, and after- ward washed and toned. No development, it will be per- ceived, is required. The details of the process are not yet sufficiently succinct ; but, as far as we have been enabled to ascertain them from the French specification, they stand as follows : Preparation of the Sensitive Salts. The author recommends the operator to treat the nitrate of uranium of commerce by the following process : Dissolve a given quantity of nitrate of uranium in water ; to this solution add ammonia as long as a precipitate is thereby produced. This precipitate, after subsidence, is separated from the supernatant liquid, and carefully washed in several changes of water. It is finally dissolved in pure nitric acid, by the aid of heat, taking care to have an ex- cess of the precipitate in the acid, in order that all the acid may be completely neutralized. The author supposes that thus he has obtained a double salt of uranium and ammo- nia. This is an error ; he has simply produced nitrate of uranium, sometimes, probably, in a purer condition than it was at the commencement of the operation. With this 366 THE WOTHLYTYPE. prepared specimen of nitrate of uranium proceed to the fol- lowing formulas : Formula No. 1. No A I Nitrate of cranium, . . 6 drachms. ) Disgolve \ Distilled water, . . . . 3 drachms, f JJlssolve - No B -S Nitrate of silver . . . 15 grains. [ Dissolve JN0 *- b - I Distilled water, . . . . 30 minims. ) ^ lssolve - Mix the two solutions together and put the mixture in a warm place to crystallize. This is a double salt — the ni- trate of silver and uranium. Formula No. 2. Nitrate of silver and uranium, 3 drachms Alcohol, 8 drachms. Distilled water, 15 minims. Nitric acid, 1 minim. With this solution the collodion is to be sensitized. Preparation of the Resinized Collodion. Formula No. 3. ( Alcohol, 10 ounces. No. A. < Ether, 30 ounces. ( Pyroxyline, 220 grains. {Canada balsam, 1 drachm. Castor oil, 1 drachm. Ether sufficient to cause the solution to press through the filter. The solution B is now to be evaporated on a water-bath until it has the consistence of oil. Formula No. 4. Resinized Collodion. Take of plain collodion, No. A, 20 ounces. Take of Canada balsam, etc., No. B, . . . .10 minims. Preparation of the Sensitive Collodion. Formula No. 5. Sensitive Collodion. Take of the solution for sensitizing collodion, Formula No. 2, ' . 6 drachms. Take of resinized collodion, . ... 12 drachms. Take of nitric acid, 2 drops or more. THE WOTHLYTYPE. 367 This collodion must be prepared in the dark-room, and preserved in a bottle well protected from actinic rays by means of several folds of orange-colored paper or cloth. A tin case surrounding the bottle is about the best pro- tection. Preparation of the Paper for receiving the Sensitive Collo- dion. Formula No. 6. Arrowroot starch, 1 ounce. Water, 34 ounces. Acetate of lead, 10 drops. To this mixture, heated to a temperature of 100° Fahr., add four ounces of albumen. Stir the ingredients intimate- ly together. It is then ready for use. The sheets of paper may be either floated on this sizing for about five minutes, or may receive the proper amount of sizing by means of a soft, clean sponge. If the latter plan be adopted, the paper is placed upon a flat board or a plate of glass. Apply the sponge upon the middle, and then work to the right and to the left from the middle until the whole surface is covered ; now equalize the longitudinal streaks by operating with the sponge in the same manner from the middle, but trans- versely to the preceding direction, until the surface of the paper is evenly covered with the size. The sheets so covered are finally hung up and dried. Coating the Paper with Collodion. Take a smooth board, somewhat larger than the sheet of paper to be coated, and pin three corners of the sheet to the board. The collodion is then poured upon the paper, as if it were a plate of glass ; the excess of collodion is al- lowed to flow off into the vial by the corner which is not pinned to the board. With a little practice, paper can thus be coated with collodion as easily and dexterously as a negative plate. Of course the paper which is thus coated is the arrow- root paper, as prepared by the preceding formula. Hang up the collodionized sheet in the dark-room to dry. Printing. This operation is in no respect different from that of printing on sensitized albumen. Place the paper beneath the negative, and expose to the direct rays of the sun or to diffused light. The paper will bear slightly over-printing 368 sutton's dry process. Fixing Solution. Formula No. 7. Distilled water, 40 ounces. Acetic acid, 1 ounce. Hydrochloric acid, 1 ounce. The prints are placed in this solution for ten or fifteen minutes and then washed in two or three changes of water. Toning. It is not absolutely necessary to tone the prints, but they are improved by this operation. Any of the ordinary gold toning solutions may be used in this process. Finally, wash the prints thoroughly and hang them up to dry. To secure permanency in the prints, it is an advantage to fix them after toning in a solution of hyposulphite of soda, and then to wash them as usual and dry them. Sutton's Rapid Dry Tannin Process. Preparation of the Plates. Plate glass is recommended in this process, because it is less liable to break by pressure in the printing-frame, and because it can be more easily brought into contact with the paper than ordinary glass. The edges are first of all abraded by means of a file or a sand-stone. Fresh plates of glass, that is, such as have not been used before, are rubbed with a piece of flannel dipped in a thick mixture of chalk and water, which is afterward removed beneath the tap with a sponge ; they are next immersed in a bath of dilute acetic acid, in order to neutralize the alkaline earth, and again well rinsed, and finally dried with a clean old linen cloth, which is used for this purpose alone. This cloth, naturally, must be quite free from any trace of alkali, as of soap, etc. Plates that have been used before may be immersed in a bath of dilute nitric or chromic acid, and then washed, etc., as just indicated. It is well to have two cloths — one for each hand — when wiping the plates, for then the plates do not come in con- tact with the hands. Rub off all chalk-powder from the edges, and dry the plates by artificial heat ; finally, place them in a clean plate-box until required for use. Immediately before use each plate is thoroughly dried sutton's dry process. 369 and polished by a piece of clean buckskin, the plate being held between the folds of a silk handkerchief in the left hand during the operation. It is then ready for the next operation. Substratum for preventing the Collodion Film from slid ing off. Dissolve one grain of India-rubber or gutta-percha in an ounce of benzole or of chloroform. Each plate when pol- ished and dry is coated with this solution, which is poured upon the surface in the same manner as collodion. The film is then dried by artificial heat. When this operation is properly performed, the surface which has received the film is undistinguishable from the one which has received no coating ; in consequence of this, it is requisite to indicate the coated surface by means of a diamond scratch or by some other expedient. Sometimes the plates are simply varnished round the edges to the depth of one eighth of an inch with the same varnish. The author does not recommend the use of either gelatine or albumen in solution for the purpose just men tioned. Coating the Plates with Collodion. Formula for Plain Collodion. Pyroxyline, 3 drachms. Ether, concentrated, 150 drachms. Alcohol, 90 drachms. Iodizing Solution. Iodide of cadmium, 8 drachms. Bromide of cadmium, 3 drachms. Alcohol, sp. gr. .810, 240 drachms. Bromo-iodized Collodion. Plain collodion, 3 fluid ounces. Iodizing solution, 1 fluid ounce. After the mixture has been well shaken, it is put aside for a few hours to ripen and settle. Decant the clear superna- tant part by means of a siphon or filter. This collodion is quite colorless, and can be kept a long time in a cool place without undergoing decomposition. The pyroxyline recommended by the author must be of such a nature as to form a clear solution and free from any acid reaction, and the ether and alcohol must be neutral and devoid of impurities. Coat the plates with this collodion in the usual manner. 370 button's dry process. Sensitizing the Film. The nitrate of silver bath is composed as follows : Nitrate of silver, 4 ounces. Distilled water, 64 ounces. Nitric or acetic acid, 20 minims. Immerse a collodionized plate in this bath for a number of hours, the solution is then ready for use. The bath works best when freshly prepared. Use glass vessels for the subsequent operations in prefer- ence to any other. The collodionized plate is retained in the bath until the film has assumed a greenish-yellow, cream-like color. This will be effected by an immersion of three minutes in summer and of six in winter. The plate is then taken out and rinsed until the oily appearance has been removed ; it is then al- lowed to drain, after which it is immersed in another bath, containing distilled or rain-water, where it remains until another plate has been coated with collodion and sensitized. The plate is moved about in the water several times. As soon as another plate is ready to take its place, the first plate is taken out and washed in rain-water, by allowing it to fall upon every part of the film from a height of two or three inches. Tannin Solution. Tannin, . 2 drachms.. Distilled water, 8 ounces. Dissolve and filter the solution. A small portion of the filtered tannin solution is poured upon the washed collodion film and kept in motion a short time; it is then poured away and a fresh solution takes its place. This being done, the excess of tannin is poured off, and the plate is reared on one corner on a piece of clean blot- ting-paper, or placed in the drying-box to dry spontaneously. Artificial heat is applied only in order to remove the last traces of moisture, when the plates have to be kept for some time. If the plates are to be kept a long time, they are tied to- gether in pairs, the collodion films facing each other, and prevented from coming in contact by means of a strip of card-board all round the edges. Each pair is then folded up in three folds of yellow paper or cloth to prevent all in- gress of white light. Previous to thus packing them up in pairs, each plate is well dried over a hot plate of iron, or a copper vessel filled with hot water. sutton's dry process. 371 Exposure of the Plate, There is a wide scope for the length of the exposure of a tannin plate, but the safest plan is to expose longer than would be required for a wet plate. The longer the expos- ure, the greater the harmony of the negative. Considerable over-exposure gives rise to a defect called blurring, which is manifested when the lights and shades of the negative encroach upon one another. This is an optical defect, and is caused by the reflection of the rays of light from the posterior surface of the glass plate, being always most visible where the rays are most oblique. In landscape photography it is recommended to give the sky less exposure than the foreground. Before the plate is placed in the holder, or at least before it is developed, in case no previous substratum of India- rubber, gelatine, etc., has been used, it is necessary to var- nish the edges of the film with the India-rubber, etc., so- lution. The development of a tannin plate is the most critical part of the whole manipulation of the tannin process, and requires most judgment and experience, the appearance of the negative with the alkaline developer being so very dif- ferent from that with the common wet process. By reflect- ed light, negatives developed by the alkaline process appear quite fogged ; it is only by transmitted light they exhibit their beautiful properties. Other negatives may be more beautiful to look at, but these produce the best prints. If it is known beforehand that the plate has been over- exposed, it is better to make use of the acid developer con- taining nitrate of silver. The development of a negative by the alkaline develop- ment is divided into two distinct operations : in the first place, the development proper, by which the picture is made visible ; and secondly, the intensifying of the image, by means of which the feeble details of the picture are made sufficiently dense. To bring out the latent image with the alkaline developer the two following solutions are required : XT , ( Bicarbonate of soda, . 10 grains. ) m u j u /• No ' j Water, ..... 1 ounce. \ To be filtered before use ' Development of the Image. No. 2. \ Pyrogallic acid, \ Absolute alcohol, 10 grains. 1 ounce. 372 sutton's dry peocess. To develop the picture, measure out one ounce of water, to which add one drachm of the soda solution, and fifteen minims of the pyrogallic acid solution. In the mean while the exposed negative film has been uniformly covered with water so as to moisten it ; the pyrogallic acid mixture is well shaken, and then poured upon the moistened film and moved about so as to cover every part. In a few seconds the sky appears and the high lights ; in two or three min- utes the darker details of the shadows present themselves ; but the negative is quite thin and can not be made more dense by this developer. If a picture is required to be en- dowed with much contrast, the developing process is soon brought to a close ; if, on the contrary, the negative is re- quired to be very soft and harmonious, and more replete with detail, the development is continued much longer. The rule is, to give a long development to a short exposure, and a short development to a long exposure. » The negative, at this stage, is thoroughly washed, in order to remove every trace of the alkaline developer, which, if any remained, would be apt to fog the plate in the subse- quent treatment. The negative is now of a light brown color by reflected light, and of a reddish-brown color by transmitted light ; it is easily intensified. If the exposure has been long, it may happen that the picture may appear before development, because both the bromide and iodide of silver in combination with tannin are blackened by light. The alkaline developer must be used immediately after its preparation, as it will not keep. Intensifying the Negative. In the first place, prepare the following solutions : ( Pyrogallic acid, 2 grains. No. 1. ■< Glacial acetic acid, . 20 minims. ( Distilled water, 1 ounce. ( Nitrate of silver, 20 grains. No. 2. •< Glacial acetic acid, . 20 minims. ( Distilled water, 1 ounce. The alkaline developer having been carefully removed by washing from the developed picture, a sufiicient quantity of the acid pyrogallic acid solution No. 1, in a vial for this purpose, is poured upon the film, in order to neutralize any remaining trace of the carbonated alkali, and returned to button's dry process. the vial. Five drops of the acid silver solution -(supposing the plate is of the stereoscopic size) are now added to the mixture in the vial ; the mixture is well shaken and then applied to the plate in the usual manner of intensifying. Gradually the whole film becomes slightly fogged ; but this is of no consequence, for the shades remain quite transparent by transmitted light. As soon as the dense parts of the negative have become sufficiently opaque, the plate is well washed and fixed. Some persons prefer citric acid to glacial acetic acid. The former produces a bluish-black deposit, and the latter one of a reddish color, which alone is capable of restraining the action of light, and thus of producing vigorous and bril- liant prints. Citric acid, however, on a tour is more con- venient, one grain being equivalent in working properties to twenty of the glacial acetic acid. Fixing and Washing the Negative. The plate, already thoroughly washed, is immersed in a saturated solution of hyposulphite of soda, where it is al- lowed to remain until all the unaltered iodides and bromides are removed. The intensity of the picture is not at all de- teriorated by this solution. If the plate has not received any substratum, the utmost care is now required in finally washing it, lest the film slide off. The negative is allowed to drain and is then dried either spontaneously or by artifi- cial heat. If the film should show any signs of splitting up, a solution of gum-water is poured upon it as soon as the plate has drained, and after this precaution the negative is allowed to dry. 'Varnishing the Negative. A spirit lac varnish appears to be the best adapted for negatives ; it is prepared by dissolving shell lac in absolute alcohol. The plate is gently warmed over the stove or lamp, and then coated with varnish as with collodion. After the excess of varnish has drained off, the plate is again placed over the stove or lamp until the varnish is perfectly dry. The negative is now finished. Dry Collodion — Raisin Process. BY DR. SCNAUSS. Preparation of the Collodion. Fill a large bottle two thirds full w T ith carded pyroxy- line, pour in a little alcohol, sp. gr. .835, and shake the THE RAISIN PROCESS. mixture. The pyroxyline diminishes considerably in vol- ume by this proceeding. Ether is now poured in so as to fill the bottle two thirds full, and the remaining one third is filled with absolute alcohol. Shake the mixture and set it aside for several weeks. The clear supernatant plain collodion is decanted, and diluted with a mixture of equal volumes of ether and alcohol. In summer more alcohol than ether is employed. Judgment and experience must decide when the collodion has the requisite consistence ; it must not be too thin, on the one side, nor too thick to pre- vent it flowing without furrows. If it is not thick enough, more pyroxyline must be added. The bromo-iodizing solution is prepared in the following manner : Iodide of ammonium, 4 drachms. Iodide of cadmium, 2 drachms. Bromide of cadmium, 1 drachm. Alcohol, spec, grav., .835, 40 drachms. This solution may be prepared a week before it is re- quired to be used. It is filtered through paper moistened with alcohol. A sufficient quantity of this solution is added to the plain collodion so as to produce in the silver bath a fine white film. The bromo-iodized collodion is allowed to settle and ripen for a few days ; it becomes very clear and yellow. Shake the mixture well, and then expose it to the direct rays of the sun for a number of hours. A negative is now prepared by the wet process with the collodion, the silver bath, and the ordinary developers. If the image appears vigorous and free from fogging, the solutions are in a good condition ; if otherwise, add a few drops of acetic acid to the silver bath. The Silver Bath. Nitrate of silver, . . Distilled water, . . . Bromo-iodizing solution, . . 30 drachms. 360 drachms, from 3 to 5 drops. Alkaline Developer. Prepare the following solutions : No. 1. Dilute Alcohol. Alcohol, Distilled water, 18 drachms. 30 drachms. THE RAISIN PROCESS. 375 No. 2. Carbonate of Ammonia Solution. Dilute alcohol, No. 1, 6 drachms. Carbonate of ammonia, 1 drachm. No. 3. Pyrogallic Acid Solution. Pyrogallic acid, 1 drachm. Absolute alcohol, 15 drachms. The latter solution will keep a long time ; it becomes red, but produces no deposit. No. 4. Aqueous Pyrogallic Acid Solution. Dilute alcohol, No. 1, 4 drachms. Pyrogallic acid solution, No. 3, 6 drops. No. 5. Gitro-nitrate of Silver. Nitrate of silver, 20 grains. Citric acid, 20 grains. Water, 16 drachms. The alkaline developer is especially adapted for winter operations ; in summer the following acid developer will be found more simple : Acid Developer. Pyrogallic acid, 5 grains. Distilled water, 5 ounces. Formic acid, 1 drachm. Alcohol, 15 minims. The exposed plate is previously flowed with the dilute alcohol, No. 1, and then washed until the surface appear uniformly moist ; a sufficient quantity of the preceding acid developer is then poured upon the plate, and moved about awhile ; it is then poured back into a vial, and a few drops of the citro-nitrate of silver are added. The mixture being well shaken, is again poured upon the plate and kept in motion until the picture is well out. The ordinary developer of the double sulphate of iron and ammonia may be used, and with advantage, in the de- velopment of dry plates ; only in this case the plate is first immersed for a few seconds in an acid silver bath, drained, and then flowed with the developer. Preservative Solution. One ounce of large raisins are boiled in ten ounces of distilled water ; the decoction is then put aside to cool, 376 THE RAISIN PROCESS. after which it is filtered and is ready for use. A few drops of acetic acid will increase its keeping properties. Preparation of the Raisin Plates. The plates are to be thoroughly cleaned and polished in the usual way, the edges having been previously roughened by grinding on a grindstone. If a substratum of gelatine is employed, four grains of gelatine are first soaked and then dissolved by heat in four ounces of water ; the gela- tine solution is filtered while hot ; and to the filtered solu- tion a drachm of alcohol is added. With this solution each plate is coated in the usual way, and set aside to dry. If the edges of the plates are well roughened and the surfaces thoroughly cleaned, the substratum is not necessary. The next operation is to coat the plates with the bromo- iodized collodion, and to sensitize the collodion film in the silver bath in the usual manner. The plates are then re- moved from the silver bath and placed, collodion-side up- ward, in a large, clean vessel of distilled water, and fre- quently moved. In five minutes each plate is taken out, well drained, and then flowed three times in succession with fresh portions of the raisin solution, which must be kept carefully in motion so as to cover the whole of the plate uniformly. The plate is finally allowed to drain, and is then put away in a dry, dark place to dry spontaneously. The depth of intensity of these plates varies according to the intensity of light as well as the nature of the devel- opment, the alkaline developer requiring the shortest ex- posure, (twenty seconds being about sufficient with a pair of landscape stereoscopic lenses and a good light ;) the or- dinary pyrogallic acid developer requires the longest expo- sure. The iron developer, in point of sensitiveness, stands next to the alkaline developer, and finally, close to this, the formico-pyrogallic acid developer above given. Mode of Development. Cover the exposed plate with the dilute alcohol, No. 1, pour off the alcohol and wash the film until it is uniformly moist. Now take a sufficient quantity of the solution of carbonate of ammonia, mixed with one fourth its volume of the pyrogallic acid solution, No. 3. Pour this mixture over the plate and keep it in motion until the image is tho- roughly developed. The image at this stage is very thin and has to be intensified. Wash the film thoroughly, and then intensify the negative with a mixture of a sufficient A RELIABLE TANNIN PROCESS. 377 quantity of N"o. 4, and a few drops of No. 5. To prevent fogging, when there is reason to expect it, add plain citric acid solution. Use the best glass plates you can procure, free from flaws, flat and colorless, grind or file the edges ; and, whether they have been used before or not, immerse them for a number of hours in the chromic acid bath, which is pre- pared as follows : Bichromate of potassa, 2 ounces. Sulphuric acid, 2 ounces. Water, 20 ounces. When the plates are taken out, allow them to drain, and then wash them at the tap thoroughly, and rub the surface while they are being washed with a clean nail-brush, which must be kept and used for this purpose alone. Each plate, while still wet, is coated with the following solution of albumen : White of egg, (already clear after beating,). . . 1 ounce. This solution of albumen must be filtered before use through moist paper. Cover the plate uniformly with the solution, and see invariably that the surface is free from particles and bubbles. Begin again with the plate, where the film is thus defective. The plates, as they are coated with albumen, are reared on the drying rack in a clean, quiet place where there is neither dust nor draught of air. A solution of India-rubber is sometimes used instead of that of albumen for the substratum. The solution is made as follows : Sheet India-rubber, 2 grains. Benzole, 2 ounces. Cut the India-rubber into small narrow strips to facilitate the solvent action of the benzole, and set the mixture aside in a stoppered bottle for a day or two. The solution is finally filtered two or three times through fresh filtering paper ; it is then ready for use. The plates, when properly cleaned and polished, are first gently warmed over the stove or a flame, allowed to cool, and then coated with the India-rubber solution in the same A Reliable Tannin Process. Water, . Ammonia, 6 ounces. 1 drachm. 378 A RELIABLE TANNIN PROCESS. manner as with collodion ; after draining, they are again warmed over the stove and finally stored away for use. To coat plates with the latter solution is a much easier operation than with the albumen solution, and the plates are sooner ready for the next operation; still, most opera- tors will prefer the former solution, because they are familiar with its use. Coating the Plates with Collodion, The collodion for dry plates is prepared as follows, al- though almost any other good bromo-iodized collodion would serve the purpose : Collodion for Tannin Plates. Alcohol, 10 ounces. Ether, 10 ounces. Pyroxyline, 120 grains. Bromide of cadmium, 100 grains. Iodide of ammonium, 60 grains. Prepare this collodion in the usual way, and, when the cotton and the salts are thoroughly dissolved, filter the so- lution and set it aside a day or two. It may, however, be used immediately ; but cadmium collodions seem to be more efficacious after they have been prepared a day or two. The plates are coated with the collodion in the usual way. Previously to flowing the plate, however, the albu- menized plates are held over a flame, the film being up- ward, and are kept in motion for a moment until the mois- ture in the albumen has evaporated. They are then allowed to cool, when they are ready to be coated with the collodion. As soon as the film has sufficiently set, the plate is immersed in the silver bath, and retained there until the film assumes a uniform cream color. Silver Bath for Tannin Plates. Pure crystallized nitrate of siiver, 3 ounces. Distilled water, 24 ounces. Nitric acid, 6 minims. To twelve ounces of this solution add a drachm of the bromo-iodized collodion ; shake the mixture well, filter it, and then add it to the remaining twelve ounces. The bath is then ready for use. As soon as the collodion film is sufficiently sensitized, that is, has no tinge of blueness about it, take it out of the bath, A RELIABLE TANNIN PROCESS. 379 let it drain, and then place it in a bath of distilled water until the oil marks have disappeared. From this bath it is re- moved to the second bath, which contains the following solution : The plate is kept in the bromide bath about a minute. The bromide bath requires strengthening from time to time, as also filtering, in order to remove the bromide of silver which is formed by the removal of the unaltered ni- trate of silver in the collodion film ; with these occasional manipulations the bath will keep for an indefinite time. The plate is taken out of the bromide bath and immersed again in a bath of distilled water, in which it is left a min- ute or two ; from this bath the plate is removed and placed on the rack to drain for a couple of minutes. The operator will naturally comprehend that all these operations are performed in the dark, or non-actinic room. Be careful, if yellow or orange-colored light is admitted, that this light is non-actinic, because it is a disagreeable piece of business to fail with dry plates after all the trouble that is bestowed upon them ; and frequently the failure may be traced to actinic rays exercising their influence during tho preparation of the plates. Wipe the back of each plate carefully after it has drainec awhile, and immerse it in a bath containing the following solution of tannin : Tannin, 300 grains. Loaf sugar, 300 grains. Water, 20 ounces. The tannin and sugar are dissolved in the water, being all placed in a large stoppered bottle holding about twenty-four ounces. Shake the mixture occasionally until the solution is complete. The letter is filtered through a moist filter. Now add to the solution an ounce of alcohol. Pour the solution back again into the stock bottle every time the operation of sensitizing a given quantity of plates is fin- ished ; and keep the bottle well corked. Filter the solu- tion when necessary. The plates are left in this bath two or three minutes, and then taken out and allowed to drain. Finally they are stored away in the drying chamber to dry either sponta- neously or by artificial heat, Bromide of cadmium, Water, .... 100 grains. 12 ounces. 18 380 A RELIABLE TANNIN PROCESS. Exposure of the Tannin Plates. Considerable experience is required to know, under given circumstances, the length of exposure that would most likely be correct. From our own experience, an exposure two or three times longer than that required by a wet plate will be necessary, to produce a good picture by the tannin process, even with the alkaline developer. In every case do not practice short exposures, for they generally either fail altogether, or yield at the best harsh contrasts, when the negatives are forced up to full intensity. A full exposure produces full detail ; and an over-exposed plate can be con- trolled by the development. It is true that too long expo- sures will produce, if the negatives are carelessly managed, harsher contrasts than under-exposed plates. The develop- ment of a dry plate, therefore, has to be carefully studied. Development of a Tannin Plate. The development of a tannin plate is divisible into two operations ; the first consists in bringing out the picture faintly but distinctly in all its details, with the alkaline so- lution ; the second consists in rendering all the parts of the picture more intense, so as to make it suitable for printing from. Solutions required in these two operations. No. T. Dilute Alcohol. Alcohol, 2 ounces. Water, • .... 2 ounces. No. 2. Alkaline Solution. Carbonate of Ammonia, 48 grains. Water, 6 ounces. Two drachms of this solution contain two grains of the alkaline salt. No. 3. Pyrogallic Acid Solution. Pyrogallic acid, 48 grains. Absolute alcohol, 1 ounce. Ten minims of this solution contain one grain of pyro* gallic acid. No. 4. Nitrate of Silver Solution. Nitrate of Silver, 20 grains. Water, 2 ounces. A RELIABLE TANNIN PROCESS. 381 No. 5. Solution of Citric Acid. Citrid acid, Water, . 2 drachms. 4 ounces No. 6. Water, 1 pint. Alkaline Development — First Operation. As soon as the plate is removed from the plate-holder or changing box, in the dark-room, pour upon the film a suffi- cient quantity of dilute alcohol, No. 1, until the film is uniformly covered with it ; then allow the solution to flow back again into the vial. Now immerse the plate in a dish of water until the greasy appearance passes off. In the mean while make the following mixture : Alkaline solution, No. 2, 2 drachms. Water, 1 ounce Flow the plate uniformly with this solution, which is im- mediately returned to the developing vial, and mixed with three minims of the alcoholic pyrogallic solution. This mix- ture is poured upon the plate and kept in motion. Soon the image will begin to appear, if the right exposure has been given, and will proceed until it is complete in all its detail. It is, to be sure, but a faint picture ; but this picture by the second operation can be made as intense as the operator may wish. Should it happen that the picture appears with great rapidity on the application of the alkaline solution, pour the latter off directly and wash the plate. Such a rapidity of development indicates that the plate has been over-exposed, in which case the action of the second ope- ration with the acid developer will be sufficient of itself to bring out the picture. To Intensify the Image — Second Operation. Wash the faint image gently at the tap, and then pour upon it the following solution: Solution of citric acid, 20 minims. Water, 4 drachms. The intention of this solution is to remove all traces of the alkali. Pour this solution off after it has remained about a minute, and then flow the plate with the following solution : 382 russell's improved tannin process. Intensifier — Citro-nitrate. Water, . . 4 drachms. Pyrogallic acid, No. 3, .... 2 minims. Citric acid, No. 5, 10 minims. ) Previously Nitrate of Silver, No. 4, .... 3 minims. ) mixed. Shake the mixture well up, and then pour it upon the plate. Gradually the faint image becomes more and more intense. If the intensity increases too rapidly, and the lights begin to fog, add more citric acid to the intensifier ; on the con- trary, if the delineations of the picture are slow in becom- ing more dense, add more of the silver solution. If the in- tensifier becomes red and turbid, throw it away and prepare a fresh solution. The picture when intensified by this citro-nitrate of silver solution becomes of a grayish black appearance ; but if the acetic-nitrate of silver were substituted, the picture has a reddish tone ; and negatives thus prepared produce very excellent prints. Intensifier — Aceto-nitrate. Water, .4 drachms. Pyrogallic acid, No. 3, .... 2 minims. Acetic acid, 15 minims. ) Previously Nitrate of silver, No. 4, .... 3 minims. ) mixed. Proceed with this intensifier as with the citro-nitrate, only using more acetic acid when fogging sets in instead of citric acid. The picture being now sufficiently intense is thoroughly washed at the tap, and then immersed in the bromide bath for a minute. It is again well washed and fixed in a satu- rated solution of hyposulphite of soda. Finally the negative is again thoroughly washed, then dried and varnished. Major Russell's latest Improvements in the Tannin Process. Prepare the plates as already described in the preceding process, either with an albumen or India-rubber substratum. The collodion recommended by the Major is as follows: Alcohol, spec, grav., .810, 5 ounces. Ether, 5 ounces. Pyroxyline, 50 grains. Bromide of cadmium, 150 grains. russell's improved tannin process. 383 This collodion contains only a bromide. The silver bath is prepared as follows : Place a bromized plate in this bath for an hour or two, and then filter it. The bath is now ready for use. Coat a prepared plate with the bromized collodion, and immerse it in the silver solution in the usual manner. The plate, when the film is quite creamlike in color, is removed from the sil- ver solution and placed in a bath of distilled water, where it remains until the greasiness disappears. It is then placed in a second bath of distilled water for a minute or two. From this the plate is removed to a third bath containing the following solution : Albumen, 24 minims. Distilled water, 12 ounces. Iodide of cadmium, 8 grains. Bromide of cadmium, 1 drachm. Camphor, 1 drachm. The plate remains in this bath a minute or two. The ob- ject of this bath is twofold; firstly, the albumen acts like sizing to paper, by rendering the collodion film less porous or permeable to fluids than it was before ; secondly, the cadmium salts remove every trace of unaltered nitrate of silver. The iodide of cadmium, too, is intended to intro- duce a trace of iodide of silver into the film, which is in some way regarded by the author as beneficial. From the bromide bath the plate is removed to a fourth bath of common spring-water, and thence to the bath con- taining the tannin solution, where it remains about one minute. The plate is finally taken out, thoroughly washed at the tap, and then set away in a convenient place to dry. As soon as the plates are dry, the Major paints the backs of the plates with an orange-colored paint, mixed up with gum or dextrine and a little glycerine. The paint is laid on thickly with a broad brush, and after exposure it may be peeled off with a fine pallet knife, and dissolved again in water for future use. The object of this film of orange- colored paint on the back of the glass is to prevent all the effects of reflections from the back surface of the glass, Nitrate of silver, Distilled water, Nitric acid, . 2 ounces. 14 ounces. 14 minims. Exposure. 384 russell's improved tannin process. called blurring. The author is very strong in the recom« mendation of this course. When the paint is dry, the plates are ready for exposure. After exposure, the plates are first covered uniformly with the dilute alcohol of the preceding article, and then immersed in a dish of water and left there until the greas- iness has disappeared. The following solutions are used in the development : No. 1. Pyrogallic Acid. Pyrogallic acid, . 16 grains. Alcohol, 1 ounce. Distilled water, 1 ounce. No. 2. Carbonate of Ammonia. Sesqui-carbonate of ammonia, 48 grains. Distilled water, 3 ounces. No. 3. Intensifier. Bromide of potassium, 3 grains. Sesqui-carbonate of ammonia, 32 grains. Water, 1 ounce. Take a mixture of one drachm of the first solution, and one drachm of the second solution, shake it well up ; this is the alkaline developer. Cover the wet plate with this solution, and keep the latter in motion until the image ap- pears perfect in detail. After the image is thus brought out thoroughly by the al- kaline developer, it may be intensified by dropping into the developer a minim or two of the intensifier No. 3. The author remarks of this intensifier as follows : u Three grains of bromide of potassium in one ounce of the thirty- two grain solution of carbonate of ammonia will make a very good intensifier, and it may be used to develop when much diluted, instead of the plain carbonate of ammonia solution, when soluble salt enough has not been left in the film, or when this is the proper condition, after a longer ex- posure. This is a good plan when great vigor and bright- ness are more important than sensitiveness. Using more or less bromide in the developer is the best way yet devised of regulating intensity. In this way we are able — when time of exposure is not an object — to obtain great vigor under almost any circumstances ; such as a very dull light. In this way also, plates prepared for instantaneous, pictures will answer as well as others for any kind of subject." MODIFIED FOTHERGILL PROCESS. Instead of using the bromide intensifies naturally, the ordinary acid, pyrogallic acid, and nitrate of silver may be used as in the preceding processes. Modified Fothergill Process. The public are indebted to Mr. Ackland, an experienced photographer, and one who has tried all the dry processes, for the following modification of the Fothergill process. The author prefers it to all of them ; and reliable judges pronounce the negatives taken by the process irreproacha- bly good. The plates, too, are said to- be very sensitive ; and there seems to be no doubt of their keeping qualities. The collodion most suitable for this process is the ordi- nary bromo-iodized used in general by photographers. If it be newly made, a sufficient quantity of tincture of iodine to communicate to it the color of sherry wine will be found advantageous in preventing fogginess. The only point to be attended to in selecting a suitable collodion is to take one which yields a full creamy film in the silver bath, and which has no tendency to leave the plate during washing. As most of our operators now use a substratum of albumen, it will be well to use plates previously so coated, in order to avoid all risk, in the film, of slipping off. The silver-bath must have a slight acid reaction, and con- tain not less than thirty-five grains of nitrate of silver to the ounce of water. The author of this modified process pre- pares the bath in the following manner : Dissolve an ounce of re-crystallized nitrate of silver in two ounces of water; to this solution add two drachms of the bromo-iodized collodion intended to be used. After the mixture has been well shaken up, ten ounces more of water are added ; it is again well shaken and then set aside for a few hours, after which it is filtered for use. Such a bath will be found sufficiently acid for the purpose. Mr. Ackland prepares the albumen solution as follows : Separate the yolks from the whites of any number of eggs, and to every eight ounces of the albumen thus obtained, add twenty drops of glacial acetic acid previously diluted with one ounce of water. The mixture is intimately stirred up with a glass rod, and then set aside for an hour. After this it is strained through coarse muslin, and to the strained liquid are added thirty minims of concentrated ammonia. This forms the stock solution of albumen, which will keep for an indefinite time in carefully stoppered bottles ; it is 386 MODIFIED FOTHERGILL PROCESS. also limpid, clear, and bright, and may be filtered through ordinary filtering-paper with facility. Besides the albumen solution, six others are required in the process. Solution A. Prepared albumen, 4 drachma. Concentrated ammonia, 1 drachm. Water, 4 ounces. Solution B. Nitrate of silver, 8 grains. Distilled water, 4 ounces. Dilute Acetic Acid, Glacial acetic acid, 1 drachm. Water, 10 ounces. Plain Solution of Pyrogalliv Acid. Pyrogallic acid, 100 grains. Absolute alcohol, 2 ounces. Acid Solution of Pyrogallic Acid. Pyrogallic acid, . , , 8 grains. Citric acid, , % ounces Distilled water, , , , 4 ** Acid Silver Solution, Nitrate of silver, 30 grains. Citric acid, 30 " Distilled Water, 1 ounce. The solutions A and B are to be mixed in equal propor- tions for present use. This mixture soon decomposes, and then produces foggy plates. Coating the Plates loith Collodion, This operation requires no instructions ; it is performed in the usual manner, after which the plate is immersed in the silver as soon as the collodion film has properly set. The film having assumed a uniformly cream-color, it is taken out and kept moving about in a tray of water until the greasiness has disappeared ; it is then allowed to rest in the water while another plate is coated and immersed in the silver solution. Ordinary well or spring-water may be used in this and the subsequent washings. The plate that has been soaking is now washed again in several changes of water for the space of two minutes, and finally flooded with solution of common salt, formed by dissolving a table* haakman's fothergill process. 387 spoonful in twenty ounces of water. After this solution has remained on the plate for about half a minute, it is poured off, and the plate is washed carefully under the tap in order to remove every trace of the salt solution, and is then reared with one corner on several folds of blotting-paper, and with the other against the wall to drain. Coating the Plates with the Albumen. Other plates are prepared in like manner. Before the - film is dry, that is, while it is uniformly moist, each plate is flowed with the mixture of A and B ; this solution is poured away, and fresh solution is poured on and off seve- ral times ; the plate is then reared up as before on blotting- paper, and allowed to drain, but not to dry. Half a dozen plates may thus be prepared before the next operation is commenced with, that is, before the plates begin to get dry. Immersing the Plates in Acetic Acid. The plates that have been albumenized and drained are immersed in a bath of the dilute acetic acid for the space of a minute or so ; they are again washed thoroughly for half a minute, then allowed to drain and dry spontaneously in any convenient drying-chamber. A Second Modification of the Fothergill Process. By Mr. Haakman. The plates are prepared as before up to the albumenizing. The albumen solution contains a few drops of ammonia to every five ounces. After beating together, it is left to set- tle over night, then filtered through wet sponge and pre- served in combination with a piece of camphor for future use. With this solution the collodionized and washed film is coated carefully ; the first portion being allowed to flow forward, but not backward, and then thrown away. The plate is then flowed once more with a fresh portion of the albumen, and drained. The back of the plate is dried witli a pad of blotting-paper. The plate is now ready for the next operation, which is the essential modification. Washing the Plate in Hot Water. Take a clean tray about twice as large as the plate, and pour sufficient boiling water into it to cover the bottom to the depth of a quarter of an inch ; then tilt the tray, and place the albumenized plate on the dry end, the film 388 haakman's fothergill process. being upwards. By a quick but gentle motion, the plate can be covered uniformly with the hot water ; this is kept in motion for half a minute, when the plate is taken out, and the back being again wiped with blotting-paper, it is put away to dry in the drying-chamber. Developer. Pyrogallic acid 3 grains. Water, ... 