r T "n i 1 kJ 1 'T iJA^‘ ia V ,Gi ^ : PERSONAL LIBRARY VERNON D. TATE ORGANIC PHOTOGRAPHIC DEVELOPERS COPYRIOKT, 1950 . BY FORTY -SECOND STREET COM M srcIAL STUDIO. ORGANIC PHOTOGRAPHIC DEVELOPERS By Samuel Wein Formerly Editor Perfumery Art; Managing Editor Color Trade Journal Author of “Modern Photographic Developers” “Selenium Cells and Hbw'They are Made” Forty Second Street Commercial Studio 1 19 West 42nd Street New York SAMUEL WEIN •r. • PREFACE The major portion of the literature of photographic developers is of recent date. It is true that scientific journals of the latter part of the 19 th century are replete with learned dissertations on the properties and various compounds used as developers, but it is quite natural that it should be so. The information contained in such discussions is how- ever of pure academic interest. Chemists and photographers have neither the time nor the inclina- tion to wade through the “misty tombs” in the vaults of the libraries. In many cases the original manuscript or patent have appeared in a foreign tongue, often in a highly involved style and necessitating laborous dictionary work before a usable abstract of the required fact is available. In addition to this, many of the libraries are closed to the public during the very hours which the chemist or photographer usually has at his disposal. The following pages therefore constitutes an attempt to present to the busy chemist and photographer a concise chronological review of the literature of photographic developers. The aim in compiling the work has been to present practical information alone- — -cold facts — not academic controversies. With this explanatory introduction the following pages will; it is hoped, be clear to all whose interest in photographic developers leads them to consult this — a bibliographical dictionary of photographic de- velopers. In conclusion the writer wishes to thank all those who have helped to make this compilation a possibility, and in particular to Mr. Harvey Sears for his assistance in typing and reading the manuscript. Samuel Wein. Dedicated To My Beloved Wife and Daughter Blanche THEGr . CONTENTS CHAPTER I. PAGE Organic Photographic Developers CHAPTER II. Dye Sensitizers CHAPTER III. Characteristics of Developers List of Developers - _ - - 1-31 32-35 36-47 48-49 Index 50-51 CHAPTER I. Andresen. German patent 46915 Aug. 1, 1888. Para-phenylenediamine and caustic alkalies is employed, the developing is rapid and even. Schwartz and Merck! in. British patent 741 Jan. 15, 1889. Formaldehyde, para- formaldehyde, or hydroxylamine oxymethy! sulphonate is added to ferrous oxalate as a developing agent. Andresen. British patent 5207 March 26, 1889. Diamidonapthaline monosulphonic acid *Diamidonapthaline disulphonic acid Amidonapthol monosulphonic acid Amidonapthol disulphonic acid Dioxynapthaline monosulphonic acid Dioxynathaline disulphonic acid C^oH 5(NH2)2S020H C^OHKNH2)2(S020H)2 CioH^OH NH2SQ20H CioH^OH NH2(S020H)2 Ci0HHOH2)2SO2OH Ci0HHOH)2(SO2OH)2 Stebbings. Jour. Soc. Chem. Ind. page 817, 1889. Amido - B - naphthol - a - sulphonic acid and its isomeride, amido ~ B - napthol - B - sulphonic acid acts as energetic developers. The latter compound is obtained by reducing the orange dyestufl: produced by combining diazobenzene chloride with Schaeffer’s B - napthol • B - sulphonic acid. Dimethyl para-phenylenediamine may be obtained by reducing nitroso dimethyl 1 JS 1 "o B (U jB a o ■T3 "O -B _B o o i-< 'T 3 >' £ ^ cC -r >1 a £ 3 -a « a « y c ^ _e ^ §“ C o -B a o B O E 3 3 a ni B (S -B a E .3 SSQd:QQc^aa:a:Jl O 33 3 ^ E ns a B 3 "S (U ^ ^ i 3 “ E 3 B -B V o- "S 0 3 3 "a 1 cO CO }.< ?• a •— ' V S' 3 Q- 3 2 ^ ° i a 2 S CU 3 "S ■§ "O *'* ■ a >w^ o B V ■S'i S .2 a ns 0 S ns c •3 > W) e a — < -H o U 3 2 c M -a IS a o a 3 33 T^S 3 o <50 3 Vh '*73 OJ o> *TDn 3 S* 22 ^®_ <<» Hydrazine Hydrazine C®H^(NH 2 ) 2 HC 1 Hydrol Paramidophenol hydrochloride C^H^OHNH^ HCl Hydroquinone Paradioxy-benzole C®H^(OH) X o X z o CO CN X (TJ X ^ X z £ z X o ^ O wO XXX <£> CD O u o o X o o X u X z X o VI< X CD CD u u V}« O y ^ o a H- CO T' JU 2i^ S_^ CO 'X^x ^ JT' o y o z X£^ Zz£ O ^ CO v-1 vj< XXX Duuuooooo 0> X z X o o* X u X z X o X X o >—✓ X CO u NJI VJ< oou CO co-r XXST xx5 Gi >w XX o X »»'> T3 C O w N s 2 J >» -S X & .2 -2 o I n cC O CU 6 o -4^ X >> S ^ ns V a o • S .3 O' £ 2 J3 2 'C3 S C ca -C a m H3 u o 0) 4 -> o .X5 O 5* e X .a S 4J X ns > b o o OS “ " j3 X ^ -G "O X E G ca rt ^ >. O .£ ■£ "S o o G C V V JS jG a a o o ns ns 'B 'B « ca u X • S G c » ^ c -c 0 a. X ns G 1 fl - (o — c -c ^ 2 S'- E -§ I 9- 1 o H* ns G "S cuSSSScua,a.OcuOHSSHcuSSQcu _G 9“ o »« TS CU O cJS - g'^jO 'n C) .x; 9“ G <-> o o 2 • ~ .a T3 S 2 . >* ns ?-C -2 a-d o O _i, >. g S ■£ s §* S 9 § 2 i O 0) • 1 I ^ X X X C 3 C 3 ^ .2 a a-c ■G o o y ^-O'd ^ill ft ft 5 2 „ T" T' c 3 fi ^ >> >> o ^ J 3 n-C i? Q, ^ 4 -» 4 -» O 5 T* O 0 > 0 ) 1 O X E S-^X B h 6 ^ B G c G E G O O G Jg V C S "o X -C J " O O o 'tS ^3 ia G o V a o c ’3 O' o § lU _G ft O 0) c ’S G V X X >> "f^ — C o o -1-* aj _a fli j O c ft-G_c a-d^ 2~ -sX *— < E ^ , . ■“ “ 2 -S G g_E-,-;g 2 X G ao 6000 G ta o o t; c ^ i-Q-2T?y£!'^G ■ a o B B (d ns G G G ?a >» >,X 3 o q XXi^i^^SSSOCUCUOiCUDlCU CU CU aca ca CO CO CO D NAME AND SUBJECT INDEX AEG A Co. Page p-phenylenediamine 6 amido-p-phenylenediamine — oxy - p - phenylenediamine — amido-p-toluylenediamine 7 diamido-naphthol disulphonic acid 15 p-oxy-phenylglycinamide 23 metol 25 oxy-phenyl methyl glycine — methyl p-amidophenol 28 Anresen p-phenylenediamine — amidonaphthol monosulphonic acid — dioxy naphthol monosulphonic acid 1 a-amido-J3-sulphonic acid 8 dimethyl-p-phenylenediamine 4 dimethyl-p-amidophenol 4 Baum o-bromophenol — o-chlorophenol — pyrocatechin — a- phenol disulphonate 7 Bayer o-nitrophenol 16 pyrogallol 17 p-amidosaligenin — p-nitrophenol — o-nitrophenol 18 chlor-methyl-p-nitrophenol 19 m-amido-o-oxy benzyl sulphonic acid 21 Buisson p-amidophenol — diamidophenol — hydroquinone — pyrocatechin 13 Brocket p-amidophenol — p-phenylenediamine 28 Cassella acetyl oxyazobenzene — oxy diamido diphenyl 14 Cazeneuve pyrogallol 6 Claus dinitrophenol 25 51 Page Cramer hydroquinone — pyrogallol 15 Darmstadter hydroquinone 14 p-amidophenol 16 Eichengrun and Demeler chlor methyl-p-nitrophenol 20 Fischer p-phenylenediamine — p-amidophenol 26 Gatterman o-nitrophenol — p-nitrophenol — phenyl hydrazine hyro- chloride 12 Grandmougin p-hydroxyazobenzene 25 Harger hydroquinone — metol 31 Harrison and Bottomly Pinacyanol 34 Orthochrome T 35 Hauff metol 3 o-p-diamidophenol — o-p-diamido-o-cresol — o-p-diamido- m-cresol — methyl-o-amidophenol — hydroquinone — pyrocatechin . 10 p-phenylenediamine — hydroquinone — pyrocatechine — p-toluylenediamine — p-xylenediamine 13 p-phenylenediamine — p-toluylenediamine 14 hydroquinone — hydrotoluquinone — pyrocatechin — pyrogallol — hydronaphthoquinone 15 Hoffman naphthol green 32 Jacobsen Quinoline red — Quinoline yellow 32 Jansen p-phenylenediamine 28 Kempf hydroquinone 16 Leaper Quinoline blue — Cyanin — Isokol. 34 Lembach and Schleicher o-quinoline — p-quinoline 13 52 Page Levinstein and Pollak a-amido-a-nitro-a-sulphonic acid — a-a-naphthylamine-a- sulphonic acid 15 Lumiere oxy-quinoline — oxy-tolu quinoline 4 methyl amido p-oxybenzene sulphate 22 Lumiere and Jougla adurol 30 Lumiere and Seyewetz constitution of developers 5 p-tolyl B-hydroxyl amine 9 p-amidophenol 8 hydroquinone 16 trioxy methylene and pyrogallol 22 benz amido semicarbide — benz amido semicarbazide — benzamide hydrazine 22 p-phenylenediamine 23 methyl hydroquinone 30 Luttke and Arndt p-amidophenol hydrochloride 23 Meister-Lucius and Pruning dihydroxy naphthol 30 p-amidophenol sulphate 16 sodium glycocol 21 Meldola Eikonogen 2 Merck hydroquinone — metol 29 Meyer Quinoline yellow 35 Miethe and Traube Pinacyanol 34 Monnet and Cartier p-nitrophenol — p-amidophenol — o-nitrotoluene p-sulphonic acid — p-toluene sulphonyl chloride 9 Noyes and Clement p-amidophenol 6 Paul p-nitrophenol — o-nitrophenol — p-amidophenol — p- amidophenol sulphate — metol — p-hydroxyglycine . .10-15 Pellizzari p-amidophenol acetone bisulphite — metol 23 Perkin pyrocatechin — guaiacol 2 Reverdin and de la Harpe dinitrophenol 4 53 Page Schwartz and Mercklin hydroxylamine oxymethyl sulphonate 1 Stebbings amido-5-naphthol a-sulphonic acid — dimethyl p-pheny- lenediamine * 1 Sobering hydroquinone 8 p-amidophenol — benzyl p-amidophenol 23 9 hydroquinone — pyrocatechin — pyrogallol 13 Society of Chemical Industry p-amidophenol 31 Tafel hydroxylamine 22 Tauber p-amidophenol — p-azophenol 16 Thorpe hydroquinone — pyrogallol 26 Ufer-Driebrodt and Rohler glycolates 30 Vidal dinitrophenol 17 p-amidophenol — o-amidophenol 14 p-phenylenediamine 25 Weinberg Formyl violet 33 54 Wein p-amidophenol hydrochloride 36 metol 37 amidol 38 ortol 39 hydroquinone 40 adurol 41 pyrogallol 42 Eikonogen 43 pyrocatechin 44 glycine 45 Diogen — Paramine 46 Diamine 47 Reducin — Diphenyl 48 table of developers 49-50 WOLFFENSTEIN AND BoLTERS dinitrophenol . 29 Ziegler Tartrazine 33 VOLUME II. I The following pages is a complete survey of all the chemical manipulations involved in photography. Samuel Wein. N 58 CHAPTER I. DEVELOPING. The term “developer” is often misunderstood, some are inclined to believe that it applies to the solution itself. Whereas, the fact is that it only applies to the compound or agent which actually reduces or makes visible the “latent image” or exposed silver salt. The composition of developing solutions varies not only with the compound used, but even with the individual photographer. The following is a review of the developing solutions and some of its characteristics, this by no means is complete. For detailed informa- tion concerning these developers, reference should be had to such per- iodicals as are referred to throughout the text. / ADUROL. The development with Adurol is preferred to Hydroquinone, in view of the fact that it gives much softer negatives and prints, with plenty of density and good detail. Its solution is not so readily affected by atmospheric changes as it is with Hydroquinone. On developing with Adurol the high lights and shadows quickly appear and the half tones are built up little by little, giving a blue black image which is desirable for bromide prints. A typical developing solution being; Water 7 ounces Adurol ounce Sodium sulphite ounces Potassium carbonate 2Yl ounces For use dilute with from five to seven times its volume of water. 59 amidol Amidol is one of the fines^ developers, giving fine detail in the shadows and free from fog. It develops in the presence of sodium sulphite only and in fact the neutral salt is preferred for this. In alkaline solution it rapidly oxidises and is unfit for use as a developer as it stains the negative yellowish. The following solution is recommended as giving very strong contrasts and being suitable for bromide prints: Amidol 24 grains Sodium sulphite 80 grains Sodium bisulphite 1 ounce Potassium bromide 20 grains Water 10 ounces This solution will keep well for a long time. EDINOL. Edinol as a developer the fine qualities of Pyrogallol with those of the more rapid developers, giving great density or softness, according to the manner in which it is used. With caustic alkalies very soft gradations may be obtained, while with the use of sodium carbonate, the tendancy is towards strong contrasts. The following solution is recommended for all aronud work: Edinol 9 grains Soodium sulphite 18 grains Potassium carbonate 90 grains Water 20 ounces Edinol develops free from fog and does not stain or affect the skin as other developers do. 60 DIAMINE. The developmemt with Diamine is very much the same as with Amidol, in that it develops in the presence of sodium sulphite only. A typical formula is: Sodium sulphite 250 grains Diamine 85 grains Water to 20 ounces This solution will keep well in amber colored bottles. DIPHENAL. This developer is supplied in the form of a brown solution, it is used much the same as Rodinal. With correctly exposed negatives it is dulated with from 15 to 20 parts of water. For over exposed negatives, it is diluted with from 8 to 1 0 parts of water. For under exposed negatives it is diluted with from 20 to 25 parts of water. DURATOL. Duratol has unusual developing strength, is soft working and is recommended for snap shots. It does not spoil in solution so readily as other developers do. It is no longer obtainable on the market. EIKONOGEN. Eikonogen is a soft working developer, the range of gradation in tones is more harmonious than is possible with Pyrogallol. It gives blue black or grey prints. The following is recommended for portrait negatives: Eikonogen 52J/2 grains Sodium sulphite 52*/2 grains Sodium carbonate 52^ grains Potassium bromide 2 grains Water 5 ounces For softer effects add up to an equal volume of water. The image appears quickly and builds up in density quite fast. 61 Eikonogen is widely advocated for very rapid exposures, for which the following solution is suitable: Eikonogen 100 grains Sodium sulphite 200 grains Sodium carbonate 100 grains Potassium bromide 5 grains Water 16 ounces , The small quantity of potassium bromide added appears to in- crease the density of the negative, if the negative is under exposed or a soft negative is desired, it is better omittd. GLYCIN. Glycin is a slow working developer and keeps well for a long time in solution. It is for this reason that it is suitable for tank develop- ment. The negatives developed with it are perfectly clear and free from stain. Von Hubl recommends the following Glycin paste consisting of: Sodium sulphite 2Yl ounces Water (boiling) 4 ounces When dissolved add: Glycin 1 ounce And then in small quantities: Potassium carbonate 5 ounces This forms a thick paste, which must be well shaken and then diluted with water, for normal exposures dilute 1 ounce of the paste with 1 2 to 15 ounces of water, for very soft results dilute with 30 ounces of water. A single Glycin solution is made up from: Glycin 1 ounce Sodium sulphite 2Yl ounces Potassium carbonate 5 ounces Water to 30 ounces For normal exposure dilute with an equal bulk of water. 62 METHYL GLYCIN. A suitable formula which must be diluted with an equal quantity of water before used is the following: Methyl Glycin 350 grains Potassium carbonate 175 ounces Sodium sulphite 2 grains W ater 16 ounces A similar solution was prepared with the ordinary Glycin and comparative results proved that the new preparation gave good, clean negatives in a much shorter time than the older developer. As regards and Metol. The sensitiveness of the developer to changes of tempera- speed of development Dr, Valenta places it midway between Glycin ture, appears to be about the same as that of Glycin. The action of potassium bromide appears to be about one-fourth of that of Glycin. HYDRAMINE. This developer works best with lithium hydroxide, the following solution is recommended by Lumiere: Hydramine ounce Sodium sulphite ounce Lithium hydroxide 65 grains Water 50 ounces For over exposures add several drops of a 10 per cent, solution of potassium bromide, for under exposure add several drops of a 1 per cent, solution of lithium hydroxide solution. HYDROQUINONE. Hydroquinone like Pyrogallol is used to a great extent. It is a slow working contrasty developer. Hydroquinone is more sensitive to temperatures than other developers, in fact by increasing the temp- erature of the solution it will give excessive contrasts and fogs the negative. Should the temperature be lowered it is apt to crystallize out. The ideal temperature is between 65 to 70 deg. F, 63 Sodium hydroxide accelerates the development of hydroquinone giving soft contrasts, while sodium carbonate produces stronger contrasts. Here is a satisfacctory all around solution: Water 8 ounces Hydroquinone Y 4 ounce Potassium carbonate 3 ounces Potassium bromide 9 ounces Sodium sulphite 2 ounces With normal exposures dilute with 2 to 3 times its bulk of water. METOL. Metol is an extremely rapid developer producing soft delicate negatives. On developing with Metol it will be found to bring the detail out first and gradually builds up the density afterwards, and is admirable for negatives where detail rather than contrast is desired. If a dilute solution is used, a little potassium bromide should be added; but for average work this is unnecessary. The following solution is recommended for all around work: Metol 35 grains Sodium sulphite Yl ounce Sodium carbonate J /2 ounce Potassium bromide 3 grains W ater 10 ounces This solution does not keep quite as well as others. METOQUINONE. This is an energetic developer and is used with or without the usual alkalies, Lumiere suggests the following solution: Metoquinone 43 grains Sodium sulphite 1 '/4 grains Water . 10 ounces , For snap shots add about % ounce acetone. 