1 ounce. Citric acid, 2 grains. The exposed plate is washed under the tap before devel- opment ; it is then flowed with a sufficient quantity of py- rogallic solution, which being poured back into a develop- ing vial, is strengthened with a few drops of a two per cent nitrate of silver solution. If the development proceeds, although slowly, yet gradually, add no more of the silver- solution ; on the contrary, more of this solution is to be added if the picture ceases to proceed in development. The author gives a second mode of development, as fol- lows. Prepare the two following solutions : Solution A. Gallic acid, , . V2 grains. Boiling water, 4 drachms. Allow it to cool, then filter, and add twelve minims of acetic acid. Solution B. Acetate of lead, 5 grains, ) To be filtered after Water, 4 drachms. ) solution. The plate, after exposure, is wetted with water, and then flowed with solution A. The solution is then poured back into the developing vial containing a few drops of a two per cent nitrate of silver solution, and a few drops of the solution B. A precipitate is formed, which is not regarded. Stir the solution and pour it quickly over the plate. Gen- erally the picture appears at once in all its details, and fre- quently, though not always, of the necessary strength. If found necessary, the plate, after washing, is intensified with pyrogallic acid and silver. THE COLLODIO-BROMIDE PROCESS. 389 Photography without a Nitrate of Silver Bath. Wet and Dry Negative Processes with Collodio-bromide of Silver, by jB. J. Sayce. The author of this process has prepared a large number of plates by it with unvarying certainty and cleanliness. There can be no doubt as to its practicability, and the beautiful results to be obtained by it. Preparation of the Collodion. The collodion which the author has used for now three years, contains only bromides, as the reader will see. Pbrmula. Ether, 1 ounce. Alcohol, 1 " Bromide of cadmium, 6 grains. Bromide of ammonium, 2 " Pyroxyline, 6 " Prepare as much as may be required for a given opera- tion, and when mixed, set it aside for a week and filter. The collodion is now ready for being sensitized. Take twenty-four grains of crystallized nitrate of silver, and re- duce it to a fine powder in a mortar ; then add a drop or two of water, that is, sufficient to convert the powder into a pulp. This pulp is finally mixed with the collodion in the dark room, and stirred about with a glass rod until the mixture is quite uniform. The latter is then poured into a vial for its reception. The mixture is well shaken, and then set aside to settle for an hour or two. At the end of this time the clear portions are decanted into a vial for present use. Use of the Collodio-bromide in the Wet Process. The plates, after cleaning, are coated with either the al- bumen or India-rubber solution, as already recommended in the preceding processes, or the edges alone may be var- nished all round to the depth of one eighth of an inch on the flat surface, to be coated with the collodion. This sur- face is then coated with the collodio-bromide in the usual manner. After the film has set, the plate is placed in a dish of water Until the greasiness has disappeared ; warm water is to be preferred, because the film is more sensitive after treatment with it. 390 THE COLLODIO-BROMIDE PROCESS. As soon as the water flows uniformly over the surface of the collodio-bromide film, the plate is removed from the water-bath, is allowed to drain, and the back of the plate is wiped with a pad of blotting-paper. It is then placed in the plate-holder and exposed. The exposure is a little longer than is required by the ordinary wet collodion plate. After exposure, a little water is poured over the film, and afterward the developer. To three drachms of this solution, add two drops of a twenty-grain solution of nitrate of silver. This solution is well shaken, and then poured over the moist film. The im- age appears quickly, and in all respects is similar to that which is produced by the ordinary wet process. The ope- rator will soon be enabled to regulate the time of exposure from the nature of the development. If the picture is not sufficiently intense, it may be rendered so by any of the common modes of re-development or intensification. The developed image is fixed in a solution of cyanide of potassium, containing twenty grains to the ounce of water. Use of the Collodio-bromide in the Preparation of Tannin Plates, The glass plates are prepared as just described for the wet process ; they are also coated in the same manner with the collodio-bromide. As soon as thus coated with the col- lodion, each plate is reared away in a pail of water, until the proper quantity has been so far prepared. The number of plates being completed, they are placed in rotation in a dish of hot water, as hot as the hand, can bear, for about thirty seconds, and then removed and im- mersed in the tannin solution, containing fifteen grains to the ounce of water, and well filtered, or into a bath of the following solution, which the author finds superior to the or- dinary tannin solution : Developer. Protosulphate of iron, Glacial acetic acid, . Water, 25 grains. 25 minims. 1 ounce. Mr. Verity's Tannin Bath. Tannin, . . Gallic acid, "Water, Grape sugar, Alcohol, , 10 ounces. 50 grains. 100 minims. 100 grains. 50 " THE COLLODIOBROMIDE PROCESS. 391 Dissolve the tannin in a portion of the water, and filter. The gallic acid is dissolved in another portion by the aid of heat, and is likewise filtered. The two solutions are mixed together, and then the grape-sugar is added. After this is dissolved, the mixture is again filtered. The alcohol is finally added ; the bath is now ready for use. The plates are kept in the tannin solution three minutes ; they are then taken out, drained and dried evenly and quickly in any convenient and suitable manner. The exposure of these dry plates is about half the time of ordinary tannin plates with bromo-iodized collodion. If the exposure is properly timed, very little intensification is necessary. Development of the Collodio-bromide Plate. Prepare, in the first place, the following solutions : No. 1. Dilute Alcohol. Alcohol, 2 ounces. Water, 2 " No. 2. Carbonate of Ammonia Solution. Carbonate of ammonia, 40 grains. Water, 20 ounces. No. 3. Pyrogallic Acid Solution. Pyrogallic acid, 96 grains. Absolute alcohol, .1 ounce. No. 4. Solution of Bromide of Potassium. Bromide of potassium, . 10 grains. Water, 1 ounce. No. 5. Acid Nitrate of Silver. Nitrate of silver, 30 grains. Citric acid, 15 " Distilled water, 1 ounce. The plate, after exposure and immediately before develop- ment, is flowed with a sufficient quantity of the dilute alco- hol, No. 1. The excess is poured back again into the vial for future use. After this operation the plate is immersed in a dish of water, and kept there until the greasy appear- ance has vanished. When the water flows easily over the plate, it is flowed * with the following solution : 392 THE PORCELAIN PICTURE. Alkaline Developer. A sufficient quantity of No. 2. Two or three drops of No. 3. Two drops of No. 4. Shake the mixture and pour it upon the plate, and keep it in motion so as to avoid unequal development. The image will soon appear, if the exposure has been right. Continue to develop until all the detail is out, and as long as there is no fogging on the shadows. The plate is now thoroughly washed in water, and after- ward flowed with dilute acid, (glacial acetic, two drops ; water one ounce ;) finally it is again washed. If the picture requires intensification, prepare the follow- ing solution : Intensifier. Water, 2 drachms. Three drops of No. 3. Three drops of No. 5. Shake the mixture, then pour it upon the plate, and keep it in motion until the proper degree of intensity is obtained. If the mixture becomes turbid or highly colored, prepare a fresh solution, and continue the operation. Finally, when the image is sufficiently dense, the plate is thoroughly washed and then fixed in the solution of cyanide of potas- sium of the same strength as for wet plates. Strong cyanide answers better than a weak solution, as the film is apt to split up and slide off with a weak solution. Still, if the plates have previously been coated with albu- men, etc., such an accident will not happen. Porcelain Pictures, or Opaltype. This is a very pleasing picture, when properly executed with the proper amount of detail, and the regular gradation of lights, shades, and middle tones ; it is, as may be implied from its name, a photograph on white or opalescent glass. There are several methods of preparing this delightful pho- tograph. We shall describe those which we practice suc- cessfully ourselves. The first is effected by means of the camera, and the second by the dry process. To take Opal Pictures by means of the Camera. Select the flattest pieces of porcelain glass for photographic purposes, and such as are quite free from flaws of every kind; THE PORCELAIN PICTURE. 393 if by accident you find a number of opal plates that are con- cave on one side and convex on the other, (and you will cer- tainly find such, if you do not make your own selection,) you need not be particularly alarmed on this account ; for, by means of the process about to be described, such plates can easily be used up, taking care to place the picture on the concave surface. Preparation of the Opal Plates. Grind or file the edges of porcelain glass as you would those of your negative plates. Clean and polish them, too, precisely in the same way. In this process it is particularly advisable to coat one surface of each plate (the concave surface if the plate is curved) with a substratum of albumen ; the albuminous solution is prepared as follows : Separate the whites from two or three eggs carefully, and for each ounce of the albumen take eight ounces of distilled or rain-water, and one drachm of ammonia. Stir the mix- ture with an egg-beater, and when it is entirely reduced to froth, set it aside to settle. In the course of twenty-four hours the albumen will have settled, and may easily be separated from the hardened or insoluble crust by decanta- tion. It is now filtered through a piece of clean and moist sponge, and is then ready for use. The plates, when clean, may be left in a dish of perfectly pure water. Each one is then taken, allowed to drain a moment, and then coated with the filtered albumen in the same manner as with collodion. Caution is required, how- ever, not to let the albumen fall from a great height, but to place the mouth of the vial which contains it just in contact with the surface of the plate to be coated. This surface being moist, and not greasy, the albumen will easily spread, and, driving the moisture before it, will soon cover the whole plate. If there are any bubbles or any insoluble and pro- tuberant particles on the film, it will be necessary to flow the plate once more, or, in fact, many times more, until the surface is in every respect irreproachable. It is folly to ignore bad workmanship at the outset, by allowing a faulty plate to pass ; for the rest of the labor will be all invain. As soon as the film is uniform, the plate is reared on the dry- ing-rack to dry. Of course such a rack must be located in a clean place, where there is neither dust nor draughts of air. This sort of work can be performed during idle or unoccupied hours. 394 THE PORCELAIN PICTURE. Some of the dealers in photographic stock keep porcelain plates for sale, which are already coated with albumen. Coating the Opal Plates with Collodion. Any of the bromo-iodized collodions in commerce will be suitable for the preparation of opal pictures. If the opera- tor wishes to make his own collodion, he may follow the following formula : Alcohol, 6 ounces. Ether, 5 ounces. , , , Pyroxyline, 60 grains, \ (™ re or l ess ' f ma ? Iodide of cadmium,. . . . 40 grains. < be required.) Bromide of cadmium, ... 20 grains. Iodide of ammonium, ... 10 grains. Make the solution of the cotton and salts in the usual way, and set it aside for a number of days to settle and ripen. It is then filtered or decanted from the sediment, and is ready for use. Each plate is coated, after first warming it and then allowing it to cool, like any other glass plate ; and, when the film has set, the plate is immersed in the silver-bath, and retained there until the soluble iodides and bromides have been sufficiently converted into iodide and bromide of silver. It is then taken out, allowed to drain, and placed in the plate-holder, which is immediately transferred to its posi- tion in the copying camera. At the anterior end of the camera the negative is placed in its holder ; the film of the negative looks toward the lens ; and the picture is inverted, a condition which aids in focusing. Negative for the Porcelain or Opal Picture. It is quite an art to take a good and proper negative for this process, as well as for the solar camera. The qualities of the two negatives are exactly the same. Such a negative must be clear, sharp, full of detail, endowed with the three gradations of shades, lights, and middle tones, and yet, after all, it must be very thin. Now, how can such a nega- tive be taken ? Certainly not if the exposure is only long enough for an ambrotype, because then the middle tones will be wanting. You must expose for a full negative, and develop so as to get the proper result. The collodion, too, is made one half more dilute with a mixture of equal volumes of ether and alcohol. An iron developer, suffi- ciently restrained with acetic acid, will undoubtedly be THE PORCELAIN PICTURE. 395 the best; for the collo-developers in general produce too much intensity in the shades, whilst the lights themselves are scarcely acted upon. Such contrast is a bad condition in the negative for copying purposes. Of course, intensify- , ing is out of the question, being altogether unnecessary, if the negative is only complete in detail and gradation. Nor is it necessary to varnish negatives for this process ; for every little flaw or speck in the varnish is transcribed by the rays of light upon the porcelain picture in copying. It is true, porcelain pictures can be obtained from a nega- tive intensified for printing on paper ; but the results with such a negative are far from being pleasing and artistic, with every assistance to boot. Such assistance consists in cutting out a shield in thin paper, that shall hide or cover up the thinnest parts of the negative and allow time for the dense parts to be acted upon. If this precaution were not taken, the porcelain picture would be a black and white imagine, without * any detail and intermediate tones ; it would be a horrid picture ! Such as is but too frequently paraded as a splendid result ! But make your negatives as we have just described them, and you will see the difference of results, when the two pictures stand side by side in stern contrast. Copying cameras can be obtained from the stock-dealers, made expressly for the purpose of preparing opal pictures. They are constructed neatly and with accuracy. Between the lens and the negative there is a movable frame carry- ing a vignette, which can be shaped according to the re- quirements of the case, and introduced and adjusted with facility. The focusing of the negative on the ground glass is effected roughly with the naked eye, and finally with the utmost degree of refinement by means of a magnifying lens. In the winter season the negative may be directed to a bank of snow, and in summer to a white cloud ; or a door, covered with a white reflecting surface and moving on a hinge, may be adjusted in front of the negative at an angle of forty-five degrees, (more or less,) in order to receive the light from the sky and to reflect it along the axis of the lenses. Such an arrangement is very practical at all sea- sons of the year, and can be placed beneath the skylight, without entailing any necessity of opening a window. 396 THE PORCELAIN PICTURE. Exposure of the Opal Picture. The exposure can not be determined beforehand, de- pending as it does on such a variety of conditions ; as, for instance, on the focal power of the lens, the perfection of the lens, the state of the weather, the season of the year, the time of the day, the brightness of the light, the sensi- tiveness of the chemicals used, etc., etc. Begin with a short exposure first, and proceed gradually until the picture is correct. Development of the Picture. Greater care is required to exclude all actinic light whilst developing a porcelain picture, than in the development of any other sort of collodion picture ; probably from the cir- cumstance that every trace of development is so easily dis- tinguished when projected on the white porcelain surface beneath. In reality, probably, the same amount of care and precaution is necessary with every negative ; but the errors and troubles are not so visible in these as in that. The developer, too, has to be diminished in strength, and must be quite clear and free from extraneous organic mat- ter. Formula for the Developer. Protosulphate of iron, 2 drachms. Water, 8 ounces. Acetic acid, 6 drachms. Alcohol, 3 drachms. Pour a sufficient quantity of this developer over the plate and watch the progress of the development. If the exposure has been right, the picture will soon appear and become sufficiently intense. Arrest the development in time, that is, as soon as the image is complete in detail, although not very intense, by plunging the plate into a dish of water. Wash the plate w^ell and then fix the picture in a saturated solution of hyposulphite of soda. We prefer using a fresh portion of the hyposulphite for each plate, for we have al- most invariably observed that an old hyposulphite bath produces gray or dark-colored stains in the collodion film, in places where there were none before. The picture, being thus cleaned and fixed, is thoroughly washed, and may then be examined by diffused light. Clarifying the Porcelain Picture. With the best and most successful manipulations, it fre- quently happens that there are stains on the corners of the THE PORCELAIN PICTURE. 397 plate, and on other parts, and the white of the collodion film is not sufficiently white. The stains are removed ex- peditiously in the following manner : Prepare in the first place tincture of iodine by dissolving twenty grains of iodine in an ounce of alcohol. Have on hand a vial of a solution of cyanide of potassium, such as is used for fixing purposes ; and place a large dish of water right in front of you. A beaker glass full of water also is placed in a convenient place where it can be used with facility. Now proceed to work ; drop a little of the tincture on a given stain, and see that it does not come near any of the delineations of the picture as it spreads. If there is any danger of this result, immerse the plate immediately in the water beneath. The iodine combines with the silver stain and converts it into iodide of silver, which immediately dis- appears as soon as the cyanide solution is applied. If some portion of the stain still remains, apply more tincture of iodine, wash the spot, and dissolve it with the cyanide. In this way all stains may be removed, unless some of them should be located on or near the picture itself ; in this case the tincture would spread and convert the delineations of the picture into iodide of silver, which would be .removed as soon as the cyanide is applied. It is better to reject such an unfortunate picture at once, rather than lose your time in attempts at correction. If the white of the collodion is not stained, but of a slight gray tinge, a considerable improvement is effected by flow- ing the plate with dilute nitric acid, which dissolves the gray metallic tinge, and renders the collodion white. All stains being thus removed, and the collodion film rendered clear and white, the next operation consists in toning the picture. If the picture is intended to be stippled, or indeed only colored, very little toning is necessary. To tone the porce- lain picture completely, when it is to remain uncolored, is a compound operation. The plate, being still wet, is covered quickly with the above solution. The tone of the picture soon changes to a blue- black, and then a retrograde action seems to start up. Wash off the toning solution immediately when this action com- Toning Solution. 0 Terchloride of gold, Water, .... 1 grain. 2 ounces. 398 THE PORCELAIN PICTURE. mences. It frequently happens that this operation is all that is needed ; and then again, there are cases where the following additional toning solutions are found to give a richness not to be attained by the gold solution. Make the following solutions : m. 1. Bichloride of mercury, 1 drachm. Water, 1 ounce. No. 2. Citric acid, 1 drachm. Water, 2 ounces. Intensifying Solution. Of No. 1, 1 drachm. Of No. 2, 1 drachm. Water, 10 drachms. Cover the plate with a sufficient quantity of the intensify- ing solution, which works with great rapidity, and -converts the tone into an agreeable black. Watch proceedings care- fully, and, as soon as the tone is pleasing, wash off the solution immediately. The picture now will be complete. The plate is finally thoroughly washed under the tap, and then dried. It will be unnecessary to varnish the film, if the plate is to be mounted in a case with a glass in front, particularly, too, if the preservative glass is convex. To Prepare Opal Pictures by Contact Printing. There are two independent methods of printing by con- tact, the one by the direct rays of the sun, the other partly by light and partly by development. We shall explain an example of either of these two methods. In both these processes it is quite indispensable that the porcelain glass shall be flat and smooth, otherwise it will not be easy to bring the negative and the porcelain plate into intimate contact. It is equally requisite, too, for the negative to be endowed with the same conditions of flat- ness and smoothness. The negatives, therefore, for contact printing must be taken on flattened plate-glass ; and the porcelain plates you must select yourself, and afterward grind them flat. This is rather a tedious operation ; but if you have a boy in your establishment he can easily be set to work and perform this task. Many of our stock dealers grind porcelain plates, and keep them on hand ready for the operation. THE PORCELAIN PICTURE. 399 To Grind Porcelain Plates Flat for Contact Printing, Upon the upper surface of a flat table fix with glue, or, still better, with small screws or tacks, slips of hard wood, somewhat thinner than the thinnest of the porcelain plates to be ground, in the form of a rectangular frame just large enough for a given sized plate to lie compactly within it and not stir when submitted to friction. A flat porcelain plate is placed in this frame, and, when in position, it is evident its upper surface will be higher than the surface of the slips of wood around it. Secondly, a small rectangular piece of wood is selected of the shape and thickness of an ordinary book, and about an inch longer and wider than the plate to be ground. A similar rectangular frame is constructed and screwed upon one of the flat sides of this piece of wood, to accommodate another plate when placed within it. The plate must be quite tight when it lies within the frame, so as not to fall out when the wood is turned wrongside up. Scatter some fine emery powder upon the porcelain plate lying on the table and moisten it with water ; now lay the other plate upon the emery, and by means of the wooden handle, as it were, in which it is located, rub the two plates together, backward, forward, round about, and in all di- rections, adding, as occasion may require, both more emery and more water, until the surfaces of the two plates are not only ground, but lie evenly and horizontally and in perfect contact with one another. The precautions necessary to be taken, are, to be quite certain that there are no particles of sand or emery in the powder larger than those obtained by subsidence ; for a single particle will scratch the surfaces so deeply that it becomes almost impossible afterward to grind the plates sufficiently deep to eradicate them. As soon as the two surfaces lie in intimate contact, they are thoroughly washed and afterward ground with finer emery dust. The plates at last are taken out of the rectan- gular frame, carefully washed, dried, and packed away for use. To pHnt on Ground Opal Glass by Contact by means of the Collodio-chloride Process. Coat the plates previously with dilute albumen, as before described ; and, as soon as the plates are dry, they are ready to receive the sensitized collodio-chloride. This collodion is prepared as follows • 400 THE COLLODIO-CHLOKIDE PROCESS. Formula for the Collodio-chloride. We are indebted to G. Wharton Simpson, M.A., for the discovery of this process ; and the following formula by Mr. Britton is a neat way of preparing the collodion. Pre- pare the four following stock solutions : No. 1. Plain Collodion. Alcohol, 10 ounces. Ether, 10 ounces. , , , 120 i ^utir may Shake the mixture well until the cotton is dissolved, set it aside for a few days ; decant and filter when required for use. No. 2. Nitrate of Siher Solution. .Nitrate of silver, 2 drachms. Distilled water, 2 drachms. No. 3. Chloride of Calcium Solution. Chloride of calcium, 32 grains. Alcohol, 2 ounces. No. 4. Citric Acid Solution. Citric acid, 32 grains. Alcohol, 2 ounces. To one ounce of plain collodion the preceding solutions are added in the following proportion : To a drachm of alcohol add nine minims of No. 2, and add this to the collodion, which must be well shaken. Now add a drachm each of No. 3 and No. 4 to the collodion ; shake the mixture intimately ; it is now ready for use. Some operators add two drops of castor oil, or three or four of sweet oil to each ounce of the collodio-chloride, in order to prevent bronzing during the printing operation. The col- lodio-chloride, being a highly sensitive substance to light, must be kept in a non-actinic bottle and in a dark room. Coating the Porcelain Plate with the Collodio-chloride. The albumenized plate is first warmed over a flame or stove, and when cold, the collodio-chloride is poured over it in the same manner as ordinary collodion. This opera- tion, naturally, is performed in the dark-room. The film is allowed to dry, by placing the plate on a drying-rack in a dark corner of the room. As soon as the film is thoroughly THE COLLODIO-CHLORIDE PROCESS. 401 dry, the plate is transferred to the fuming-cupboard, where it is allowed to remain in the fumes of ammonia for about three minutes. From these fumes it is placed again on the drying-rack for five minutes, and afterward placed upon the negative in the opal plate-holder. The plate-holders for opal pictures are of a peculiar con- struction. The operator is aware that the ordinary print- ing frame could not be used, from the fact that the porce- lain plate can not be bent back and examined like a piece of albumen paper. All the frames for this purpose are so arranged that one part holds the negative, and the other the opal plate, each of these parts working on^ hinges, and allowing the picture to be examined and replaced with- out having disturbed the relative position of the opal plate and negative. The first printing-frame for this purpose was invented by Mr. Shive, of Philadelphia ; in its present im- proved form it answers every variety of application. An- other frame, which is exceedingly neat and practical, is made and sold by Mr. Chapman, of ISTew-York. A third, equally ingenious as the preceding, and as practical probably, is made and sold by the firm of H. & E. Anthony, New- York. It is possible there are other forms, but we are ac- quainted with these alone. The sensitized plate is exposed to the sun or diffused light, and printed in the same manner as a sensitized sheet of albumen ; in fact, the film contains the same salt in either case, namely, the chloride of silver. It is necessary to print a little deeper than is required in the finished picture ; be- cause its intensity is slightly diminished by the subsequent operations of toning and fixing. Toning and Fixing of the Collodio-chloride Print. The plate is removed from the printing-frame, and wash- ed gently in order to remove the soluble salts of silver, etc. ; it is then immersed in a weak gold toning solution, and toned precisely the same as a print on paper. When the depth of tone is suitable, the plate is taken out of the gold bath, thoroughly washed and then placed in the fixing solution: two ounces of hyposulphite of soda in twenty ounces of water. As soon as all the unaltered silver salt has been removed, the plate is finally thoroughly washed either by soaking some time in several changes of water, or under the tap. A richer black may be communicated to the picture by treating it at this stage with the solution of bichloride of 402 OPAL PICTURE BY CONTACT. mercury and citric acid, recommended as the final toning solution of the opal picture by the wet process. This print, after it has been carefully washed, is dried, and may be colored and varnished, or not, according to taste and circumstances. To take an Opal Picture by Contact on a Bromo-iodized Film. Any of the dry processes would be suitable for this pur- pose ; but we give preference to the dry-tannin process, probably-owing to the fact that we are most conversant with it. Coai the cleaned plates with albumen, as before recom- mended, and when dry, flow them with any good bromo- iodized collodion made by our stock-dealers. Let the film set, then immerse it in the silver-bath. In fine, wash and sensitize the film in the manner minutely explained in the chapter " A Reliable Tannin Process." The dry porcelain plate is then placed in contact upon the negative in the ordinary printing-frame, which lies on a piece of smooth board a little longer than itself. The slide is removed as it thus lies on the board. In this way it is carried on the board into the light either directly beneath the skylight or in an open doorway or window. The board is held in the left hand; the right hand now seizes the printing-frame and turns it over and thus exposes the nega- tive to the light for one or more seconds, as may be found necessary. A single second is frequently a sufficient ex- posure. The frame is again laid flat upon the board, so that the negative is again excluded from the light, and is then carried into the dark-room for development. All the subsequent operations are in every respect the same as those already described for the development, etc., of a tannin negative. If the plate is in any way stained, it may be treated as described in the article on the preparation of opal pictures by the wet process. In both these processes for printing by contact, the vignette arrangement is attached to the printing-frame in front of the negative in the usual manner. This print may receive a system of toning exactly similar, from beginning to end, to the one used and recommended for toning porcelain pictures by the wet process, if found necessary. THE EBURNEUM PROCESS. 403 If a porcelain print is to be handed over to the artist to be colored by stippling, he will prefer receiving the picture full of detail, of course, but not intense and scarcely at all toned; for all that he requires is a complete likeness, but faint, in order that he may give the requisite brilliancy of light and shade by the correct intermixture of color. On the contrary, the toning and proper intensity must be present, if the coloring is to be effected either by dry colors or a thin wash of wet colors, for in these two cases the shades are already effected, and the lights alone require color. The prints made by this process have a striking resem- blance to those on ivory, hence the name from the Latin word Ebur, (ivory.) They are exceedingly soft and bril- liant, and never fail to give great satisfaction. They are altogether superior to the Sennotype or Typolite, which will be described hereafter, from the fact that they do not change by keeping. This process originated with Mr. Burgess, of Norwich. The first part of the process consists in obtaining a trans- parent positive on glass, which can easily be separated from the glass plate afterward and transferred to another medium. Mr. Wenderoth, of Philadelphia, was the first to describe a method of preparing glass plates by means of which collodion films, when the picture is finished, can easily be separated from the plate. The wax soon dissolves by shaking, and then the solution is ready for use. The plates are first cleaned thoroughly, and then coated with the ethereal solution of wax. As soon as the wax film has concreted, it is rubbed off with a piece of clean buckskin, so that apparently scarcely any thing is left; but there is in reality, however, sufficient wax remaining to perform the office required. The collodion, which is suitable for the purpose, must be of the tenacious kind, one that is not rotten or easily dis- integrated. The following formula yields a collodion of the kind intended : Wax Solution for Coating Plates. White wax, Ether, . 2 grains. . 1 ounce. 19 404 THE EBURNEUM PROCESS. Collodion for the Eburneum Process. Alcohol, 3 ounces. Ether, 4 " t , . Pyroxyline, 42 grains, \ ( mor £ or les ?' a * f a J Iodide of cadmium, 28 « < re late ; so PHOTO-RELIEF PRINTING. 429 that the variation of tone in the picture depends entirely upon the thickness of the colored him, and ranges between the absence of film to the extreme depths of the shadows. The impression thus obtained, as is evident, will be a fac- simile of the original bichromated gelatine picture obtained beneath the negative. The relief, which at the first is mani- fest, disappears as the film dries. In its present condition, the gelatine picture is soluble, and on this account would be liable to speedy destruction from a variety of causes. The easiest mode of rendering gelatine insoluble is to immerse it in a solution of alum ; the prints are consequently placed in such a solution and afterward washed in water ; they are then dried, cut, and mounted. The operation of printing with a proper number of appro- priate presses is quite rapid, a single man being thus capa- ble of producing a thousand prints a day. Photo-Relief Printing. The name at the head of this article is given to the pro- cess of obtaining prints from an intaglio relief in metal by Walter Woodbury, Esq. This process is in no respect dif- ferent in principle from from the Photo-Mezzotint Printing by Mr. Swan ; but the modes of operation are in some re- spects different. The process is divided into three parts : firstly, the Preparation of the Gelatine Relief ; secondly, the Production of the Metal Intaglio ; and thirdly, the Printing Operation from the Metal Intaglio. The Preparation of the Gelatine Relief Take a number of thin layers of mica of the required size and uniform in thickness, and affix them by moisture to a large plate of glass. When the excess of water is pressed from beneath the micaceous layers, they will adhere with considerable tenacity, and admit of being easily cleaned and polished like an ordinary plate of glass. The bichromatized gelatine is prepared in the following manner : " Dissolve four ounces of Nelson's opaque gelatine in twenty ounces of water ; clarify with white of egg, and filter. To four ounces of this solution add sixty grains of bi- chromate of ammonia, dissolved in half an ounce of warm water and a small quantity of Prussian blue. This serves to give the finished relief, a color by which to judge of its printing qualities, and does not interfere with the action of the light in penetrating the gelatine." The ingredients are 430 PHOTO-RELIEF PRINTING. intimately mixed together ; the mixture is then filtered through muslin, and, whilst still warm, is poured in suffi- cient quantity upon the plates of mica (the plate of glass to which they adhere having previously been placed on a leveling-stand) so as to cover the whole to incipient run- ning over. In this condition (the operation of course hav- ing been performed in the dark-room) the plate is left in a warm place to set. As soon as the gelatine tissue is suffi- ciently dry, it is cut through along the edges of each layer of mica to the glass plate beneath ; and, by raising one corner with the knife-blade, each layer of mica may thus be strip- ped from the glass plate. Place each of the layers of gela- tine tissue on a piece of blotting-paper of the same size, and clean the surface of the mica. The latter is now placed in contact with a negative, and a piece of glass is placed be- hind on the blotting-paper and submitted to pressure in the printing-frame. The light of the sun is concentrated by passing through a condensing lens. After exposure for one or two hours, according to the intensity of the light and the opacity of the negative, the gelatine film is placed in a dish, and hot water is poured upon it until all the soluble parts have been dissolved and removed. The relief picture is then allowed to dry at a gentle heat. When nearly dry, the film is removed from all artificial heat, and allowed to dry spontaneously, otherwise the gelatine would be apt to split from the plates of mica. As soon as the film is quite dry, the plate is put away between the leaves of a book until it is required for the next operation. Production of the Metal Intaglio. A sheet of soft metal, a mixture of lead and type-metal, with perfectly smooth surfaces, is placed upon a rigid and smooth plane of steel ; over the soft metal is laid the hard gelatine print face downward ; and finally over this is laid another rigid and smooth plane of steel. This combination is subjected to a pressure of four tons to each square inch of surface. Although our first conceptions would be that the gelatine picture would, by this pressure, be crushed or flattened, the result is a perfectly sharp and accurately de- fined metal reverse of the gelatine picture. This operation is the effect of a moment's labor. Other metal intaglios may be obtained from the same gelatine picture in case it is necessary to print with a number of presses at the same time. THE F0XTYPE. 431 Printing Operation from the Metal Intaglio. The ink consists of a thick and warm solution of gelatine, colored to any tint desired. The author of the process finds that the water-colors sold in tubes are the most suitable, as these can be mixed directly, and the quantity can easily be measured. Lampblack tinged with various proportions of crimson lake yields a variety of fine tones. The press used by Mr. Woodbury consists of a shallow box with an extra and movable bottom supporting a strong plate of glass. The plate, by means of four screws beneath, can be raised and leveled as required. The metal intaglio is placed on the plate of glass. Another strong plate of glass is fixed in the under side of the lid of the box, and can be depressed and raised by hinges on one side. The lower plate is now raised and leveled so that the upper surface of the metal intaglio is in accurate contact with the lower surface of the upper plate of glass in the lid of the box. This adjustment being complete, the lid is folded back, and sufficient of the melted ink is poured upon the metal intaglio so as to cover it, or nearly so. The pa- . per is now laid upon the ink, and the lid is brought down into contact with the paper, and bolted down for a minute or so, according to the setting property of the gelatine. On raising the lid, the paper may be lifted up, and along with it the ink in relief. FOXTYPE. This printing process has been patented in Great Britain by the discoverer Thomas Fox, Esq. Ordinary unsalted pa- per is used ; and a transparent positive is required, because the action of the light is the reverse of that in the ordinary process : Sensitizing Solution. Bichromate of potassa, 1 drachm. Sulphate of copper, 2 drachms. Water, 4 ounces. Float the papers on this solution for four or five minutes, and then hang them up to dry either spontaneously or by artificial heat. When dry, place the paper on the transparent positive, and submit it to the action of light as you would if a nega- tive were used. The time of exposure is about two or three minutes. 432 selle's intensifying solution. Development of the Picture. Boil the shavings of logwood in water for a couple of hours ; the decoction is then filtered and used hot. Float the pictures on this solution until they are suffi- ciently intense and the detail is all out. Next immerse them in a hot solution of alum, which removes the yellow color from the lights. They are finally well washed, dried, and varnished. Different shades of color, from blue, purple, light black, and deep black, can be obtained by varying the strength of the sensitizing solution, as also the decoction of logwood. Selle's Intensifying Solution. This intensifier has been very satisfactory in our hands. It produces a brownish-red film when applied to the nega tive after development. Dissolve in one stock-bottle twenty grains of ferridcyan- ide of potassium in two ounces of water. In another similar bottle dissolve twenty grains of sul- phate of uranium in two ounces of water. While the negative is still moist, (after development, fix- ing, and washing,) mix a drachm of each of the preceding solutions, and pour the mixture over the negative. Keep the solution in motion until the proper degree of intensity is attained ; finally pour off the residue, and wash the film. The Aniline Printing Process. This process is a discovery of Mr. Wm. Willis. A trans- parent positive is used in the operation. Preparation of the Paper. Unsalted and plain paper is floated on the following solu- tion, in the usual way. Sensitizing Solution. Bichromate of potassa, 5 drachms. Phosphoric acid, 100 grains. Water, 10 ounces. After floating for two minutes, hang up the paper to drain and dry. THE ANILINE PROCESS PHOTOGRAPHIC RESIDUES. 433 Exposure. This paper is more sensitive than the ordinary silver- paper. Expose to the rays of the sun for a few minutes, (from two to ten) and to diffused light from a quarter to half an hour. The picture becomes visible by light alone, if exposed long enough. Development Cover the bottom of a flat dish with the following solution : Commercial aniline, 1 drachm. Benzole, 2 ounces. Develop in the dark-room. Attach the print to a piece of board, and expose it to the aniline fumes. The latter act upon those parts that have not been affected by light, and relatively to the influence of the shades of the positive. A variety of tones can thus be produced, depending upon the proportion of free acid and other causes not yet thor- oughly understood. Improved Method of Treating Wastes. Cut your prints before toning, and send the clippings with your silver filters in bulk, or burn them in an old iron pot, or other vessel (out of a strong draft), and pack them separately. Save your sink wastes, print-washings, and collodion skins as follows : Place two half barrels or buck- ets in your sink, as in the following figure : 434 REDUCTION OF WASTE RESIDUES. Develop and wash lightly over tub No. 1, and finish wash- ing over the sink. Pour your paper-washings containing silver into No. 1, adding a little chloride of sodium, or common salt, and allow the water to pass off through a pipe placed near the top of No. 2 ; also put your old collo- dion skins into these tubs. Insert a spigot two inches from the bottom of No. 2, in order to draw off the clear water each morning, and also to collect the deposits when- ever desirable. Hypo. Tonings, when no longer wanted for use, should be precipitated with sulphuret of potassium. Gold Tonings should be poured into a large bottle or pitcher, and when no longer required they may be precipi- tated with protosulphate of iron. Great care is necessary in the precipitation; for if too much salt or sulphide be used, the silver will be reduced and pass off into the water. This method of saving wastes is recommended by Mr. Bur- well, an experienced photographer, of the Willard Manu- facturing Company. The Mast Furnace and Rotating-Fan. There are three different furnaces in use for the reduc- ing operations. The "Wind Furnace, in which the draft of the chimney alone urges the fire ; common stoves belong to this class. If properly built, and provided with a high, clean and unobstructed chimney, they answer tolerably well for reducing operations. The Reverberatory Furnace, in which the flame of the fire is condensed and reflected upon the fused mass by a funnel-shaped dome, which will be further explained on another page. This furnace is best adapted for the reduction of gold and silver wastes, giving great intensity of heat with continuity of action; and lastly, the Blast Furnace, used to produce a quick and intense heat. The combustion in this case is urged by a current of air, forced through the fire by means of a bel- lows or rotating-fan. This style of furnace is used mostly in the refining or granulation of the precious metals. An ordinary small cylinder stove may be readily altered into the three different forms above mentioned. When used as a wind furnace, the degree of heat which can be produced in it depends upon the height of the chimney into which the flue passes, and, as a general rule, the higher the chimney the greater will be the heat. It is, therefore, preferable, if possible, to have the stove REDUCTION OF WASTE RESIDUES. 435 placed in a cellar, or at least on the lower floor of a build- ing. The intensity of the heat may also be vastly increased by so proportioning the dimensions of the furnace and the chimney that their diameters are equal, and the height of the chimney be, if possible, fifty or sixty times the diameter of the body of the furnace. By following these directions a wind furnace of the best kind can be obtained; but it is always preferable to use a reverberatory or blast furnace, especially in the reduction of paper ashes and sulphide of silver. The first being dif- ficult of fusion on account of the large amount of silicious and carbonacious matter which it contains; the second being one of the most obstinate compounds, in regard to perfect reduction, known in metallurgy. To construct a furnace on the reverberatory principle, the body should first be lined with a thick coating of re- fractory clay, that it may more perfectly withstand the in- tense heat to which it will be subjected. This done, the orifice on the back of the stove, intended to receive the stove-pipe, should be plastered up with a thick lump of fire-clay. A funnel-shaped dome with an opening at the top, and large enough in diameter to fit tightly, as a cover on the top of the stove, should be ordered at the tinsmith's. Figure 1 represents the dome Fig. 1. with the smoke-pipe attached. The pipe should be self-supported, so that the dome may be lifted on or off to supply fuel, or to observe the progress of the operation. Figure 2 represents this arrange- ment complete. A is the cylinder stove, of which the smoke-pipe B is plugged up with fire-clay; C is the funnel-shaped sheet-iron dome, ta- pering off into the smoke-pipe D; E E are two handles which may be attached to the dome to facilitate its removal. The great simplicity of this arrangement can be seen at a glance. A Blast Furnace is constructed by setting a cylinder stove, with smoke-pipe attached, in the ordinary manner, closing the draft-hole below the grate with a piece of sheet-iron, having a circular hole large enough to admit the nozzle of a pair of bellows, or rotating-fan arrangement. 436 REDUCTION OF WASTE RESIDUES. Of these two methods of creating a current of wind we de- cidedly prefer the latter. A very simple and efficient rotating-fan arrangement may be made as follows: Take a ribbon-block, two inches in diameter, and fasten into this at right-angles four sheets of iron or stiff pasteboard, four inches wide by six long, or of any size convenient to the operator. A hole should be drilled through the center of the block, and a tightly-fitting wooden axle passed through it. This ar- rangement completed should be mounted in an airtight wooden box, just barely large enough to ad- mit of its turning freely, and a crank attached outside of the box to one end of the spindle. Two circular holes, about three-quarters of an inch in diameter, are now cut at both ends of the box, one an inch from the bottom, and the other an inch from the top. A piece of iron gas-pipe, about six inches long, being firmly secured in the lower hole, the arrangement is complete. Figure 3 represents a sectional view of this wind arrangement. A is the ribbon-block ; BBBB the four sheet-iron fans ; C the spindle upon which the whole revolves; D the wooden encasement into which the fan arrangement closely fits; E represents the crank, allowed to pass through the wooden side of the en- casement, and by which the fans are set in rotary motion; F the circular opening at the back, one inch from the top of the box; Gr the orifice, with pipe attached, through which the air is forced when the wheel is in motion. When the fans are rapidly turned by the crank, a strong and steady current of air is forced through the outlet. "When it is required to use the blast, the outlet tube of the fan arrangement is allowed to project through the circular hole in the sheet-iron, placed before the draft-hole of the circular stove, and the connections are made perfectly air- tight by a lute of fire-clay or putty. If the fan is now set in motion, the air is forced through the fire, causing it to burn with the greatest intensity. The power of this little device is wonderful; and we have frequently brought a REDUCTION OF WASTE RESIDUES. 437 mass of gold, weighing twenty ounces, to thorough fusion in five to seven minutes. "When a cylinder stove cannot be readily obtained, a very cheap and efficient furnace may be put together as follows: Take a piece of stove-pipe, eight to ten inches in diameter and ten to twelve inches in height, and line it evenly from top to bottom to the thickness of about one inch with fire-clay,* or, in default of this, with a mixture of equal parts of kaolin or pipe-clay and fine white sand. This mixture should be made into an even, smooth dough or batter with water. Previous to the lining, however, a circular hole should be cut large enough to admit the noz- zle of the rotating-fan arrangement, and about one inch from the bottom; or it might be Y\g. 2. provided with a small door to admit the draft, if used as a wind or reverberatory furnace. This being done, a series of short, stout pieces of wire, from one-eighth to one-fourth of an inch in thickness, should be em- bedded in the fire-clay, about an inch from the draft-hole to serve as a grate. For convenience' sake, three sheet-iron legs should be riveted to the body of the furnace, so as to raise it six to eight inches from the ground. The bottom is provided with a movable sheet- iron cap, like those on blacking-boxes, to render the re- moval of the ashes more easy. The top being furnished with a movable sheet-iron dome and smoke-pipe, commu- nicating with the chimney, the furnace is complete. This simple little device is admirably adapted to the wants of the practical photographer, being small, neat, compact and very efficient. Used in connection with the wind arrangement, it is capable of melting steel in from fifteen to twenty minutes. In many cases, however, it may be more convenient to buy a complete reducing furnace. The neatest and most economical of the ready made fur- naces is that known as Kent's, which has all the appli- ances so that it may easily be changed into either wind, blast or reverberatory furnace. * Fire-clay of the consistency of thick dough may be obtained at any fire* brick factory. 438 REDUCTION OF WASTE RESIDUES. Treatment of the Cyanide Fixing Solution. It has been generally customary to throw away waste cyanide fixing solutions, as they become weak by use. They contain, however, a large amount of silver, which may be readily and economically utilized. The precipita- tion of silver from a solution of its cyanide depends, of course, on the addition of a reagent, having a stronger chemical affinity for the silver than the cyanic acid with which it is combined in the solution. This manipulation is attended with considerable danger, owing to the large amount of cyanic acid gas — a most potent poison — which is evolved during the operation. But with proper manage- ment and care, not only the silver, but the active principle of the cyanide may be regained from such waste solutions. Take a wide-mouthed bottle, of about two quarts capacity, into the neck of which fit a smooth and very tight cork, through which pass two glass tubes, one reaching within a few lines of the bottom of the B | u ■ I bottle and projecting an inch over the cork, Sg Jm the other passing only about half an inch V, Gj through the cork and bent at right-angles I on the outside. The neck of a small fun- II nel is secured to the top of the longest tube B by means of a little wax. Figure 4 repre- I sents this arrangement. A second bottle, MBBB I^B wn ^ cn ma y ^ e about half the size of the IBHBHBBI former, is provided with a tight cork and a glass tube of the same diameter as the last (which should be about a quarter of an inch), is let through this until it reaches within the fourth of an inch of the bottom, and like the former is bent at right-angles. Having completed this arrangement, half fill the first bottle with the waste cyanide solution, and into the second one place a solution consist- ing of — Pure caustic potash, 4 ounces. Water, 1 ounce. And make the cork and joints of both bottles perfectly air- tight by brushing over the following mixture : Beeswax, .... Resin, Turpentine, Vermilion, enough to color. 2 ounces. I ounce. * 44 Place the wax and resin on the fire in a tin vessel, and REDUCTION OF WASTE RESIDUES. 439 when thoroughly melted stir in the turpentine and ver- milion. The latter is only for appearance and may be omitted. Figure 5 represents the complete arrangement. A is the larger bottle containing the waste cyanide solution; B the longer tube with the funnel attached ; C the shorter tube connecting with the rubber-pipe D, through which the cyanic acid gas evolved is lead by means of the glass tube E into the solution of pure potash F. Having concluded these preliminary arrangements, com- mon hydrochloric or muriatic acid should be slowly added to the cyanide solution in the larger bottle by means of the small funnel. Upon each addition of the acid the solution foams and seathes violently, and care should be taken that it does not boil over. Simulta neously with the addition of the acid, a white curdy precipitate of chloride of silver is formed, which, however, is at first redis- solved as it descends into the so- lution. Acid should be added as long as it occasions the slightest precipitate or foaming in the so- lution, or until it is considerably in the access. At the close of the operation a heavy precipitate of pure chloride of silver is found in the first bottle, and a solution of cyanide of potash in the other. If, after the close of the operation, the solution of cyanide of potash in the smaller bottle should be somewhat weak, another quantity of the cyanide solution may be treated with acid, and the result- ing gas allowed to pass into the weak liquid. It, however, generally happens that the fresh cyanide solution obtained by this method is too strong for photographic purposes; in that case it may be simply diluted with water. This process works very beautifully, and the resulting substan- ces are nearly chemically pure. When it is desired to save the silver only, the waste cyanide solution may be precipi- tated in an open vessel with strong hydrochloric acid, as before mentioned; but the operation should be conducted in an open place, with the back against a strong draft of wind, so that the poisonous fumes arising may be carried away from the operator. We would recommend, however, the first process as the best, having used it with great sue- 440 REDUCTION OF WASTE RESIDUES. cess in the reductions of the waste cyanide solutions occur- ring in the electro-plating* art. Another very excellent method of utilizing the cyanide solutions, is to evaporate them to dryness. By these means a solid is obtained (containing all the silver), which may be employed with the greatest success as a flux for the re- duction of sulphide of silver and other wastes. In evapor- ating the solution great care is also necessary, as fumes of prussic acid are given off. The evaporation should be con- ducted either in a fireplace or in the open air. Filtration and Decantation. The mode most generally resorted to for the separation of precipitates, from liquids in which they are suspended, is that of filtration. The process consists simply in pass- ing the substance to be operated upon through some me- dium, fine enough to intercept any solid particles, however finely divided, still of sufficient porosity to allow water to pass through readily. Paper is the substance most gener- ally used for this purpose. The paper best adapted for the filtration of the bulky and heavy gold and sil- ver precipitates, is that known as German filter- ing paper, which, besides being very strong in tex- ture, allows the water to run through very rapidly. "When a precipitate is of a bulky nature, and, es- pecially if accompanied by much water, a plaited filter should be made use of, as it prevents a close adhesion of the paper to the glass, thereby greatly expediting the process. To form a plaited filter, take a square of good porous paper and fold it diagonally, as in Figure 6. Turn A upon B to obtain the crease E, and open it; then double A upon E in the same direction to make crease G; and holding this plait between the fingers, make the fold between P and D divide the space between E B and B D in the same manner. Figure 7 shows the position of the filter in the funnel. After the filter has been properly secured in the funnel, REDUCTION OF WASTE RESIDUES. 441 and previous to the addition of a liquid containing a pre- cipitate, the filter should be thoroughly wet with some clean water, as by these means the pores of the paper are opened, rendering the filter less liable to clog than if the turbid liquid were added immediately. There are, however, some precipitates, like the chloride and sulphide of silver, which, so completely clog certain kinds of paper, as to prevent the slightest passage of water. In such cases a bag of felt must be made use of. A very convenient filter for chloride of silver, when large quantities are operated upon, is an old felt hat, suspended from four corners by means of strings, which should be fastened to the ceiling above the ^ sink. When paper is used for fil- tering liquids which pass through very slowly, a series of small funnels with plaited filters should be made use of. Large funnels are objectionable, as the filters are very liable to tear from the weight of the liquid having no proper support at the bottom ; but this trouble may, in a meas- ure, be remedied by placing a piece of cotton loosely in the bar- rel of the funnel, so that it reaches to the paper, and it will now act as a support for the filter. Loose plugs of cotton alone are very useful. When a corrosive liquid is to be filtered, as a strong acid or alkali, a plug of asbestos, placed loosely in the barrel of the funnel, is the only suit- able medium. Decantation has the same object as filtration, namely, the separation of water from a precipitate. It is only re- sorted to when the sediment is very heavy and subsides readily to the bottom of the vessel without being easily agitated, as for instance the chloride of silver. It consists simply in inclining the vessel gently to let the supernatant fluid run off, or in draining it off with a syphon. The sy- phon is a very convenient little instrument and should al- ways be kept at hand. The most simple form of a syphon is a small glass tube, bent so that it has two arms of unequal length. (Figure 8.) 442 REDUCTION OF WASTE RESIDUES. The long arm may be twenty inches in length, the shorter one about fifteen inches. The syphon is filled with water, the mouth of the longer arm closed with a finger, and the shorter branch introduced, mouth downward, into the liquid to be decanted, until it nearly reaches the level of the precipitate without disturbing it. "Upon removing the Fig. 8. finger the liquid runs out in a continu- ous stream and may be almost wholly drawn off. If the liquid is not injuri- ous or unpleasant to the taste, the sy- phon may be inserted into the liquid without previous filling, being drawn over by suction with the mouth through the lower end. A small piece of rubber gas-tube makes an excellent syphon It should be filled with water and placed into the liquid in such a manner that the end hanging over the side of the vessel is considerably longer than that in the liquid. All precipitates should have the superfluous water decanted off be- fore they are thrown upon the filter, as much time is saved thereby. For more complete and exhaustive details of the various manipulations for reducing Photographic Wastes and Res- idues, the reader is referred to the illustrated work entitled the Reducer's Manual, by Victor G. Bloede, to which book we are indebted for some valuable extracts. CHAPTER XLVIIL THE SOLAR CAMERA AND SOLAR ENLARGEMENTS. The solar camera is in reality a copying camera, with the simple addition of a lens or other attachment, by means of which the sunlight can be condensed upon the negative, and thus made more powerful. There are two distinct kinds of solar cameras : one is fixed in its place and the sun, by means of a reflector, is made to shine along the axis in whatever part of the heavens this orb may happen to be; the other is suspended on two axes, a vertical and a horizontal, and is thus capable of moving in any direction whatever, and consequently of following the sun's motion, Fig. 1. both in altitude and azimuth. All solar cameras of the first class are exact imitations of the well-known solar mi- croscope. Woodward's solar camera was the first in date, and, wonderful enough, it is protected with a patent! al- though the special function of the solar microscope, previ- ous to this patent grant, was to produce a picture, on a screen behind the lens, of another picture or object placed in the conjugate focus in front. Some improvements, in the way of directing the reflector horizontally and verti- cally, have since been made in this camera; for instance, in Gale's improved camera (Figure 1). 444 THE SOLAR CAMERA AND SOLAR ENLARGEMENTS. The diagram (Figure 2) shows — A the mirror; B the condensing lens; C the negative; D the camera-tube and lens; E a rod for adjusting the negative; F a set screw; the lines G G and H H represent the cone of light thrown by the condensing lens. The cost of this solar camera is about one hundred dollars, including patent mirror and condensing lens, and is now made by the Willard Manu- facturing Co. Some solar cameras have attached to them an arrange- ment of clockwork, called a Heliostat, which regulates the motion of the reflector according to the motion of the sun, and thus keeps the sun's rays always parallel with the axis Fig. 2. of the instrument. This attachment makes this sort of solar camera, in one sense of the word, perfect. Such a camera is fixed in a window facing the south. This window is boarded up, so that no light can enter the room, except- ing through the lens. This room becomes the dark cham- ber — the camera obscura. The screen which receives the image is movable upon the floor behind, so that it can be brought nearer to the lens or well drawn from it, accord- ing to the size of the picture required. This is a conveni- ent property of this sort of camera, an advantage which cameras of the second class do not possess to the same ex- tent. The general construction of Gale's solar camera, and of all its congeners, is as follows : First comes a rectangular reflector placed outside the Avindow, and capable of moving vertically and horizontally, and of thus reflecting the sun's rays perpendicularly upon a condensing lens, which is generally a plano-convex lens, the convex surface receiving the rays. The negative comes next in order. It is inverted and the film looks toward the portrait lens, and is capable of motion to and from this THE SOLAR CAMERA AND SOLAR ENLARGEMENTS. 445 lens by means of a horizontal slide. The portrait lens or distributing lens comes next. It is fixed upon a frame which slides horizontally; the axis of this instrument is a line which passes through the center of the condensing lens of the picture and of the portrait lens, which latter is placed at such a distance from the condensing lens as to allow the cone of condensed light to come to a focus in the optical center of the combination, or at least in such a po- sition that the conjugate cone of light, and that of the pic- ture itself, shall occupy as nearly as possible the same posi- tion and be of the same size on the screen. To produce this result satisfactorily, requires a certain ratio to exist between the power of the condensing lens and that of the distributing lens. This subject has not met with the study which it deserves ; and to the want of accurate knowledge in this respect, may be attributed the general failure of or- dinary operators. If the cone of the con- densed light, and if the cone of the pic- ture do not coincide, it is impossible to obtain a picture to- tally free from what is denominated the ghost, which is a cir- cle of greater actinic force in the center than on the peri- phery of the illuminated disc, unless the former cone be thrown entirely out of axis. Another cause that tends to produce this ghost, is to be traced to the spherical and chromatic aberration of the condensing lens. In some instruments this condenser is partially corrected by the interposition of a concave, or a concavo-convex lens, just before the light reaches the negative. This second or cor- recting lens, converts the converging ra} r s of light into a parallel beam of light, which simply illuminates the nega- tive with a highly condensed and nearly uniform light; and Fig. 3. 446 THE SOLAR CAMERA AND SOLAR ENLARGEMENTS. then, of course, the two cases, of which we have just above spoken, must of necessity coincide. By such an arrange- ment the best work may be expected. Dr. Van Monck- hoven's instruments are arranged somewhat in this man- ner; and the results are well known and are recommenda- tions of the cameras. The screen which corresponds to the ground glass in the ordinary camera, is placed vertically behind the distributing lens, and so accurately that its center coincides with the axis of the instrument, and also the distances of either edge, laterally or vertically to the center of the lens, are in pair respectively the same. In the portable solar camera the screen which is intended to hold the sensitized sheet, has, but comparatively speak- ing, a short space to move in; and consequently with this instrument it is very difficult to obtain life-size figures, be- cause an instrument that would do such work must, of ne- cessity, be very unwieldy from its size. Notwithstanding the advantage of Shive's and Roettger's solar cameras, yet their great cost has been the means of contracting their sale. Roettger's camera complete, with a fourteen inch lens, costs three hundred and fifty dollars; Fig. 4. In the portable camera, of which Shive's Helio- tropic, Figure 3, and Roett- ger's Parallactic, Figures 4 and 5, are examples, there is no reflector. The instrument itself is tilted by the mechanism peculiar to each instrument, so as to receive the direct rays of the sun. This is an ad- vantage over the preceding instrument, because there is always a considerable loss of light after reflec- tion. Another disadvan- tage of the Gale solar cam- era arises especially in winter, when the sun's al- titude is small and the angle of incidence and of reflection is very large : the light is thus made very weak by such reflection. THE SOLAR CAMERA AND SOLAR ENLARGEMENTS. 447 and the price of Shive's is even greater. These solar cam- eras are only adapted for the operator in large cities, who have plenty of orders for enlarged work. The country operators generally find it cheaper to send their work to parties in the cities, who make a specialty of this kind of work, and do no other. Any stock house in New York will receive and execute orders for solar camera work in the best possible manner. For the benefit of those who can afford a solar camera of their own, we will give the following directions for using it : The Negative. Fi S- 5 - The solar camera nega- tive is, next to the camera itself, an object of the ut- most importance ; for if this is not endowed with necessary and normal con- ditions, all attempts at perfection will fail. The shades of the negative must be much thinner, much more transparent, than those of an ordinary negative; in fact, the rule we formerly gave on the subject remains valid, namely, " that a page of print must be legible through the densest parts of the negative." The light, after concentration upon the negative,"is not power- ful enough to penetrate parts that are more dense than those indicated; and, therefore, great opacity is permis- sible only where the paper is to remain perfectly white. Furthermore, the negative must be endowed with the regular gradations of light and shade; must contain the requisite amount of detail; all the middle tones between mere outline and a fully-shaded picture. For instance, take a portrait combination, a one-third or card picture lens, stopped down to half an inch, and take a negative of a burdock standing in the shade. "We will suppose you gave an exposure of ten seconds. What is the result ? The result is this: With all imaginable fixing by means 448 THE SOLAR CAMERA AND SOLAR ENLARGEMENTS. of intensifiers, the negative is a black and white picture — a sketch — a congeries of mere outlines; the shadows of the depressions and undulations in the leaves are totally want- ing; even the skeleton, the branches and fibers on which the chlorophyl is built, is invisible. It is true the negative gives one the conception of a burdock; but the mind has to fill up the contour. Such a negative will produce only a black and white picture in the solar camera. Try again; expose the negative twenty seconds. The result is quite an improvement; there is light and shade; nevertheless, there is something yet wanting. The medium and lateral branches of the skeleton are all here, but the minor reticulations and interlacings, as well as the protrud- ing fibullse, are still invisible. Try once more. Give an exposure of thirty seconds. This appears enormous to such of you who have been in the habit of taking views in eight or ten seconds; but you will find that such an exposure is necessary to obtain what we call a perfect negative of the object in question. Now you distinguish on the negative all the detail that the eye can descry on the object; the lights and shadows, too, are in perfect relief. Such a negative is a delightful thing to look upon; it will bear the most minute scrutiny. Com- pare it with those you have been in the habit of taking; in yours the leaf of the maple, the chestnut and the plane is a black blotch, that cannot carry to the mind what it represents. You know now what we mean, when we assert that the negative must be full of detail, of middle tone, of light and shade in regular gradation. Such must be the quality of a negative for the solar camera; and with such a negative you may obtain, by proper management, an enlarged pic- ture almost, if not quite, as good as one taken by contact printing. Now in order to take such a negative, you must make certain changes in your working materials. In the first place, dilute the collodion with a mixture of equal parts of ether and alcohol, until it flows quite easily over the glass plate and leaves no lines on the dry film. Add to it also a few drops of tincture of iodine. In the next place, filter the collodion and wash the collodion bottle, the ori- fice and the stopper carefully, and rub off all adhering pieces of collodion. All this is necessary to ensure success. Choose the finest and clearest plates of glass for this pur- pose. Reject every plate that contains a flaw of any kind. THE SOLAR CAMERA AND SOLAR ENLARGEMENTS. 449 Filter the silver solution as well as the developer. Have everything in good working condition. Expose long enough to get detail. We cannot prescribe a definite rule on this score ; you must study it out in con- nection with the objects to be delineated, and the intensity and direction of the light; but expose long enough; over- exposure is better than under-exposure; for the former can be controlled in the development, but we cannot pro- duce by development what light has not instituted by its physical impression. As soon as the picture is complete in light, shade and detail, stop all further development; wash, fix and again wash. Now examine the negative. If the shades are too thin, too transparent, add a drop or two of the silver solu- tion to two or three drachms of the developer, shake the mixture and pour it upon the negative ; this will soon pro- duce the requisite amount of intensity; but the probability is that no intensification is necessary, and will seldom or never be necessary. We mention the expedient to be re- sorted to in case of necessity. If there are any specks or flaws in the negative, it must be taken over again; for every speck and flaw will be magnified in the print. Get the negative right to begin with, then you have a fair reason to hope for success. Of course it is supposed all the time that there is not the slightest veil or tendency to fogging on the negative film; this would be a great det- riment to its good working qualities, and would cause it to be rejected at once. Dry the negative when complete; do not varnish it, un- less your varnish is colorless and entirely free from par- ticles of every description. The Camera. When about to print take out the camera upon the roof or elsewhere, if it is of the portable kind, and place it in a position where there will be no need of moving it -from this position, until the printing operation is complete; place it, too, where it is not liable to be jarred or agitated by the wind. Previous to undertaking any print, ysu must ex- amine the screen on which the sensitized sheet is to be pinned or tacked, in order to ascertain whether it is verti- cal to the axis of the distributing lens, and parallel to the board on which the lens is screwed. You must be very particular about this point. In order to test this parallel- 450 THE SOLAR CAMERA AND SOLAR ENLARGEMENTS. ism, we find the center of the screen and draw a circle on it and two diameters, one horizontal and the other vertical. A circle is also drawn on the board to which the lens is attached, concentric with the periphery of the brass flange, and two similar diameters are constructed. If the two planes are parallel, the distances from the extremities of the corresponding diameters must be all equal to each other See that this is so before you proceed. See, too, that the screen can be firmly adjusted in its place. Pin a sheet of white paper upon the screen, and place the negative in the holder. Now cause the sun to shine upon the condenser, and in the direction of the line of col- limation, or along the axis that joins the center of the con- denser and the lens. Move the carriage containing the negative backward and forward, until the picture upon the sheet of paper is sharp and clear. Bind the carriage in position, and adjust the focus to the greatest accuracy in the following manner: Provide yourself with a small Galilean telescope, such as is used in opera glasses — one of the components of an opera glass is just the thing. This is your focusing glass. Adjust it to focus at a given distance from the picture, where you can easily rest the telescope against some rigid support, and, at the same time, move the focusing screen that moves the plateholder. If the negative is sharpest in the middle, or on a given part, focus upon this part, and make the picture upon the screen sharp in reference to this particular part. There is no possibility of equalizing the focus here, by focusing half way between the center of the picture and the peripheral parts, as we are sometimes wont to do with a landscape; for by doing so the parts (if cen- tral) that are sharp will now not be sharp in the picture. Focus upon the sharp parts. Bind or screw the lens, the plateholder, the condenser, and the screen firmly in position. Furthermore, ascertain whether your lens produces any flare or ghost. It is very probable that it will produce a company of these infernal genii, even although the lens may have no stop, which is supposed by some persons to be the prime cause of the fraternity. We do not intend here to discuss the subject of their cause, but will show them to you. Let the sun's disc move quickly over the surface of the condenser, while at the same time you observe the picture on the screen. You will perceive one, two, three, etc., illuminated circles move across the field of vision over THE SOLAR CAMERA AND SOLAR ENLARGEMENTS. 451 the picture — these are ghosts. One — the principal one — moves in a direction opposite to that of the sun's motion; the others cross the surface of the picture in an opposite direction. If these ghosts are left to disport themselves on your picture, they will spoil its beauty in the same way as a herd of grasshoppers devastate a country wherever they prowl. Exorcise them, therefore; enunciate the wizard spell; besprinkle them with holy water, or invite them out to a dinner party — invite them out of the picture. As we have just observed, by causing the sun's disc to move across the condenser, the ghosts move across the pic- ture; but as we cannot move the sun, let us move the con- denser to the right or left until the ghosts have been con- ducted just off the face of the picture — this is the position of the camera in reference to the sun, by means of which your print will be free from the central flares or ghosts. Mark this position, and keep your camera in it during the exposure. The Sensitized Paper. The albumen paper is sensitized in the usual way and hung up to dry. As soon as all excess of silver has drained off from the lowest corner, and the sheet is no longer wet on the surface, but simply imbued and expanded with moisture, place the sheet on a large flat board and pin down the edges all round firmly to the board, and set it aside to dry completely. While drying the sheet contracts and becomes perfectly flat. When dry the film may be formed just as you are accustomed to operate in this respect. Be very careful that the sheet is perfectly dry before you substitute it for the focusing paper. Pin it well in place, turning the portable camera, of course, away from the sun during the operation. Let on the sun and keep it in its proper direction during the whole exposure. During half the exposure the ghosts may change place, thus equalizing the light on the picture. If the sensitive sheet were not dry when the sun was turned on, the picture will be nowhere sharp ; for, by con- tracting as it dries, the paper gradually recedes from the picture and makes the impression nowhere perfect. Fre- quently the drying is irregular, or the pins give way more on one side than on another, in which case the contraction is sudden in a given direction. By this means lines, points, 21 452 THE SOLAR CAMERA AND SOLAR ENLARGEMENTS. leaves, etc., become doubled. All this sort of trouble is very common, but it can be avoided : Let the paper be quite dry before you begin to print The toning and fixing need no instruction. There are several methods of printing by development. The following is the one preferred by M. Libois : Take thin Saxe paper and float it for a minute on the following salting solution: The citric acid is first dissolved in two and a half ounces of water, and completely neutralized by bicarbonate of soda, five drachms of which are required to neutralize three drachms of the acid. The solution of citrate of soda thus formed, is added to the solution of the chloride of ammo- nium. The solution must have a slightly acid reaction, which is attained by the addition of a few drops of citric acid in solution. A small quantity of boiled arrowroot is also mixed with this bath, which is said to improve the final tones. The paper is then hung up to try; after which it is sen- sitized by floating it on the following bath for half a minute : This bath is acidified with a few drops of a solution of citric acid. The first few drops produce a slight precipi- tate of citrate of silver, which is immediately dissolved by the succeeding drops. When this is effected the bath is sufficiently acid. This paper when dry is ready to be tacked to the focus- ing screen. You expose until the print assumes a lilac hue, which will be a few minutes at most. The image in this time will be just visible. The paper is now taken out and immersed in the following developing bath : Printing by Development Chloride of ammonium, Citric acid, Rain water, . , . . 4 drachms. 4 " 25 ounces. Nitrate of silver, Water, . 1 drachm. 18 ounces. Gallic acid, Acetate of lead, Rain water, . 6 grains. 3 " 40 ounces. To be prepared as follows: THE SOLAR CAMERA AND SOLAR ENLARGEMENTS. 453 Dissolve a drachm of gallic acid in four drachms of alco- hol, and a drachm of acetate of lead in twelve ounces and a half of water. Take a drachm of the alcohol solution and twelve drachms and a half of the solution of acetate; add these to one hundred ounces of water, and then drop in just enough glacial acetic acid to redissolve the slight precipitate of acetate of lead that falls. A number of prints may be immersed at the same time in this bath. The development requires five or six min- utes in the dark-room, and is stopped the moment the prints appear perfect; over-printing is not needed; for the fixing solution seems rather to improve the detail than to destroy it. "Wash the prints and then immerse them in the follow- ing fixing solution : Water, 20 ounces Hyposulphite of soda, .... 6 " In this bath the prints remain about four minutes, they are then washed thoroughly in a running stream of water. The color of the prints, when they leave the water, is red- dish, but it assumes a beautiful deep brown on drying. Naturally the print may be toned like any other silver print. In this case the print, after development, is first carefully washed, and then immersed in the ordinary gold toning solution, and afterward treated in other respects like any other silver print. CHAPTEE XLIX. failures; their origin and remedies. All photographers have been more or less troubled with imperfections in their negatives, and it is a frequent source of annoyance, and we shall now proceed to examine such imperfections and show their nature and origin, and this portion of his experience is of as much or more value to the operator as any; for in a process consisting of a great variety of manipulations, on the complete success of each of which the perfection of the resulting picture is depend- ent, it becomes of great importance to possess the power of distinctly referring any failures to their exact origin, and thus being enabled to apply the necessary cure. Other- wise, the student would have the mortification of seeing plate after plate appear on development with the same blemishes, to which, having been enabled to trace their source, he would be incapable of applying a remedy. It is well, therefore, to acquire the habit of never pass- ing an imperfection, and not resting satisfied until in all the various processes the one causing it has been discov- ered; for the following information on this branch of our subject we are largely indebted to Mr. Lake Price. Fogging. The first defect we will notice is of frequent recurrence; it is a general obliteration of the forms of the subject in an opaque film, which prevents them from being clearly dis- tinguished, in whatever direction they may be viewed. This is termed " fogging," and is caused in a variety of ways. It may result from the unskillful use of the devel- oper itself; if it is of too great strength in warm weather, when it should have been reduced in power by the addi- tion of distilled water and acid, fogging will ensue; or, at a more moderate temperature, prolonging the time of de- FAILUBES; THEIR ORIGIN AND REMEDIES. 455 velopment beyond a certain limit, will cause the same blemish. If weakening the solution in the one case, and shortening the development in the other, does not remedy the evil, the nitrate bath must be tested for alkalinity with reddened litmus or turmeric paper.* If its condition is found satisfactory, L e. f neutral or just acid, which will be seen by its allowing the reddened lit- mus paper to retain its color, the fault is not there. If it restores it to its former tone it is alkaline, and a drop or two at a time of the dilute nitric acid must be added; test- ing between each change with the blue paper, so as not to exceed the quantity necessary, which will be when the paper is tinged with red. Stir with a glass rod during the time, that the drops of acid may be equally distributed throughout the bath solution, and their action not confined to the mere surface. When there is only a very slight tendency to fog, it is better not to touch or alter the bath; by using a more highly colored sample of collodion perfect clearness of def- inition will be restored to the film, while at the same time every plate of such quality of collodion that is dipped will tend gradually to displace, more and more, the small tend- ency to alkalinity existing in the bath. Indeed, with such a combination and balance of proper- ties, an acid collodion and a neutral bath, most excellent qualities are produced in the picture; the bath, on the one hand, possessing the power to accelerate the action and delineate the difficult colors or obscure radiations from the subject; while its inclination to fog is bridled by the acid state of the collodion, which keeps the general definition of the plate and its darks and half-darks bright and clear. Should the bath, when tested, be found in good condi- tion, the fault maybe with the acetic acid; if it is deficient in strength it will not moderate sufficiently the action of the pyrogallic or iron in the developer: on adding about a sixth to one quarter more than its original proportion to the solution clear plates will be obtained; for extreme heat use citric acid. When not arising from these sources, fog- ging may be caused by diffused light having acted upon the film either in the operating-room, the slide, or the * Litmus paper, when used to test for alkalinity, is first reddened. This is best done by taking out the stopper of an acetic acid bottle, and holding a strip of the paper in the fumes inside ; it will immediately change from blue to red. Actual contact produces a less sensitive test paper, its texture being completely saturated with the powerful acid. 456 failures; their origin and remedies. camera, or from the reflexion of light from bright surfaces in the studio, or portions of sky acting directly on the lens. Carelessness in the operator, viz., handling the nitrate bath dipper with dirty fingers, contaminated by contact with the developing solution or fixing hypo., will creep down the dipper into the bath solution; any messing or allowing splashes of chemicals to fall into the bath, must be avoided — it should be kept rigorously covered with a loose cap. An old bath has occasionally a tendency to fog, from the accumulation of organic matter and presence of oxide and nitrate of silver; the best remedy in this case is to replace it by an entirely fresh one. Lastly, and more frequently than any of the preceding causes, over-exposure at large apertures of double lenses is a fertile source of this imperfection, especially when used in the open air and their surfaces carelessly exposed to the action of diffused light. This especially applies to the por- trait, orthoscopic, doublet, and rapid rectilinear. Shade the front of the lens more completely. One general line of demarcation exists in fogged plates, which materially assists the operator in discovering the origin of the evil; it is that when fogging proceeds from impurity in the chemi- cals it is on the surface, and is removable by gentle friction with the finger. If it has been produced by over-exposure or diffused light it is in the body of the film, as much as any portion of the subject itself, and is incapable of re- moval. Insensitiveness. The next blemish we will notice, is in the direct opposite to the fogged appearance on the plate : it is the insensi- tiveness evidenced by the too great quantity of bare glass seen on the plate ; this is caused probably by acidity of the bath, which must be tested for it; if there, its presence will be denoted by the greater or less degree of intensity of the red color which it imparts to the litmus paper, and accord- ing to the proportion^ so must the quantity of the alkali, applied to rectify it, be regulated. Some operators recom- mend ammonia for this purpose ; the writer advises drops of a solution of carbonate of soda, dissolved in distilled water, to be used in preference, having found it in practice give much better results. It must be applied very gradu- ally, and the test-paper and stirring-rod used as mentioned before. If on testing the bath its acidity is not considerable, and failures; their origin and remedies. 457 the operator has been working it with a rather highly col- ored collodion, instead of meddling with the bath, the bal- ance before mentioned can now be restored in the contrary direction — namely, by using the most neutral sample of collodion at hand, which will be found as efficacious in re- storing sensitiveness, and giving delineation of forms in the bare portions of glass, as the acid collodion was in clearing the obscured plate. If the bath is not in fault, the exposure in the camera has probably been of too limited duration, or the diameter of aperture less than the quality of light would bear; in- creasing the time of the first, or enlarging the other, will entirely alter the character of the succeeding plate. Waviness. Eeaminess, or wavy marks, of Fig. 1. uneven thickness in the film, fig. 1,- are most likely to occur in thick viscous samples of collodion, which are difficult to get off the glass with sufficient celerity; in hot weather all collodions will be apt to have this defect, owing to rapid evaporation of the ether in manipulating.