64 MONOMET. This product was introduced in the latter part of 1916, being made in England. Its composition is not known, the manufacturers say it is a derivitive of cresol and that it is similar to Metol in every respect. In actual practise this was found to keep better in solution, negatives developed with it have more density. The prints are a rich carbon black instead of the usual blue black of Metol. Monomet is extremely sensitive to potassium bromide. ORTOL. Ortol behaves the same as Pyrogallol, with the exception that it gives excellent black negatives and free from stain. If made up with Sodium sulphite or potassium metabisulphite it will keep fairly, well in amber colored bottles and may be used repeatedly within reasonable limits, growing slower in action each time. For tank development where various negatives with widely dif- ferent exposures are dealt with the following is recommended: Water 10 ounces Potassium metabisulphite ^Yz grains Ortol 5 grains Sodium sulphite 32 '/i grains Sodium carbonate 32J/2 grains The time for development is about 1 5 minutes. PARA AMIDOPHENOL. Para amidophenol is a developer having remarkable properties all its own. It is a curiously balanced developer, in that it can behave in a weak way, both as an acid and a base. As a base it combines with strong acids, such as hydrochloric or sulphuric acid, forming salts. With strong alkalies (sodium hydroxide) it behaves as a weak acid, forming sodium Para amidophenolate. The first addition of sodium hydroxide precipitates the Para amidophenol (base) itself as an insoluble compound, but this latter redissolves as more alkali is added, in this way a very concentrated solution can be made corresponding to Rodinal of commerce. 65 Para amidophenol (free base) with sodium sulphite alone develops very slowly, this being due to the fact that very little of it is in solution (on account of its solubility). In order that it may be used with little trouble it is converted into a salt that is readily soluble in water. Para amidophenol hydrochloride is readily soluble in water (1:10), its keeping qualities are better in fairly strong solutions rather than in dilute solutions. It dissolves in a 5 to 10 per cent solution of sodium sulphite and keeps clear, retaining its characteristic quality for days. When made up in developing solutions where the sodium car- bonate predominates, para amidophenol will keep indefinitely. When Para amidophenol is dissolved in sulphite or carbonate solutions, there results a formation of the true “base” in solution. In this way the solution is minus the Para amidophenol and it is said to “slow up” or “run down” more quickly than Metol. On the addition of a little sodium hydroxide to the solution, just enough to redissolve the precipitate first formed, it will become effective again for use. Many photographers advise to use Para amidophenol “the same as Metol,” i.e., replacing the amount of Metol for that of Para amido- phenol and its salts. This is not so, because Para amidophenol, unlike Metol, is extremely sensitive to the restraining action oi potassium bromide. In many formulas the amount of bromide equals that of Metol itself. With Para amidophenol the proportion should rarely exceed 1 part of potassium bromide to 1 0 parts of Para amidophenol. Generally a smaller quantity can be used to advantage. Many photographers advise to use Para amidophenol “the same as Metol”, i. e. ; replacing the amount of Metol for that of Para amido- phenol and its salts. This is not so, because Para amidophenol unlike Metol is extremly sensitive to the restraining action of potassium bromide. In many formulas the amount of bromide equals that of Metol itself. With Para amidophenol the proportion should rarely exceed 1 part of potassium bromide to 1 0 parts of Para amidophenol. Generally a smaller quantity can be used to advantage. 66 A developer advocated by Dr. Liesegang, who found that citric acid is an excellent solvent for Para amidophenol, 97 parts by weight of which are soluble in 200 parts of a 50 per cent, solution of citric acid in water. The Para amidophenol should be added gradually at a temperature of 65 to 68 deg. F. The Para amidophenol citrate so formed is employed as a developer in the following proportions; Para amidophenol citrate (solution) 1 part Sodium sulphite (concentrated solution) .... 5 parts Sodium carbonate 5 parts Potassium hydroxide (10 per cent, solution) 2 parts Water 50 parts This is ready for use and may be employed repeatedly. It gives blue black images with normal exposures. Many photographers fail to get sufficient density with Para ami- dophenol or Rodinal to give good printing negatives. This is generally due to the fact that, with Para amidophenol, as with Metol and Amidol, the image appears rapidly but gains density slowly. Also a little density is lost during the fixing process. The remedy is obvious, carry the development a little further than seems necessary by the usual visual test, in order to make sure of a negative of sufficient density to yield good graduations in the prints. PHENYL HYDRAZINE. This developer acts very weakly and for that reason it is not used. ✓ Recently a small per cent of Phenyl hydrazine was incorporated into the negative during the course of sensitising, on development it was found to prevent “halation” to a great extent. In fact this idea is used in the manufacture of the non over expoure negatives called in com- merce “Hydra” plates. 67 PARA PHENYLENEDIAMINE. This developer is not so popular here in America as it is in Europe, due perhaps to the lack of definite information concerning it. It is a slow working developer giving good details in the shadows with a brownish black print, free from fog or stain. Brewster advocates the following formula: Para phenylenediamine 10 grains Sodium sulphite 10 grains Sodium nitrite 10 grains Sodium carbonate 2 grains Water 8 ounces This solution works quite rapid and will keep well for a long time. PHENYL HYDROXYLAMINE. This compound acts vigorously as a developer, but is of no prac- tical use as nitrogen gas is evolved during development, this reticulates and pits both the negative and prints. For the benefit of those who might want to try this developer the following is suggested: Phenyl hydroxylamine hydrochloride.*. .... 2 grains Sodium hydroxide 3 grains Potassium bromide j /2 grain Water 1 ounce This developer should be used only once and the negatives washed thoroughly. PYRAMIDOL. This developer is particularly admirable for developing negatives of gross over exposures. It will develop much the same as Amidol without the use of the usual alkalies. The following solution is found to give satisfactory results: (A) Sodium sulphite 1 1^2 ounces Pyramidol 90 grains Water 20 ounces (B) Potassium carbonate 1 ounce Water 29 ounces For use mix A and B in equal proportions. 68 PYROCATECHIN. This developer gives clear printing negatives with less density and no greater detail for a given exposure than Pyrogallol or Hydroquinone, but has the advantage that it works well in dilute solutions. A curious and valuable property possessed by Pyrocatechin is that it gives better results with stale negatives than any other developer. The following solution is recommended for all around work: Pyrocatechin 120 grains Sodium sulphite 4.80 grains Citric acid 20 grains Water . 