* This unevenness is most offensive in large flat tints, backgrounds, etc., with whose perfect appearance it of course greatly interferes, but it is highly detrimental and objectionable in all parts of a picture, for as the thickness of the collodion film is doubled in such parts, no treatment which will apply to them will be successful for the rest, and vice versa. If the film be detained until they are set, the other parts will be dry and insensitive ; if they are im- mersed when the rest of the film is ready, from not being dry they will be still unset, and being soft the other por- tions of the film will drag them, and they will be full of crapey marks, which conditions occurring across features, etc., are very destructive to the picture. In warm weathqr, especially, the state of the collodion must be carefully * Cadmium-iodized samples are most apt to become thickened ; indeed, it is probable that the one cause of the superior sensitiveness of this class of collo- dions is due to the spongey thickening or opening of the structure of the film, which becoming in excess must be moderated as directed. 458 failures; their origin and remedies. •watched, and as it thickens by evaporation, newly washed ether must be added until the necessary fluidity is attained. White Rings. Small white circles, as given in fig. 2, appear in the sub- ject. This blemish is caused by the operator elevating the Fig. 2. mouth of the collodion bottle too far from the glass in laying the film ; the action established in the liquid, by the minute bubbles cre- ated, remains after they may have dispersed, and their traces appear in the finished work in the man- ner shown. If care is taken to depress the mouth of the bottle sufficiently, before beginning to pour the collodion, these marks will not occur. Serrated Marks. Peculiar serrated marks, fig. 3, are caused by a greasi- ness or scum on the surface of the bath, which attaching Fig. 3. itself to the film, slides down it when put to drain. This defect disappears after dipping two or threo plates, showing that they have exhausted the impurity and cleansed the surface for succeed- ing ones. This blemish is entirely consequent on the contact of gutta percha with the bath solution; all other precautions being taken to avoid the presence of organic matter, dust, etc., it is un- known in a photographic ware or glass bath. Spots. Spots, fig. 4, are of two kinds; those of defective action, leaving bare glass, and printing black, are caused in the following manner : Tripoli and nitric acid, recom- mended sometimes for use in cleaning the glasses, adhere most tenaciously to their edges, and if present will, wh6n the plate is dipped in the bath, be dispersed failures; their origin and remedies. 459 by the solution though it was intractable to water, and settling on it, and on succeeding films, causes spots of bare glass to appear. A film that has been kept too long in a new bath, or that has been delayed before exposed in the camera, will thus become dry, and the collodion being acted upon by the nitrate of silver, numerous minute spots are eaten into its structure. The contrary appearance — that is, spots of opacity on the plate, printing white, fig. 5 — is produced by dust set- tling on the film in certain stages Yig. 5. of adhesiveness of the latter, and MaaBMmifTiiintffpflifl^^ not forming " Comets," but spots, by minute centers of increased ac- ^^^^^^^^^^^P^fef tion. By the film being laid from ^^y^^^^^^^^^^W] a highly colored sample of collo- dion, and excited in an old bath R^^^^^^^^^^!^?! which has become over-iodized; lastly, and most frequently, by too B^^^^^^feSrtftl prolonged development of an un- EBMBBSb^ der-exposed plate, and using excess of drops of bath solu- tion in the developer, the effect of which is to cover the surface with minute specks of concentrated deposit of silver. Comets, Photographic " Comets," fig. 6, are defects which bear a remarkable resemblance to the forms of their prototypes; they are caused by particles of dust in the atmosphere of the developing-room, which, de- j?\g. 6. scending on the wet film, reappear ^^^—^.—m^ in the picture in the shape of spots, comets, etc., by the action H||HBS for which they serve as nuclei; lil llB^Mr^ HB^it^^^ when they arise from this source, NHB the tails, etc., stream from them Hun in a vertical direction as they lie DnH on the surface of the film, and are BB^jji^i^^PsMrl j caused by action in the bath liquid, retained by them, flowing downward. Greater care in clearing away dust, etc., will prevent their being seen on the plate. They will likewise arise from an inferior quality of collodion; from carelessness, with a good sample, in not decanting the upper part of it from a large stock bottle into a smaller, tjius leaving all impurities of former manip- ulations behind ; by using the collodion immediately after 460 failures; their origin and remedies. iodizing; or from not wiping, with sufficient care, the necks of the bottles from dried fragments of collodion or dust, or Fig. 7 from any flue, etc., off the glass- cloths, adhering to the surface of the plate. When they are in the collodion itself they may be known by the tail-like appendages, etc., taking a curved form of direction, as in fig. 7, consequent upon the rotary motion imparted to the liquid in laying the film ; whereas those dependent on the action of substances merely resting on the surface of the film, have direct vertical lines of drainage action. Straight lines, of varied intensity, crossing the plate from side to side, are caused by any pause of hesitating move- ment with which the dipping of the film into the nitrate bath may have been accompanied. As has been mentioned the action should be firm, prompt and consecutive. Stains. Marks often appear like small beards of light following the forms of the high lights of the subject, and streaming Fig. 8. downward from them in the di- rection in which the film stood when exposed in the camera, as shown in fig. 8. This defect is caused by the plate not having been sufficiently drained before ex- \ posure ; the action is caused thus : The rays of light which delineated the fingers, linen, etc., in the im- age, were diverged and reflected by the descending liquid, and possessed, in the immediate Fig. 9. vicinity of the high lights, suffi- cient power to impress an action. Remedy — to obtain a clearer out- line, drain the plate more before putting it into the slide. The marks do not attach them- selves to the forms in the picture, but are seen as a parallel streaki- ness of various intensity and width across the picture, as in fig. 9. failures; their origin and remedies. 461 These appearances may arise from three causes, and the following tests will enable the operator at once to decide to which he should refer them. The subject was taken in the camera, of " landscape " form, but the marks appear in the contrary sense. The defect was in the dark-room; dif- fused light, some crevice, or insufficient yellow blindage, were the causes — that is to say, if they are incapable of re- moval when the film is gently rubbed either with cotton wool or the finger. Marks similar in appearance to those just described, but appearing in the sense in which the film stood in the ni- trate bath are due to alkalinity or nitrites, or some impuri- ties in the nitrate bath, and are often met with in an old bath, in which organic matter in one shape or other is present. They may at once be perfectly distinguished from the preceding defects, which are similar in appear- ance, by being entirely on the surface of the film, and cap- able of removal by friction. Another cause for the appearance of such marks is the following: When working with sensitive conditions of chemicals, if with deficient quality of light, or small area of size in the subject to reflect back the pencils of light to the film, the operator should use too small a diaphragm in proportion to either; or that the focal length in the camera should be considerable — the darks of the picture are not thrown with sufficient vigor on the film to guarantee it from the general action, which partakes more of the nature of diffused light than of those distinct pencils of light — with intervals of partial or total privation of it — which a more complete action would possess; the consequence is, that the lights are not intense, the shadows are weak, and that the drainings of the bath, liquid in their course down the film act upon it lenticularly in concentrating light, leave traces of their passage. But if, on testing, the defect arise from the causes given above, the whole will be found in the body of the film, impressed by the ac- tion of light, and not capable of removing by friction, as some parts would be if caused by impurities in the ni- trate bath. Distinct smears, with fainter deposit on them, are visible across the subject. They are probably caused by drops of saliva, in blowing the surface of the glass, or by perspira- tion on the hands of the assistant who cleaned them, hav- ing found its way first to the clothes, and from thence to the surface of the glasses. The only remedy, in warm 462 failures; their origin and remedies. weather especially, is to have a good relay of white cotton gloves for him to use. Marks at the top and corners of the subject, see fig. 10 — which in the camera was the bottom — arise either from the film having been too little drained, and the accumula- tion of bath at the bottom during exposure — or from neg- lect in blotting out the slide between each picture. Both study, the "collodion back," or holder, becomes sodden with bath solution, having to work long and much at one time, two or more backs and inner frames will tell in the improved results. A mark of greater light occurs along the whole of the bottom of the subject. The light has got in at the top of the slide while the film was exposed, showing the necessity of keeping it covered with a cloth while in the camera. A margin of insensitiveness, i. e. t bare glass, sometimes above half an inch wide, occurs all along the top of the subject — this generally happens most when long exposures are ne- cessitated, as in interiors, etc. The cause is the accumu- lation, at the bottom of the film during exposure in the camera, of a band of drainage which obstructs the action on the film. Drain more closely, and connect the pieces of blotting-paper at the corners with that behind the glass, so as to attract, or suck off, the super-abundant moisture. The subject has a vigorous deposit on the lights, but the shadows are too much filmed over to be bright and telling. It cannot be over-exposed, or the lights would not be so vigorous ; it most probably, particularly if work- ing with a double lens, arises from diffused light or reflec- tions. It would doubtless be more advantageous that the lens and camera should be so enclosed that the lens, through an aperture, should see only the subject, thereby avoiding all reflections from surrounding light objects and giving the purest definition of which it is capable; but this, in Fig. 10. of the above will be aggravated, if, in' taking the slide from the camera, it is not carried in the same sense in which it stood, but tilted or reversed; or if the flap, after the picture is taken, is too violently closed, which has the effect of splashing the liquid col- lected in the groove upward over the subject. As with prolonged failures; their origin and remedies. 463 practice, especially out of doors, is found troublesome, and loses much time. A much larger and deeper brass shade than is usually sold with each size of lens, diaphragmed or lined with black cotton velvet (a great absorbent of light) answers every purpose; and has the advantage of allowing the operator much more freedom of action in placing his cam- era, while the shade being on the lens, follows its move- ments, when it may be necessary to shift its position in the field, by altering the sliding fronts. Stains of development, see fig. 11, are in the earlier part of the photographer's practice, very annoying; the most frequent are those of inequality of action, caused by un- skillfulness in not covering at one sweep the whole of the plate, or of not keeping the de- j?\g. 11 veloper in continual motion, and thus allowing its greasy streaks and stains to impress their image on the film. Using the solution of too great strength will mark a sensitive film by its sudden and violent action, and the impossi- bility of evening it quickly enough; lastly, using too small a quantity, in proportion to the superficies of the film, is sure to create stains from its inefficiency to cover the ex- tent of surface. Patches of insensitiveness arise in two ways, but may each be distinctly referred to its origin. The first are caused in the development, by the operator having poured the solution continuously on one portion of the film, in- stead of distributing it all over. The result has been that he has washed away the silver, which should have formed the image, from that part, and a bare patch is seen in the film; but when arising from this cause there is a remedy. Add drops of bath to the developer, and tilting the plate, apply it neatly to the deficient portion, in which the sub- ject will immediately appear, and if done skillfully, not al- lowing the other parts to be strengthened, it will not be perceived in the finished picture. The same sort of appearance results from keeping the film too long before dipping it in the bath, especially in hot weather; but there is one appearance which at once marks the difference of the cause, namely, that when aris- ing from this source, iridescent tints accompany the mark, 464 failures; their origin and remedies. which in the other were not seen, and the application of the nitrate drops, the effect of which was instant in the former, is powerless in this ; the only remedy is in greater pronrptness with the next film. The defect caused by the opposite treatment, namely, dipping the film too soon, makes itself visible in thickened edges of insensitiveness, called "fringes," on the pouring- off margins of the plate, and a general rottenness, reticula- tion and crapeyness of the film, which will probably tear up with the action of the water. Reticulations, likewise, are the effects of breathing over the glass, or neglecting precautions in damp weather; water is thereby added to the collodion. This is the reason why, in inferior or un- skillfully prepared samples of collodion, reticulation is a frequent blemish — the alcohol and ether contain water, and we thus perceive the necessity of the caution given for their preservation, in perfect order, in small bottles. Hypo stains are of the most formidable and hopeless de- scription; generally traversing the whole plate from the corner where a finger or thumb unwashed, after the devel- opment and fixing of the last subject, came in contact with the film — caused by messing. Continual use of clean water and towel (no soap) is necessary in operating. We have thus examined the various causes of failure in the manipulation of the collodion process, and although many precautions may have been more dwelt upon than their nature would apparently warrant, such minute de- tails are entirely necessary, and if the reader will only strictly adhere to them, he need never doubt that in taking up a subject he will be secure of an unblemished negative. CHAPTER L. PHOTOMICROGRAPHY PHOTOGRAPHING ON CANVAS — ENAMELING, OR BURNING-IN PROCESS PRINTING ON IVORY ENLARGING BY THE SERUM OR WHEY PROCESS. The following is M. Grirard's method of photographing microscopic objects: The application of photography to micrography is one of the most useful accessions to the natural sciences, in consequence of the exactness with which the subjects are represented. If the most conscien- tious designer cannot depict with sufficient faithfulness the marvelous organization of infinitesimal objects, light pos- sesses an infallibility in doing so. Fig. 1.* Fie Fig. 3. Photomicrography consists in the substitution of a very short focus for the ordinary objective lighted by reflection; it is a kind of enlarging apparatus, only very powerful. The microscope, inclined in the horizontal position with the eye-glass removed, has its body continued by an expanding cone up to the dark slide. The entire ap- paratus is made to rest on a stand even with the eye, mounted with the greatest firmness, so as to prevent all vibration. This arrangement is much more simple and practical than using one entire piece darkened, and at the window of which a solar microscope is placed. * A description of the woodcuts in Chapters L, LI and LII will be found in Chapter LIII. 466 PHOTOMICROGRAPHY. The photographic processes used are those ordinarily employed in practice; it is only necessary to mention that the development by pyrogallic acid alone is often prefer- able, owing to the uncertainty there exists as to the exact intensity of the light. The principal difficulties are in the lighting. The focusing requires the greatest precision, the focus of the objective being so very short; it is commenced with the coarse, and finished with the fine adjustment, and a magnifying glass applied upon the ground glass. When the length of the apparatus is very great, it is necessary to have recourse to an assistant, who acts according to the instruction of the observer. On the exposure depends, in a great measure, the value of the proof. The direct solar light can alone unite the necessary photographic quali- ties; the diffused light is too feeble in most cases to be of any utility. The artificial ex- posure by electric light, mag- nesium, gas, or Drummond's light have only an experimental interest, and are unsuited to the usual exigencies of practice. It is necessary to have a pure and homogeneous light, free from any inactive parts, upon the sensitive surfaces. The so- lar rays generally come through vapors suspended in the atmosphere; they have then, when reflected, a yellowish tint detrimental to the proof. In order to correct this PHOTOMICROGRAPHY. 467 defect, the light should be decomposed by passing it through an agent which keeps back the inactive part and only allows the spectral rays to penetrate, which are the most useful for the impression. Count Castracan was the first who employed a prism, which acts by dispersion, but has the disadvantage of absorbing a great quantity of light. Mr. Woodward, and afterward M. Moitessier, made use of a vessel faced with two parallel glasses, containing a solu- tion of sulphate of copper and ammonia. This is the most advantageous corrective employed for rendering light hom- ogeneous, but it is often with great trouble and difficulty installed in its interposition on the course of the luminous Fig. 6. rays. As a substitute, a very pure cobalt-blue glass may be used, which is easily placed on the plate of the microscope. Although it does not possess the same qualities as the so- lution of sulphate of copper, it is more practical. Such is the opinion of Dr. Maddox, who is an incontestable au- thority on photomicrography. For the minor enlargements the manipulations do not present any serious obstacles; the lighting is easy and the quantity of light always suf- ficient. But when a power- ful objective is made use of, the front lens of which is not a millemetre in diam- eter, and on which the lu- minous rays, after their rec- tification by the cobalt glass, are condensed, there is a great loss of intensity, especially when combined with a length of camera extended to two metres. It is necessary, then, to condense the solar light by means of several con- verging lenses placed upon its course. 468 PHOTOMICROGRAPHY. The great degree of enlargement obtained is the triumph of photomicrography. For obtaining this with clearness, objec- Fig 8. tives must be employed wherein the principle of correction is most carefully attended to. They should be cor- rected beforehand for each preparation, on account of the varying thicknesses of the glass covering used to pro- tect the object. It is by these precautions, and the improvements made by the construct- ors of instruments, that we are enabled to re- produce with clearness these powerfully-mag- nified specimens. Instead of obtaining directly a great en- largement, a cliche may be taken with a weak objective and enlarged by the processes gen- erally practiced. This method is very attractive, in conse- quence of its success in portraits, but does not succeed so well with photomicrography. The infinite minuteness of the details requires no common precision, the least imper- fections assuming, in the enlargements, extraordinary pro- portions ; and, further, the difficulty of developing the Fig. 9. PHOTOGRAPHING ON CANVAS. 469 cliche to be enlarged with the intensity desired, and the complications which result from the manipulations, demand special skill. Photographing on Canvas. The following is Dr. Loewe's method of obtaining pho- tographs on textile fabrics : I prepare linen, cotton, silk, and other similar material by giving it, firstly, a solution of two ounces of gelatine dissolved in ten ounces of water; I then treat it in the manner hereinafter described with ref- erence to the canvas. I take canvas prepared in the ordin- ary way for photographic purposes, that is by using oxide of zinc or lead, and I avoid the use of iron instruments, and use instead thereof those of ivory or wood for spreading the coating upon the canvas; I then add one and a half ounces of virgin wax dissolved in es- sence of lavender to one pint of turpen- tine. The canvas is prepared with three coatings and dried spontaneously, and when dry I dissolve sixty grains of iodine of zinc in two pints of distilled water and with half a potato and very fine pounded pumice stone; rub this solution on the canvas, and dry it with a soft flannel fill the surface becomes brilliant. In carrying this invention into effect I further use the following three solutions : The first for printing out or de- veloping the object on canvas by sunlight; the second, for enlarging by artificial light; and the third for printing by contact in a pressure-frame : First Solution. To the albumen of one hun- Fig. 11 dred eggs I add ten pints of dis- tilled water, ten ounces of chlo- ride of sodium, five ounces of chloride of ammonia, sixty grains tartaric acid, one and a half ounces carbonate of soda, two ounces iodine of potassium, one ounce iodine of ammonia, half an ounce bromide of potassium, one-quarter of an ounce bromide of ammonia, one-third of 470 ENAMELING, OR BURNING-IN PROCESS. an ounce pure iodine, twenty grains nitric acid, one hun- dred and twenty grains chloride of gold, one pint of sul- phuric ether saturated with virgin wax, beaten together, and filtered in a funnel hermetically sealed. The solution remains five or six minutes on the material, which, when dry, is rubbed over with a soft flannel until a shining sur- face appears. Second Solution for Enlarging by Artifical Light I use the same chemicals described in solution No. 1, in the same proportions, but add three ounces chloride of ammonia, two ounces of magnesium, one hundred and twenty grains of pure iodine, one hundred and twenty grains iodine of lithium, and sixty grains of iodine of cadmium. Third Solution for Printing in a Pressure- Frame by Contact. To two parts of distilled water I add one part of solution No. 1, and add one hundred and fifty grains of chloride of sodium, and eight grains of gold to each pint. Fig. 12. In addition to the directions given on page 309 for the Enameling process, the following by E. J. Fowler, giving extracts from M. Camarsac's new work on the subject, will be found interesting: The first chapter is on the prepara- tion of the sensitive " collodion," which is no collodion at all, if we adhere to the usual acceptation of the word, for it is composed of — Enameling, or Burning-in Process. ENAMELING, OR BURNING-IN PROCESS. 471 20 grains. 40 " £ ounce. 10 ounces. 10 44 and in winter the proportion of bichromate of ammonia can be increased. It is said that the bichromate of ammo- nia is to be preferred to the potash salt, as it gives more intense pictures, and the " collodion " retains its sensitive- ness longer. The solution of gum, sugar, and honey is prepared in daylight, and the bichromate is added in the dark. "When dissolved, the whole is filtered and kept from the light. It is very ne- cessary that this solution 13 * be perfectly clear, if pic- tures without specks are desired, and it should not only be well filtered, but allowed to stand for some days in a tall, nar- row glass jar, and then only the upper portions used by the photogra- pher. The glass plates must be of the best qual- ity, and exceedingly clean and free from dust. And here let me reproduce a hint from our authors, which w r ill be useful in everyday work : Never rub a glass plate clean just before pouring on the collodion, for the surface is rendered highly elec- trical by the friction, and attracts all the dusty par- ticles in its neighborhood. It is necessary to take trans- parent positives for enamel pictures, and good ones too. They can be judged to some extent by placing them face downward on a piece of white paper, and noting if the picture be as full of detail as required in the enamel. There are some important hints in the chapter upon ex- posures, based upon the theory that the decomposition which is effected in the sensitive film gives rise to water, Honey, .... White sugar, Gum-arabic, . . . Bichromate of ammonia, Water 472 ENAMELING, OR BURNING-IN PROCESS. and that the glass of the pressure-frame will become dim- med with more or less moisture, according to the exposure ; and it is said that a little practice will enable operators to judge of the proper time from this effect. There are sev- eral circumstances which would influence the regular pro- duction of this test moisture, and the subject is practically treated in the chapter I refer to. Fig. 14. The fourth chapter is devoted to the development of the image in the dark-room, and it is recommended that the ex- posure be strictly timed rather than any defects of exposure should be left for correction in the developing process. The correction may be made, but never yields so good a picture as one which needs no correction. ENAMELING, Oil BURNING-IN PROCESS. 473 For a transfer collodion for general use, that made from the following formula will be found serviceable : Gun-cotton, 85 grains. Alcohol (.830), . 5 ounces. Ether (-735^ ... . , . 5 " It is recommended never to pour back into the bottle the excess of collodion from the bichromate picture ; rather waste it, for it takes up a little bichromate, and thus pro- duces soiled pictures. A collodion that will do for trans- ferring a picture the size of a large brooch will be too thick for small pictures for rings, etc., so that the operator must use his judgment in the choice and pre- paration of his transfer collodion. The film with the picture is placed in sugared water, and the importance of this proceeding is shown in subsequent operations. The collodion film must be de- stroyed, and sulphuric acid is the agent recommended for the purpose. Take care and do not burn your fingers in performing this operation ; if you do you will, perhaps, not be inclined to try the acid again, so you must employ a longer method, which consists in steeping the enamel plate for twenty-four hours at least, with the collodion trans- fer upon it, in — Oil of lavender, 100 drachms. Oil of turpentine, 3 '« It is often necessary to retouch the picture upon the enamel before burning it in. Perhaps there are black specks, etc., to be got rid of. These are removed under tvater oy means of a needle which is stuck in a handle; the black points are " pecked " out carefully, and float to the surface of the water. If white specks are the trouble, they must be covered with the same powder as that of w r hich the image is composed; and this powder is ground up with sugared water not of the same strength as that in which the picture was washed, but a syrup, for if weaker 474 ENAMELING, OR BURNING-IN PROCESS. it will damage the image already formed. We now are ready for the burning-in, and can get the enameler's fur- nace ready after it is lighted put in the muffle, and let the fire be well placed all round it. When the furnace has at- tained a cherry-red heat the enamel can be put in, and a few minutes' burning is all that is required. Here prac- tice is necessary, but it is easily acquired, and we need not spoil more than one enamel except from inattention. Fig. 16. After all the care that may have been bestowed upon the enamels up to this point, it may be found that a few black points require removing or white specks filling up. The enamel powder is not now ground up with syrup, but with oil of lavender, and certain precautions are neces- sary, which are fully detailed in the chapter. Fluoric acid diluted with water is used for taking away specks, etc., at this stage, and for softening down any lines or shadows that may be too black; but avoid all these retouches as much as possible by great care and attention in the early operations. The various enamel powders are referred to, and it is recommended never to use them as found in com- merce ; even those made by the best houses can be im- proved for photographic purposes by being re-ground in small quantities on a glass plate, with a glass muller and a little water. Fig. 17. Here is a plan for judging of the quality of an enamel powder for photographic operations : Prepare a plate with the bichromate solution, and develop the image with fine plumbago powder. If the picture come out well, the ex- posure and the " collodion " are all right. Now repeat the PRINTING ON IVORY 475 experiment, with the same exposure and the same positive, and develop with the enamel powder to be tested. If the result be the same, well; if not, reject the powder and grind it again. The finest black enameling powder is produced by the oxide of iridium; but, as a pure black is not always desired in an enamel photograph, it may be warmed by the admix- ture of other colors, and the following is given as a recipe for powder of this kind: Oxide of copper, 2 parts. " cobalt 3 " " iridium, i-10 part. Burnt sienna, . .... 1 44 Flux, ... 18 parts. As a flux, it is recommended to grind up very finely bits of optical flint glass, which can be readily obtained from any working optician who grinds his own lenses. Fig. 18. Printing on Ivory. By David Duncan. Gollodio- Chloride Process. Very much depends upon the ivory having a smooth or polished surface. There are various methods of obtaining this. A nice surface can be obtained by rubbing the ivory with a piece of wash-leather, occasionally dipped in putty- powder. When polished, immerse the ivory in a thin so- lution of spirit varnish, and dry gently over a gas stove or before the fire. Any kind of varnish will do that is white and clear. Then prepare the following: 22 476 PRINTING ON IVORY. French gelatine, 1 drachm. Water, 1 ounce. Loaf sugar, . ...... ^ drachm. Coat one side of the vanished ivory (the polished side) by pouring collodion fashion, or with a camel's hair brush. The gelatine solution should be strained through fine mus- lin, or filtered through cotton wool, until very clear. When dry, coat with collodio-chloride of silver in the dark-room ; dry, and print deep ; wash, either under the tap or in a flat dish. Any old toning bath will do to tone the picture. Fix in a weak solution of hypo ; say — Hyposulphite of soda, .... 2£ ounces. Water, 20 " Very beautiful pictures can be obtained by the above. Fig. 19. U Ill ml i' iiiiii!iiiiiiiiiiiiiiiiiiii!iniiiiiiiiiii» nil iii in ii mill ii iiiiii.'^'^MIlii iiiiyiiTipipI Photo- Diaphanie Process. The following is interesting, and the results are beauti- ful, but it is difficult to manage. Procure albumenized trans- fer paper — that made expressly for photo-diaphanie ; float five minutes on — Nitrate of silver, 120 grains. Water, 1 ounce. Print in the sun, if possible, and until the high lights are well covered. The right amount of printing required can only be judged by experience. Wash, and tone in — Distilled water, 10 ounces. Pure chloride of gold, .... 15 grains. It will take some time to tone. "When toned, wash, and immerse the picture in a saturated solution of hyposul- phite of soda for five minutes. Now wash in several changes of water until the albumen film upon which the picture is printed loosens itself from the paper. When detached, the film floats on top of the water as a delicate transparency. The polished ivory is now brought under the film in the water, and gently arranged by the fingers. ENLARGING BY THE SERUM OR WHEY PROCESS. 477 The picture, after coming from the water, is placed be- tween smooth note-paper, inserted in a book, and left until dry. Enlarging by the Serum or Whey Process. The following is Mr. A. J. Drummond s process for en- larging prints, as practiced by him for some months with perfect success: First take sixteen ounces of condensed milk, and dissolve in forty-eight ounces of boiling water; heat this solution to the boiling point, and add, drop by drop, one ounce of acetic acid No. 8, stirring gently all the time. Care should be taken not to break the curd, and wnen the serum is formed decant in a porcelain dish, and allow it to cool. Then filter it carefully, after which the solution should look bright and clear. Iodize by the following formula : Dissolve and filter as before, after which it is ready for use. Brush over the paper, with a wad of canton flannel, a little of this solution, being particular that every part of the surface is covered. Hang up to dry away from dust. For sensitizing, use a solution of thirty grains of nitrate of silver to one ounce of water; place it in the sun until it becomes clear, then add a few drops of acetic acid to pre- serve the lights of the picture. Fig. 20. Iodide of potassium. Bromide of potassium, Serum, 7 grains. 5 « 1 ounce. 478 ENLARGING BY THE SERUM OR WHEY PROCESS. This also should be spread upon the paper with a wad of canton flannel. For a developer I use the filtered solution of — Pyrogallic acid 48 grains. Acetic acid No. 8, 4 ounces. Water, 28 " Fixing Bath. Hyposulphite of soda, 3 ounces. Carbonate of ammonia, .... ^ ounce. Water, ......... 16 ounces. Fig. 21. From time to time a little carbonate of ammonia should be added, as the bath is apt to be too acid. First focus the picture, sensitize the paper, expose while wet, as the action on the iodide of silver is much quicker when in that state. The pictures should be seen plainly in the shadows. When printed and laid on a piece of glass, pour a little of the developer upon the middle of the paper, and spread it quickly over the paper, either with a glass rod or a Avad of canton flannel. The picture then slowly appears, When it is dark enough immerse it in the fixing bath, and rub the surface with the palm of the hand to clear the paper of the developer. The picture does not lose any of its strength in the bath. Continue the use of the fixing bath until all yellowness of the picture has dis- appeared. I would also add that a little citrate of soda in solution, say to the amount of a few drops in the sensitizing solu- tion, will give the picture a warm tone; but, if much be added, the picture will print more slowly. A very intense negative can be printed much quicker by using three ENLARGING BY THE SERUM OR WHEY PROCESS. 479 ounces of water to one ounce of serum iodizer; this is, however, at the expense of the picture. I hope all who are interested in enlarging by the use of the lime or electric light will try this simple process, and report for the benefit of non-believers respecting the pictures developed by it. The advantage I claim in using condensed milk is that it gives the picture a richer tone. Fig. 2a CHAPTER LI. ON THE REPRODUCTION OF ENGRAVINGS AND LINE DRAWINGS IM- PROVED DRY PROCESSES PROCESS FOR OBTAINING POSITIVES IN COLORS. The following is F. Fink's method of reproducing en- gravings and line drawings : The publication of the follow- ing remarks on the copying of engravings by means of photography has been decided upon by myself, less in the hope of making known new data in connection with such a proceeding, as for the purpose of pointing out certain reliable facts which may be serviceable to photographers engaged upon this description of work. Those who have ■p. ^ experimented at all in this direction know that a col- lodion which gives excel- lent results in portraiture will yield but a poor, weak negative when used for the reproduction of an engrav- ing or a line drawing. The reason of this is very sim- ple : the iodizing of the col- lodion has been insufficient to produce the necessary vigor required in a picture made up solely of fine lines. To produce a good negative of this description it is ne- cessary that a somewhat strongly iodized material be used, as, for instance, a collodion containing one- third more of the iodizer than would be required for por- traiture work ; such a collodion as is condemned by the portrait photographer because it is over-iodized and gives hard pictures is most suited to the purpose. REPRODUCTION OF ENGRAVINGS AND LINE DRAWINGS. 481 A negative of an engraving taken with collodion of this description, if sensitized in a slightly acid bath and ex- posed for a suitable period, should exhibit perfectly clear, transparent lines on an opaque, inky black ground. The exposure should be, if anything, rather too short than too long, for a full exposure, so necessary to the production of an artistic portrait, is fatal to the existence of fine lines in a negative of this kind. Over intensification of the negative must likewise be avoided, as the more delicate lines are easily destroyed by carrying this part of the process too far. The intensifying solution I would recommend is a devel- oper prepared according to either of the following formulae: No. 1. Water, . 20 ounces. Sulphate of iron. 1 ounce. Nitrate of potash, J " Alcohol, 2 ounces. Sulphuric acid, ' . J ounce. No. 2. Water, 10 lbs. Citric acid, 3£ ounces. Sulphate of iron, 2 " Alcohol, 6 After the picture has been completely developed, the image is intensified by adding a few drops of a twenty per cent, solution of nitrate of silver, the treatment being car- ried on as long as the fine lines re- Fig. 25. main visible. After fixing, the plate should be well washed, and then again intensified with a concentrated solu- tion of bichloride of mercury, the treatment with the latter material being repeated as often as may be thought necessary — say from one to four times. With No. 2 solution the subsequent intensify- ing with bichloride of mercury may sometimes be dis- pensed with. The picture to be copied should, if possible, be lighted from the front, direct sun rays falling at an angle of from 50 to 80 degrees, yielding the best illumination; if the sun is higher and the rays fall at an angle of 10 to 30 degrees, shadows are cast by the texture of the paper, and the negative produced presents a rough, mealy appearance, which will be found to be in the highest degree objection- able when an enlargement of the original is prepared. 482 IMPROVED DRY PROCESSES. Improved Dry Processes. The Washed-Plate Process. This is tlie simplest of all dry processes, and consists in preparing and sensitizing the plate as for the wet method, then washing it well in distilled water, to get rid of all the superficial nitrate of silver solution. The plate is then to be carefully dried in the dark. The exposure should not be much more than for a wet plate. Prior to de- velopment the plate must be re-immersed in the nitrate bath, and the development conducted just the same as for a wet plate, the ordinary developing solution being used. These plates will not keep. They should be pre- pared over-night, and used the next day, and developed in as few hours as possible after exposure. With favorable samples of collodion this process yields good pictures. TJie Morphine Process. This process was introduced by Mr. Bartholomew, and has for its merits considerable sensitiveness united with vease of preparation. The plate is prepared with the usual bromo-iodized collodion, in all respects the same as for the wet process. After the plate is sensitized it is washed well with distilled water, and solution of ace- tate of morphine, one grain per ounce, is flowed over and the plate allowed to dry. The washing and flowing over of the morphine may be conveniently done by the use of dipping baths. The plates are nearly as sensitive as ordinary wet plates. The development may be either with iron, neutral pyro., or al- kaline pyro. If iron be used, the following developer, as recommended by Mr. G. "Wharton Simpson, may be em- ployed: Double sulphate of iron and ammonia, . 20 grains. Sugar candy, 20 Water, 1 ounce. The film after exposure must be moistened with water, and the above developer flowed over. In a few minutes a IMPROVED DRY PROCESSES. 483 well-defined phantom image will appear. A little acetic acid and a drop of a 10-grain solution of nitrate of silver are then to be added to the developer, and the image be- gins to gather strength. Additional acid and silver may be added to a fresh por- tion of the developing solution in such proportion as the appearance of the image suggests; the acid and silver ad- ded cautiously in case of under-exposure, and freely if the detail is very fully out. In some persons' hands iron has not been so successful as a developer as pyrogallic acid. In case therefore of failure recourse may be had to that agent. It should be mentioned that as these plates are not to be depended upon for keeping, they should be used within a few days of their preparation. The Coffee Process. This is a simple but excellent dry process; its peculiar- ity consisting only in the preservative solution being a sweetened extract of coffee. The plate is prepared exactly Fig. 27. as for the wet process, and after sensitizing has to be well washed ; it is then ready to be flowed over with the follow- ing solution, and allowed to dry: Ordinary ground coffee, £ ounce. Loaf sugar, £ 44 Water, 16 ounces. Let the water be boiling when the coffee and sugar are added. Cool and shake the vessel. The solution will keep good for a week, but must be filtered for use. The exposure is three times that of wet plates. The de- velopment may be by either neutral or alkaline pyro. 484 PROCESS FOR OBTAINING POSITIVES IN COLORS. Process for Obtaining Positives in Colors. The following is M. Niepce de St. Victor's method for obtaining positives in colors : Red Color. Prepare the paper with a solution of nitrate of uranium, strength 24 grains to the ounce. Leave the paper from fifteen to twenty seconds upon this solution; then dry it before the fire, in the dark. Expose it in the pressure- frame from eight to ten minutes in sunshine, and from one to two hours in the dark. Wash it for some seconds in warm water (120° Fah.), and then immerse it in a solu- tion of red prussiate of potash, strength 10 grains to the ounce. In a few minutes the print will acquire a beautiful blood-red color. Wash it in several changes of water, un- til the water remains perfectly colorless, and then dry it. Fig. 28. Green Color. Take a red print obtained as before described. Im- merse it for a minute in a solution of nitrate of cobalt. Remove it without washing, and dry it before a fire; it will become green. Fix it by putting it for a few seconds into a solution of sulphate of iron, 20 grains to the ounce, and sulphuric acid 1 scruple to the ounce. Wash it once in water, and dry it before the fire. Violet Color. Prepare the paper with nitrate of uranium, as in the red process. Expose it in the pressure-frame; wash it with warm water; and develop the image with chloride of gold, PROCESS FOR OBTAINING POSITIVES IN COLORS. 485 2 grains to the ounce. "When the print has acquired a fine violet color wash it in several changes of water, and dry it. Blue Color. Prepare the paper with a solution of red prussiate of potash, 100 grains to the ounce; dry it in the dark. Re- move the print from the pressure-frame when the shadows have acquired a light blue tint. Immerse it for a few sec- onds in a cold saturated solution of bichloride of mercury, wash it once in water, and then put it into a solution of oxalic acid, saturated when cold, and heated to about 100° Fah. Wash it three or four times, and dry it. Fig. 29. CHAPTEK LII. SEL CLEMENT MEZZOTINT PHOTOGRAPHS THE MAGIC PHOTOGRAPH CABINET PORTRAITS GAGE's IMPROVED PHOTOGRAPHS. A short time ago, says the British Journal, we mentioned that we had received a specimen of a new salt, containing silver, which is sought to be introduced in England as a substitute for the ordinary nitrate of silver which we have been so long accustomed to use. As many were anxious PI gQ to know the constitu- tion of this salt, we submitted a sample to analysis, and obtained the results which we shall now give. As the reader is probably aware, the sel clement is sold in small, broken, trans]ucent cakes of a slightly greenish tinge, and which are deliquescent, and therefore, require to be retained in a well-closed bottle. The cause of this tend- ency to deliquesce will be presently shown. The salt is readily soluble in water without the slightest turbidity being produced, and can then be employed for sensitizing paper, etc., just as in the case of the ordinary silver salt. When submitted to analysis, the sel clement was found to be composed of — Nitrate of silver, Nitrate of magnesia, Combined water, 31 5 per cent. 570 " 8-5 " 1000 It will be seen, therefore, that nitrate of silver consti- tutes but little more than one-third of the salt, the nitrate of magnesia and its combined water forming the bulk of the sample. In using the nitrate of magnesia it is impos- SEL CLEMENT. 487 sible to avoid the presence of a certain proportion of water, as, when a solution of the nitrate is evaporated to dryness, -and the last portions of water are expelled by heat, the salt decomposes, and a basic compound is left behind, which yields but little soluble matter to water. Hence, if the evaporation be carried so far as to drive off more water than the proportion shown in the above analysis, the risk would be incurred of producing the insoluble com- pound above referred to. The set clement may be prepared in the following way. Take of— Silver, 100 parts. Magnesia, calcined, 66 " Nitric acid (sp. gr. 1*42) a sufficient quantity. Dissolve the silver in three times its weight of the nitric acid diluted with its own bulk of water; then add the mag- nesia, stirring well, and gradually pour in sufficient nitric acid to dissolve all the mag- Yig. 31. nesia and leave the solution but slightly acid. The mixed solution, which should be filtered if not quite clear, is then to be evaporated in a shallow dish to a very small bulk, with the acid of the water bath, to such an extent that a portion when removed on a glass rod immediately solid- ifies on cooling. When suf- ficiently evaporated the whole may be left aside until cold, taking the precaution, however, to cover the capsule so as to prevent the access of moisture; the cakes of salt should then be broken up and preserved in a stoppered bottle for use. "When treated with water the salt should dissolve completely without leaving any residue. Any difficulty which exists in preparing the salt — or rather the mixture of salts — above mentioned is encoun- tered during the evaporation of the solution, as the incau- tious continuance of a high temperature for a considerable time is certain to interfere with the production of a satis- factory sample, such as that we have examined. Few will care to go to the trouble of preparing a salt which can be 488 SEL CLEMENT. now so cheaply procured; but those who wish to test the manifold virtues of this new claimant for photographic favor will find the above directions sufficient to enable them to attain their object. Now, as to the value of this set clement it has been al- ready stated that there are some respects in which it may prove a useful substitute for a strong bath of pure nitrate tion, which probably can then less freely permeate the sur- face of the albumen; hence the tendency is to retain the sensitive material more completely on the surface of the paper. It is probably in this way that the nitrate of pot- ash acts when added to the nitrate bath, as there can be no question about the advantage resulting from its addi- tion to very weak baths; and the new salt is, therefore, a convenient form in which to use the material for a com- pound bath, and yet one containing a minimum of silver. There is another advantage arising from the employment of a neutral salt as an addition to the printing bath, and that is the tendency which these bodies possess of pre- venting the albumen, or silver compound of albumen, from entering the solution. Even apart from the preceding considerations, it is an Fig. 32. of silver. Its chief advan- tages probably depends on the improved tone which the prints take when the double salt is used to sensitize the paper. The difference in price, as the above analysis proves, is only an apparent and not a real one; but the chief point is that, in employ- ing a bath of forty grains of the set clement, it is possible to get results in printing similar to those afforded by a bath of nitrate of silver of nearly eighty grains in strength, although the actual amount of silver salt present forms but little more than one-third of the whole. The advantage appears to arise chiefly from the in- creased density of the solu- MEZZOTINT PHOTOGRAPHS. 489 interesting fact that the presence of a salt of magnesia is found to exercise such a marked influence over the tone which the prints take on immersion in the gold bath, and adds an additional fact to the long list which we already have in proof of the power which many of these neutral salts — such as those of baryta, lime and magnesia — un- questionably possess of influencing the deposit, or rather substitution, of metal in the toning bath. Mezzotint Photographs. Mr. Carl Meinerth has obtained a patent for " Mezzo- tints " which he describes as follows : This style of picture is the result of a process obtained by me after following with great interest the path pointed out by Claudet, Dall- meyer and other distinguished leaders of our fraternity, with the great object in view of equalizing focal differences and blending light and shade in portraiture. I have experimented with the various methods, but as far as my own experience goes, and what I have seen from the results of other co-laborers, the necessary detail in the parts of the face is rather too much " blurred " in the effort, and I would be very glad to see a specimen which would convert me to a different opinion and to immediate public recantation. To obtain, then, this beautiful "blurring," and yet retain all necessary clearness in detail, was my aim and end; and so far I have yet to meet a photographic or other artist who is not struck with admiration at the roundness and softness of my result, and the absence of all harsh shadows. There are some artists among us who prefer taking and showing the wart on a nose, not only so but also the hairs growing on it ! To such "there is no heaven of art," how- ever; they had better remain on terra firma and focus on hairs, and even split them ! It is true the shadows spoken of can be artificially re- moved by retouching the negative or the print; but this is, of course, an artificial effort readily perceived, and con- nected with additional labor and expense. Moreover, it is natural to infer that even the best photographs, produced without any such retouching, will and must greatly improve by my method of printing, and still remain to be a purely photographic production, leading our art on steps higher toward the realm of all art. Now, as to my method: I first conceived the idea last 490 THE MAGIC PHOTOGRAPH. winter that the desired diffusion of light might be obtained between the negative and the paper. My first experiments were made by inverting the negative itself. The diffusion, however, was too great as many a printer may have seen, who threw away the print after having accidently placed the negative upside-down, except when the negative glass was very thin. The image, however, was produced re- versed, like an ambrotype or positive, and very thin nega- tives are not desirable on account of their liability to break. The result, however, was very promising. It led me natu- rally to substituting a thin layer of mica, of glass, or a mat, simply to introduce a very short transparent space be- tween the negative film and the material to print upon, whether the glass of the negative itself or another trans- lucent medium. This is the specification of my idea, which I now have perfected and put into practical use, and for which United States Letters Patent was granted to me. The intelligent photographer will, of course, understand that while this new principle of using the light in printing requires no change whatever in the common process of silver printing, it is as necessary to have a good negative for this as for any other process, in order to insure the best results. Besides the beauty of the effect, there is another benefit derived from this simplest of all processes, every picture flatters ! Since I have made the first mezzotintoes, I had scarcely any others ordered. Freckled faces, high cheeks, sunken eyes, all are delighted with their pictures. Those ugly defects are so much subdued, if not entirely removed, and all this simply by the printing. And you will find that no other but this method will do this so effectually with- out any artificial means, without detriment to the likeness and the pristine purity of the photograph. The Magic Photograph. Some time since much interest was excited by the above novelty, and we think that a formula for making it should have a place in this work. Take in the first place an ordinary print, a card picture for instance, on albumen paper, beneath the negative in the usual way, and when sufficiently printed let it be carefully washed in the dark-room, so as to remove all the free nitrate of silver, etc. Now immerse it in the following solution, also in the dark-room: THE MAGIC PHOTOGRAPH. 491 Saturated solution of bichloride of mercury (corrosive sublimate), 1 ounce. Hydrochloric acid, 1 drachm. The saturated solution is previously prepared by putting into water more bichloride of mercury than it will dissolve by shaking in about twelve hours. Pour off the quantity required. The print will gradually be bleached in this liquid, in the ordinary meaning of the word, that is, it will disap- pear; but the fact is, the print is still there, its color alone is changed, a double salt having been formed of mercury and silver which is white, as many of our readers who have been in the habit of intensifying with a mercurial salt are aware of. As soon as the print has quite disappeared, the paper is thoroughly washed and dried in the dark-room; it is also preserved between folds of orange-colored paper, in order to keep it from the action of light, for the surface is still in some measure sensitive to light. The bleaching of the print, that is, its conversion into a white salt, is effected more quickly by keeping it in motion in the mercurial solution. As we have said before, the print has not been bleached in reality; the substance which originally formed it is still there, together with a new substance, a salt of mercury. But the two salts of silver and mercury may be easily brought out and made visible by several solutions, such as sulphide of ammonium and a solution of hydrosulphuric acid; in fact, any of the double sulphides, ammonia and hyposulphite of soda; the latter salt is used in preference to the others. Small pieces of blotting-paper, therefore, of the same size of the prints, are cut out and steeped in a saturated solution of hyposulphite of soda and then dried. The magic photographs are packed, as before stated, be- tween folds of orange-colored paper. The papers dipped in hyposulphite of soda are the developers, and may be packed between two sheets of common writing-paper. The development is effected in the following manner: Place the albumen paper which contains the whitened print on a pane of glass, print side upward; on this lay the dry piece of blotting-paper that has been previously dipped in hyposulphite of soda; moisten the latter thoroughly; then place over it a pane of glass, and upon this a weight to bring the two pieces of paper into intimate contact. In a very short time the picture will appear in all its original detail and of a sepia tone. 492 CABINET PORTRAITS GAGE'S IMPROVED PHOTOGRAPHS. Cabinet Portraits. The success of the carte de visite has induced enterpris- ing photographers to extend the idea; hence the "Cabinet" portraits. These may, in one sense, be considered as cartes of a large growth, but the size is improved in its propor- tions. The same treatment should be used in producing these pictures as in cartes; that is, as full-lengths, vignet- tes, etc., and with the usual accessories characteristic of indoor or outdoor scenery. A different lens will be neces- sary, as those used for the cartes are too short in focus. A half or whole-plate lens, or one made expressly, will answer best. The adopted size of the cabinet portraits is as follows: There can be but little doubt that, by united action, this size may become a standard one, especially as albums are constructed expressly for it. This new size, among its many 'advantages, is well suited for portrait groups, in- teriors, landscapes, and many other subjects for which the dimension and proportion of the carte are quite unfitted. It will also afford a worthy opportunity for skillful photo- graphers to break away from the little and petite effects that are of necessity peculiar to the carte size, and may lead the public to appreciate and desire larger pictures and better work, thus improving the art in every way. Mr. Gage takes a photographic impression in the usual manner, and then places some plain, dark, dead surface in front of the camera, the sensitive surface still remaining in the camera. He then removes the covering from the lens tube, and exposes the sensitive surface on which the im- pression has been formed to the light reflected from the dark surface, while the dark surface is kept in gentle mo- tion, so as to prevent the sensitive surface from taking an impression of any wrinkles or other variations on the sur- face from which the light is reflected. The time of this exposure is varied according to the amount of light re- flected and the effect it is desirable to produce. The usual amount of time occupied in this exposure will be from one- fourth to double the time employed in taking the invisible Size of mounted picture, . Mounting card, . . Opening in album, 5| by 4. 5* " 3 7-8. Gage's Improved Photographs. gage's improved photographs. 493 impression; but in some cases it can be extended much beyond this time. For a dark, dead surface Mr. Gage usually uses a piece of thick black woolen cloth about eighteen inches square, attached by one edge to a stick about two feet long, which is held horizontally and gently moved in front of the camera with the left hand, while the lens tube is uncovered with the right hand. It is not ab- solutely essential that this dark surface be kept in motion, but it is safer. This exposure of the sensitive surface to the light reflected from a dark, dead surface apparently leaves the lightest portions of the impression but little changed, while it effects a much greater change in the darkest portions of the same, and thus harmonizes and properly blends the two, giving to the whole an atmos- pheric effect never before realized in photographic impres- sions; it also renders it less difficult to obtain the neces- sary intensity in negatives. CHAPTER LIH. newton's dry processes — description of apparatus, as illus- trated WITH WOODCUTS, IN THE THREE PRECEDING CHAPTERS. We give here two entirely new Dry Processes discovered by Mr. H. J. Newton, and now published for the first time, the results of which, as exhibited to us, are far more beau- tiful than those of any wet or dry process with which we are acquainted. The Tea Process. Take a large tablespoonful of Japanese tea, put it into a bowl and add about eight ounces of boiling water; cover it over and keep it hot for about an hour; then pour the liquor off from the leaves, and add sufficient water to make the whole measure ten ounces. "While the tea is still warm add one-half ounce of finely pulverized sugar of milk; when it is all dissolved filter and it is then ready for use. In this condition it will keep for several weeks. Sensitize your plates in any bath which will make clean negatives by the wet processes. The best collodion for dry plates is that which works the most intense. Make it of cotton which has been prepared with especial reference to inten- sity. After sensitizing wash in water procured by melting ice; this is more reliable than the distilled water usually procured at drug-stores. The plates should have two wash- ings in this water, which is best done by having it conven- iently placed in two dishes ; then wash under the tap, and put them into a dish containing the tea solution, where they should remain one or two minutes; then remove them and set them away to dry. There should be no waves or currents of air pass over the plates while drying, as they will cause ring marks which will show in the negative. In cold or damp weather an oven is preferable for drying them. I have one so arranged that it can be heated w T ith gas, which answers the purpose well, drying them perfectly in five minutes. I find that plates dried in this way keep Newton's dry processes. 495 better and give more brilliant negatives than those drying spontaneously. To develop these plates make two developers as follows: No. 1. Hot water, 5 ounces. Gallic acid, 30 grains. Pyrogallic acid, 30 44 Citric acid, 30 " Glacial acetic acid, 30 drops. Saturated solution of acetate of lead,* 10 " The glacial acetic acid dissolves the precipitate formed by adding the lead. This forms a very energetic developer. I have no sympathy with those who advocate slow devel- opment. A powerful developer, with the smallest trace of silver to start the picture, I have found always to give negatives full of detail without the hardness so often found in dry-plate negatives. Another great advantage in the use of a strong devel- oper is, that it requires much less time to expose the plates. The second developer is made as follows: No. 2. Gelatine, 20 grains. Double sulphate of iron and ammonia, . 80 44 Sulphate of iron, 80 44 Soak the gelatine about fifteen minutes in cold or tepid water; then put the above together in a bowl, with the soaked gelatine, and pour on ten ounces of boiling water. "When the gelatine and iron have dissolved, add ten drops of concentrated ammonia and shake thoroughly; then add sufficient glacial acetic acid to dissolve the precipitate, which will require about forty drops ; then add twenty grains of tartaric acid. This developer should be about two weeks old before it is used. In developing an exposed plate use these developers alternately. If the pyrogallic and gallic acid developer is used first, the exposure should be from four to six times as long as when using the iron developer first. To develop, by using the pyrogallic developer first, pre- pare a ten-grain solution of nitrate of silver, acidified with * The addition of the acetate of lead to a gallic acid developer, to increase its developiDg power, should be credited to M. Carey Lea. 496 newton's pry processes. glacial acetic acid about five drops to the ounce; put two or three drops of this — the quantity required for a stereo- scopic plate — into a small cup; then wet the exposed plate, and flow sufficient of the developer over it to cover it; let it remain from thirty to sixty seconds and pour off into the dish containing the silver, and immediately pour it back over the plate and off again into the dish and then back again on to the plate. In this way even action on every part of the plate will be obtained; if the exposure has been right the picture will immediately appear and continue to develop until most of the detail is out. As soon as the de- veloping action ceases, wash the plate thoroughly, and treat it the same as with the iron. If the exposure has been too long for the pyrogallic developer, reduce it until it is of the right strength. The same directions will apply for the use of the iron developer, but in that case we use double the quantity of silver solution. The negative comes out under the iron developer in ap- pearance the same as under the alkaline, and the exposure need be no longer. As soon as the detail is nearly all out, or when the action ceases, wash it off and apply the pyro- gallic developer. Care must be taken not to get too great intensity, as this gallic and pyrogallic acid developer gives a wine-colored negative of great brilliancy and of beauti- ful printing qualities, the peculiar color, however, making it unnecessary to have very great intensity. Those devel- oping dry-plates, whether with a weak or strong pyrogallic acid developer, both in time and beauty of negative, will find a great advantage by alternating with a proper iron developer. These tea plates % keep, I should judge, as well as tannin, and produce much superior negatives. Newton's Opium- Tannin Process. This process is the application of morphia, in tincture of opium, combined with tannin. When the acetate of morphia was first introduced in the production of dry- plates as an accelerator, it was very soon discovered that the plates did not keep good for more than twenty-four hours. Then I combined the morphia with tannin, calcu- lating to retain the keeping qualities of the tannin and the sensitive qualities of the morphia. It answered my expect- ations in that respect, but the tannin solution soon changed DESCRIPTION OF APPARATUS. 497 and became unfit for use. I then compounded the follow- ing solution: The water should be hot and the sugar of milk finely pulverized, and the ingredients added to the water in the order given above. The addition of the laudanum causes a precipitation of the gum from the tannin, and conse- quently filters perfectly clear, differing in this respect from the simple tannin solution. This solution will keep for months without undergoing any change that is perceptible ; and as a preservative makes by far the most sensitive plates — with perhaps the morphia excepted — with which I have ever experimented. They have, however, the advan- tage over the acetate of morphia, as they keep the same as an ordinary tannin plate. The same developers should be used as with the tea plates, as given in the preceding article; but when using the iron developer first, flow the plate with a weak solution of iron and then wash before using the iron with silver. By making the gallic and pyrogallic acid developer stronger, the time of exposure can be still further reduced. Ten grains each of the gallic and pyrogallic acid to the ounce of water, will give equally good negatives with about two- thirds the time of exposure, from thirty to fifty seconds being all that is required. In the summer, with the opium process and iron developer, six seconds' exposure only is necessary. Fig. 1 represents one of C. C. Harrison's Portrait Lenses and fig. 2 his focusing lens. Fig. 3 is one of the celebrated Globe Lenses, which are intended only for copying and making views. Figs. 4 and 5 represent one of the Ameri- can Optical Company's carte de visite cameras, and fig. 6 one of their universal cameras, which are very useful in galleries where the amount of business is not sufficient to require a separate camera for each lens, as with the trouble of changing fronts, they can be used for large plates, cards and copying. Fig. 7. is their universal Ferrotype and card camera box, and is arranged for four or sixteen small heads, with four gem tubes. Water, Sugar of milk, . Tannin, Tincture of opium, , 6 ounces. i ounce. 40 grains. £ drachm, Description of Apparatus. 498 DESCRIPTION OF APPARATUS Fig. 8 represents a new camera stand just manufactured by the same company. It is made of thoroughly seasoned black walnut, and the movements of the various parts are ingenious and, at the same time, simple and easily adjusted. The top is tipped by means of a sliding rack and pinion, which is so constructed that it cannot get out of order, and is perfectly firm. The column is raised and lowered by means of a snake screw, turned by a crank, and remains firm and stationary by the peculiar construction of the combination rack and screw. Figs. 9 and 10 represent one of J. Stock & Co.'s view cameras, with brass guides, and screw focusing adjustment, and folding platform; very portable. Fig. 11 is a stereo- scopic camera of the same maker, with vertical sliding front for adjustment of foreground and sky. Fig. 12 shows Stock's improved instantaneous drop, by means of which operators are enabled to obtain views with an instantane- ous exposure. Fig. 13 is J. Peace's camera stand made in Philadelphia, and fig. 14 shows an excellent dark tent, made by the American Optical Company. Fig. 15 is their tripod stand for field work, and fig. 16 their improved box for holding negatives or cleaned glass. Fig. 17 is one of their whalebone dippers, and fig. 18 a plate cleaner. Fig. 19 represents a leveling stand made by the same company. It is furnished with adjusting screws for laying plates with albumen and fixing collodion pictures. Fig. 20 is one of their printing-frames, and is so constructed that a uniform pressure is obtained. Whitney's printing-frame is represented by fig. 25, and Pratt's in figs. 27, 30 and 31. The Photographic Ware Baths and Dishes are repre- sented by figs. 21 and 22. This ware has considerable popularity on account of its strength, cheapness and per- fect reliability; it is as capable of resisting the action of all chemical solutions as is glass, and will last for years. It is highly recommended by all who use it, and can be had of any stock dealer. Fig. 23 represents the Coleman Seller's card press, and fig. 24 an ingenious camera stand. Fig. 26 is an improved still for the purpose of distilling water; it is furnished by Edward Parish of Philadelphia. Fig. 28 is a print-cutter introduced some two years since, but we believe it is not now to be had. Fig. 29 is a stand for field work, and fig. 32 is a camera stand sold by J. H. Simmons of Philadelphia. Total number of woodcuts in this work fifty-nine. CHAPTER LIV. WEIGHTS AND MEASURES. 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 water 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 and fifty-eight one thousandth parts of a grain ; of such grains 5760 are required to make the impe- 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, are 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 called a gramme, which is divided deci- mally above an.d below. A cubic decimetre is called a litre, which is the unit of the measures of capacity, and divisible decimally. 23 500 WEIGHTS AND MEASURES. Comparison of Weights and Measures, Apothecaries' Weight. 20 grains 60 grains 480 grains 6760 grains 3 scruples = 8 drachms = 12 ounces = 1 grain 1 scruple 1 drachm 1 ounce 1 pound French gramme, = 0.0647 = 1.295 =b 3.885 s= 31.08 = 372.96 Symbols. Grain = gr. Scruple = 3. Drachm = 3 . Ounce = § . Pound : Apothecaries' Measure of Capacity. (United States.) 1 fluid drachm. = 1 fluid ounce. — 1 pint. = 1 gallon. 60 minims = 480 minims = 8 fluid drachms 7680 minims =16 fluid ounces 61,440 minims s= 8 pints 16 drachms 16 ounces 112 pounds 20 hundred weight Avoirdupois Weight. 1 drachm =b 1 ounce — 1 pound 1 hundred weight 1 ton French gramme. = 1.77 = 28.328 sb 453.25 1 drachm s= 1 ounce =s 1 pound = 1 hundred weight = 1 ton s= Apothecaries' grains. = 27.34375 437.5 7000. 784000. 15680000. Apothecaries' ounce Avoirdupois ounce United States pint Imperial or British pint United States gallon 480 grains. 437.5 grains. 16 fluid ounces. 20 fluid ounces. 128 fluid ounces. = Imperial or British gallon =160 fluid ounces = 10 Weight of Water at 62° and Capacity of : 8 pounds aroirdipj Cubic inches. Grains, 1 gallon (Imperial) 277.274 70000. 1 gallon (U. S.) 231.000 56000. 1 quart (Imperial) 69.318 17500. 1 quart (U. S.) 57.750 14000. 1 pint (Imperial) 34.659 8750. 1 pint (U. S.) 28.875 7000. 16 fluid ounces 28.875 7000. 1 fluid ounce 1.732 437.5 1 fluid drachm 0.216 54.7 1 minim 0.0386 0.91 WEIGHTS AND MEASURES. 501 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 Grain*. 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 =s 2 lb. 3.27 oz. French Liquid Measures. United States Liquid Measure*. Cubic incites. 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, . . . 610.280 2.6419 gallons. Hectolitre, . . . 6102.80 26.4190 " Kilolitre, .... 61028.0 264.1900 " Myrialitre, . . . 610280 2641.9000 * CHAPTER LV. COMPARISON OP THERMOMETRY INDICATIONS ON TUB PRINCIPAL THERMOMETERS IN USE. Thermometers are instruments for ascertaining the tem- perature of bodies, whether liquid, solid, or gaseous. The principal thermometers in use are : the Centigrade, which 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 States. 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. 32° on Fahrenheit's scale. 7%e 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 Reaumur'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. COMPARISON OF THERMOMETRY INDICATIONS. 503 Table of the corresponding degrees on the Scales of Fahren- heit^ Reaumur, and the Centigrade. JXtjllU/lllUI • "Rfttlinc "nnint. 919. 80 100 203 7fi 95 194 72 90 185 68 85 176 64 80 167 60 75 158 56 70 149 52 65 140 48 60 131 44 55 122 40 50 113 36 45 104 32 40 95 28 35 86 24 30 77 1 1 20 25 63 16 20 59 12 15 50 3 10 41 4 5 82 0 0 23 —4 —5 14 —8 —10 5 —12 —15 —4 —16 —20 —13 —20 —25 —22 —24 —30 —31 —28 —35 —40 —32 —40 All the intermediate indications can be obtained by the use of the preceding rules. CHAPTER LVL COMPARISON OF HYDROMETRIC AND SPECIFIC GRAVITY INDICATIONS. 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 water. 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 gravity. Baum6's Hydrometers are in extensive use in France, and Twaddell's Hydrometer in England. Baume has two Hy- drometers : one for liquids heavier than water, and one for liquids lighter than water. For Liquids Heavier than Water. Baume* . Deg. Sp. Grav. Deg. Sp. Grav. Deg. Bp. Grav. Deg. Sp. Grav. 0 . . 1.000 20 . ... 1.152 40 .. . . 1.357 60 .. .. 1.652 1 ... , . 1.007 21 . ... 1.160 41 .. . . 1.369 61 .. . . 1.670 2 .. . . 1.013 22 . ... 1.169 42 .. . . 1.381 62 .. . . 1.689 3 .. . . 1.020 23 . ... 1.178 43 .. .. 1.395 63 .. . . 1.708 i .. . . 1.027 24 . ... 1.188 44 .. . . 1.407 64 .. . . 1.727 5 .. . . 1.034 25 . ...1.197 45 .. . . 1.420 65 .. . . 1.747 6 .. . . 1.041 26 . . . . 1.206 46 .. . . 1.434 66 .. . . 1.767 7 . . . . 1.048 27 . ... 1.216 47 .. . . 1.448 67 .. . . 1.788 8 .. 1.056 28 . ... 1.225 48 .. . . 1.462 68 .. . . 1.809 9 .. .. 1.063 29 . ... 1.235 49 .. . . 1.476 69 .. . . 1.831 10 .. . . 1.070 30 . . . . 1.245 50 .. . . 1.490 70 .. . . 1.854 11 .. . . 1.078 31 . ... 1.256 51 .. . . 1.805 71 .. . . 1.877 12 .. . . 1.085 32 . ... 1.267 52 .. . . 1.520 72 .. . . 1.900 13 .. . . 1.094 33 . ... 1.277 53 .. .. 1.535 73 .. 1.924 14 .. . . 1.101 34 . ... 1.288 54 .. . . 1.551 74 .. . . 1.949 15 . . 1.109 35 . ... 1.299 55 .. 1.567 75 .. . . 1.974 16 .. .. 1.118 36 . ... 1.310 56 .. .. 1.583 76 . . 2.000 VI .. .. 1.126 37 , ... 1.321 57 .. .. 1.600 > .. 1.134 38 . . . . 1.333 58 .. .. 1.617 1 i 1.143 39 . . . . 1.345 59 . . 1.684 HYDROMETBIC INDICATIONS. 505 For Liquids Lighter than Water. BaumJk. Deg. Sp. Grav. Deg. Sp. Grav. Beg. Sp. Grav. Deg. Sp. Grow. 10 . . . . 1.000 23 .. 0.918 36 .. . . 0.849 49 . . . . 0.789 11 . . . . 0.993 24 .. 0.913 37 . . 0.844 50 . . . . 0.785 12 . . . . 0.987 25 .. . . 0.907 38 .. . . 0.839 51 . ... 0.781 13 . . . . 0.980 26 .. . . 0.901 39 .. . . 0.834 52 . . . . 0.777 14 . . . . 0.973 27 .. . . 0.896 40 .. . . 0.830 53 . ... 0.773 15 . . . . 0.967 28 . . . . 0.890 41 .. .. 0.825 54 . ... 0.768 16 . . . . 0.960 29 .. . . 0.885 42 .. . . 0.820 55 . . . . 0.764 IT . . . . 0.954 30 .. .. 0.880 43 .. .. 0.816 56 . . . . 0.760 18 . . . . 0.948 31 .. . . 0.874 44 .. 0.811 57 . . . . 0.757 19 . . . 0.942 32 .. . . 0.869 45 .. . . 0.807 68 . . . . 0.753 20 . . . . 0.936 33 . . 0.864 46 .. . . 0.802 59 . . . . 0.749 21 . . . . 0.930 34 .. . . 0.859 47 . . 0.798 60 . . . . 0.745 22 . . . . 0.924 35 .. . . 0.854 48 .. . . 0.794 61 . . . . 0.741 TwaddelVs Hydrometer. The degrees on Twaddell are converted into equivalent specific gravities by multiplying them by 5 and adding 1000 ; then mark off three figures as decimals. Deg. Sp. Grav. Deg. Sp. Grav. Deg. Sp. Grav. Deg. Sp. Grav, 1 .. . . 1.005 8 .. . . 1.040 15 .. . . 1.075 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 26 .. .. 1.125 6 .. . . 1.025 12 .. . . 1.060 19 .. . . 1.095 26 1.130 6 .. . . 1.030 13 .. . . 1.065 20 .. . . 1.100 27 1.135 .. 1.085 14 .. . . 1.070 21 .. .. 1.105 28 . . 1.140 CHAPTER LVII. TABLE OF THE ELEMENTS OF MATTER, "WITH THEIR SYMBOLS AND CHEMICAL EQUIVALENTS. ^Elements. Symbol. Aluminum, . Al. Antimony, (Stibium,).. . .Sb. Arsenic, As. Barium, Ba. Bismuth, Bi. Boron, B. Bromine, Br. Cadmium, Cd. Caesium, Cae. Calcium, . . . Ca. Carbon, C. Cerium, Ce. Chlorine, CI. Chromium, Cr. Cobalt, Co. Columbium, (Tantalum,). . Ta. Copper, (Cuprum,) Cu. Didymium, Di. Erbium, Er. Fluorine, F. Glucinum, . .v. Gr. Gold, (Aurum,) Au. Hydrogen, H. Ilmenium, II. Iodine, .1. Iridium, Ir. Iron, (Ferrum,) Fe. Lanthanum, La. Lead, (Plumbum,) Pb. Lithium, Li. Magnesium, Mg. Manganese, Mn. Mercury, (Hydrargyrum,) Hg. Chem. 14 129 15 69 213 11 IS 56 123 20 6 46 36 26 30 184 32 48 ? 19 1 197 1 126 99 28 44 104 1 12 28 100 Elements. Molybdenum, Mo. Nickel, Ni. Niobium, Nb. Nitrogen, N. Norium, No. Osmium, Os. Oxygen, O. Palladium, Pd. Pelopium, Pe. Phosphorus, P. Platinum,.. Pt. Potassium, (Kalium,). . . ,K. Rhodium, Ro. Rubidium, Kb. Ruthenium, Ru. Selenium, Se. Silicon, Si. Silver, (Argentum,) Ag. Sodium, (Natrium,) Na. Strontium, Sr.; Sulphur, S. Tellurium, Te. Terbium, Tb. Thorium, Th. Tin, (Stannum,) Sn. Titanium, Ti. Tuogsten (Wolfram,). . . .W. Uranium, U. Vanadium, V. Yttrium, Y. Zinc, Zn. Zirconium, Zr. Chem. Equiv. 38 30 14 32 99 39 52 85 52 40 22 108 23 44 16 64 ? 60 59 24 92 60 68 32 32 34 The Elements printed in italics are the Metalloids; the rest are the Metals. CHAPTEK LVIII. THE SEVENTH EDITION ADDITIONS THERETO HERR ALBERT^ MECHANICAL PRINTING PROCESS SARONY's PHOTO-CRAYON POR- TRAITS — PRINTING WITH COLLODIO-CHLORIDE OF SILVER ON PAPER AND OPAL GLASS — PRINTING ON PAINTED CANVAS. THE SEVENTH EDITION. We will here commeilce our additions to the Seventh Edition of The Silver Sunbeam. There will be found con- siderable information in the following new processes which have appeared since our Sixth Edition was published, and as we are anxious that this work shall be a complete store- house of photographic knowledge, we shall give in each edition everything new in the art up to the time of our going to press. We will commence with: — herr Albert's mechanical printing process. Herr Albert's process is analogous to that of Tessie du Motay and Mareschal, and both are allied to photo-lithog- raphy ; but as a film of gelatine is made to acquire pro- perties resembling those of the lithographic stone, we propose that processes of this kind should be styled photo- collography. The principle upon which this method of printing is based may be explained as follows : — A plate is covered with a solution of gelatine and a chromic salt, dried, and exposed under a negative. It is then washed in cold water, not with a view to remove any portion of the gelatine, but simply to get rid of the chro- mic salt, and to permit the gelatine to become saturated with moisture, which it will absorb in the inverse ratio of the action of light; that is, the portions of the gelatine coating which have been very fully exposed — such as the deepest shadows of the image — will have been rendered insoluble and impermeable to water; those parts upon 24 508 herb Albert's mechanical printing process. which the action of light has been less complete absorb water in just such degree as they have been rendered partially insoluble and impermeable ; whilst the parts completely protected from light absorb water freely. This film, after treatment with water, is just in the condition of a moistened lithographic stone. If a roller charged with greasy ink be applied to its surface, the ink will be repelled by the moist portions, but will adhere to the dry or insol- uble portions, as it would to the greasy image on the stone. The ink adheres to the image in the exact ratio of its free- dom from moisture. In the deep shadows, where light has acted fully, the film having become quite insoluble and unabsorbent, the ink adheres freely ; to the parts partially moistened it adheres less perfectly ; and so on in exact rela- tion, the action of the light on the film being registered by degrees of impermeability or permeability to moisture, and these degrees of permeability again registered by the reception or rejection of a fatty ink applied to the surface. An exact transcript of the negative is thus secured in printing ink on the layer of gelatine, and a sheet of paper being placed upon it and suitable pressure applied, a print is produced. The details of Herr Albert's process, briefly stated, as given in the French specification, are as follow : — A thick plate of glass, about five-eighths of an inch in thickness, is used for receiving the printing surface. The glass is coated with the following preparation : — Filtered water, 300 parts. Albumen 150 " Gelatine, ' 15 " Bichromate of potash, • . . 8 11 The glass coated with this solution is dried, and a piece of black cloth placed behind it, after which it is exposed to light for some time — our correspondent thinks about two hours. Next a coating of gelatine and bichromate solution is applied, as follows: — Gelatine, 300 parts. Bichromate, 100 " Water, 180 " It is evident that an error is made in stating the amount of water, as the gelatine and bichromate could not be dis- solved in so small a proportion; it is probable that one figure has been omitted, and that instead of 180 parts, 1,800 should be read, as with the latter proportion of water sarony's photo-crayon portraits. 509 a workable solution could be made. The plate is coated with the solution of gelatine and bichromate, dried, and exposed under a negative, care being taken to secure direct rays. After sufficient exposure the plate is washed; it is then treated as a lithographic stone — that is, it is coated with a fatty ink by means of a roller — and im- pressions printed by means of a lithographic or other press. sarony's photo-crayon portraits. This new style of portraiture consists in using the image as a transparency enlarged from a small negative. It is a vignetted image, and is backed with crayon paper with a hatched vignetted design, giving the effect of a fine crayon drawing. The important point in the character of the transparency is, that it shall be thin, delicate, bright and clear, so as to form a good picture when backed up and viewed by reflected light. In producing it the idea must be constantly kept in mind that a picture to be looked at y not to be looked through, is required. The quality of image, in fact, is needed which answers best for Eburneum pictures or transferred collodion prints. There should be no trace of fog; the highest lights must be perfectly clear, bare glass; and from that the more gra- dation, of course, the better. A good commercial bromo-iodized collodion is used; one which is tolerably ripe will answer best, and if any tendency to deposit on the shadows is present, the addi- tion of a little tincture of iodine to the collodion will be found useful. Excite in a strong bath containing (say) from thirty-five to forty grains per ounce, slightly acid with nitric acid. The time of immersion should be short. A short immersion, which leaves a portion of the iodide and bromide unconverted into salts of silver, is the essen- tial condition of brilliancy and freedom from foggy de- posit. A moderately full exposure is desirable. The developer consists of — Pyrogallic acid, 1 grain. Citric acid, 1£ grains. Water 1 ounce. Alcohol, quantum suff. The addition of acetic acid and tartaric acid often improves the tone. Great care must be exercised not to carry the 510 PRINTING WITH COLLODIO-CHLORIDE OF SILVER. development too far, as over-development causes the de- tail to appear buried, and only visible by transmitted light. Fix with hyposulphite. If the chemicals are in good condition and the develop- ment is rightly managed, a picture of good quality and satisfactory warm brown color is produced without toning; but in most cases some toning will be necessary. Various methods are possible, few exceeding gold toning as used by Mr. Burgess. Mercury and hypo can also be used for toning. When the right tone is produced, wash, dry, and finally varnish. PRINTING WITH COLLODIO-CHLORIDE OF SILVER ON PAPER AND OPAL GLASS. BY G. WHARTON SIMPSON. Many photographers have made extensive application of our collodio-chloride process, some preparing, by its means, for sale, a very excellent sensitive paper, ready for use. It has also been extensively used in producing enlarged nega- tives. We here subjoin brief and simple formulae, which we have found successful: — Mix three stock solutions — No. 1. — Nitrate of silver, 1 drachm. Distilled water, 1 " No. 2. — Chloride of strontium, 64 grains. Alcohol, 2 ounces. No. 3.— Citric acid, 64 grains. Alcohol, , . . 2 ounces. Now to every two ounces of collodion add thirty drops of No. 1 solution, previously mixed with one drachm of alco- hol; then one drachm of No. 2 solution gradually, shaking well at the same time; lastly, half a drachm of No. 3 solu- tion. In a quarter of an hour it will be fit to use. Paper. A sizing of gum tragacanth should be applied to the paper, to render it non-absorbent. In applying the collodio-chloride, about one-eighth of an inch is turned up all round, leaving a corner from which to pour. The paper is attached by pins to a flat board, and coated as a glass plate would be. It should dry very thoroughly before being placed in contact with the neg- ative. M. de Constant has found that prints are much improved, if the sensative paper or glass is fumed with ammonia ; PRINTING WITH C0LL0DI0-CHL0RIDE OF SILVER. 511 and Dr. Monckhoven points out that fuming prevents so- larization, or the formation of a light-brown by over print- ing. Opal Glass. Flashed patent plate answers best. It should not under any circumstances, receive a preliminary coating of albu- men, which is a source of fading. Preparing the Plate. The plate should be quite clean. We have found that running an edging of dilute albumen all round, and allow- ing it to dry before coating the plate, prevents the loss of the film in toning, fixing, &c. After the film of collodio- chloride has set, we finish chying before a bright fire, taking care that the thick edge where the plate was drained is quite dry, or the negative will be injured. The plate is left a few minutes to cool, and is then placed in the print- ing-frame. Printing. It is better to use one of the many printing-frames made for the purpose, which permit the progress of printing to be examined without risk of movement. The printing should be a little deeper than is required for albumenized paper. Toning, Fixing and Washing. If the edging of dilute albumen has not been used, an edging of a solution of wax should now be run round the film, and this will prevent it from slipping or becoming loose. An old and dilute acetate bath answers best ; but any toning bath may be used, provided it is not too active, as in some cases the image tones in a few seconds to a slate color, and is spoiled. It is generally important that the bath should be weak and old. A bath of hypo and gold also answers well. Fix in a solution of hypo three ounces to a pint of water. Five minutes' immersion is generally sufficient. Wash for five minutes under a tap. The prints should not be toned deeper than a warm brown or purple, as they lose no depth in the hypo, and are blacker after drying. Dr. Liesegang recommends chloride of lithium instead of chloride of strontium, and we have found the results good, but not better than with our own formula. The 512 PRINTING ON PAINTED CANVAS. lithium salt is more soluble in alcohol and ether than the strontium salt ; and little more than half of the former is required, since forty-one parts of chloride of lithium con- tain as much chloride as seventy-nine parts of chloride of strontium. Collodio- Chloride made Useful for Printing on Ivory. No modification of the formula is required : a sample of collodio-chloride which works well on paper or opal glass will give admirable pictures on ivory. The prepared ivory is coated with collodio-chloride, and when dry, is printed, toned, and fixed in the same manner as a picture on opal glass. The film adheres with sufficient tenacity to render any edging of varnish unnecessary. A more perfect wash- ing to remove the hyposulphite is necessary than with opal glass, because of the more absorbent character of the ivory. A NEW PROCESS FOR PRINTING ON PAINTED CANVAS. BY W. T. BOVEY. In a former publication of mine, I made known a method of printing on artist's canvas ; but the process is so beset with difficulties that failure has proved the rule, success the exception, with experimentalists who have worked by my directions. Desirous of simplifying what must prove a valuable process, I have labored on patiently until the working out of the method I am about to describe, which'leaves nothing to be desired in the quality of the print it is capable of producing. First, saturate strong methylated alcohol with soft soap (it is sold by all chemists), allow the excess of soap to sub- side, then decant the clear liquid. Next, take zinc white (dry), place in a mortar, add about ten grains of pure chloride of calcium to each ounce of the pigment, triturate to a fine powder, and mix to the consistency of a paste with the alcohol and soap solution. Grind with a pestle as fine as possible. Thin with spirits of turpentine to which a little linseed or nut oil has been added ; a very small quantity of a quick-drying varnish or japanner's gold size should be added also, to " stay" the pigment, which is then ready for use. Select painted canvas, known to the trade as single primed. Brush on the pigment in the usual way with an ordinary paint brush. When the whole PRINTING ON PAINTED CANVASS. 