10 ounces Vogel first discovered that Pyrocatechin will develop in the pres- ence of hypo and that it may be used to simultaneously develop and fix the image; the following solution was suggested by him: ^ Sodium sulphite 468 grains Potassium hydroxide 108 grains Pyrocatechin 108 grains Water 3 ounces Take of this solution 3 drams and dilute with 1 ounce of water and add drams of a 1.5 hypo solution. Fixing and developing is complete in a few minutes. PYROGALLOL. Pyrogallol, the oldest organic developer, is at the present day still used very extensively. The fine gradations of the negative, the great power of variations for errors in exposure, are properties which have created a lasting place for Pyrogallol, although it quickly spoils when exposed to the air. Pyrogallol has not the characteristic properties of an acid — it has a bitter, not a sour taste and it does not redden blue litmus — hence chemists do not consider it as a true acid ajjd in chemical text books it is now termed “Pyrogallol,” but to photographers it is familiarly known as “Pyrogallic acid” and also as “Pyro.” 69 PYROGALLOL ACETONE. Commercially it comes in two forms, resublimed and in crystals. Of the two forms, photographers prefer to use the latter as it is easier to handle. In solution, its keeping qualities are very poor, for this reason it is preferred to be made up before it is ready for use. Potassium bromide has a ready and energetic effect in restraining the developing action of Pyrogallol. This developer yields a brilliant negative with a rich gradation from intense high lights to clear shadows, it consists of: Pyrogallol 30 grains Sodium sulphite 120 grains Acetone — 40 minims Water 12 ounces This solution is intended for tray development and the development is complete in about 6 minutes. For tank development the amount of water can be increased to 30 ounces and the time for development will be about 30 minutes. PYROGALLOL SODA TANK DEVELOPER. The Eastman Kodak Co. advocates the following receipe, the outstanding features claimed for this solution is its excellent keeping qualities and the production of remarkably clear negatives. The for- mula is: Pyrogallol 2 ounces Sodium sulphite (neutral) 20 ounces Potassium metabisulphite 2J/2 ounces Sodium carbonate TYl ounces Water to 280 ounces The following instructions must be strictly followed, as the keeping qualities of this developer depends entirely upon the method of making it up. 70 Dissolve the sodium sulphite in 60 ounces of hot water (not boil- ing). When dissolved, add the potassium metabisulphite and then boil for 5 minutes. Cool down to about 70 deg. F. and add the h'yrogallol. Dissolve the sodium carbonate in 20 ounces of warm water. Pour these two solutions into the tank and make up to 280 ounces of water. The time for development is about 1 8 minutes at 65 deg. F. An acid fixing bath should always be used. REDUCIN. Reducin works like Amidol, the following solution is recommended by Vogel: Reducin 26 grains Sulphuric acid 5 minims Sodium sulphite 218 grains Water 10 ounces This solution keeps well in amber colored bottles. RODINAL. The use of Para amidophenol in the form of a concentrated solu- tion has attained wide popularity, such solutions only requiring dilution for use. Rodinal, which was the first commercial form of Para ami- dophenol, has subsequently had other competitors and though as far as I am aware, the base of these other single solution developers has not, in any case of any any one of them, mentioned as Para amidophenol, it may be taken that it is this compound which is used. HOW RODINAL IS MADE. Several years Desalme in a paper before the French Photographic Society, gave working instructions for making a solution similar to Rodinal. I cannot do better than give his directions. Make a solution of: Para amidophenol hydrochloride 7^ ounces Water (hot) 60 ounces Now prepare the following: Sodium carbonate ouncgs Sodium sulphite 1 ounce Water (warm) 20 ounces 71 add this solution to the above, a precipitate of Para amidophenol will form. It is allowed to cool and filtered through a linen bag, from which as much water as possible is allowed to drain. The bulk of the paste thus formed should not be more than 30 ounces. Dissolve the paste in 10 ounces sodium bisulphite (25 deg. Be.) and then add little by little a strong solution of sodium hydroxide (5 ounces and sufficient water to make a bulk of 1 0 ounces) , stirring all the time. The paste will gradually dissolve. Great care must be taken not to add too much of this alkali. After this the bisulphite solu- tion is added to give a slight permanent precipitate. Water is now added to make a total bulk of 50 ounces and the solution is ready for bottling in which it keeps excellently. To form the working solution it is mixed from 20 to 40 times its bulk of water. For average negative work a dilution with 20 parts of water is about the best, but many photographers prefer to dilute it with 1 0 parts of water, in order to get ample density. Another concentrated one solution developer like Rodinal may be made from: Potassium metabisulphite ^ ounce Para amidophenol '/4 ounce Water (hot) 21/2 ounces Dissolve in the order given tand add slowly a comcentrated solution of sodium hydroxide until the precipitate first formed is dis- solved. For use, dilute with 1 0 to 30 parts of water, an average strength being 24 drops to each ounce of water. SYNTHOL. Synthol is used in the same way as Amidol, a typical solution consists of: Water 10 ounces Sodium sulphite 300 grains Synthol 30 grains Potassium bromide 5 grains This solution will give good snapy prints. 72 9 CHAPTER II. FACTORIAL DEVELOPMENT. The factorial system of developing was originally suggested by Alfred Watkins in 1893, its object is to determine the time of develop- ment. This is done by noting the time it took to produce the first trace of an image on the negative and multiplying this time by a given factor, the result being the total duration of development required to produce a negative of given density. Only experienced photographers can determine the exact time to stop development, this they ascertain by judging the negative aS it is being developed. With the factorial system of development all that requires to be done is to calculate the time as already described and after the expiration of this time the negative is removed and ready to be fixed. This system has been found to be very reliable in actual practise and in fact one large motion picture laboratory uses this system throughout, in this way they are enabled to produce negatives and posi- tives of equal density. Every developer irrespective of concentration and composition of its solution, has a specific ratio between the time required for the negative to assume all the contrast possible in the given circumstances and the time required for the image to make its appearance after inmersion in the developer. This ratio is known as its “factor . Like all physical laws, it elastic and capable of adjustment tto tthe individual requirements and ideas of what is a correct negative, or, in other words by reducing or increasing the factor a thinner or denser negative may be obtained. 73 The following factors are those generally used for the principal developers Adurol 5 Amidol 8 Edinol 20 Eikonogen 9 Glycin 8 Hydroquinone 5 Metol 30 Ortol 10 Para amidophenol 16 Pyrocatechim 10 Quinomet 30 Rodinal 30 To illustrate this fact we might use Metol as the developer, it will be found to produce the first trace of an image in 1 0 seconds. The developing factor of Metol is 30, now therefore multiply the time of the first trace of the image with the factor, the result is 300 seconds or exactly 5 minutes. If the worker will look on the negative at the expira- tion of that time he will find the negative to be of correct density. THE FACTOR OF PYROGALLOL. Pyrogallol and Amidol are exceptions to the rule, being dependant on the number of grains to the alkaline solution and also on the quantity of potassium bromide used. The following table will enable the factor of any Pyrogallol developing solution to be readily calculated, provided of course the formula is known. Grains of F actor Grains of Factor Pyrogallol without bromide with per ounce bromide per ounce bromide I 18 /4 9 2 12 !/2 5 3 10 4/2 4 8 1 4 5 6/2 2 3 74 THE FACTOR SIX. A developer having 6 as its factor is very convenient to work with, all we must do is to divide the time of the first appearance of the image by 1 0 to obtain the number of minutes, thus saving the time of dividing by 60. For example, if the time of appearance is 20 seconds, by the ordinary method the calculation would be 20 times 6 equal 1 20 divided by 60 equal 2 minutes, whereas by the quicker method it is 20 divided by 1 0 equal 2 minutes. THE FACTOR OF COMBINED DEVELOPERS. The factor for a combined developer with the agents in equal proportions will be practically equal to the average or mean of their constituents. For example, equal parts of Hydroquinone and Metol would have a factor of about \ lYi. When two developers are used in unequal proportions the calculations are done somewhat differently. Thus with a mixture of 3 parts Metol to 2 parts Hyroquinone, the factor would be found as follows: Metol (3 parts) 30X3=90 Hydroquinone (2 parts) 5x2=10 90 plus 1 0 equal 1 00 divided by 5 equal 20, the required factor. Supposing one were using a Metol-Hydroquinone developer with a factor of 1 5 and the timfe of appearence were 9 seconds, the total' duration of development would be 1 5 times 9 equal 1 35 seconds or 2|/2 minutes. The advantage of the factorial system of development over the visual is obvious in that it reduces a rule of thum method to that of an exact one. 75 CHAPTER III. BLEACHING AND INTENSIFICATION. There are a number of occasions that poor negatives are obtained, due perhaps to an incorrect exposure or development. Or in other cases the negative is found to be too opaque, due to an over exposure or a continued development. In the first case the negative is said to be too “thin” and requires intensification, the second case requires “reduction’’ or “bleaching” in order to make a decent print of it. Before bleaching or intensification is carried on, the negatives must be perfectly free from hypo and also the so-called “dichroic veil.” The hypo is best disposed of by continued washing, it is well to test this from time to time, in order to get the best results and free from chemical coloration. DICHROIC VEIL. This defect is produced by a lengthened development, or by an excess of developer in the fixing solution. This causes the high lights of the prints to become fluorescent and blocked. It is readily removed in any of the following solutions: Water Example /. . 