513 surface of the canvas is covered with the pigment, cross and recross with the brush rapidly and light-handed, and finish by removing the brush marks with a grainers' badger. [Note. — Those who are not skilled in the handling of a paint brush would do well to entrust the work to some in- telligent house painter or decorator. J When dry, the canvas is ready for sensitizing. Sensi- tize by floating on the silver bath, strength sixty grains per ounce, in the ordinary way. If too much oil has not been mixed with the pigment, it takes kindly to the silver bath. Should there, however, be any sign of glaze when the paint is dry, the surface of the canvas should be rubbed with a wet sponge, previous to sensitizing, until all trace of greasiness is removed, otherwise the canvas would be unevenly sensitive, and the picture would be spotty. The printing should be permitted to be deeper than needed in the finished picture. Tone, if desired, by any of the usual formulae. Fix in hypo, eight ounces to a pint of water. Wash thoroughly and dry. If care be observed the operations may be executed without wetting the back of the cloth until the final washing. Caution, Use as little oil as possible, or the pigment will resist the action of the hypo, and the picture will remain unfixed and the paint will continue sensitive. CHAPTEE LIX. ADVANTAGES OF A SUBSTRATUM FOR THE COLLODION FILM — CHROMO-PHOTOGRAPHY OR PHOTO-MINIATURE A SIMPLE APPA- RATUS FOR ENLARGEMENTS PHOTOGRAPHING MACHINERY. ON THE ADVANTAGES OF A SUBSTRATUM FOR THE COLLODION FILM. BY SAMUEL FRY. Anything that tends to reduce the manipulatory diffi- culties of photography is a direct assistance to more artistic productions, by enabling the operator to free his mind from mechanical details, and devote his energies en- tirely to his composition. Now, with a great number of persons, matters of continual difficulty occur by such things as spots, comets, dirty plates, film splitting off, and such like matters. And yet a very simple plan exists for getting rid of all fear of any one or all of those trouble- some visitations. This plan is not new ; it was proposed years ago, and lately revived in the Photographic News, whence I took it. It is simply to coat the plates with dilute albumen before taking pictures. You have thus a pure, uncontaminated surface to work upon : nothing has ever touched it. The following advantages are claimed for such procedure, and the writer is stating his own experi- ence in asserting that they are really found by the use of albuminous substratum : A complete absence of spots, comets, or markings of any kind on the plate (to test this, take a plate known to be dirty, and coat one side only with albumen) ; great adhe- siveness to the plate ; a better printing color ; a perfect cleanness of picture, and complete transparency of shadows on those parts not acted on by light ; every plate is like a new patent plate glass ; great labor in plate cleaning and polishing is saved, as the plates only require rinsing and drying. ADVANTAGES OF A SUBSTRATUM FOR THE COLLODION FILM. 515 I take one white of egg to ten ounces of water, and a small quantity of liquor ammonia, and after the usual agi- tation, filter very carefully. The plates are dusted, and a small pool formed in the middle ; this is guided over by a piece of glass a quarter of an inch narrower than the plate. The albumen should not quite reach the edges, as there would be a chance of contamination of the bath. In practice I have never yet found my bath in the least de- gree injured. The plates are placed on the rack, and soon dry. The drop at the lower corner should be wiped off. It is very important to have no dust about during drying. The plates keep well in a dry place. The albumen may be poured back into the funnel, and, after re-filtration, rather improves. For large plates the time saved is very great, and there can be no doubt as to the perfect cleanness of the plate. I had by me a large quantity of glass which, from some peculiarity, was not fit for use, from its being found impossible to give it a per- fect polish ; the albumen has enabled me to use it with complete satisfaction. Old plates are often difficult to clean, and unsatisfactory after all ; this plan will utilize them, and give pictures as clean as on new glasses. Just a word of caution in conclusion. Do not be tempted to use gum arabic for this purpose in lieu of albumen, as it is brittle, and possessing a different • con- tractile and expansive power to the glass, will split the film. Do not use, either, the solution of india-rubber, for well-known reasons. Albumen is the right thing and will be found very valuable. CHROMO-PHOTOGRAPHY, OR PHOTO-MINIATURE. BY A. DE CONSTANT. Under this name a process has for several months past been practiced in Paris. It consists in cementing photographs upon glass possessing a slight convex surface, and in render- ing the picture transparent by treatment with a certain de- scription of varnish. A photograph is slightly colored at the back, and placed accurately upon another similar pho- tograph painted with less care, and mounted upon a card of the same size as the glass. In this way the transparency of the print attached to the glass allows the picture under- neath to be seen and to become blended with th e upper 516 CHR0M0-PH0T0GRAPHY OR PHOTO-MINIATURE. one, whereby an effect of relief and of remarkable depth is secured, while the convex surface of the glass imparts a softness similar to that possessed by a charming miniature painting. The photographic production may be said even to surpass a painting in effect, as in the former no trace of a brush is to be detected. I remember, some time ago, an effort was made to render lithographs transparent, and to color them at the back, with the intention of thus producing a substitute for oil paintings, but the result was an ugly parody; whereas chromo-photographs (although based upon the same mode of production) leave nothing to be desired when executed with taste. It is a matter for surprise that in England, where water color painting is so much cultivated, that this process has not been successfully practiced; and, moreover, that in none of the photographic publications mention has been made of it. The method has for a long time been appre- ciated in Faris, and is now being adopted in Germany, where a work on the subject has just been published, by Gustav Meyer, of Friburg (Brisgau). I do not know any- thing of the formula therein recommended, but the pro- cess generally employed in Faris appears to me to present certain difficulties which I will indicate for the informa- tion of those who may feel tempted to make a few experi- ments in this branch of the art; communicating, at the same time, my own manner of working, by means of which the freshness and purity of the prints is not interfered with. According to the Paris mode of working, the trans- parency of the prints is brought about at the same time as it is cemented to the glass. The photograph is cut of the same size as the oval glass plate, and placed for a few moments in a mixture of — Canada balsam 70 parts. Gum mastic 15 " Spermaceti 15 " heated in a water bath. The print is then applied, face downwards, to the glass, and pressed well with the fingers, so that it adheres perfsctly over the whole surface, the superfluous solution being pressed out from the centre to the margin. This solution is very resinous, and clings so tenaciously to the fingers that the use of essence of tur- pentine is necessary to remove it, thus rendering the work CHROMO-PHOTOGRAPHY OR PHOTO-MINIATURE. 517 both difficult and dirty in its character. Moreover, the solu- tion appears to me, after a short time, to assume a yellowish tint, which interferes much with the pure tones and fresh- ness of the photograph. To remedy these defects I con- ceived the idea of rendering the photograph in the first place transparent, and afterwards cementing it to the glass in a second operation. To render the Print Transparent. The portrait, printed vigorously upon a fine albume- nized paper free from defects, is cut of the size of the glass, and plunged in a mixture of — Paraffine 3 parts. Virgin Wax 1 part, Fine olive oil . . . . , . . 1 " This mixture is maintained in a liquid state in a water bath, and after the lapse of four or five minutes the print is taken out, drained, and placed between sheets of filter paper, and ironed in the same manner as a w r axed paper negative. Prints prepared in this manner are perfectly transparent, and, when dry, may be placed in a portfolio. The Cementing Material I prepare according to the following formula: — Virgin wax 1 ounce. Gum dammar 23 grains. Gum elemi 23 " Oil of lavender 10 cent. cub. This is dissolved in a bottle placed in hot water, and, when well mixed, applied by means of a piece of flannel to the albumenized surface of the print. A small quantity of the same material is heated in one of the convex glasses, and so manipulated that the surface is covered with an even film of it. The print is then, placed, face downwards, upon the glass surface in such a manner that the adhes- ion is in the first instance effected in the hollow portion of the plate. Then, with the end of the fingers, the excess of solution is pressed outwards, care being taken to allow the glass to cool somewhat, in order that the print may not shift from its proper position; at the same time the cooling should not proceed too far, otherwise it will be impossible to press out the superfluous wax, which militates against the production of a perfect result. This operation demands, indeed, a certain amount of dexterity, upon 518 APPARATUS FOR ENLARGEMENTS. "which depends the beauty of the picture and the absence of air-bubbles between the glass and the photograph. The upper face of the glass is next cleaned (the convex surface) with oil of lavender, and after a short time, the cement being cold and set, the picture is ready for coloring. The second picture, of which mention was made at the beginning, is prepared upon plain salted paper, and print- ed of the same degree of vigor as the first. In the second print the ground must be as white as possible. It may be mounted upon stout cardboard, or upon a second glass fitting exactly into the other, according as it is found that a greater or less distance between the two images pro- duces the best effect. In any case it is necessary that the second glass, or the cardboard bearing the second print, should be fixed in such a manner that the two photographs are exactly superimposed. I come now to the painting, which is executed in water colors, those portions of the dress such as lace, embroidery, ornaments, &a, being treated with body color, or gold and silver. There are two methods of coloring: by paint- ing very lightly on the back of the transparent image, indicating the principal tints, and giving detail only in the hair, eyes, and ornaments; or by coloring the print more elaborately, as in the ordinary manner of painting. As to the second print, it may be colored more coarsely in brilliant, vigorous colours, which, however, must be sub- dued in the vicinity of the face. It is necessary to place one photograph upon the other occasionally, during the operation of coloring, to judge of the effect. I believe that the more complete coloring of the trans- parent print, although an operation of longer duration, yields a better imitation of an oil painting, and is softer in the flesh tints. But all this is a mat- ter of taste for the t artist, whom a modest pho- tographer like myself must not pretend to advise. My object here is merely to indicate a simple and easy manner of practising this interesting method, in which the painter and photographer will for a moment forget their rivalry, by working amicably together. APPARATUS FOR ENLARGEMENTS. BY W. H. DAVIES. Among the many methods for the enlargement of our small sized pictures — such as the solar camera with sun APPARATUS FOR ENLARGEMENTS. 519 and daylight, or the simple elongated copying camera, &c, as well as by the artificial lights of the lime, electric, and magnesium lanterns — there are, doubtless, many ingenious adjuncts to the practice which have either remained un- published, or have not received sufficient publicity. This, I think, is one of them. I was pressed by a friend, a short time ago, to devise a mode of enlargement which should be at once the cheap- est, simplest, and most completely effective for all pur- poses, either of positive or negative work, for either large or small sizes. After some cogitation, I fixed on the fol- lowing plan ; and as every little advance in the construc- tion of apparatus is worth recording, if it be an advance, I have "made a note" of this, which, although it is perhaps the oldest in principal, is yet so perfectly efficient that it ought to be better known than it is, and more ex- tensively used than it has ever yet been. An empty room, fully sixteen feet long, was chosen, with a window having a clear skyward exposure to the north. The shutters of this window were made to close properly, and the joints rendered light-tight by fixing cloth, hinge-fashion, wherever it was needed. This con- verted the room into a earner a-obscur a — a dark chamber. The next operation was to arrange the plate-holder and lens, which was done in this way : a bellows-camera, which was capable of focussing with any lens in stock, from the shortest to the longest, was chosen, the base-board was unscrewed, and the camera reversed in position, the part holding the dark slide being now fixed to the base-board, and the front portion carrying the lens being made mov- able and capable of being fixed at any distance from the plate-holder by the clamping screw (a screw arrangement would have been better but it was not at hand). This camera was fitted with a double sliding front, to move horizontally and vertically, together with adaptors for every lens that could be used w T ith it. The dark slide was put aside as being of no use, and the focussing glass frame chosen as the holder," and was fitted with carriers to hold the various sized positives and negatives. The altered camera was fitted on a sloping board, adjusted and fixed at the proper angle to the window shutter, from which a piece had been cut, (and which was hinged to move back out of the way} the size of the holder, and the sloping space between the camera and the opening filled up. That part of the arrangement was now complete, as all 520 APPAKATUS FOR ENLARGEMENTS. the light which could pass into the room must now pass through the negative or positive, and then through the small camera and lens behind it. All that was wanted now was an arrangement to receive the magnified image, and this was simply managed. A stout easel was made with parallel slides and sliding plate carrier, and a triangular or T frame for the bottom of it, to which the three legs were made fast at the same angle as the camera. Attached to the T, base of the easel, were three grooved wheels made from two-inch pulleys (not castors) ; as many beads to fit the grooves were made, and fitted to the floor like rails at the proper distance and position, and on these the grooved pulley wheels ran as smoothly as possible, perfectly parallel to the lens (the planes being coincident), and capable of being moved quite close to the lens, or any distance from that to the further end of the room, sixteen feet away; thus giving any scale of enlargement, by using any size of either lens, transparency or negative. The arrangement of the focus- sing and the centering of the image is by the double mo- tion of the lens in the camera front, and an up and down motion of a frame, with a ledge and catch, for glass or paper fixed to the easel. By getting behind the easel and focussing through, either on a ground glass well rubbed with chalk, or direct on the collodionized plate, the utmost possible sharpness is obtainable. The focussing on the ground glass is easy enough, but the method on the sensitized plate is not so, and is effected in this way : A cap is made for the lens with yellow glass inserted in front, instead of the opaque brass or leather which is usual, and through the yellow glass, which must be a choice bit, free from specks or striae, the image is pro- jected. "When all is ready, and the focussing quite correct, the cap is removed and the exposure proceeds. There are several advantages gained by this mode of working, and among others this may be mentioned in reference to the Sarony transparencies. By interposing an opaque card with a suitable opening, and keeping it in motion between the lens and sensitive plate, the vignet- ting can be carried to any extent or made to any shape, besides the pleasure of seeing what you are doing. If the room also contains a water pipe and sink it becomes at once operating room and camera, and is as near an ap- proach to perfection as can be expected in this sublunary PHOTOGRAPHING MACHINERY. 521 sphere, and, as I said to begin with, the cost is a mere trifle. The only method of enlargement I know of, for which it is not fitted, is printing from a small negative by direct sunlight on sensitive paper without development, and in England this method has never enjoyed much popularity; but for all other, either positive or negative, it is well fitted, and certainly worth attention. PHOTOGRAPHING MACHINERY. — BY H. BADEN PRITCHARD. The depiction of machinery by means of the camera is a task not unattended with difficulty. This is, in the main, due to two reasons : In the first place, the lighting up of the object is generally very defective; and, secondly, the bear- ings and more important parts of the machine are so bright and polished that the light is reflected therefrom in patches, and forms upon the negative white irregular blotches. If a machine is situated in a dark corner of a dark work- shop — as, indeed, machinery generally is, the difficulty of reproducing the same in the camera becomes greater still, for when the employment of artificial or reflected light is rendered necessary, the portions of machinery which pre- sent a bright surface are even more troublesome to deal with, from the fact that they reflect an increased quantity of light, while the darker parts of the machine, situated in the recesses, are not illuminated to any perceptible degree. A great deal may be done by diffusing the light as much as possible, by the employment of white sheets, white boards and the like, but the real source of the difficulty lies in the nature of the object to be photographed. In a recent article by Dr. Vogel on the employment of reflected light, that gentleman recommends the use of a mirror, which must be kept moving during exposure in such a manner that the darker and more essential por- tions of the machine are more frequently, and for a longer period, illuminated than others. This mode of operating is doubtless a very good one, and very feasible when a sufficient source of light is at hand, but when the latter is weak and diffused, the plan would, I think, scarcely be practicable. According to my own experience, the best method is to apply a suitable coloring matter of a light neutral tint to 522 PHOTOGRAPHING MACHINEEY. all those portions of the machine exhibiting a bright sur- face, or, indeed, anywhere where the metal is not other- wise painted or lacquered. The mixture or paint I em- ploy is very suitable for the purpose, from the fact that it is easily applied, readily dried, and is afterwards rapidly and completely cleaned off by the application of a little cotton waste moistened with turpentine. It is thus com- posed : Dry white lead 5 pounds. The amount of lampblack is varied according to the depth of tint required, but on no account must the pro- portion of gold size be augmented, as otherwise the paint, when dry, is not so easy of removal. The advantages of applying a colored matter of this de- scription to machinery about to be photographed are very evident ; the glaring points are obviated, the more intri- cate and darker parts are lighted up effectually, and extreme contrasts being avoided, a more harmonious pic- ture is the result, requiring for its production a much less prolonged exposure than would otherwise have been necessary. Lampblack, Gold size, Turpentine, 3 to 5 ounces. . 1 pint. • . 1£ pints. CHAPTER LX. HOW TO MAKE RIPE COLLODION AT ONCE — STIPPLING GLASS IN STUDIO — PRINTING ON WOOD BLOCKS — THE CALOTYPE PROCESS. HOW TO MAKE RIPE COLLODION AT ONCE. BY ALFRED HUGHES. It is very generally known, I believe, that if ether be left in contact with the atmosphere through the bottle- stopper flying out, or from other causes, the ether becomes practically unfit for photographic use. The collodion made from it becoming intensely red, gives thin, hard, wiry images, all roundness, richness and bloom being lost. Some little time ago I had some ether (a Winchester quart full), the bottle-stopper of which had been out from Saturday till Monday. At that time I was experimenting with iodides and bromides, and accidentally found out the following way of using up acidified ether : With the ether above described I made collodion, and, taking twenty ounces, iodized it as follows : ^grains £ per ounce. The collodion immediately turned a deep brown, and remained so, giving hard images, and having the appear- ance of a very old sample. Twenty ounces more plain collodion were taken, and iodized as follows : Iodide Cadmium, 4 grains. Bromide Cadmium, 2 ** This collodion remained quite colorless. Knowing that if this had been made with pure ether, about ten or twelve months' rest would have been needed for it to Iodide ammonium, . Bromide ammonium, 524 STIPPLING GLASS IN STUDIO. ripen, and thinking that the acid in the exposed ether might need the effect of time, I allowed the collodion two days' rest, and tried it. It fogged slightly. It was put aside again. In ten days it was clean, gave beautiful negatives (better than those produced by a similarly iodized collodion made of pure ether), and kept for nine months. Wishing to test this result a little more, I made another collodion, iodized as follows : Iodide ammonium, .4 grains. Bromide Cadmium, 2 " I mixed the bases as above, so as to get by the ammonium a collodion to work on the instant, and by the cadmium, one that would also keep. The collodion was tried at once. It worked exceedingly well, but in about a week it became hard, slow, and as useless as that which was made with ammonium alone. So I concluded that to use acidified ether, cadmium salts alone must be used; and that for ammonium salts, the greatest care must be taken to have the ether as pure as possible. I have written the above simply as a note of experience, there being, I think, only one practical result ; that is, a hint how to rapidly make a ripe cadmium collodion. STIPPLING GLASS IN STUDIO. BY B. J. EDWAKDS: In order to produce the best result in photographic portraiture, it is frequently found necessary to soften or diffuse the light as it enters the studio or glass room. This has usually been effected by a system of white blinds or screens covered with tracing-linen. Another plan, which has been successfully adopted by some of the best continental and English photographers, is to stipple or partially obscure the glass in the roof and side of the studio. This plan I consider far preferable to the use of white calico blinds. It is difficult to obtain the latter sufficiently thin and transparent, and they very soon become discol- ored, and render a prolonged exposure necessary. On the other hand, if the glass be properly stippled to the required extent, the light may be modified to any degree without increasing the exposure; while, in many instances, STIPPLING GLASS IN STUDIO. 525 a great increase in rapidity is the result. This is especially the case where the direct light from the sky is obstructed in trees or buildings outside the studio. As regards the material best adapted for stippling the glass. I have made many experiments in this direction, and now give the formula for a varnish which I have found to answer the purpose in every way. It will not change color, crack, or peel off ; can be washed with cold water without injury ; and, if required, can be easily removed and renewed. To make the varnish, take one tube of best flake-white, and one tube of prepared sugar of lead, as sold by artists' colormen. Empty the tubes into a jar, and add one ounce (by measure) of good mastic varnish, and- from two to three ounces of spirits of turpentine. When mixed, the varnish should be about the consistency of new milk ; if too thick, add more turpentine, taking care to keep the right proportion of mastic varnish to give body to the mixture. This may be ascertained by pouring a little of the compo- sition on to a glass plate ; if too thin, it will run in streaks, and a little more mastic varnish must be added, but only sufficient ; if too much be used it will become sticky and unmanageable in working. To stipple the glass, make a pad or a dabber of a large tuft of cotton wool covered with fine cambric or muslin ; then, with a brush, rapidly paint over one square of the glass to be stippled, and immediately dab it all over with the pad. This must be done quickly, and before the var- nish has had time to act. It is better to finish at once, and not attempt to go twice over the same place, or the work will appear patchy when dry. If properly managed it will have the appearance of very fine ground glass by transmitted light. The tint may be altered, if desired, by the addition Ox a little Prussian blue or indigo to the flakd white when mixed. If, at any time, it should be desired to remove the varnish, this may easily be done with a solution of common wash- ing soda in warm water ; and the glass, after well rinsing with cold water, may be again coated with the composi- tion. 526 PKINTING ON WOOD BLOCKS. BY W. T. BOVEY. A gentleman, who is intimately acquainted with the art of wood engraving in all its details, once remarked to me, that a certain fortune awaited the individual who could succeed in producing a sharp photographic image on the surface of a wood block. In reply, I pointed out the dis- similarity between a photograph from nature, and a pencil sketch drawn by the hand of a " wood draughtsman/' and inquired whether the difficulty would be surmountable. " Yes, certainly," was the response ; " that is to say, if the photograph could be produced with a material similar to that usually employed as a facing on which the pencil drawings are made." A few days only had elapsed subse- quent to the holding of the conversation above briefly alluded to, when the process, with every condition fulfilled, was mine. The fortune, however, is as far off as ever — possibly because process-making is more my peculiar/brfc than skill in fortune-getting. Such being my weakness, I am content to yield up freely all chances of pecuniary benefits, together with exhaustive details of my process, which directions will, I think, enable any photographer to succeed in producing the picture, if not the promised for- tune. First. Procure the finest quality white of zinc (dry). Second, mix to saturation chloride of ammonium, or other chloride salt, with water. Next, take the requisite quantity of white of zinc, and triturate to a fine powder on a slab or in a mortar ; then add sufficient of the chlorodized solution to the powder to form a thick paste, which should then be ground to a de- gree of fineness equal to butter. The paste must be thinned with albumen diluted slightly with the chloride solution (the albumen must be well beaten before used), and the pigment is ready for immediate use. To coat the block, a flat, soft hair brush is most suitable. The pigment should be laid on in a thin and even coating, and the brush marks removed with a grainer's badger. The block may be set aside in a warm place to dry. When thoroughly dried, proceed to sensitize in the following described way : — Dip a soft hair brush into a silver solu- tion (the ordinary printing bath will answer the purpose thoroughly), and, whilst the brush is full of liquid, brush over the surface of the block very lightly. This operation THE CALOTYPE PROCESS. 527 effectually prevents the forming of air-bubbles and streaks when the prepared surface is brought into contact with the silver bath. To bring the face of the block into contact with the silver bath, commence at one of the side edges of the wood, and bring the block gently down until the whole surface is resting on the bath solution. Hold the block in such a position as will prevent any part but the surface from con- tact with the sensitizing fluid. From three to five minutes will suffice to render the preparation sensitive. On re- moval from the bath, place the block on edge on a few thicknesses of blotting-paper to drain and dry. When dry, the block is ready for printing, which operation may be executed in a suitable printing frame, or the negative may be held to the sensitive surface firmly with the fingers whilst the printing is going on. The printing moves rapidly, so that patience is not severely taxed. When the primitive mode of working is resorted to, register marks applied to the edges of the negative in India ink afford valuable aid in readjusting the negative, in the event of its being moved before the print has attained sufficient depth. Print but little deeper than the depth required in the finished picture, which, when complete, is produced in a thin layer of pigment that will not wash off ; and I am persuaded that the pressure of the graving tool would not cause the color to " chip." The print need not be toned. Fix in hypo : hypo, four ounces ; water, one pint. Wash thoroughly under a tap, and dry. The work, as far as the photographer is concerned, is then completed. A little scraping with a piece of glass will remove the stains on the edges of the block ; these, however, are not injurious if left alone, but their presence does not denote a neat finish. THE CALOTYPE PROCESS — BY COL. A. G. GREENLAW. First examine and select thin negative paper, and reject all that show any irregularities, holes, patches of unequal density, &c. 528 THE CALOTYPE PROCESS. Iodize. Make a solution of — Iodide of potassium . Bromide of potassium 1,000 grains. 300 grains. (For much foliage the latter may be increased to 450 grains.) Distilled water 40 ounces, and add enough of pure iodine to give the solution a dark claret color. Then filter. Into this place as many sheets of paper as you can do easily, being careful that no air-bubbles exist. Allow the papers so immersed to rest for one hour ; then turn the whole upside down, and hang the sheets up to dry, taking off the last drops with white blotting-paper. This may be done in diffused light. "When dry, place sheet over sheet evenly in a portfolio in which no other papers, except blotting-paper, are placed. They are then iodized a dark purple, which will keep any time. They, however, turn a light brown color. Be sure, in working, that nothing touches the paper, for the very slightest touch is sure to cause a stain in the development. Now float a sheet of your iodized paper on this (smooth side downwards) until the purple has turned an uniform yellow, which is iodide of silver. Allow it to rest for one minute ; after this, remove and immerse in distilled water, where it should remain for two or three minutes ; if to be kept for some time, remove to another dish of distilled water. Place now on clean white blotting-paper, face up- ward, and remove by blotting-paper all moisture from the surface (these sheets can be again used for ironing out the wax by-and-bye) ; then place between blotting-paper, or hang up to dry ; when quite dry, place in your dark slides. Sensitizing Solution. Nitrate of silver . Glacial acetic acid Distilled water . 2$ ounces. . 2£ ounces. 40 ounces. Development. Gallic acid . . Spirit of camphor Distilled water . 200 grains. . 1 drachm. 40 ounces. THE CALOTYPE PROCESS. 529 This is a saturated solution of gallic acid ; it soon de- composes ; the spirit of camphor is added to preserve it. When about to develop, filter, and add to every five ounces one drachm of the following solution : — Pour into your dish quickly, and immediately float the picture side of your paper, which is slightly visible, on it, being very careful that there be sufficient liquid to pre- vent the paper touching the bottom of the dish. Con- stantly watch it until the picture becomes visible on the back, and the paper has a kind of brown, greasy appear- ance. Continue the development until, in holding up a corner when the sky is before the light, you cannot see your finger when moved about between the light and the paper. If it is not dark enough before the gallate of sil- ver decomposes, you have under-exposed. Decomposed gallate of silver ceases to develop. Do not, when examining your paper, lift more than the corner, as an oxide of gallate of silver forms rapidly on the surface like a crust, and, on replacing your picture, it causes innumerable marble appearances ; so also if you do not place your paper speedily on the solution in the first instance. It may be removed by drawing a sheet of blot- ting-paper over the surface of the solution. Eemove to a dish of common water, and wash out the brown tinge caused by more or less decomposed gallate of silver. When well washed, you may Fix it by placing it in a solution of hyposulphite soda, one and a-half ounce to one pint of water, till every ves- tige of the yellow iodide of silver be removed, after which wash in eight or ten different changes of water ; you have then a fine, clear, and dense negative. To render it suffi- ciently transparent for printing you must proceed to Wax it. This is done as follows : — Place it, when dry, face downwards on clean blotting-paper ; upon it put a sheet of blotting-paper, and pass a moderately hot iron over it; this is to ensure the picture being perfectly dry be- fore waxing. Now remove the upper blotting-paper, and pass the iron over the picture, following the iron with a piece of white wax until the whole picture is saturated ; do each picture thus. If travelling, you may wax all your Nitrate of silver Glacial acetic acid Distilled water . 30 grains, f drachm, 1 ounce. 630 THE CALOTYPE PKOCESS. sheets together like a block, with a piece of clean blotting- paper waxed to the top, and another to the bottom. To print from it, you need to remove all the wax you possibly can by placing a sheet of old, used blotting-paper, and passing a hot iron over it, and repeating it till not a ves- tige of wax appears on the blotting-paper (use red, as it shows the wax spots better than the white.) I have used this process for years in India, and find it most simple. I obtained the first prize for my pictures so taken at an exhibition. With cleanliness it is certain. CHAPTEE LXI. THE FERROTYPE. The general treatment of the chemicals, the posing, and lighting are the same in taking a ferrotype as in taking a negative, and need not be repeated under this head. There is one thing, however, that should be done to avoid the yellow appearance that ferrotypes are apt to have, and that is as follows : After having developed the impression and washed off the developer, flow the plate thoroughly with a strong solution of gallic acid, and wash well again before fixing in the cyanide of potassium. The best varnish for ferrotypes is Anthony's Diamond Varnish, which does not change color by the action of light, as many others do. Ferrotypes, as ordinarily made, are reversed. To remedy this partial defect a reflector is used. This is made of a prism of white glass, silvered on two of its sides. The metal frame in which it is held screws on the front of the tube and the camera, and is placed sideways to the sitter. Another mode of making ferrotypes with pure whites is to redevelop, be- fore fixing, with pyrogallic acid, acetic acid, and silver, exactly as in redevelop- ing a negative. Medallion ferrotypes are made by in- terposing between the sitter and the camera a sheet of white card board, with a large, oval opening. This is supported by a light frame of wood in a slightly inclined position. The background should be of a dark color. The effect of taking a picture in this way is to produce an oval picture with a white border. Pictures made in this style are especially adapted for being embossed by means of the cameo press. Vignetted pictures are made in the same way, the differ- ence being in the making the edge of the opening in the card board serrated, and placing it quite out of focus. (See Fig. 31). 532 THE FERROTYPE. Ferrotypes are now usually mounted on ornamented cards, which are perforated or punched with openings of varying size and shape. The ferrotype is fastened to these by means of gummed paper, and the aperture, being embossed, has an indented border or edge to receive the ferro plate. Many of these cards have gilt or tinted lines, similar to the ordinary carte de visite, printed on plain and tinted boards. Again, it is very common to place the fer- rotype in prettily-designed paper cases or envelopes. (See illustration, No. 54). These are made of tinted papers, with oval and arch openings, and of several sizes. They are provided with a flap, which protects the portrait from injury. The carte envelope also forms a very suitable cover- ing to deliver the picture in, and has generally the name and address of the photographer printed on it. Open view of Fig. 7. CHAPTER LXII. COLLODIONS. Fig. 3. The principal new feature in connection with this article is the making of emulsions, containing nitrate of silver and bromide of silver. These emulsions, which were first success- fully used by Mr. Sayce, have been made a special study by Mr. M. Carey Lea, who introduced important modifications. There was, however, a disad- vantage in their use, arising from the fact that it was necessary to use the emulsion at just the proper time after making it, or run great risk of not succeeding in getting satisfactory pictures. Mr. Lea's formula has been modified by Col. Stuart Wortley, and the result of the combined efforts of these gentlemen is as follows : Plain collodion, .... Pure anhydrous bromide of cadmium, Nitrate of uranium, Nitrate of silver, .... 1 ounce. 7 grains. 30 18 " Dissolve one part of nitrate of uranium in two parts of ether, and let stand for some hours ; the water of crystalliza- tion that is in the uranium will fall to the bottom of the bottle, leaving a top layer of ether containing pure uranium, and it is this top layer which is used for the emulsion. It is desirable that the nitrate of uranium should be acid ; and should it not after solution in ether test acid, it will be ad- visable to add a minim or two of acid per ounce — nitric acid in preference. The quality of an emulsion depends very greatly on the cotton used in making the collodion — a short, powdery cotton being best. After the plate has received its coating of collodion, it is placed in a dish of distilled water, and left until all greasi- ness disappears. It is then taken out and drained, and placed for three minutes in the preservative. Mr, H. Cooper makes his preservative as follows : 534 COLLODIONS. Distilled water, . 4 ounces. White sugar, 20 grains. Gum Arabic, 60 " Gallic acid, 12 " The plates are then dried carefully in the dark. These plates are said to be as sensitive as the wet, being developed by the Fig. 4. Alkaline Development. Mr. M. C. Lea recommends the following mode. Make three solutions, viz. : 1. Progallic acid in alcohol, sixty grains to the oumce. 2. Carbonate of ammonia in water, eighty grains to the ounce. To be kept well corked. 3. Bromide of potassium in water, sixty grains to the ounce. When ready to develop, mix together in a small vial half an ounce of the bromide solution and three quarters of an ounce of the carbonate of ammonia solution, and mix them well. Then put into a dish of proper size four ounces of water, to which add half a dram of the pyrogallic acid solution, and immerse the plate so as to avoid uneven wetting. Then take out the plate and add fifteen or twenty drops of the mixture of bromide and carbonate, and put the plate back again in the mixture. If the plate has been properly exposed, it develops rapidly. When the details are well worked out, COLLODIONS. 535 add at once half a dram of the solution of carbonate of am- monia. This will give the negative its proper density. Fix in a very weak hypo bath, one ounce of hypo to fifty of water. Mr. Lea advises the use of water solutions at the tempera- ture of seventy or eighty Fi degrees, and in cases of under exposure consider- ably warmer. In case very warm water be used, a little more bromide of potassium should be used in the developer. The remarks made by Mr. Lea as to the origin of the use of ammonia in connection with dry plate photography are not ex- actly correct. The first use of ammo- nia in connection with a negative was by Mr. H. T. Anthony — this was very long ago — a simple, dry bromo-iodized plate without pre- servative being exposed to the vapor of ammonia and pro- ducing a negative with an instantaneous exposure. The knowledge of the ac- tion of an alkali upon the dry salts of sil- ver, some three years after the ex- periment alluded to, was the cause of the trial of its action up- on the chloride of sil- ver i n connection with albumen. The first experiment in this direction was a perfect success. Upon the intro- duction of the dry tannin plates, it oc- curred to Mr. An- thony that the vapor of ammonia might be used with them Fig. 6. Secrete/- 536 COLLODIONS. Closed view of Fig. 7. to advantage. A trial was made and was perfectly success- ful, an instantaneous negative having been made. Subsequently a society of amateurs was formed for the purpose of mutual aid and exchange of pictures. Mr. Borda, of Philadelphia, was one of the members. It was suggested to him by Mr. Anthony to try the ammonia with his tannin plates. Mr. Borda, fearing that his plates would not keep long after fuming, conceived the idea of exposing first and fuming afterward. In carrying out this idea, he found that the picture was developed to a certain extent by the action of the ammonia. The publication of this fact induced other gentle- men to investigate the matter, and thus has been worked out the proc- ess of alkaline development. The yellow light ordinarily used to illuminate the dark room in the wet collodion process is too strong for the bromide emulsion process. A dark ruby red glass is required with the latter process on account of its excessive sensitiveness. Pure distilled water, or water ob- tained by melting ice, should be used for making the silver negative solution. Rain water should never be used unless it has first been puri- fied by adding a little nitrate of sil- ver to it and leaving it to stand in the sunlight as long as any deposit takes place. Collodions for all photographic uses are manufactured by us ; we also keep a supply from all other makers. CHAPTEE LXIII. ORGANIC DEVELOPERS. There have been used many developers compounded of the ordinary salt of iron and different organic matters. One of the best of these is made as follows : Make a solution of gelatin, ten grains to the ounce of water, and a solution of tan- nin, fifteen grains to the ounce of water. While the gelatin solution is warm, add to it three drops of the tannin solution, and mix thoroughly. Add one drop of this mixture to each Fig. 8. ounce of the ordinary developer. This slight addition makes a remarkable difference in the action of the developer, and enables one to use it over and over again merely by filtering. Instead of gelatin, various other organic matters can be used with the tannin, viz., starch, tapioca, gum Arabic, etc. Another excellent developer is compounded as follows : Double sulphate of iron and ammonia, ... 4 ounces. Rock candy, | ounce. Water, 64 ounces. Acetic acid, No. 8, 4 " 538 DEVELOPING. An excellent developer for ferrotypes is made as follows : Prepare a saturated solution of protosulphate of iron, also dissolve two grains of tannin in an ounce of alcohol. Add gradually of the tannin solution to that of iron until the lat- ter ceases to redissolve the precipitate formed. Then add a Fiff 9 very little nitric acid to redissolve the precipitate. Dilute the solution by the addition of twelve times its bulk of water. Now, by adding to each ounce about half the quantity of acetic acid ordinarily used, the de- veloper will be ready. This developer gives fine, vel- vety blacks and rich, pure whites. The ordinary developer for ferrotypes can be very much improved by merely adding a trace of tannin to it just before being used. A defect, frequently occurring in ferrotypes, viz., a yellow color after being varnished, can be prevented by proceeding as follows : After developing and washing, flow the plate with a two-grain solution of gallic acid. After a short time wash well again and then fix Developing. Photographers continue to use generally the simple iron developer, ordinarily obtaining sufficient intensity without recourse to redeveloping. The demand for pictures called " Kenibrandt's," has somewhat modified the character of neg- atives, a thin collodion and a weak developer being used. The negatives are printed from in the shade. As organic mat- ter added to the developer in- creases the reducing action, it is sometimes desirable to use it. An excellent organic devel- oper is composed of protosul- phate of iron and gelatin — one of the best of these is "Miller's Intensifying Iron Developer." This works best mixed in small proportions with the double sulphate of iron and am- DEVELOPING. 