10 ounces Sodium bisulphite . 5 grains Water Example II. 10 ounces Alum 1 ounce Thiocarbamide . Example III. . . 1 dram Alum 1 dram Citric acid .... 1 dram Water .. 10 ounces The negative should immediately be removed after the high lights are found to be perfectly clear. It is now washed in running water and allowed to dry. 76 TEST FOR HYPO. The following receipe is one of the oldest and yet reliable methods of testing for the presence of minute traces of hypo. The test solution consists of: Potassium permanganate 5 grains Sodium hydroxide 20 grains Water 5 ounces A few drops of this solution is added to from 1 0 to 20 ounces of water. The negative or print that is to be tested for hypo is allowed to drip or soak in the above solution. The water will remain a pinkish tinge for some time, but if there is a slight amount of hypo present, the solution rapidly assumes a greenish tint. The strength of the solution should not be exceeded or the delicacy of the test is impaired. This test should be repeated until no reaction is seen, thus indicat- ing that there is no hypo present in the print or negative. HARDENING. Some photographers make it a practice of hardening the negative or print after it is fixed. This is advisable in the summer time, sincd it prevents the surface from frilling. Here are two solutions found to give satisfactory results: Example /. Formaline 1 ounce Water 30 ounces Example II. Alum 8 ounces Acetic acid 20 ounces Sodium sulphite 3 ounces Water 20 ounces These solutions can be used over and over again, as its keeping qualities are excellent. BLEACHING. There are a great number of compounds used in bleaching and intensification, some are modifications of others. Each one of these processes has its own characteristics and find some special advantage for a particular purpose. 77 MERCURY CHLORIDE. Of all the bleaching solutions in use, there is none as popular as that mailing use of mercury chloride. A typical solution being: Mercury chloride 105 grains Water 8 ounces Ammonium chloride 42 grains The bleaching action taking place immediately due to the fact that a chlorine radicle is being split off from the mercury chloride and attaches itself to the silver image, forming white silver chloride and mercurous chloride (calomel), thus: 2Ag+2HgC12=2AgCl+Hg2CP. Mercury solutions are extremely poisonous and great care should be used in handling this. MERCURY IODIDE. Edwards was the first to publish the use of mercuric iodide dis- solved in hypo as a direct intensifier for negatives. Later, Vogel slight^ modified the composition of Edwards’ solu- tion. According to these investigators, the solution consists of: Mercury bichloride 4 grams Hypo 8 grams Potassium iodide 10 grams Water 4 ounces This solution can be used repeatedly until exhausted. After intensification the negative should be washed so as to cause the maximum formation of yellow mercuric iodide. This yellow iodide must then be thoroughly removed in a weak hypo solution, which should be allowed to act on it until no yellowness is visible on examination of the glass side of the negative. For this reason the intensification should be done only in day light, otherwise it is not easy to tell when the yellow iodide has been perfectly disposed of. The results prove quite permanent when these precautions are taken. If the negative, on drying, proves to be too dense, it can be reduced to some extent by immersion in the ordinary fixing solution. 78 Here are two modified and simple formulas: Example I. Mercury iodide 15 grains Sodium sulphite 300 grains Water 3/2 ounces Example II. Mercury chloride 54 grains Potassium iodide 33 grains W ater 8 ounces BLEACHING WITH THE FERRICYANIDES. Besides the mercury salts those of the ferricyanides produce equally good results, in fact, in some processes as for toning it is preferable. Here are a few typical solutions ; Example /. Potassium ferricyanide 20 grains Potassium bromide 30 grains Water 5 ounces Example II. Potassium ferricyanide I grain Potassium iodide 1 grain Water 5 ounces Example III. Potassium ferricyanide 75 grains Ammonium bromide 25 grains Water 5 ounces Example IV. Potassium ferricyanide 1 ounce Chromic acid 1 ounce Water 1 gallon Example V. Potassium ferricyanide 12 grains Sodium phosphate 12 grains Water 5 ounces 79 , Example VI. Potassium iodide 15 grains Iodine 8 grains Water 10 ounces FARMER’S REDUCER. This solution is very popular and consists of: Potassium ferricyanide 3 grains Hypo 30 grains Water 4 ounces Inasmuch as this solution does not keep well it is prepared before it is intended to be used. Gear, in the course of his experiments on the addition of various substancecs to Farmer’s reducer (hypo ferrocyanide) for the purpose of prolonging the time during which the reducecr retains its activity, has found that on the addition of 4 grains potassium bromide to each ounce of the mixed reducer prolongs the time during which the reducer keeps in working condition by about 30 per cent. Brougham finds that the addition of ammonium sulphocyanide to Farmer’s reducer prolongs the time of effective action. He makes 10 per cent stock solutions and uses of them as follows: Potassium ferricyanide 2 drams Hypo 2 drams Ammonium sulphocyanide ........ 2 drams Water 2 ounces The keeping qualities of this solution it is found to be good. POTASSIUM PERMANGANATE. Next in importance comes the potassium permanganate intensifier. This gives excellent results and very great intensification can be obtained with it, the image being black. With a weak acid solution of potas- sium permanganate the image turns pinkish yellow and after washing and redeveloping with Hydroquinone or Metol-Hydroquinone, the bleached image again becomes black and the density is thus obtained. 80 A typical solmtion suggested by Namias is: Potassium permanganate 123 grains Water 34 ounces Water 34 dunces Keep this stock solution in an amber colored glass stoppered bottle. For use dilute 1 part of the solution with 30 parts of water. This bleaching solution finds application for negatives of normal strength. The bleaching action is extremely rapid. When the right degree of bleaching has been obtained, the negative should be immedi- ately placed in the following solution : Water 3 ounces Sodium bisulphite 2 grains Which will eliminate the yellow tint of the manganese dioxide, after which the negative should be wadiel for 1 5 to 30 minutes and dried. The bleached negative is redeveloped the same as is done in the case of the chromium bleacher. AMMONIUM PERSULPHATE. This solution is a simple one to prepare and consists of: Ammonium persulphate 15 grains Water 1 ounce This solution attacks the high lights without affecting the detail in the shadows. Hunter recommends a mixture of the Farmer and ammonium per- sulphate reducer. By adding 1 part ammonium persulphate ( 1 to 20) to 3 or 4 parts of the Farmer reducer we obtain a proportional reducer as near perfection as there is any need for. The combined reducer does not stain like the Farmer reducer by itself; it acts very quickly, especially if negatives are put in dry; there is no need for sodium chloride or sodium sulphoccyanide to keep it in working order longer; one solution will reduce a dozen or more negatives in succession and there is no need for a sodium sulphite stop solution. 81 Deck recommends the following solution: Potassium permanganate ( 1 per cent, solution) .... 20 minims Ammonium persulphate 10 grains Water to 2 ounces This reducer should preferably be made up just before use. The reducer is found to have the following advantages: The action starts at once and is regular, that is it does not spurt towards the end like ammonium persulphate. Hypo in the negative through imperfect washing does not interfere with it. The solution is not liable to fail in its action at times from some unknown cause; also it is easier to judge of the action than with potassium permanganaije alone and the solution appears to remain active working longer than acid perpian- ganate. So far as can be judged from trials, its action is proportional throughout the tones of the negative. COPPER BROMIDE. The copper solutions bleach quite well. Here are some popular receipts : ^ Example /. Copper sulphate 1 ounce Sodium chloride 1 ounce Water 25 ounces When dissolved add enough ammonia (.880) to clear the solution, which should be a ricch ultramarine color. Example II. Copper sulphate 30 grains Potassium bromide 30 grains Water 7 ounces Example III. Cupric chloride 180 grains Hydrochloric acid 20 minims Water 20 ounces These solutions keep well: LEAD NITRATE. With lead nitrate the silver image is converted into lead and silver ferrocyanide : 3Pb3Fe2Cn2 4Agi2 3Pb2Fe(Cn)6 2AgFeHCn)6. Here are two typical solutions: 82 Example I. Potassium ferricyanide 6 grains Lead nitrate 4 grains Water 10 ounces Example II. Potassium ferricyanide 600 grains Lead nitrate 400 grains Acetic acid 1 dram Water 20 ounces Example II consists of a stock solution, this will keep well for a long time in amber colored bottles and preferably in the dark. The negative after bleaching is washed once very carefully in a 1 0 per cent nitric acid sblution, then in running water and darkened in any of the intensifying solutions given. The lead intensifying solutions permits great intensification and increases the harshness of the negative. CHROMIUM In this process, which was worked out in detail, though not actually invented, by Piper and Carnegie (Amature Photo, page 366, 1904, page 453, 1905), the negative is treated with a solution of potassium bi-chromate acidified with hydrochloric acid and the bleached image, after washing, is treated or darkened with an ordinary developer. According to these investigators, the bleached image consists of a chromium compound, which they suggest may be the so called chromium dioxide CrO^, generally regarded as cromic chromate Cr^C®. They established the presence of chromium, but not the precise nature of the chromium compound. The three working formulas recommended by Piper and Carnegie are: A B C Potassium bichromate . . Hydrochloric acid . . . . 5 grains 1 0 grains 10 grains (sp. gr. 1.1 60) . . . . 1 minim 5 minims 20 minims W ater 1 ounce 1 ounce They found that formula A gives a high degree of intensification, formula C a low degree, whilst formula B gives an intermediate result. 83 The chromium salts are of great practical value, as many have already recognized, it is easy to work and if great care is taken in mak- ing up the solution it will give concordant results. Moreover, it is ap- plicable to negatives, lantern slides and bromide or prints. Formula C not only gives that slight degree of intensification which a print often needs, but may also greatly improve the color of the image. With a still larger proportion of acid there is still less intensification, but at the same time a distinct improvement of color, if, for example, the original image has had the well known olive green tint. CALCIUM CHROMATE. A less stable chromium salt may be used in order to accelerate its bleaching action, for this purpose calcium chromate is used, the following is a typical receipe: Calcium chromate 1.5 grams Hydrochloric acid 1.5 grams Water 100 grams About three minutes immersion in this solution will suffice; the negative is then thoroughly washed and redeveloped in a Hydroquinone solution. A few minutes washing is necessary after development. CERIC SULPHATE. This bleaching solution was originally introduced by Lumiere in the form of a concentrated solution. It can be readily made of: Ceric sulphate 1 ounce Sulphuric acid (1.84) 20 minims Water 10 ounces Hard negatives are placed in a mixture of this stock solution and diluted with nine times its volume of water. It reduces contrast. Over exposed, long developed negatives are dipped dry into a mixture of the stock solution and an equal part of water and carefully watched as the action is very rapid. INTENSIFICATION. The following solutions consists of such compounds that will intensify the bleached image. It is well to wash the bleached image before intensification is carried on. 84 SODIUM SULPHITE. By treatment with sodium sulphite, the following takes place: 2Hg2CP+4HgCl=8Na2S03=Ag2+Hg+8NaCl+ 3Hg (NaSQS) 2+2AgNaSQ3. The blackened image consists of mercury and silver. A typical solution being: Sodium sulphite 1 ounce Water 10 ounces This solution will keep fairly well. SODIUM SULPHIDE. By treatment with any soluble sulphite as sodium, potassium, am- monium, barium, etc., the reaction taking place being: Hg2CP+2AgCl+2(NH^)2S=rHg2S+Ag2S-f4NH^Cl. The blackened image consists of a mixture of mercurous and silver sulphides. The solution consists of: Sodium sulphide 1 dram Water 3J/2 ounces This solution should be fresh in order to secure the best results. AMMONIUM SULPHIDE. On treating the bleached image (using the ferrocyanides) with ammonium sulphide, the two salts become converted into black sulphides as follows: Pb^Fe (Cn) 6+ AgFe (Cn) 6+4 (NH^) 2S=2PbS+2 AgSS+ 2(NH^)'Te(Cn)6. A typical solution consists of: Water 10 ounces Ammonium sulphite 3 grains This solution should be made up before it is to be used, as its keeping qualities are very poor. AMMONIA. By treatment with ammonia dimercurous ammonium chloride is 'formed : Hg2CF+NH3=NH2Hg2Cl+NH^^HCl. The solution consists of: Ammonia (.880) 20 drops Water 1 ounce This solution gives great intensification and a good black color. 85 SILVER NITRATE. After the negative has been completely bleached in the copper bleacher it is then washed in five changes of: Sodium sulphite 50 grains Sulphuric acid 100 minins Water 20 ounces The immersion should be for about three minutes in the first change and for four in the subsequent ones. After this washing has been carried out, the negative is immersed in a dish of water for about five seconds and then placed in: Silver nitrate 80 grains Nitric acid 80 minins W ater 10 ounces and then left there until all action is at an end. The action taking place in the silver solution is: Cu^Br^x 4 AgNQ3=2Cu (NQ3) 2+ (2 Ag+2AgBr) . We get thus an image consisting of silver bromide and a silver and silver sub-bromide. The negative is now thoroughly washed and after this bleached in bichromate bleaching solution. It is then redeveloped. FERROUS OXALATE. By treatment with ferrous oxalate the following takes place: Hg2CF+2AgCl+4FeC20^+4K2C20i=Ag2-fHg +Fe(C20^)3+KCl. The blackened image consists of silver and mercury. The following is a typical solution made use of in practise: Ferrous oxalate 5 grains Water 10 ounces Since this solution does not keep well it is best that fresh solutions should be made as is required. HYPO. An ordinary hypo fixing solution will blacken the bleached image. Here is a typical solution made use of: Hypo 4 ounces Water 20 ounces This solution keeps well and may be used repeatedly. ^ 86 COPPER SULPHATE. The bleached and washed print is placed in: Copper sulphate 100 grains Water 3 ounces This solution keeps well and is therefore kept in bottles ready to be used. URANIUM NITRATE. The bleached print is washed in running water and intensified in: Uranium nitrate 40 grains Acetic acid 27 minims Water 10 ounces The high lights will be found to be a brownish tint, this is disposed of by placing the negative before the final wash in a 5 per cent, solution of ammonium sulphocyanide. Washing is carried on for about 2 minutes only. SCHLIPPE’S SALT. This solution should be prepared just before it is to be used: Schlippe’s salt 150 grains Water 10 ounces The intensification is very great and yields a nice warm brown tone. ALKALINE DEVELOPERS. Alkaline developing solutions may be used with equally good re- sults for blackening the