539 proper pro- all the in- rtionia. The portions of gredients must be determ- ined by experience. Mr. H. J. Newton's latest formula is : Fig. 11. Protosulphate of iron, 1 ounce. Sulphate of ammonia, 1 " Water, 16 ounces. To the above solution add thirty drops of concentrated am- monia, and redissolve the precipitate by adding Acetic acid, No. 8, 1J ounces. Julius Krueger's new developer : a. Sulphate of iron, 1 ounce. Distilled water, 16 ounces. Absolute alcohol, J ounce. 0. Morphia, 8 grains. Glacial acetic acid, J grain. Distilled water, 2 grains. When the developer is required for use, a mixture is made of eight parts of solution a and one part of liquid b for the weak developer. Ferrotype developer : Protosulphate of iron, 1 ounce. Water, 20 ounces. Acetic acid, No. 8, 2 " Sulphate acid, CP., 12 drops. Or, Water, 16 ounces. Protosulphate of iron, 1 ounce. Epsom salts, 1 " Acetic acid, No. 8, ..... 1J ounces. CHAPTEE LXIV. PROCESSES OF MR. T. C. ROCHE, THE CELEBRATED PHOTOGRAPHER. Negative Bath, Nitrate silver, 4 ounces. Water distilled, .... 40 " When the silver is all dissolved, add eight grains of iodide of potassium dissolved in one ounce of water. Shake the whole well up and filter. In trying a plate, if there is any trace of fog (not from over exposure), add one or two drops of nitric acid, C. P. After constant use the bath becomes saturated with excess of iodine, ether, alcohol, and organic matter. When in this state, it is almost impossible to Fi &* 12 - get anything like clean work. The quickest and best remedy to rectify the bath is Boiling. For a bath of forty ounces, pour one pint of distilled water in an evaporating dish $ now pour the bath solution in and mix up with a glass rod ; then add two or three drops of liquid ammonia and mix well up. Now test the bath for alkalinity with red lit- mus paper. If it does not turn blue, add more ammonia, one or two drops, or enough to show a decided blue color on red litmus paper. Set the evaporating dish on a stove, or use any other mode of heating, so as to bring the solution to the boiling point When the heat begins to act on the bath, it will turn pink, brown, dark brown, and, as it approaches the boiling point, it will become quite black. It is better to let it boil a little, say five or ten minutes. When it begins to boil it will be PROCESSES OF MR. T. C. ROCHE. 541 clear, and all iodides and organic matter will be separated, and the ether and alcohol will evaporate. The next opera- tion is to set the bath away to cool, and when cool filter clear ; then test for strength. If too strong, reduce with distilled water ; if too weak, add silver to the proper strength, thirty-five grains for summer and forty grains for winter. This bath is alkaline, and it is neces- sary to add, drop by drop, C. P. nitric acid to it until it shows an acid reac- tion with blue litmus paper. The bath will not require re-iodizing, and, as a general thing, with Anthony's new negative collodion, will give clean, brilliant negatives, full of detail and free from hardness, and work quickly. This mode of treating a bath in the studio or field is quick and certain — no sunning, no making of new solutions or waste of silver. It has been thoroughly tested for the last twelve years. The Developer for Field Work. Double sulphate of iron and ammonia, ... 4 ounces. Water, 64 " Yellow rock candy, ....... | ounce. Acetic acid, No. 8, 6 ounces. Or, Double sulphate of iron and ammonia, . . 3 ounces. Yellow rock candy, | ounce. Miller's developer, 1 " Acetic acid, 4 ounces. Water, 64 If the silver bath has been in use long, or is old, the ad- dition of one or one and a half ounces of alcohol to the above developers will cause the solution to flow more freely. As a general rule, these developing solutions reduce the time for dark details at least one-half. For studio work, this de- veloper is too strong, and should be reduced with water to suit the light. Instructions for Field Work. For field work, don't stint yourself in lenses. Have plenty, or at least three pairs for stereoscopic . use. In going but a short distance from your home, you will require only a dark box or tent, with all necessary chemicals, camera stand, 542 PROCESSES OF MR. T. C. ROCHE. and negative box ; but for an extended trip you will require a chemical box or miniature stock depot, divided up into square compartments, to pack your bottles and extra stock in, as on railroads they are handled rather roughly. If trav- eling over mountains on mule paths, you will require the boxes made long and narrow, so that they can be packed readily on each side of the mule, and can be well tied, so that if your mule chooses to roll over he can hurt noth- ing. It is always best to make out a careful list of everything needed, for if you wish to do good work go prepared for it, and do not begin to make excuses about forgetting this or that article. Take a pride in your work, and take all inconveniences you may meet with in good part. Keep your temper and powder dry. It is better, if you have the time, to reconnoitre the place on some other day. Pick out your standpoints ; look out for what will make good stereoscopic views, and what will make good eight by ten or larger size. Mark down the time of day the light is most suitable. In this way you can start in the morning with your things, keeping the sun three-quarters on your work, and follow him all day — except for strong cloud or moonlight effects ; for these you will require a box with a lid over the lenses, and will have to work directly toward the sun. Watch until the sun is capped on the edge by a cloud, then expose two or three seconds. For the clouds, close the lid half down and keep moving it slightly up and down between the horizon and foreground. For detail in the picture, as a general thing, this class of views is more for cloud effects than a picture full of details and half tones. The latest mode of working is now to give a good expos- ure for detail, and in developing get out all you can ; but do not over expose or develop, so as to have a flat or fogged PROCESSES OF MR. T. C. ROCHE. 543 negative. For general work a well-lighted picture will not require, if your chemicals are in good working condition, any redeveloping or intensify- ^. lg ing, by using Anthony 7 s new negative collodion. Some of the best landscape photog- raphers have been for some- time developing inthe field, and fixing at home in the evening or next morning. The mode is as follows : After developing the plate, wash off with water, or put the negative in a dish with good water, enough to rock the plate in. When all the greasy lines disappear, flow over the plate a solution of glycerine : Glycerine, 1 ounce. Water, 3 ounces. Alcohol, • 1 ounce. Then put the plate in the Fig ' negative box, and keep on taking negatives. When you get home (those plates with glycerine on will keep a week or more) wash off the glycerine, - fix the negative in weak cyanide, wash well, and force up, if required, with any of the well-known methods. I prefer, after fixing, to flow over the plate an acid solution of Acetic acid, No. 8, 4 ounce. Water, . . .4 ounces. I then drain and flow a solution of pyrogaltic acid, No. 1, mixed with a few drops of acid silver, as per formula No. 2. ' No. 1. Pyrogallic acid, ........ 60 grains. Water, 20 ounces. Citric acid, 20 grains. No. 2. Silver, 20 " Citric acid, 20 " Water, 1 ounce. 544 PROCESSES OP MB. T. C. ROCHE. This will bring the negative up to a good printing color, and will not change. Dry and varnish. Keep your shield and box free from dust in working, and take an interest in your apparatus. Cameras and Lenses for Field Work. Fi s» 18 - One R success view cam- era, with double swing back and folding bed, for eight by ten plate; one Dallmeyer wide angle rectilinear ; one Dall- meyer rapid rectilinear. By taking off the front combination from either you lengthen the focus, and can get a larger view. For Stereoscopic Work. One eight by five Z success camera box, one pair Dall- meyer wide angle rectilinear, two and a half inch focus, one pair Dallmeyer rapid rectilin- ear, and one pair Dallmeyer four and a half quick-acting stereoscopic landscape lenses. Fig. 19. CHAPTEE LXV. DEFECTS AND BEMEDIES. 1. Fogging. Fogging arises from various causes, which generally are easily detected. A fog which is uniform over the plate, and can be readily rubbed off with the finger, is caused by the condition of the chemicals. The fog caused by improper action of light on the plate de- velopes in the film, and not on Flg ' 20 * the surface. This rule will generally indicate to the oper- ator in what direction to look for the cause. The intrusion of light may be through small holes in the wood work of the box, or in the bellows, or the cut off in the plate shield may not operate, or the shield may not fit closely in its place in the box. If the chemicals are at fault, the causes are found in either the bath or the collodion or the developer. A very light col- ored collodion will sometimes be the cause — the remedy is the addition of a little tincture of iodine. If, while using a ripe collodion of a deep straw color, fog should occur, the fault is probably in the bath — a drop of nitric acid to each twenty ounces of the bath will be sufficient in case the bath has been neutral. If this does not remedy the fog, the cause may be organic matter in the bath. The remedy for this is to neutralize the bath with bi-carbonate of soda and allow to stand in the sunlight until 546 DEFECTS AND REMEDIES. all precipitation ceases and the bath has become clear. Then filter and try a negative. A little ni- tric acid may be needed. Unclean glass is fre- quently a cause of fog : this can readily be de- tected by its appearance, as it is always found be- tween the collodion and glass. Hard rubber baths sometimes contaminate a silver solution. Before being used they should be cleansed by using a strong alkaline wash, and while being used the sil- ver solution should never be left in, but should be poured out and the bath washed as soon as the day's work is done. Lime water, rain water collected from the roofs of houses, and water containing alkaline salts, if used in the develop, may cause fog. The vapor of ammonia, or the presence of sulphuretted hy- drogen, will cause an undue deposit of silver on the plate. Fogging is sometimes caused by removing the glass from a cool place and taking it into a warm, damp room — a coat of moisture is thus produced upon the plate which is sure to cause fogging. The vapor of turpentine destroys the sensitiveness of iodide of silver. If the temperature of the bath and developer are too high, fogging ensues. If the temperature be too low, the chemicals do not combine properly ; consequently, in very hot weather or very cold, means should DEFECTS AND REMEDIES. 547 be- used to regulate the Fi s- 23 « temperature of the bath and developer. The tem- perature should range from fifty-five to seventy degrees Fahrenheit. A slight fog may fre- quently be removed by pouring upon the devel- oped plate, after it has been fixed and well washed, a solution of io- dine and iodide of potas- sium in water. This pro- duces a very thin coating of iodide of silver, which can be removed by im- mersing again in the fix- ing bath . Collodion tran- sparencies that may have been over-developed can be rendered clear by this means. A change of tempera- ture may cause a film of moisture on the lens — this would necessarily pro- duce fog on the plate. A great excess of diffused light in the skylight room is a frequent cause of veiling 'of the plate. To prevent this, a black hood of some kind should surround the lens, extending some distance in front of it, to cut off side light. 2. Thinness of the Film. The collodion may not have sufficient soluble cot- ton, or may be under-io- dized. An old collodion may make a very thin coating upon the plate. Fig. 24. 25 DEFECTS AND REMEDIES. 3. Irregularity of the Film. Crapy Lines. — S o m e- times caused by too much water in the collodion. If the operator makes his own collodion, he should be careful to use a dry bottle, or in case the bot- tle is freshly washed, it should be well rinsed with alcohol . Sometimes caused by neglect to change the po- sition of the plate while the collodion is draining Ridges. — Collodion too thick. A large excess of alcohol. Gummy cotton. Mottling arises from the undue thickness of col- lodion, caused by the evap- oration of the solvents. 4. Defects in the Image. Too much Contrast is caused generally by un- der exposure. Too little bromide in the collodion, or too much. Acid, old collodion. Too little cotton in the collodion. Old, disordered nitrate bath. Cotton working too intense. Too little Contrast. — Over-expos- ure. A collodion not sufficiently acid. As a general rule, very strong negatives must be printed on paper floated on a weak nitrate bath, and printed in the sun. A weak nega- tive should be printed on paper floated on a strong nitrate bath, and be printed in the shade. DEFECTS AND BEMEDIES. 549 Half Tone, — Strong contrasts in portraiture are not as popular as they once were. To secure half tone give plenty of exposure, and use a rather weak developer. After the Pig. 27. 4f details are brought out, finish with a strong developer, in order to give strength to the lights. Delicacy of modelling can also be aided by allowing the developer to remain on ~ 0Q the plate with- „. „ Flg>28 - , out moving. p *- 29 - Flowing the de- ^^^^ veloper back- ^ f ward and for- (T*^^ ward on the *^s* plate tends to harshness of im- age. 5. Blurring is generally c a u s ed by a strong light and dark shadow side by side. The light may be re- flected from the back of the glass, and thus cause an im- proper effect in the film. This effect is very perceptible in taking interiors, where the light from the windows is received directly upon the plate. It also oc- curs in taking landscapes where dark objects are projected against a strongly lit sky. This trouble occurs more in dry plates than in wet. To prevent it in dry plates, coat the 550 DEFECTS AND REMEDIES. Fig. 31. back of the negative before exposure with a surface that will absorb the light that passes through the film, and in wet plates press a piece of wet, dark-red blotting paper against the back of the negative. 6. Stains of Irregular Development. — Caused either by the developer not being flowed evenly upon the plate, or by excess of ether and alcohol in the bath. If the. latter be the case, add some alcohol to the developer. Asa general rule, it is bet- ter to avoid the use of alcohol in the de- veloper, as it has been found to have a tendency to cause a crystallization in the film, and thus pro- duce pin holes in washing. Thin, weak Nega- tives quite frequent- ly are obtained in taking a view from an elevation in warm weather. This arises from the refraction of the rays of light passing through strata of air of different densities. There is no remedy for this trouble except to take the view on a cloudy day. Splitting and Slipping Fig. 32 decomposed collodion. of the Film.— 1. Collodion not suffi- ciently set before immersion in the bath. 2. Damp glass. 3. Too much iodizing in the co llodion. 4. Too contract- ile cotton. Splitting in Washing. — B a d cotton and old DEFECTS AND BEMEDIES. 551 Splitting in Drying. — Fi g« 33 » Whatever may be the cause of this trouble, it may be remedied by flow- ing the plate, after being washed, with a weak so- lution of gum Arabic, say twenty grains to the ounce of water. Slipping of the Film. — Immersing too soon in the bath. A very acid silver bath. An acid surface of the glass. A solution of albumen will prevent the above irregularities. 7. Want of Sharpness. Taking it for granted that the operator is supplied with a good lens, care must be taken to keep the position of the glass in the shield identical with that of the ground _. _ . glass, otherwise the pic- ture will lack sharpness. In case the lenses have been taken out and cleaned, they must be put together again in their proper position. The arrangement of the different parts of an ob- jective can be seen by referring to page 561. In taking views, shaking of the box will cause lack of sharpness. As the moving of the box is likely to be caused solely by a strong wind, operators should be careful to have a very stiff tripod for this pur- pose. 552 DEFECTS AND BEMEDIES. 8. Streaks Fig. 35. Arise from a variety of causes. 1. If the plate be im- mersed before the collodion is sufficiently set, streaks, com- mencing at the bottom of the plate and extending up- ward, sometimes occur. 2. Not moving the plate after immersion in the bath. In all cases, immediately after placing the plate in the bath, it should be moved both vertically and horizon- tally for a short time, other- wise streaks in the direc- tion of the dip are likely to occur. 3. Streaks across the plate at right angles to the line of dip are caused by irregularity of motion in dipping the plate. It is very important to acquire a uniform, steady movement of the hand in dipping the plate, and care should be taken not to lift the upper portion of the plate out of the solution * until it has been some- time immersed, as by so doing marbled stains and rings are apt to be formed on the exposed part. 4. In case any foreign solu- tion should become mixed with the developer at the time of pouring upon the plate, such as the drip- pings of former develop- ments running off the bot- tom of the developing glass, unpleasant stains will occur. To avoid this, keep a rag or piece of blotting paper ready to absorb any fluid that may be found on the bottom of the glass. 5. Streaks of DEFECTS AND REMEDIES. 553 Fig. 37. a zigzag shape sometimes will be found proceeding from the point where the dipper touched the plate. This is more likely to occur with hard rubber dippers than glass or porcelain. To avoid this trouble, dip the plate slowly. 6. Keversing the position of the plate after taking it out of the bath is likely to cause streaks. As a general rule, the direction of the drainage of a plate should not be changed from the time of removal from the bath until the application of the devel- oper. 7. Using the dusting brush, care must be taken to have the broad brush used to clean dust from the surface of the plate perfectly dry. 8. Streaks in the direction of the dip are caused by lack of acid in the bath. The obvious rem- edy is to add carefully a little nitric acid. 9. Spots and Pin Holes. Occur from two or more causes — dust and crystals of iodo-nitrate of silver. These, occurring upon the face of the negative, prevent the action of the light upon the film beneath them, and when the nega- tive is fixed and washed, Fi 3g transparent spots are found where they were located. If the dust come from the bath, it can be fil- tered out. If it come from an unclean apart- ment, sprinkle the floor thoroughly with water. To remedy the forma- tion of the iodo-nitrate of silver, all that is nec- essary is to precipitate from the solution the excess of iodide of silver, which facili- tates their formation. The usual and best mode of doing this is to take one-fourth the quantity of your bath of water 554 DEFECTS AND BEMEDIES. Fig. 39. and pour the bath into it. This will precipitate considerable iodide of silver, which must be filtered out. Then boil the bath down to the original amount, having first neu- tralized it with a little am- monia or bi-carbonate of soda ; stand it in the sun for a few days. Subse- quently, if necessary, add a very small quantity of nitric acid. Large, semi-transpar- ent places occur some- times when the developer is poured on. This is oc- casioned by a lack of acetic acid in the devel- oper. If the bath should not be sufficiently iodized, the iodide of silver formed in the film is dissolved out, commencing at the edges of the plate. Plates that are kept too long before development sometimes become injured by the increased strength of the silver solution, caused by the evaporation of the Fig. 40. water, and the iodide of silver as in the former case being partially dis- solved, and the coating thus rendered thinner. 10. Comets, etc., Are intense opaque spots, which are not observed generally before develop- ment. Their general ap- pearance, as the name in- dicates, is that of a nu- cleus and a tail attached. The causes of these are various ; but the princi- pal one is the pressure of some substance tending to a strong reduction of DEFECTS AND KEMEDIES. 555 Fig. 41. the nitrate of silver, particles of protosulphate of iron, of hyposulphite of soda, that may exist as dust in the dark room, unfiltered collodion or pieces of dry collodion from the lip of the collodion vial, and metallic particles coming from the hinges of the door of the shield. Where the comets occur from the condition of the collodion, which is fre- quently the case, the addi- tion of tincture of iodine to it will entirely remedy the evil. Tincture of iodine should never be added in ■ such quantity as to produce | a deeper tint than a lemon color. 11. Stains and Surface Markings. Oyster shell markings, also called " matt silver/' consist of metallic silver reduced locally by the action of the devel- oper. They generally 42 occur when the plate has been kept a long while before development, and in contact with a surface from which the silver so- lution upon the surface may become contamina- ted with organic matter or a solution of some me- tallic salt. The forma- tion of these spots is very capricious, and they fre- quently occur on parts of the plate the least sus- pected. In the early days of photography, a collodion made with the iodide of ammonium then manufactured was especially subject to these and other sur- face markings. The explanation seems to be, that in the decomposition of the iodide of ammonium and the formation of iodide of silver, an excess of ammonia may be eliminated, 556 DEFECTS AND KEMEDIES. which reduces a little of the nitrate of silver to the state of oxide of silver. This attaches itself to the film and produces sometimes one kind of marking and sometimes another. The remedy in this case would seem to be to increase the acidity of the bath. As the larger and heavier of these stains ap- pear to proceed from the re- action of the drained silver solution upon the film, the best way to prevent the trouble is to absorb the drained solution by means of a piece of blotting paper placed under the plate, ex- tending from one corner to the other. Brown Stains. — In case it is found necessary to rede- velop with pyrogallic acid after fixing, care must be taken to remove all the hy- posulphite, otherwise the plate will be stained a transparent brown in the . shadows. Defects in Paper Prints. Fipr. 44. 1. Weak Prints. — Nega- tive too thin — remedy, make silver bath strong and print in the shade. The use of nitrate of mag- nesia or nitrate of alumi- na in connection with ni- trate of silver facilitates the printing of weak neg- atives. 2. Harsh Black and White Prints. — Negative too intense — remedy, re- d u c e materially the strength of the silver bath and print in the sunshine. 3. Yellow Whites.— A strongly acid silver bath ; allowing DEFECTS AND KEMEDIES. 557 the prints to remain without constant motion in the fixing bath ; allowing them to remain an unnecessary long time in the fixing bath ; the presence of acid gold upon the paper when placed in the fixing bath. A method of obviating some of the above troubles is to immerse the toned prints first in a weak solution of nitrate of silver — this will reduce the chloride of gold and strengthen the tone ; subsequently, put in a moderately strong solution of salt and carbonate of soda — this will convert the silver into chloride of silver, and neu- tralize the print at the same time. Now, when the print goes into the fixing bath, there will be nothing present to cause the yellow color of the whites. Sometimes, where the washing, toning, and fixing are done in the same apartment, hyposulphite is spilled upon the floor, dries, is ground to dust by the feet, pervades the air of the room, gets into the water of the washing tank, and turns the whites yellow before the prints #0 into the toning bath. No well arranged gallery should have the washing and fixing vessels in the same apartment. They should be separated as far as possible. 4. Prints do not Tone Readily. — This generally arises from the presence of a mineral acid in the print or in the gold bath in combination with the gold. To remedy the trouble in the print, al- ways neutralize the silver solution with ammonia before using, and subject the paper before printing to the vapor of ammonia from ten to fifteen minutes. If a blue scum appear upon the surface of the paper after fuming witn ammonia, it is proof that the silver bath is acid with nitric acid, the blue scum being nitrate of ammonia. This can be removed by breathing upon the sur- face of the paper. To prevent the presence of free acid with the gold in the toning bath, the chloride of gold should al- ways be kept dissolved in a stock bottle. Before being used, all the acidity should be removed by adding chalk and heat- 558 DEFECTS AND KEMEDIES. Fig. 46. Fig. 47. ing for some time to about one hundred and thirty degrees Fahrenheit, or by adding salt and carbonate of baryta. In the latter case no heat should be used, and the mixture should be shaken occasionally for two or three days. In either case the solution is always ready to add to the toning bath, which need not be changed, but can be kept for months, thus greatly economizing the expense of gold. Paper kept too long after printing is frequently very difficult to tone. In fuming the paper with ammo- nia, care should be taken to have the whole surface equally acted upon, other- wise lines and streaks will occur, owing to the unequal action of the ammonia. 5. The Silver Bath becomes Discolored. — The solution is either acid or not sufficiently strong. 6. Tears of Solution remain on the Paper, and Causing Brown Spots. — This most frequently occurs on high gloss papers. The remedy is to wipe the surface of each sheet well with a clean piece of cotton flannel. Some persons recommend a little glycerine in the silver solution, and others, placing the paper in a damp cellar for two or three days before using. 7. Stains occur from various causes. A brown stain may occur from a trace of hyposulphite on the hands. Brown stains with blue me- tallic surface comes from solutions of hyposulphite coming in contact with the print before toning. Yellow stains on the surface, varying in size, come from acid bubbles beneath the print in the fixing bath. To avoid this, fix prints face upward. The handling or touching the surface of the paper with sweaty or wet fingers will cause stains. Black spots in the paper after silvering arise from different causes. 1. Metallic particles in the paper. 2. Dust of sulphate of iron or particles of hyposulphite of soda becoming attached to it through carelessness. 3, By using hard rubber dishes for the silver solu- tion. These become gradually acted upon by the silver, and small particles float upon the surface and attach themselves to the paper. Never use hard rubber for floating bath. Fig. 48. DEFECTS AND EEMEDIES. 559 Fig. 49. 8. Mottling , or Irregular Action of the Silver, can arise from too short floating, too weak silver, silver solution being too cold, a large quantity of alcohol in the silver solution. The remedy in either case is obvious. 9. Scum on the Silver Solution. — In all cases where the sil- ver solution has been used for sensitizing paper, and is al- lowed to stand some time without being used, a scum of reduced silver and organic matter collects on the surface. This must be removed by drawing the edge of a piece of stiff paper over the surface. 10. Blurring. — Want of contact between the surface of the paper and the negative. This is fre- quently caused by dampness of the padding used for pressing the paper against the negative. Always thor- oughly dry the pads before using, and take the precaution to thoroughly di- vest them of dust. 11. Blistering generally occurs on highly albumenized papers. Whatever the cause, it may be obviated by soak- ing the prints after removal from the fixing bath in a solution of salt, say twenty to thirty grains to the ounce of water, for a quarter of an hour. Then wash them. 12. Fading of Prints generally occurs from the presence of hyposulphite of silver in the paper. Damp- ness will cause fading ; consequently all prints, in being put up, should be protected as much as possible from the action of moist- ure in the air. The best way now known to eliminate hyposulphite of silver is to soak the prints, after they have been rapidly washed in four or five changes of water, in a solution of acetate or nitrate of lead. The strength of this solution may depend upon the number of prints to be treated, and may vary from half a grain to two grains to the ounce of water. The action is very rapid, and the time of washing and the quantity of water for washing very much reduced. ^ 13. Cracking of the Albumen Coating arises from excessive thickness. In case it is observed, be careful not to dry the prints before they are mounted, and dampen the mounting card in order that it may shrink conformably with the print. Fig. 50. 560 COLLODIO-CHLORIDE. Collodio-Chloride. Fading, as in paper prints, is due to the presence of the hyposulphite of silver. Remedy, soaking in the lead solution just described. Unsatisfactory Toning. — The presence of free nitrate of silver in the film. Remove this by soaking for some time in a weak solution of a veg- etable acid, and tone in a bath made with carbonate of mag- nesia and some neutralized gold. Flat Blue Prints. — Pres- ence of moisture in the film. The collodio-chloride plate and the negative should both be perfectly dry and warm before being put out to print. In all photographic operations the greatest care should be taken to systematically avoid the mixing or mingling in any way of vessels or chemicals used for different purposes. Es- Fig. 52. pecially should great care be taken to prevent the contact of the hyposulphite of soda with the vessels or materials, ex- cept in its proper place, of a fixing bath. MISPLACEMENT OF LENSES. 561 Misplacement of Lenses. It frequently occurs that photographers, after separating the combinations of lenses for cleansing and other purposes, meniscus, and C the crown lens of the back combination, in their proper positions. This will enable those who are in trouble to determine for themselves if their lenses are in proper position or not, and in many cases it will save them express charges. The foregoing rule does not apply to the Dallmeyer lenses, in which the curves and positions of the various lenses are entirely different, and each lens so fastened in its cell that it is impossible to misplace either of them. misplace them. The cut is given to show the correct position of each. A is the front combination, the lenses of which, being hermetically sealed, are sel- dom misplaced. In fact, we have noticed that some man- ufacturers fasten the front combination in its cell. F represents the flint CHAPTEE LXVI. f PRINTING ON ALBUMENIZED PAPER. Fig. 53. The improved methods of working albumenized paper have made the results more certain, while the care is very mate- rially lessened. The formula most generally used at present is as follows : Make a solution of nitrate of silver from thirty to forty -five grains to the ounce of water. Add a few drops of ammonia, shake thoroughly, and then allow the precipitate to settle ; decant and add two grains of ammonia-alum to each ounce of the solution. Float the paper one minute and expose to the vapor of ammonia as long as may be found necessary. In cold weather the solution should be kept at a moderate temperature, and the ammonia box should, if nec- essary, be slightly warmed by placing a hot brick in it. In very cold weather, priuting in the open air is liable to be unsatisfactory, and many persons, who are not aware of the cause of imperfect prints produced under such circum- stances, improperly condemn the materials. Before toning, the prints should be soaked for fifteen minutes in a weak solution of some vegetable acid. If glacial acetic acid be used, ten drops to the quart is sufficient ; if good acetic acid, No. 8, be used, a dram to the quart is sufficient. A similarly weak solution of either citric or oxalic acid can also be employed. Subsequently, rinse the prints in two changes of water, and they are ready to be toned. Toning Bath. The principal point to be attained in prepar- ing a toning bath is to get a stock of neutral gold solution. This can be done in two ways. Dissolve the ordinary chloride of gold in water in the proportion of fifteen grains to the ounce, and neutralize the solution, adding either a little carbon- ate of baryta or prepared chalk. If the first, do not warm the solution, but shake it well occasionally for two or three days ; PRINTING ON ALBUMENIZED PAPER. 563 if the second, a little heat should be used. The solution is now ready for use in toning. All that is necessary is to put as much of the gold solution as may be desired in the water, add about thirty grains of salt to the pint, and a very small quantity of any of the alkaline salts ordinarily used for that purpose. By proceeding thus, a permanent toning bath is made, which can be used day after day by merely adding gold when required, and a little salt and alkali when nec- t essary. This operation is so simple, that it is not considered necessary to give any set formula for making a toning bath. We desire to call particular attention to washing in weak acid solution spoken of above, as it saves time, water, gold, and insures ease of toning. After toning, the prints should be well washed and placed in the fixing bath, one by one, face up. The top 1 ayer should be placed face down. The object of plac- ing them face up is to avoid the spots which occur when a bubble of air gets under the prints. They should be fre- quently moved while in the bath to insure uniformity of action. To avoid the risk of blisters, which frequently occur on highly albumenized paper, the prints should be transferred after they are fixed to a solution of common salt, of the strength of fifteen grains to the ounce ; in about a quarter of an hour they should be placed in the washing tank. As it is important to know when all the hyposulphite of soda has been removed, the water should be tested. The test ordinarily used is very simple and thorough. Make a thin fluid solution of starch, put a little of this in a large mouthed vial, and add to it a drop of aqueous solution of iodine : blue iodide of starch is instantly formed. Now add Fig. 54. 564 PRINTING ON ALB UMENIZED PAPER. a little of the water in which the prints are washing. If there be any hyposulphite in the water, the blue color will be immediately discharged. If the mixture in the vial re- main blue, it is evident there is no hyposulphite in the water. It is impos- sible to give rules for the time of washing ; but where large quantities of prints are washed togeth- er in running water, which comes in at the bottom and flows away at the top of the tank, about three hours are necessary. During the progress of the washing, the water should be entirely drawn off two or three times. A method, shortening the time and trouble of washing, and at the same time insuring the absence of hypo- sulphite of soda, has been proposed and is practiced by Mr. H. J. Newton, of New York. After entirely changing the water a number of times, he soaks the prints for a short time in a very weak solution (a half grain to an ounce of water) of acetate or nitrate of lead. The affinity of sulphur for lead forms sulphite of lead, which is insolu- ble, and the acetic or nitric acid combines with the soda, form- ing a soluble salt, which can easily be removed by a little subsequent washing. Care should be taken to get clear, trans- parent acetate of lead. Dr. Vogel recommends the use of a solution of iodine to remove the last traces of hyposulphite from the washing water. It is to be added and diffused through the water so long as by combining with the hypo- sulphite its color is destroyed. As soon as the water ceases to discharge the color of the iodine, the hyposulphite is elim- inated. We are not aware that Dr. VogeFs plan is practiced, but that of Mr. Newton is in actual and satisfactory use. MEDALLION PBINTING. 565 Medallion Printing Is very effective, and is now in general use. The mode of proceeding is as follows : A piece of black paper of the size of the negative is taken, and portions of the size and shape of the desired medallion cut out of it as clearly and evenly as possible. The print is first made with the exterior portion of this, black paper covering the exterior of the negative. The result will be a picture of an oval shape, with an out- side border of white. The exterior or oval portion of the black paper is now attached to a piece of glass, the picture, already partially printed, is placed underneath, so that the oval of paper exactly coincides with the outline of the por- tion of the picture already printed. Another piece of glass is now placed behind the print, and the two pieces of glass are held in position by two clothes pins. The whole is now exposed to light, and the outside of the paper is printed as deep as may be desired. Instead of being printed plain, the glass to which the oval mark is attached may be a negative with some fancy figure or design upon it, and thus the exterior part of the me- dallion picture may be ornament- ed by any pleasing design. A modification of this process is in the application of different backgrounds to a negative taken with a plain background ; the background should be white in order that, in printing, the figure alone should show, and the rest of the paper remain unchanged. After the first print of the figure is made, a second, on a small piece of paper, is made to be used as a mask while the background is being printed. This being done, the mask is prepared by cutting off all portions outside of the figure. The negative of the background is now substituted in the printing frame for the negative of the figure ; the first print made is placed upon it, and the frame closed as usual. While the background is being printed upon the paper, the mask is held outside of the negative against the glass and kept Fig. 57. 566 PBINTING ON ALBUMENIZED PAPER. Fig. 59. Fi &- 58 - slightly moving* in order to avoid printing any lines. The making of these nega- tives has been patented by Messrs. Bendann Brothers — the negatives are for sale, and as are also the cut outs and masks for the medallion pictures of different sizes Mounting. The appearance of a pic- ture is very much affected by its position upon the card. As a general rule, the trimming of the prints is left to boys or girls, who have but little judgment. One of our most successful young photographers, Mr. Frank E. Pearsall, of Brooklyn, practices a method which is both economical and produces uniform results. After his paper is sil- vered, the sheet is folded to a proper size, and by means of a drop and punch a large number of pieces of paper of exactly equal size are cut out at one blow. The position of the paper upon the neg- ative is determined by the artist who retouches, and is indicated by a small piece of paper cut with a recess, forming a right angle ; the piece of paper to be printed is laid with one corner fitting into this recess. Thus every head is printed in exactly the same position, and that the most suitable one. Specimen Books. The choice of position or style of picture that may be desired by a sitter can be determined in the office, and thus save the time of the operator in the skylight. For this purpose two books of specimens should be provided, SPECIMEN BOOKS. 567 exactly similar, one to be kept in the office for consultation by the sitter, and the other in the skylight for reference by the operator. The number of the sample upon the order borne by the sitter to the operator indicates the position and style of picture. Such books for the reception of the samples are manufactured and kept constantly for sale by E. & H. T. Anthony & Co. Among the aids to agreeable illumination of the sitter is the counter-reflector, invented by Mr. W. Kurtz, of New York. It consists of a screen, composed of a centre portion and two wings. The wings can be swung on their hinges nearer to or farther from the sitter. The surface toward the sitter is white, and the other side is black. The reflector is placed between the camera and the sitter, and the negative is taken through an aperture in the central portion of the reflector. This is a very useful contrivance. Another improvement introduced by the same gentleman consists in a moveable platform, upon which the sitter is placed in his chair, and can be wheeled to any part of the skylight with the greatest ease. By means of this also, a slight change in position can be very readily made without altering the pose. CHAPTEE LXVII. DESCRIPTION OF APPARATUS ILLUSTRATED IN CHAPTERS LXI-LXVIII. Figure 1 is a representation of Dallmeyer's Patent Portrait Lens, No. 3 A, the general favorite for cabinet portraits. If you can only afford one lens, buy this. There are six sizes of this mark. Figure 2 is an illustration of Dallmeyer's Wide-angle Eectilinear, which embraces an angle of ninety degrees. Its absolute rectitude of lines renders it very desirable for archi- tectural work, copying, etc. Six different sizes. Figure 3 is Dallmeyer's Rapid Rectilinear. It is the great group lens. Being very quick working, it is selected for interiors and for all kinds of quick out door uses. Nine sizes of this style. Figure 4 is the M Success Camera. It is supplied with Wright's patent nickel-plated swing, indestructible brass guides, solid glass corners, etc. This is the most useful of all cameras, and is adapted for cartes de visite, cabinets, and single portraits on plates up to eight by ten inches, horizontally and vertically. It is the gallery box. Figure 5 is the front view of an 0 Success Camera, fitted with nine one-ninth lenses. This is the camera, and the only one, for the ferrotyper. Figure 6 is a rear view of same camera as Figure 5. Figure 1 is the new Success Compact View Box — the light- est, strongest, and cheapest in the market. Open and closed views. Figure 8 is the Success Stereoscopic Camera, Z, for five by eight plates. The ground glass will be seen to fold over and lie flat on the top of the box. It is a beautiful piece of workmanship, both in appearance and construction. Figure 9 is one of the Victoria Cameras. It is intended also for one or two ferrotypes with one lens, and four or eight with four lenses, on a five by seven plate. Figure 10 shows No. 42 Gem Box, which is also known as the New York Gem Box. DESCRIPTION OF APPARATUS. 569 Figure 11 is a cut of our celebrated E. A. Glass Pans, the best for all photographic solutions. Figure 12 is our Glass Bath in box. This, like many other things, is extensively imitated, which proves its merit. Figure 13 is the Campbell & Adams Porcelain Printing Frame, the best of its kind for the purpose. Figure 14 is the Chapman Porcelain Printing Frame. It is very simple and practical. Figure 15 represents the Victory Roller Press. It has no competition from other low-priced presses. Figure 16 is a cut of the Sibley Press, the best ever yet constructed for photographic uses. It is also an excellent burnisher. Figure IT is a rack for holding negatives while drying. It folds, and costs but a trifle. Figure 18 is a Solar Camera — the Shive — improved in working qualities and convenience. Figure 19 is the Barker Cameo Press. It has dies of two sizes. Figure 20 is a good representation of the improved Cameo ress. It impresses cartes de visite, Victorias, and cabinets equally well. It is well made, and has several nickel-plated patent dies. Figure 21 is an engraving of the best and most approved photographic dark tent we have ever seen. It has the ad- vantage, also, of cheapness. Figure 22 is a pretty, substantial Gallery Camera Stand, for half size to eight by ten cameras. Figure 23 is the most popular Gallery Stand to be had — the Knickerbocker — with a top after Stoddard's pattern. Figure 24 is the top for the regular Knickerbocker Stand. Figure 25 is an Unjointed Tripod, simple but strong. There are three sizes. Figure 26 is the square four-post Camera Stand, very suit- able for large work. Two sizes. Figure 27 is the Manipulator, a very convenient contri- vance for protecting the hands. Figure 28 is a cut of the cheapest, good Head Rest in the market — the Tuscan. Figure 29 is the Bismark Rest. Well adapted for ladies. Figure 30 is the Rigid Head Rest. Stiffer than it looks. Figure 31 is Thornton's Vignetting Stand, which is very ingenious in construction. Figure 32 represents a couple of round cornered Negative Boxes ; the latest style. 