bleached negative. AMMONIUM MOLYBDATE. A solution of ammonium molybdate and potassium ferricyanide acidified with acetic acid also produces alteration of the image, but the slight Increase in density obtained is not in favor of its use. 87 CHAPTER IV. TONING. Toning is a chemical process in which the black silver image is converted into a colored one. There are two such processes in existence, the first is to bleach the image in the usual manner already described, using preferably any of the ferricyanide solutions given, then transfer- ring the bleached print into the toning solution after which it is washed and dried. The second process consists of preparing a combined bleach- ing and toning solution in which the print is steeped until the desired tone is obtained. The solution of the latter process unfortunately does not keep well and is sensitive to light. The former process is easily controlled and keeps indefinitely. Before the toning is carried on a word or two regarding the prints proper will not be amiss. The prints must be perfectly free from hypo and other chemicals, otherwise the tone will not be perfect throughout. Prints should be fully exposed but slightly under developed, as all the toning solutions will intensify the print and produce flat images and clogged high lights. After toning is finished the print should be washed and dried. SEPIA TONES BY SULPHIDING. We will begin with the sepia tone, since it is the most popular and pleasing of all tones. The majority of the methods employed at the present day for sepia toning are based upon the conversion of the silver image into that of silver sulphide. The silver image is first converted into some insoluble salt upon which the sulphide solution can act. Any of the bleaching solutions already given will answer the purpose. The sulphide solution commonly used is sodium sulphide, although barium and ammonium sulphide will answer. These solutions are more or less unstable and costly. The formulas about to be described are inex- pensive and the “keeping qualities’’ are excellent. 88 There are a great number of receipes for sepia toning, but, how- ever, that process in which the print is bleached and afterwards toned is by far the best. The bleached and well washed print is steeped in: Sodium sulphide 4 ounces Water 20 ounces This solution should be made up before it is used. This stock solution should be diluted by taking of it 3 ounces with sufficient water to make 20 ounces. In the course of a few minutes the prints change from a buff or very light brown to the desired sepia tone. The prints are then rinsed in water for a few minutes and dried. SEPIA TONE WITH HYPO-ALUM. Another popular process for sepia toning is the so-called hypo-alum solution. This consists of: Hypo 1 J /2 pounds Alum 3 ounces Water (hot) 40 ounces Bring the solution to a boil and permit it to simmer for 1 0 to 1 5 minutes. To this solution is added 20 grains silver nitrate. The toning process is carried on at about 1 20 deg. F. The best results or tones are had with those prints which were previously developed with Amidol. SEPIA TONES WITH SCHLIPPE’S SALT. The print is first bleached and well washed in running water for a short while, this is then transferred to: Schlippe’s salt 1 ounce Water 20 ounces This latter solution causes the print to turn to a yellowish red color, when it is placed directly into a 5 per cent, solution of ammonia to soak for a few moments. Again washing in running water, it is placed in the final toning solution consisting of: Copper chloride (10 per cet. solution) 1 ounce Hydrochloric acid ( 1 0 per cent, solution) .... 1 ounce Water 20 ounces 89 , . A half hour immersion in this solution results in a handsome sepia or rich brown tone, when it is finally washed and dried. The advantage of this process is that the objectional odor dfc the sulphide solution is absent. SEPIA TONE WITH ARSENIC ACID. Dr. Kropf (Photo. Rund. vol. 6, page 97, 1913) has discovered that arsenic acid would produce a rich sepia brown tone in about 20 minutes. The solution he recommends coiwists of: Potassium bichromate 1 ounce Citric acid ( 1 0 per cent, solution) . . 1 ounce Arsenic acid ( 1 0 per cent, solution) . . I ounce Water 12 ounces The silver image k con^ierted into that of silver arsenide. The function of the potassium bichromate is to hasten the action of the arsenic acid, which it does presumably by first forming silver chromate which is more readily susceptible to the arsenic acid than the silver itself. Great care must be taken in handling this solution as it is extremely poisonous. SEPIA TONES WITH SELENIUM. Namias bleaches the print and afterwards washes thoroughly and transfers the print to the following solution for a: Purple Brown Tone Water 20 ounces Sodium sulphide 30 ounces Selenium 3 grams The solution must first be filtered before being used. BROWN TONE WITH STANNOUS CHLORIDE. The bleached image is washed in water once or twice and a selu- tlon of sodium stannite then poured over it. The image appears rapidly. The stannite solution consists of: Stannous chloride 155 grains Water 3J/2 ounces To which is added 18 c. c. of a 40 dig. Be; sodium hydroxide solution and sufficient water to make in all 8^ ounces. Besides intensifying the image a brown tone is obtained. 90 BROWN TONES WITH URANIUM NITRATE. With potassium ferricyanide, uranium nitrate yields a brown solu- tion, containing uranyl ferrocyanide and potassium nitrate, thus: K6Fe2Cni2+UO (N03) (UO’^) 3Fe2Cn^2_^6KN03. A typical solution being: Uranium nitrate 40 grains Potassium ferricyanide 40 grains Acetic acid 27 minims W ater 10 ounces The negative is bleached, intensified and toned in the above solution. This is due to the silver image becoming converted into silver ferrocyanide, uranyl ferrocyanide being simultaneously formed. Thus: 2 (U02) 3Fe2Cn^2+2Ag2=Ag^FeCn6+3 (UO'3) 2FeCn6. Uranium nitrate is but little used, as it gives the negative (when bleached) and the print a yellowish color, intensification is very rapid and bright reddish tones are obtained. The simplest way to dispose of the coloration is to steep the negative or print in a 5 per cent, solution of ammonium sulphocyanide for a few minutes previously to the final washing. Since the brown uranyl ferrocyanide is not completely insoluble in water, negatives so intensified must not be washed for too long a time, otherwise the uranyl ferrocyanide will be washed away and the intensification will consequently disappear. RED TONES WITH COPPER SULPHATE. The well washed print is placed in: Ammonium carbonate 100 grains Potassium ferricyanide 20 grains Copper sulphate 10 grains Water 2 ounces A clear dark solution results; this gives a red chalk tone in about 3 minutes. The toning is carried on until the deepest shadow is con- verted, after which the print is again washed for about 1 0 minutes. Here is another toning solution. This one gives dark red prints. It consists of: 91 Potassium ferricyanide . . . 2-3 ounce Potassium permanganate . . . . . . 51/2 grains Ammonia (sp. gr. .91) K 2 ounce Copper sulphate . . . 1 ounce Sodium citrate • ■ . 2/2 ounces Water . . . 1 gill To remove the pinkish tints in the high lights place the print in: Ammonia (strong) 30 drops Water 6 ounces The print is again washed in water and dried. '' RED TONES WITH COPPER CHLORIDE. Dr. Namias finds that the tone can be greatly improved by using the following solution: Copper sulphate 1 ounce Sodium chloride 90 grains Hydrochloric acid 50 minims Water 20 ounces In this solution the silver ferrocyanide is converted into silver chloride and copper ferrocyanide is formed, which increases the red color of the print. This is attained in a few minutes, about five at the most. The prints must be well rinsed in water and then dipped into a 1 0 per cent solution of hypo containing 5 per cent of boric acid. In this the silver chloride dissolves. The prints obtained by this process are much more brilliant in red than those obtained with the ordinary copper solutions. CRIMSON TONES WITH GOLD CHLORIDE. By placing the sulphide sepia toned print in a gold chloride solu- tion, beautiful crimson tone is obtained: Gold chloride 2 grains Ammonium sulphocyanide 20 grains Water 20 ounces 92 The toning process is gradually built up from that of a red hue to that of crimson, taking in all but 5 to 1 0 minutes. When the desired tone is reached the print is washed for a few minutes and then transferred for a minute or two in a hypo solution consisting of: Hypo 3 ounces Water 20 ounces After which the print is again washed in running water and allowed to dry. LIGHT BLUE TONE. Example /. A single blue toning solution consists of: Ferric ammonia citrate 100 grains Potassium ferricyanide 100 grains Acetic acid 20 c. c. Water . 