570 DESCBIPTION OF APPABATUS. Figure 33 is a plain but substantial Posing Chair, with adjustable back. Figure 34 is the Anthony Sliding-Back Chair, with arms ; one of the most saleable chairs in market.' Again improved. Figure 35 is Anthony's Revolving Chair, in plush. It is strong, and more inviting than it looks to be. Figure 36, Anthony's Slidiug-Back Chair, without arms. Figure 31 is the Baby Chair. It has a little extra cushion, which is very useful for the small fry. Figure 38 is a lounge for children of larger growth. They can be had with single or double ends, as desired. Figure 39 is the Bowdish Chair without rods and rest. Perhaps the best and most suitable chair ever offered for photographic use. Figure 40 is a similar chair, but with nickel-plated rod and rest attachment. Very handsome and very desirable to many. ; Figure 41 represents the effect produced by the graduated background. Figure 42 is Mr. Kurtz's Counter-Reflector. A very suc- cessful apparatus. Figure 43 is a diagram of the Baby Charmer. An excel- lent article for attracting the attention of children. Figure 44 is Osborne's Steeping Tank, for the submersion of old plates into acid for cleansing, Figure 45 is a cut of the improved Retouching Frame, with reflector and drawer. Figure 46 is the best gas stove. Figure 41 is one of the same, only a size larger. Figure 48 is still larger. Figure 49, the ordinary gas stove. Figure 50 is a gas heating stove, excellent for operating- rooms, reception-rooms, dressing-rooms, etc. Figure 51 is one of the new Gas Ovens for drying nega- tives and plates. They are getting very popular. Figure 52 is a cut of the new Cometless Collodion Vial. It has a cork covering to the neck, which prevents the cap from sticking, and diminishes the risk of breaking. Figure 53 is a Cross Filtering and Pouring Bottle, which has some features that commend it to every photographer. It filters constantly while in use. Figure 54 is the Philadelphia Carte Envelope. It is very pretty, and very largely used. Figure 55 is the Graphoscope. This is a highly orna- DESCRIPTION OF APPARATUS. 571 mental instrument for the exhibition of large, single por- traits and pictures. It is made in four sizes. Figure 56 is a cut of the Holmes Stereoscope. Though only a skeleton, it proves to be the most perfect instrument of its kind. It is made in a great variety of styles, some folding up into a small compass. (See Figs. 60 and 61.) Figure 5T is the ordinary Revolving Scope. It is made in imitation rosewood and black walnut, and holds from thirty- six to one hundred paper views. No. 58 is the Beckers Stereoscope. It is very elegant and substantial in appearance, and is adapted either for paper or transparent views. No. 59 is the Beckers Stereoscope on stand. These will hold from one hundred to three hundred paper views. Figure 60 is the New Patent Folding Scope, after the Holmes pattern, which folds into small space. Figure 61 is the New Patent Folding Scope as folded. Fig. 60. 26 CHAPTEE LXVIII. ON THE EEREOTYPE PLATE. As the business of making pictures upon japanned iron plates is extensive, and is constantly increasing, it may not be considered out of place to occupy a short space in giving some account of the present position of the industry of making the plates. The first person to introduce this article for photographic use was Mr. Peter Neff, of Cincinnati. As some of the prin- cipal houses in the business of supplying photographic ma- terials were at that time largely interested in the manufac- ture of daguerrotype plates, the introduction of the pictures made by means of collodion was strenuously opposed by them. But our Mr. E. Anthony, who was always ready to encourage anything which tended to promote the interests of photogra- phy, and who, perceiving the great importance of the dis- covery of the use of collodion on the future of photography, had encouraged instead of discouraging it — and who was at one time the only person in this country who kept and sold the materials for collodion and paper photography in New York — having been requested to act as agent for the sale of the " Melainotype Plates," at once introduced them. Through the columns of Mr. Snelling's Photographic and Fine Art Journal they were brought to the notice of photographers, and the sale was from the beginning large. After the success of the new style of picture was assured, Mr. V. M. Griswold commenced making the plates. By great devotion to his business he finally became the largest manu- facturer. Years of application brought with them a skill in the business which left him without a rival in the market. Events having finally induced Mr. Griswold to leave manu- facturing, and Mr. John Dean, of Worcester, who had long been engaged in making other articles in connection with the photographic business, having commenced the manufac- ture of the plates, Mr. Griswold sold all his processes and recipes to him. Having thus succeeded legitimately to the ON THE FERROTYPE PLATE. 573 position of manufacturer of the best plates, it is needless to say, in view of Mr. Dean's established reputation for excel- lence and perfection in everything he makes, that the Ada- mantean plates now made by the firm of John Dean & Co., are as near perfection as possible. In the ordinary mode of making ferrotypes the picture, like the old daguerreotype, is reversed. Some of our most successful ferrotypers now make them "non-reversed." The first person to introduce this practice was Mr. E. M. Esta- brooke, of New York, whose work upon the Ferrotype is re- plete with all the information necessary for forming the expert photographer. Fig. 61. INDEX. A Aberration, chromatic, 84 ; spherical, 34. Aberration, to ascertain whether corrected for chromatic, 3T, 38, 39. Aberration, to ascertain whether corrected for spherical, 37. Acetate of silver, 112. Acetate of soda, 104, 111, 112, 190 ; pro- duces vigorous 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, 107. Acids, in developing solutions, 102 ; as re- tarders of development, 102, 103. 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, 237, 239. Acid, hydriodic, preparation of, 70. Acid, hydrobromic, preparation of, 76. Acid, hydrocyanic, (prussic,) preparation of, 119. Acid, hydrosulphocyanic, preparation of, 120. Acid, metagallic, 101. Acid, nitric, a reducing agent, 95. Acid, phosphoric, 806. 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, 285. Actinic focus, coincidence with luminous, 39. Affinity of metals, 95. Aguillon, Francis, 312. Alabastrine positives, 140; alabastrine so- lutions, 140. Albumen, preparation of, 194 ; formulas for iodized albumen, 238, 239, 240, 241, 243; albumen-process, 238; collodio- albumen-process, 237, 241 ; and bi- chromate of potassa, 299 ; and bichro- mate of ammonia, 308. Albumenized paper, preparation of, 194. Alcohol, hydrated oxide of ethyle, 56 ; pre* paration of ether from, 58; prepara- tion of, 59, 60. Alcoholic collodion, 19. Aldehyde, 111. Amber varnish, with chloroform, 137 ; with benzole, 137. Ambrotype, 23 ; how to make, 128 to 140. Ammonia, 197 ; bichromate of, 308. 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. 198. 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, 328, 329. Apothecary's weight, 339. Aplanatic lenses, 40. Aqua-tinta granulation, 289; application of, 294, 295. Arago, report of, to the Chamber of Depu- ties, 13. Arcken, first application of gun-cotton by, 19 ; and Pry published a detailed ac- count of gun-cotton, 51. Arrowroot papers, preparation of, 195. Asser, used transfer process, 21. Asphaltum in chloroform, 21 ; for black var- nish, 138 ; dissolves in benzine, 291 ; properties of, 298. Asphaltotype of Nicephore Niepce, 291. Asphalto-photolithographic process, 297. Astronomical photographers, 320; Society confer medal on De la Rue, 322. Axis, convergence of, 314. Avoidupois weight, 338. B Background, illustration of, 30; variour 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 INDEX. of filtering, 113; 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, 298. 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, 321. Bertrand's new process for positive print- ing, 209. Biology, 10. Bichromate of potassa, 11, 276, 277, 280; bichromate of ammonia, 278, 808. Bichromo-photo-lithographic 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, 169 ; prefers bromo-iodized collo- dion, 168 ; strengthened with bichlo- ride of mercury, 169. Blanquart Evrard's intensifying process by a second exposure to light, 124; bromo-iodizing solutions for printing by development, 263 ; sensitizing bath and development, 264. Blonde hair, coloring of, 227. 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., 820. Brewster, refracting stereoscope, 312. Bromides, 65 ; bromide of silver sensitive to certain colors, 66; bromide of sil- ver, 91. Bromine, 75 ; preparation of, 75. Bromo-iodized collodion, greater capacity for colors, 66, 67. Bromo-iodizing solution for printing by de- velopment, 263. Bronzing, 334. C Cadmium, symbol, combining proportions, specific gravity, 71 ; iodide of, 67, 73. Calcium, symbol, combining properties, specific gravity, 71 ; iodide of, 72. Calotype, discovery of, 17, 18 ; how to sen- sitize, 171 ; Prichard's process, 180 ; Geoffray's process, 178; Tillard's pro- cess, 180. (Vide Talbotype.) Camera, 34, 42 ; invention of, 42 ; must be horizontal for architectural purposes, 43 ; stereoscopic, 164 , If tilted, how to rectify the error, 164 * where to place, 165; camera stand, 165. Camarsac, Lafon de, 276. CamePs-hair pencil. 225. Camphene, Li transfer paper, 151. Canada balsam, in varnish, 150 ; for black varnish, 188. Cap, used as an instantaneous shutter, 1T0. Carbon, reducing agent, 94 ; lampblack in black varnish, 138; 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, 281; 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, 218; coloring of, 224. Celestial photography, 820. Cerolein, 178, 179. Centigrade scale, 340, 841. Chaldeans, 10. Champlouis, (De,) improvement in the wax- paper process, 176. Chardon, 276. Chemical equivalents, table of, 844. Chestnut-colored hair, 227. Chimenti's drawings not stereoscopic, 318. Chinese vermilion, 225 ; Chinese white, 225. Chlorides, 76; of lime, 78; chlorinetted lime, 78; of gold, 187, 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, 189 ; in black japan, 150. Chromotype, 22. Citrate of iron, 279 ; of soda, 106, 190. Citric acid, 105 ; uses of, 106. Clarifying operation of negatives, 154. Claudet's developer, 169. 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, 61, 62; least stable, 64 ; most permanent, 64 ; sensitizers, 65 ; for tannin plates, 246 ; plain or normal, 79 ; iodized, 79 ; bro- mo-iodized, 79, 80; Wortley's, Lieut. - Col. Stuart, formula of, 80; Omme- ganck's formula of, 81 ; Disderi's for- mulas of, 81 , 82, 83 ; wet process, 127 ; positives, 127, 136 ; negatives, 144 ; pos- itives on glass, 153 ; dry-process, 232 ; collodio-albumen process, 237, 241 ; for Taupenot plates, 238 ; formula of Col. Sir H. James, 303 ; imperfections of nega- tives, 326 ; remedies of, 826, etc. Coloring, of collodion positives, 136 ; of a card-picture, 224 ; of a portrait, 225 ; of the face, 226, 228, 229. Colors, not rendered permanent in helio- chromy, 323. Comparison of hydrometric indications, 504 ; of weights and measures, 499 ; of thermometric indications, 502. Condensers, 157. Contrast of light and shade, 127 ; excess of, cause of, 322 ; deficiency of, 321. Copal, soft varnish, 157 ; with benzole, 187. Copies, for the engraver to work from, 296. Copying of collodion negatives or posi- INDEX. tires, 160, 161, 162 ; of any given size, 263. Copernicus, 10. Copper, requires a strong etching fluid, 296. Corrosive sublimate, 125. Crookes, 320. Crysotype, 2T3. Crystalline lens, moved by ciliary muscle, 311. Cyanide of potassium, 119, 120, 155 ; a re- ducing agent, 121. Cyanogen, 118 ; preparation of, 118. Cyanotype, 273. D Davanne, 298. David Hilaire, 231. Daguerre, 13, 14, 15, 16. Daguerreotype, 268 ; latent image brought out by mercury, 15, 270. Dark-room, 46, 47 ; what it contains, 47, 48. Defects, in the printing of negatives, 333 ; in the paper, 333; defective sensitiz- ing, 333; defective toning, 334; defec- tive fixing, 335. Deficiency of contrast in the negative, cause of, 331. Definition, imperfect, cause of, 832. Developers, 94; negative, 145, 146; sul- phate of iron, 114, 115 ; DisderPs, 115 ; Lieut.-Col. Stuart Wortley's, 116, 168 ; Meynier's, 116; Hockins's, 116,: 169; Waldack's, 116, 117; Claudet's, 169; Crookes's, 177 ; De Champlouis's, 177 ; too intense, cause of fogging, 328. Developing, solutions, 114, 213; the pic- ture, (wet process,) 131, 132; Fother- gill's, 243; Col. Sir H. James's, 303; of the silver plate, 270. Development, of the card-picture, 219 ; of the albumen film, 287'; of the Taupe- not plates, 239 : of the tannin plates, 247, 248. Diffused light, in the camera, cause of fog- ging, 326 ; in the dark-room, etc., cause of fogging, 828. Direct rays of the sun through the axis of the lens, cause of fogging, 327. Distances, long and short, seen at the same time, 310, 312 ; theories about, 311 ; dif- ferences of, 313. Distillation of the nitrate-bath, 112. Distortion, from too great contrast of light, 27. Dolland, 9. Doublet, 35. Donne, 287. Draper, Dr., use of hot water in the tannin process, 248. Drying the positive plate, (wet-process,) 135. Drying process, of albumen films, 235. E Eclipses, photographed, 822. Edwards, 821. Electric telegraph, 10. Electricity, a reducing agent, 95. Elements of matter, table of, 506. Enamels, how to make, 309. England, formula for collodion for the tan nin process, 249. Engraving, photographic, 286 ; heliographic, 296 ; on the daguerreotype plate, 286. 290. Etching, fluid, 289, 290 ; of the plate, 295 ; on glass, 296 ; on zinc, 306. Ether, 55 ; how to prepare, 58 ; property of, on collodion, 61. Ethyle group, 55. Eureka plate, 140. Excelsior plate, 140. Exposing the glass, (wet process), 131. Exposure of the silver plate, (Daguerreo- type,) 269; photo-engraving, 293; un- der the negative, (photo-lithography,) Eye, its philosophy, 811 ; single eye cogni- zant of relief, 311. F Fahrenheit, scale, 840, 341. Fargier, 275. Feebleness of the negative image, cause ot 331. Ferrier, 119. Ferreotype plates, ajpt to blister in the dry- ing, 143. Field photography, rules to be observed, 44. Films, tender and rotten, cause of, 832. Fixation of the Taupenot plates, 239. Fixing, solutions, 118, 121 ; the picture, (positive — wet process,) 133; solu- tions for negatives, 147 ; solutions for prints, 203 ; of the card-picture, 221 ; of the image, (Daguerreotype,) 270. Fizeau, 16. Flowing the varnish, in photo-engraving, 292. Focus, of a lens, (how to find,) 36, 43, 44; equidistant conjugate, 36, 254, 255; principal, 254 ; equivalent, 254 ; actinic and luminous, (coincidence of,) 39. Fogginess, remedy for, 134, 326, 327, 328. Fogging, 111. Formic acic, a reducing agent, 95. Forrest, 321. Formula for zinc enamel, 807. Fothergill process, 242. French government, 16. Fumes of ammonia, cause of fogging, 828. Fumigation of the asphaltum film, 294. Eliminating, apparatus, 199 ; process, 198. j G Gallic acid, a reducing agent, 95 ; prepara- tion of, 100. Gallo-nitrate of silver, 17. Galls, Aleppo, 306. Gamier, 275. Gelatine, 185; operation, (tannin-process,) 245 ; process, 244. Geoffray, process with cerolein, 178. Glass, actinic, 32; non-actinic, 46; house, 28, 29 ; plates, (preparation for Taupe* not plates,) 238; vignette, 223; how to clean, 303. INDEX, Globe leng, 165. Glover'3 resinized printing process, 210. Glycyrrhizlne, makes collodion sensitive. 63. Gold, deposited by galvanism, 287 ; chlo- ride of, 187, 203 ; gold and uranium toning, 202. Grain, engravers, 298. Gramme, 337. Granulation, Aqua-tinta, (how made,) 289 ; application of, 294. Grape-sugar, makes collodion sensitive, 63. Gray hair, how to color, 228. 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. H Hardwick's views about the decomposition of collodion, 62, 63. Harshness, or excess of contrast, cause of, 332. Harrison, C. C, 41 ; Globe lens, 165. Hartnup, 321. Heat, a reducing agent, 95. Heliochromy, 22 ; or the art of taking pho- tographs in their natural colors, 323. Heliography, 11, 14; heliographic engrav- ing, Negre's process, 296. Herschel, Sir John, 15, 18, 323. Hipparchus, 10. History of photography, 9. Hockins, Developer, 116, 169. Hodgson, 821. Hoffmeister, 131. Holmes, Booth and Hayden's, 41. Honey, 308. Horn silver, 92. How to improve the color of transparent positives^ 253. How to take diminished copies of photo- graphs, 265. How to take enlarged copies of photographs, 262. How to transfer the carbon print from glass to paper, 283. Hydriodic acid, 70. Hydrobromic acid, 76. Hydrocyanic acid, 119. Hydrogen, a reducing agent, 94. Hydrometers, 842. Hydrosulphocyanic acid, 120. Hyposulphite of soda, 120, 121. I 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, 383 ; in albumenizing and salting, 333 ; washing previous to toning, 334. 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, 168, 242; Sir H. James's 302 Intensifying' first method, 147, 148, 123 ; second and third do., 124. Iodides, 65 ; alkaline all soluble, 65 ; testa 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. * J James, Col. Sir Henry, 21, 801, 308. Japan, black, 150. Joubert's process for taking photographs on glass in enamel colors, 308. Jupiter and his bands photographed, 322. K Keene's Rapid dry process, 250. Kaiserstuhl, 11. Ii Lace, how to imitate in colors, 231. Lampblack, for black varnish, 138. 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 good one, 39 ; single equivalent to a compound, 87 ; axis of, 254; optical centre of, 254 • 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, 37 , Harrison's, Ross's, Dallmeyer'SjGrubb's, Jamin*s, Holmes's, Booth and Hayden's, Voightlaender's, 41. Lerebours, 298. Light, action of, 96 ; a reducing agent, 95 ; single, 162 ; velocity of, 102 ; must entel from the north. Lime, carbonate of, 190. INDEX. Linseed oil, rubbed into an engraved plate, 28T. List of a photographic outfit, 25, 26. Lithium, Tl ; iodide of, 72. Litre, 33T. Lunar caustic, 88. M Macrophotography, 257, 262. Manipulation, of positive printing, 192. Marbled appearances in the paper, 833. Marion's, Preserving box, 210. Mars, photographed, 322. Mats, 139. Matter for the reception of the image, 23. Materials used in positive printing, 183. Mayo's Outlines of Human Physiology, 312. Mealiness, on the print, 336. Melainotype, 23 ; plate, apt to blister in the drying, 143. Mercury, bichloride of, 125 ; vapor of a de- veloper, 15, 270 ; preparation of, bichlo- ride of, 125 ; bichloride of, an intensi- fies 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, N 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, 146. Negre's process, 296. Newton's, photo-lithographic process, 300. Nicephore Niepce, asphaltotype, 291, 297. Niepce, 14, 15, 16. Niepce, Isidore, 16. Niepce de St. Victor, 18, 22, 233 ; on helio- chomy, 323. Nitrate of silver, photographic properties of, 88, 89 ; bath, 109, 110, 111 ; cause of fogginess, 327. Nitric acid, a reducing agent, 95. Nitro-glucose, preparation of, 63. Non-azotized substances, 186. Norris, Dr. Hill, process, 244. O Oil, of bergamot, in varnish, 149 ; of laven- der, 21. Ommeganck's formula for collodion, 81. Osborne, 20. Ounce, avoirdupois, 100 ; Troy, 100. Over-development, cause of fogging, 334. Oxide of silver, how to prepare, 110. P Paper, alburaenieed, 194 ; arrowroot, 195 ; for transfer-process in photo-litlio* graphy, 304. Pearl-gray, color, 230. Pension, 16. Persalts of iron, 97, 98. 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, 93. 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- graphic process, 300 ; photo-lithograph ic ink, 304 ; photo-papyrography, 308. 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, 182 ; transpar ent by contact, 159. Positives, collodion, 127 ; alabastrine, 140 ; Potassium, 71 ; cyanide of, 119 ; sulpho- cyanide of, 120 ; sulphide 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 Norris, 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, 285 ; of card-pictures, 222 ; direct, 182; transparent by contact, 159; transparent by the dry-process, 252. Process, Pouncy's carbon, 277 ; Salmon and Garnier's carbon, 278 ; Fargier's carbon, 275, 280 ; carbon with the salts of iron, 281; for colored pictures, 274, 275; albumen, 233 ; dry collodion, 232 ; Humbert de Molard, ISO ; Prichard's Calotype, 180; Talbotype, 172; wax- paper, 173; Geoffray's, 178; Tillard's, 179; Niepce de St. Victor, 216; Fumi- nating, 198; Resin, 249; Rapid dry, 250; Bertrand's, 209; Glover's, 210; drying of albumen films, 235 ; Fother- gill's, 242 ; Taupenot's, 237 ; Dr. Hill Norris's, 244 ; Tannin, 245 ; Tannin and Honey, 248 ; Fizeau's, (similar to that of Donne,) 287 ; Negre's, 296 ; asphalto- photo-lithographic, 297 ; bichromo-pho- to-lithographic, 299 ; photo-typographic, 300; Newton's, (photo-lithographic,) 300 ; Joubert's (colored enamel, 30S. Prussic acid, 119. Pyrogallic acid, a reducing agent, 95 ; pre- paration of, 101 ; developers, 115, 146. Pyroxylinc, 51 ; preparation of, 52, 63 ; foi* mulas for making, 53, 54, 55. INDEX. Q Quality of the paper used in the transfer process. B 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, 147. Reflections within the camera, cause of fog- ging, 326. Reflectors, used as condensers, 157. Resin process, 249. Retina of the eye, not a surface, 810. Rice water, 174. Ridges and undulating lines In the negative, 330. Ritter, 12. Rose-colored drapery, (coloring of,) 229. Roulette, 9. Royal Society, 15, 16. Rue, (De la,) 321, 322. Russell, (Major,) 245. S Salmon, 275 ; Salmon and Garnier's carbon process, 278. Salted paper, (formulas for,) 192. Salting solutions, (for printing by develop- ment,) 212, 213. Salts of iron, (printing with,) 273; in carbon processes, 281; 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. Seebeck, 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, 833; plain silver bath, 196 ; ammonio-nitrate bath, 197 ; for development, 214, 215, 216; the daguerreotype plate, 269 ; of wax- paper, 175. Sesquichloride of iron, 285 ; formula of, in carbon process, 281. Side-light, 29. Silver, oxide of. 110; iodide of, 90, 110; chloride of, 92, 191 ; salts, 84 ; reduc- tion of, 85, 86, 87 ; nitrate of, 88 ; pho- tographic properties of the nitrate of, 88, 89; hyposulphite of, 90; sulphate of, 90 ; bromide of, 91 ; tests of the chlor- ide of, 93 ; photographic properties of the chloride, 98. Sir Humphry Davy, 13. 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, 842. Spectrum, 12. Spots and apertures in the negative, 328, 329 ; opaque, 329 ; transparent, 329, 830. Starch, 186. Steam-engine ? 10. Stereograph, instantaneous, 116, 167 ; stereo- graphic negatives, 164; strabonic, 314, 815 ; how to see strabonic stereographs, 816,317; 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, 881. Sugar of milk, Legray's formula, 174. Suitable rooms, 27. Sulphate (double) of ammonia andiron, 98; sulphate of silver, 90. Sulphide of iron, 98 ; of potassium, (prepara- tion of,) 125; of ammonium, 125. Sulphocyanide of potassium, 120; of ammo* riium, 120. Sulphovinic acid, 58. Sulphurous acid, 58. Sulphuric acid, 58. Sun, easily photographed, 321. Sutton, 19 ; rapid dry process, 250. Symbols of elementary bodies, 844. T 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, 248 ; preservative, 249. Tartaric acid, preparation of, 107 ; printing with, 285. Taupenot process, 237. Temperature modifies development, 103. Telescopes, reflecting and refracting, 320. Tillard, turpentine and wax process, 179. Toning of prints, 201; formulas, 202; of 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 ; solution, 151; of carbon print from glass to paper, 283. Transference of the print to zinc or stone, 305. Transparent positives, 153, 159, 285, 289* by the dry process, 252. Triplet, 35. Turpentine, in transfer solution, 151. Twaddell's hydrometer, 842, 848. Tyrolese Alps, 11. INDEX. U Under-exposure, the causa of fogging, 334. Unit, English linear, French linear, 337. Undulating lines on the negative, 330. Uranium, printing with, 273 ; and gold ton- ing, 202 ; nitrate of, 189. V Varnish of Niepce de St. Victor, 291 ; for collodion pictures, 137, 139 ; black, 138, 139 ; applied cold, 139. Varnishing of collodion positives, 136. Vergennes, formula of, 256. Vicar of Wakefield, 32. Vignette-printing, 223. Vinci, Leonardo da, on binocular vision, 811. Violet color, 230 ; colored glass for focussing actinically, 39. Virtual solid image, 314. Vision, binocular, 812. W 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, 338. Weights, apothecaries and avoirdupois, 500; and measures, 499, 501 : comparison of, 500. Wet-paper process, Molard's, 180. 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, 80, 167 ; developer, 116, 168 ; intensifier, 168. Wood-spirit, 104. Y Yellow drapery, (coloring of,) 229. Yellow tone in the whites, its cause, 885. Z Zinc enamel, 307 ; white, 80T. INDEX TO THE THIRD EDITION. Tannin Process with the Alkaline Developer, 845 Collodion for do, 346 ; Nitrate of Silver bath for do, 347 ; Flowing the plates with Tannin, 348 ; Exposure of Tannin plates, 349 ; Development of Tannin plates, 349 ; Intensifying of Tannin plates, 350. Wet Collodion Process with the Alkaline Developer, 351 Alkaline Developer for do, 352 ; Intensifying of the image, 352. Tannin regarded as a Sensitizer, 353 Chromo-Photography and Positive Printing without the Salts op Silver, 356 Sensitizing the paper, 357 ; Exposing the sensitized paper, 357 ; Developing the picture, 357; Schwartz's simple process for blue pictures, 358; Motileff's process, 358 ; Signor Borlinetto's process, 358. Process without the Salts op Silver, 359 Sensitizing solution, 359 ; Exposure, 359 ; Fixing solution, 360 ; Toning of the prints, 360. FoTn ergill's Modified Albumen Process, 362 New Carbon Process by Mb. Swan, 337 362 INDEX TO THE FIFTH EDITION. A Acid, pyrogallic, 371, 372, 375, 380 ; acetic, (glacial,) 372, 386; sulphuric, 377; citric, 3S1, 398 ; nitric, 383 ; gallic, 388 ; phos- phoric, 432. Ackland, modified Fothergill process, 385. Albumen, for substratum, 377, 3S5. Alcohol, 371, 378. Ammonia, carbonate of, 380, 384, 391 ; con- centrated, 885. Ammonium, iodide of, 378, 404. Aniline, printing process, 432 : commercial, 433. Anthony, E. and H. T., printing frame, (pneumatic,) 401. Appendix to fifth edition of Sunbeam, 365. B Background, eburneum process, 405. Balsam, Canada, 419. Benzole, 377, 433. British Journal of Photography, 409. Britton, Mr., Collodio-chloride formula, 400. Bromo-iodizing, for opal or porcelain pic- tures, 402. Burgess, Mr., 402. C Cadmium, bromide of, 878, 879, 404 ; iodide of, 383, 404. Calcium, chloride of, 400. Camera, copying, 895. Caron, Mr., 414. Chapman printing frame, (opal pictures,) 401. Chevrill, Mr., collo-developer, 426. Coating the paper with collodion, (Wothly- type,) 367 ; the plates with collodion, 369, 386; with albumen, 387; opal plates with collodion, 394 ; with collo- dio-chloride, 400. Collodio-bromide, (process,) 389; prepara- tion of, 389 ; in the wet process, 389 ; for tannin plates, 390. Collodio-chloride, formula for, 400. Collodion, for dry plates, 373, 378 ; bromo- iodizing solution for (tannin process,) 374, 378 ; for the eburneum plate, 404. Collo-protosulphate of iron, 425; ferric de- veloper, modification of, 426. Copper, sulphate of, 431. D Davy, Sir Humphry 414. Developer, alkaline, 371, 374, 375. 380, 3S4, 892; acid, 375 ; for Fothergill plates, 388; collodio-bromide, 890; for opal pictures, 396 ; collo, 425. Development of the image, (tension,) 371, 380; (raisin process,) 376; alkaline, 881 ; collodio-bromide, 391 ; opal pic- ture, 396 ; of the Foxtype, 432 ; (ani- line process,) 433. Deville, Mr., 414. Distillation of magnesium, 415. Dolomite, 413. Duplex pictures, how to take two pictures of the same person on the same plate. 417. Duplicating deflector, 418. E Eburneum process, 402. Enamel, 407. Ether, 378. Exposure of the tannin plate, 371, 380, 388 ; opal picture, 896 ; (aniline process,) 483. P Fixing, solution, (Wothlytype,) 368; the tannin negative, 378 ; collodio-chloride picture, 401. Formulas for the Wothlytype, 866. Fothergill, process, (modified,) 385 ; second modification of, 887. Fox, Thomas, 431. Foxtype, 431. a Galvanic process for obtaining magnesium, 414. Gelatine, 404, 426 ; relief, 429. Glazing, albumen prints, etc., 407. Glycerine, 406. Gold, ter-chloride of, 397. H Haakman, modified Fothergill process, 387. Helenotype, 419. I Immersion of Fothergill plates in acetio acid, 387. India-rubber for substratum, 377. Intaglio, metal, (production of,) 430 ; print- ing from, 431. Intensification of the image, (tannin,) 3S1. Intensifier, citro-nitrate, 382 ; aceto-nitrate, 382 ; alkaline, 384, 392 ; for opal or por- celain pictures, 398 ; Selle's, 432. Jron, proto-sulphate of, 390, 404, Ivorytype, 419, 420. INDEX. L Lea, M. Carey, M.D., 425. Lead, acetate of, 388. M Magnesium, 412, 413 ; galvanic process for obtaining, 414 ; process for obtaining magnesium for commercial purposes, 414 ; reduction of the chloride of, 415 ; purification of, 415. Marmolite, 413. Mastic, 419. Materia medica, 413. Mercury, bi-chloride of, 398. Modes of reducing silver compounds. 423, 434. ]ST Negative, to intensify, 3T2 ; for the porcelain picture, 394. O Opal plates, (to prepare,) 393 ; picture, (ne- gative for,) 394 ; picture, (how to clarify,) 396 ; pictures (by contact printing,) 898 ; plates, (how to grind,) 399 ; pictures, (with a bromo-iodized film,) 402. Opaltype, 392 ; to take with the camera, 392. P Paper, for the aniline-printing process, 432. Photographs, how to glaze, 407, 408, 409, 410, 411 ; how to take by the magnesium light, 412, 415. Photographic News, 410. Photography without a nitrate of silver bath, 389. Photo-mezzotint printing, 427. Photo printing, 427. Photo-relief printing, 429. Pictures, duplex, (how to take them,) 417. Porcelain pictures, 392; to take with the camera, 392 ; negative for, 394 ; how to clarity, 396 ; pictures, (by contact print- ing,) 398 ; plates, (how to grind,) 399. v Potassa, bichromate of, 377, 432. Potassium, bromide of, 391 ; ferridcyanide of, 432. Preparation of the sensitive salts in the Wothlytype, 365 ; of the paper for re- ceiving the sensitive collodion, (Woth- ytvpe,) 367 ; of tannin plates, (Sut- ton's,) 368. Preservative solution, (tannin process,) 375. Printing, (Wothlytype,) 367 ; on ground por- celain or opal plates, 399 ; frames, 401 ; photo, 427 ; photo-relief, 429. Process for printing on paper without em- ploying either the chloride, iodide, or bromide of silver, and without develop- ment, 365 ; Sutton's tannin, 368 ; raisin, 873; reliable tannin, 377; Pothergill, 385, 387 ; wet and dry with collodio- bromide, 389 ; eburneum, 402 ; for ob- taining magnesium, 414 ; aniline print- ing, 432. Pyroxyline, 878. B Raisin process, plates for, 876. Reduction of the chloride of magnesium, 415; of the chloride and sulphide of silver, 423. Reflectors for taking pictures by the magne- sium light, 416. Relief, gelatine, 429. Restrainer, (in the developer,) 426. Russell's latest improvements in the tannin process, 382. S Sayce, B. J., 389. Schnauss, Dr., 373. Selle's intensifying solution, 432. Sennotype, 402, 419. Sensitizing the film, 370 ; solution for the aniline printing process, 432. ShiVe, porcelain printing frame, 401, 418. Silver, nitrate of, 372 ; bath, 374, 378 ; resi- dues, (what to do with,) 421, 422, 423, 424. Simpson, Gr. Wharton, M.A., 400. Soda, bicarbonate of, 371. Sonstadt, Mr., 414. St. Claire, 414. Substratum, (Sutton's tannin process,) 363, 377 ; wax, 402. Sugar, loaf, 379 ; grape, 390. Sutton's rapid dry tannin process, 868. Swan, Joseph W., 427. T Tannin, solution, 370, 379 ; process, (latest improvements in,) 382 ; bath, (Verity's,) 390. Toning, (Wothlytype,) 368 ; opal or porce- lain picture, 397 ; collodio-chloride pic- ture, 401. Tunny, James G., 408. Turpentine, spirits of, 419 ; Venice, 419. V Uranium, sulphate of, 432. V Varnishing, the negative, 373. W Washing in hot water, (Fothergill plates,) 387. Waste-residues of silver and gold, (what to do with them,) 421. Wax, solution, (substratum with,) 402. Wenderoth, Mr., 402, 407, 411, 420. Woodbury, Walter, 427. Wothlytype, 365. Z Zinc, oxide of, 406, 412. INDEX TO THE SIXTH EDITION. A Aniline process, the, 443. Apparatus, description of, 497. B Blast furnace, the, 434. Burning-in process, the, 470. c Cabinet portraits, 492. Canvas, photographing on t 469. Caoutchouc, coating with, 339. Carbon process, Swan's new, 357. Coating with gelatine, 341, Coffee process, the, 483. Comet stains, 459. Cuprammonium process, 342. Cyanide waste solutions, 438. D Dry processes, improved, 482. E Elementary photography, 1 . Engravings, reproduction of, 480. Enlarging by the solar camera, 443. Enlarging by the serum process, 477. Enameling, 470. F Failures ; their origin and remedies, 454. Filtration and decantation, 440. Fogging, 454. G Gage's improved photographs, 492. I Insensitiveness, 456. Ivory, printing upon, 457. M Magic photographs, 490. Mezzotint photographs, 489. Morphine process, 482. N Newton's improved dry processes, 494. P Photomicrography, 465. Photo-diaphanie process, 476. Photographing on canvas, 469. Positives in colors, process for, 484. Printing on ivory, 475. R Residues, reducing waste, 433. Rotary fan, the, 434. s Sel Clement, 486. Sensitizing carbon tissue, 338. Serrated marks, 458. Serum or whey process, 477. Solar camera work, 473. Spots, 458. Stains, 459. T Tea process, Newton's, 494. w "Wastes and residues, 433. Washed plate process, 482. "Waviness, 457. "White rings, 457. Index to Elementary Photography* Apparatus necessary, 3. Chemicals, 4. Dark-room, thQ, 5. Introduction, 1. Negatives, how to take, 13. Positives, how to take, 8, INDEX TO THE SEVENTH EDITION, B Bevey, W. T., 512, 526. C Calotype process, the, 527. Canvas, printing on painted, 512. Cementing material, 517. Chromo-photography or photo-miniature, 515. Collodio-chloride of silver, printing with, 510. D Davies, W. H.. 518. De Constant, A., 515. Development, 528. E Edwards, B. J., 524. Enlargements, apparatus for, 518. Fry, Samuel, 514. a Greenlaw, A. G., 527. H Herr Albert, 507. Hughes, Alfred, 523. I Iodizing solution, 528. Ivory, painting on, 512. O Opal Glass, 511. P Photo-crayon portraits, 509. Photographing machinery, 521. Plate, preparing the, 511. Printing, 511. Printing process, Herr Albert's mechani- cal 507 Pritchard, H. Baden, 521. B Bipe collodion at once, how to make, 523. S Sarony, M., 509. Sensitizing, 528. Seventh edition, 507. Simpson, G. Wharton, 510. Stippling glass in the studio, 524. Substratum for the collodion film, 514. T Toning, fixing, and washing, 501. Transparent prints, 517. W Wood blocks, printing on, 526. INDEX TO THE EIGHTH EDITION. A Apparatus, description of, 568. B Blurring, 549. 0 Collodion, 533. Comets, 555. Collodio-Chloride, 560. D Development, alkaline, 534. Developers, organic, 537. Developing, 538. Defects and remedies, 545. Development, stains of irregular, 550. Defects in paper prints, 556. F Ferrotype, the, 531. Field work, the developer for, 541. Field work, instructions for, 541. Field work, cameras and lenses for, 544. Fogging, 545. Film, thinness of the, 547. Film, irregularity of the, 548. Film, splitting and slipping of the, 550. Ferrotype plate, the, 572. I Image, defects in the, 548. L Lenses, misplacement of, 561. M Mounting, 566. N Negative bath, 540. P Processes of Mr. T. C. Roche, 540. Printing on albumenized paper, 562. Printing, medallion, 565. S Sharpness, want of, 551. Streaks, 552. Spot3 and pin holes, 553. Stains and markings, 655. Specimen books, 566 T Toning bath, 562. E. & H. T. ANTHONY & CO., Opposite Metropolitan Hotel MANUFACTURERS OF PHOTOGRAPHIC VARNISHES, COLLODIONS, COTTONS, IODIDES AND BROMIDES, CAMEO J PRESSES, S. V. PASSE-PARTOUTS, 591 BROADWAY, N. T. IMPORTERS OF [ SWISS PINK, DRESDEN ALBUMEN, & PLAIN \ SAXE & RIVE PAPERS, PORCELAIN WARE, \ EVAPORATING DISHES, GENUINE B. P. C. \ GLASS, GOLD SAUCERS, FILTERING PAPER. ALSO, CASES, POSING CHAIRS, f r I And l & I PYROGALLIC ACID, LOUNGES, I O L , \ \ HYPO. SODA, f /Dealer! ^ I ' J* I \Q\ GERMAN Baby Chair /n / Ya> \ £\ 6rfes Baths, and '0/^that^\^\ GRAPHOSCOPES, £J* # can contnb- ! v^. &c, &c. # £ /,te to successful v4 \ Stereoscopic Views, ALSO, S ^ I 3 • * i. 1 "* . I AS WELL AS LARGE f ^ / and convenient \ ^ \ * w holographs SILK CURTAINS, Stereoscopes i AND ALBUMS. THE ^ P SILVER SUNBEAM, ^ AND CHROMOS. f ANTHONY'S PHOTOGRAPHIC BULLETIN. ' SEND FOR COPY. -A.G-E1STTS FOR Eureka Plates, Dean's Adamantean Plates, Dallmeyer Lenses, Success Cameras, Bendann's Backgrounds, Ashe's Backgrounds, Etc. JKf Send for Catalogue. Address P. 0. Box 2200.-®a ALL OTHEES AN INFRINGEMENT. They are well made, of excellent paper, of assorted tints, with Arch and Oval openings and with End and Side flaps, neatly gilt and Embossed, and hold one carte or one dozen. The safest Envelope for mailing, the most beautiful to deliver Pictures in, and, when the flap is turned back (see cut), they form an Elegant Stand for the Picture. In similar style we make the Cabinet, for plate 4J x 5J, the Gem, for plate 2J x 3J, the Victoria and Half Size Envelopes. And in addition to the above we are now making Ferrotype Envelopes of Cards and Wrappers, to accomodate those who wish a less expensive article . These latter are of two kinds, viz., a card of size 2J x 4, with Nos. 2, 3, 4 and 5 Oval, and Nos. 9 and 10 Arch Top openings, and Bon Ton Card, 3J x 4|, with Oval and Arch openings. Both kinds are handsomely embossed and present a neat and attractive appearance, and we think will elicit the commendation of the trade gen- erally. FOR SALE BY E. & H. T. ANTHONY & CO., New York. SCOVILL MANUF'G CO., New York. GEORGE S. BRYANT & CO., Boston. WM. B. HOLMES & CO., " " DODGE, COLLIER & PERKINS, " WILSON, HOOD & CO., Philadelphia. F. HENDRICKS, Syracuse, N. Y. BENJ. FRENCH & CO., Boston. C. W. STEVENS, Chicago. AND BY ALL DEALERS. NEW PUBLICATIONS. SCIENTIFIC. TYNDALL— "Lectures on Light," RECENTLY DELIVERED IN THE UNITED STATES- BY Prof. JOHN TYNDALL, LL. D., F. E. S., FULLY ILLUSTRATED AND WITH THE AUTHOR'S LATEST CORRECTIONS. Paper, 75 Cents; Cloth, $1.00. The author, on leaving England, had no intentiou of publishing these lectures ; but, having been rewarded by the American people as no lecturer has ever been, and being unable to respond to the invitations of the cities of the West, thought it due both to those who heard the lectures with such marked attention, and to those who wished to heir them but were unable to do so, to leave them behind him in an authentic form. The enthusi- asm with which the great scientist was welcomed by the cities of Boston, Washington, Philadelphia, Baltimore, Brooklyn, and New York, and the decided success of his present lectures show, we think, both their timeliness and superior merit. TYNDALti. — Contributions to Molecular Physics in the Domain OF RADIANT HEAT. A Series of Memoirs published in the 11 Philosophical Trans- actions " and " Philosophical Magazine," with Additions. By John Tyndall, LL. D., F.R. S. , Professor of Natural Philosophy in the Royal Institution. 1vol., 8 vo. Cloth. Price, $5.00. RA.NKBN.— The Strains in Trusses. Computed by means of Dia- grams, with Twenty Examples drawn to Scale. By Francis A. Ranken, M. A., C. E., Lecturer at the Huntley Institution, Southampton. 1 vol., 8vo. Cloth. Price, $2 50. BASTIAN. — The Beginnings of Life. Being some Account of the Nature, Modes of Origin, and Transformation of the Lower Organisms. By H. Charlton Bastian, M. D., F. R. S. 2 vols., 8vo. With upward of One Hundred Illustrations. Price, cloth, $5.00. KINGSLEY. — Town Geology. By the Rev. Chas. Kingsley, F. L. S., F. G. S., Canon of Chester. 1 vol., 12 mo. Cloth. Price, $1.50. HEWITT. — Coffee : its History, Cultivation, and Uses. By Richard Hewitt, Jr. Illustrated with a Chromo-lithograph of the Coffee Plant, Original De- signs on Wood, and a Map of the World, showing the several places where Coffee is or may be produced, and where it is also used. lvol.,12mo. Price, $2.50. FIGUIER. — The Human Race. By Louis Figuier. Illustrated by two hundred and forty- three Engravings on Wood, and eight Chromo-lithographs. One vol., 8vo. 548 pages. Price, cloth, $6.00. BRASSEY. — Work and Wages. Practically Illustrated. By Thomas Brassey, M. P. Onevol.,8vo. Cloth. Price, $3.00. EVANS. — The Ancient Stone Implements, Weapons, and Orna- MENTS, OF GREAT BRITAIN. By John Evans, F. R. S. 1 vol.,8vo. With two Plates and four hundred and seventy-six Woodcuts. Price, $5.00. DESCHANEIi.— Natural Philosophy : An Elementary Treatise. By Prof. Deschanel, of Paris. Translated and edited, with extensive Additions, by J. D. Everett, D. C. L., F. R. S., Professor of Natural Philosophy in the Queen's College, Belfast. Part IV. Sound and Light. With 187 Engravings. Price, $2.00. D. APPLETON & CO., Publishers, 549 & 551 Broadway, New York. BUFFALO fan DAVID TUCKER. Dealers in every Variety of w Ed fed H S. B. BUTTS. And the most desired styles of OVAL AND SQUARE FRAMES, Also, Gilt, Black Walnut, and Eosewood and Gilt Mouldings. CAMERAS AS! AJPFAEAfUS IN GREAT VARIETY. All Goods sold at lowest Market Prices. DAVID TUCKER & CO. GEO. e. angell M(^K J(rh ^Ofe. ID MOULDINGS, RIALS, CHROMOS, Hi Mmiimwmmm Ifiiii DETROIT. 1 1 111 Ell III BRL., 216 THIRD STREET, ST. PAUL, MINN. PUBLISHERS OF Views of Minnesota, Minnehaha, Lake Superior, Wisconsin, Mississippi River, and Niagara Falls Scenery. ONLY COLLECTION OF PORTRAITS AND DOMESTIC SCENES OF THE SIOUX AND CHIPPEWA INDIANS. Your patronage solicited. Our Motto — " Promptness and Fair Dealing." MANUFACTURER, IMPORTER, * P EALER IN »BSCR*PTXGH, #1 AND 3 JOI iiiiifi No. 6 BROADWAY, ROME, GEORGIA. Have a full, varied, and well-selected Stock of AND APPARATUS, LENSES for Portraits, Views, and Copying. ALBUMEN PAPERS, all the most Popular Brands. Black Walnut, Square, and Oval FRAMES. Rosewood and Gilt, and Rustic FRAMES. Pure Chemicals, Photographic Chairs, Ferrotype Plates^ Card Stock, Display Mats, and every article used in the Picture Business. N. B. A full assortment of Anthony's Collodions and Varnishes always on hand. Study your interest, and save TIME, MONEY, and FREIGHT, by sending your orders to . CHAS. J. WARNER, Price List maiied on application. Home, Georgia. ADAMANTEAN F E E E 0 T Y P E JOHN DEAN & CO., MANUFACTURERS, WORCESTER, Mass. til m m Ferrotype Plates i THAT WILL STAND THE E. & H. T. ANTHONY & CO., TRADE AGENTS, 591 BROADWAY, New York. F E E E 0 T Y P E NOTICE. We have never deemed it necessary to employ literary " Bummers " to proclaim the merits of Our Plates, or to use a trumpt up" testimonials to attest their virtues. The in creasing demand for them too well attests their virtue, having sold more the past year than in any previous one. We are also persuaded that the intelligent Photographers of the country are too well informed to be influenced by words only, while uniformly finding our Plates of superior quality and free from all those annoying blemishes, dirty finger-marks and scratches. Our Chocolate Plates with their warm and mellow tint, are now esteemed by the tr ide to be the most reliable Plate in the market. JOHN DEAN & CO. POWERS & WEIGHTMAN, Manufacturing Chemists, PHILADELPHIA, Office, Ninth, and Farrish Streets, New York Store, 56 Maiden Lane, Offer to the Wholesale Trade, and to those who but in similar quantities, a general Assortment of CHEMICALS, MEDICINAL, PHOTOGRAPHIC, id for THE ARTS. Nitrate Silver. Sulphuric Ether. Chem. Pure Acids. Corrosive Sublimate. Bromide Potassium. Acetic Acid. Concent. Ammonia. Iodide Ammonium. Sulphate Iron. Chloride Gold. Cyanide Potassium. Sulphate Quinia. Sulphate Morphia. Mercurials. Strychnia. Alum. Epsom Salt. Oil Vitriol. COOK & LEE, No. 27 Main St., VIEWS, FROM 25 CENTS TO $10 EAOH- PAPERS, Morgan's, Trapp & Munch, S. & M.Dresden, Swiss Pink, &c. FILTER PAPER, ADHESIVE PAPER, Atwood'S Alcohol, Ether, Collodion (Blessing & Bros,' is always fresh and none better), Iodides, Bromides, Silver, Varnishes, &C, &C. In fact everything kept in a first-class Furnishing House. Send your orders to us and save freight and annoyance. All Apparatus, and the most of other goods at manufacturers' prices. Send for price-lists. HALE, KILBURN & CO., Wholesale Manufacturers, for the Trade only, of WALNUT FRAMES, MOULDINGS, BACKING, Also, Sole Manufacturers of the Original MM #v®to mmM ipi PATENTED OCTOBER 24, 1871. CAUTION. — All persons are hereby cautioned against infringing upon our rights, under the above patent, according to law. We make a specialty of manufacturing Frames in great variety for the PHOTOGRAPH trade. Particular attention is drawn to our NEW STYLES PATENTED SOLID OVALS, which, for beauty, quality, and price, have gained the highest reputation in the market. (See Cut.) The Trade Supplied at Wholesale Prices with PICTURE NAILS, CORD & TASSELS, SCREW EYES, &c. jfcg~Ask your Stockdealer for our Goods. If unable to obtain them, send direct to us. PKICE-LIST FURNISHED ON* APPLICATION. Warero r ms and Factory: 48 and 50 NORTH SIXTH ST., and 615, 617, 619 and 621 FILBERT ST., PHILADELPHIA. lav 3HX HUM Q31D3NN03 3iaVH3U 9NIHJLAH3A3 aNr "0H8 V N3T1Y H M GETTY RESEARCH INSTITUTE 3 3125 01410 3952