8 ounces LIGHT BLUE GREEN TONE. Example 11. Ferric chloride 3|/2 grains Ferric oxalate 6|/2 grains Oxalic acid 6*/2 grains Potassium ferricyanide 3 grains Water 8 ounces These solutions have a tendancy to intensify the print, for this reason it should be toned with care. BLUE GREEN TONE. Example 111. The well bleached print is washed and placed in: Cobalt chloride 10 grains Hydrochloric acid 30 c. c. Water 10 ounces This solution will keep well for a long time in amber colored bottles. 93 GREEN TONE. Example I. The following solution is found to give nice warm green tones: Ferric chloride 10 grains Oxalic acid (saturated solution) . . \]/^ ounces Vanadium chloride 20 grains Nitric acid 50 minims Water to 5 ounces This solution keeps fairly well. GREEN TONE. Fox and Hickey are granted United States patent 1166123 for the following green toning solution: Vanadium chloride 20 grains Ferric ammonium oxalate 10 grains Ferric chloride 10 mmims Potassium ferricyanide 20 grains Acetic acid (glacial) 10 minims Oxalic acid 100 grains Water to 20 ounces After the toning is complete the washing is done in running water and the print is allowed to dry. By bleaching the print and placing it in any of the following solu- tions the respective tones indicated are obtained: Orange Tone. Mercury chloride 3 grains Potassium iodide AYl grains Water 10 ounces Yellow Tone. Potassium chromate (neutral) .... 4 grains Water 10 ounces 94 Green T^one. Immerse the yellow toned print in: Iron perchloride 1 grain Water 1,0 ounces The toned print is then washed in running water and dried. TONING WITH ORGANIC DEVELOPERS. On page 26 is described a series of compounds that develop and tone the image simultaneously. The following formulas are recom- mended by Dr. Fischer, the inventor, as giving good results: Greenish Blue Tone. Trichlor alpha naphthol 2 grams dissolved in Acetone 20 c.c. being added to Para phenylenediamine hydrochloride . 2 grams Sodium hydroxide 30 grams Water 20 ounces Blue Tone. Alpha naphthol 2 grams dissolved in Acetone 20 c.c. being added to Dimethyl para phenylenediamine hydrochloride 2 grams Sodium hydroxide 2 grams Water 20 ounces Red Tone. Thio indoxyl carboxylic acid 2 grams dissolved in Acetone 40 c.c. being added to Mono ethyl para phenylenediamine hydrochloride .... 2 grams Potassium hydroxide 40 grams Water 20 ounces 95 Yellow Tone. Alpha chlor ethyl aceto acetate 2 grams dissolved in Acetone 20 c.c. Diethyl para phenylenediamine 2 grams Potassium hydroxide 40 grams Water 20 ounces Homolka (Photo. Korr., page 471, 1914) points out that with monomethyl naphthoquinone ether a deep blue image can thus be ob- tained. The working formula is: Monoethyl naphthoquinone ether .... 10 grams Potassium bromide 10 grams Sodium hydroxide grams Sodium sulphite 50 grams Water 20 ounces The image appears in a few seconds and development is complete \ in about three minutes. On fixing the color is brought out. I DYE TONING. | *■ There is still another process of toning. This consists of mordant- i ing dyes onto a bleached image. The advantage of this process is that I the colors are more transparent and they do not Intensify the print; > furthermore a greater range of colors may be had for use. It is used practically in toning motion picture films and in certain color photo- graphic processes. Of the basic dyes the following is found to give the best results. Red Dyes. Fuchsine (Magenta), Quinoline red, Rhodamine B, Phenosofra- nine. Xylene red. Acridine red B, Acridine Orange. > i Yellow Dyes. ^ Auramine, Chrysoidine, Safranine, Bismarck Brown. ^ Green Dyes. Methylene, Brilliant, Malachite, Janus, Iodine, Emerald, Dia- ^ mond, Victoria and Guinea green. 96 Blue Dyes. Methylene blue, Aniline blue, Victoria blue, Thionin blue, Tolui- dine blue, Turkey blue. Gentian violet. Methyl violet. Crystal violet. Various intermediate tones can be obtained by mixing any of the above dyes in its proper proportions. Namias. Brit. Jour, of Photo., page 69, 1909. The print is bleached in a lead ferrocyanide solution, this is con- verted into a lead sulphate by placing the print in the following solution: Sodium sulphate 1 ounce Sulphuric acid (by weight) 45 grains Water 20 ounces Onto this is mordanted any of the dyes already given. The dye is preferably mordanted by means of a one per cent, solution of copper sulphate and then washed in a concentrated hypo solution containing 7 per cent, boric acid. In place of the lead sulphate the ferrocyanide image is placed in a one per cent, solution of potassium hydroxide. After washing the dye can be fixed on this image. Since lead hydroxide is less opaque than the sulphate, there is, as a general rule, no need to remove it from the image. Tauleigne and Mazo. United States patent 1059917, April 12, 1913. The well washed print is placed in a solution of copper chloride. The silver image is seen to change to a white color, being transformed to a double silver chloride and copper. It is then washed in running water and then placed into a one or two per cent, solution of potassium iodide, the image assumes a greenish white color. The print is placed in any of the dye solutions enumerated, after which it is washed in water made acid with acetic acid. The print is fixed in a 20 per cent, solution of potassium iodide, or in a 3 to 10 per cent, solution of tannin and afterwards washed in a solution of hypo and fixed in a 1 0 per cent, solution of potassium cyanide. This is again washed in an acidulated (acetic acid) solution and then in running water. 97 Traube. United States patent 1 093503, April 14, 1914. The print is converted into silver iodide by placing it in the bleach- ing solution described under Example VI and then transferred to a dye solution, after it is fixed in the ordinary hypo solution. Miller. United States patent 12‘14940 Feb. 6, 1917. The well washed print is bleached in the solution given under Example VI and cleared in sodium bisulphite; the toning is done in an acid dye solution until the desired tone is obtained, washed and dried. Crabtree. United States patent 1279276, Sept. 17, 1918. The method of procedure was to first tone the image in the copper toning solution, wash and dyed until the desired tone is obtained. The copper toning solution consists of: Copper sulphate 16 grams Ammonium citrate (neutral) .... 50 grams Potassium ferricyanide 16 grams Ammonium carbonate 8 grams Water to 1 gallon The toning should be carried on for about 5 to 1 5 minutes at 70 deg. F. It is important to keep the bath covered when not in use so as to exclude the light, since the solution is light sensitive. After washing, it is immersed in the dye solution, a specific formula advocated is: I Fuchsine 4 grams Acetic acid (gliwiial) 20 c.c. Water to 1 gallon Of course any dye may be used in the place of the one given. The dyeing is carried on for 5 to 1 5 minutes ; wash until the high lights are clear. > 98 Compound Tones. By first partially toning the print in a copper solution so that the half tones are completely toned but the shadows only partially, washing for 10 minutes and then completing the toning process in a blue toning solution, the residual silver in the shadows is toned blue. In this way a double tone is obtained, the shadows appearing dark blue and the half tones reddish brown. By immersing the toned print in any of the dye solutions and washed, the dye will mordant itself to the half tones producing a striking double tone effect. A suitable blue toning solution suggested is: Potassium bichromate 0.1 gram Ferric ammonium sulphate 5 grams Oxalic acid 12 grams Potassium ferricyanlde 4 grams Ammonium alum 20 grams Hydrochloric acid ( 1 0 per cent) . . 4 c.c. Water to 1 gallon The print should be washed after the toning process is completed. Ives. United States patent 1 278668, Sept. 10, 1918. The well washed print is placed in the bleaching solution des- cribed as Example IV and transferred immediately to running water and allowed to remain therein for about a half hour or more to free the print from the excess chromic acid, but discharges rapidly in a weak solution of sodium bicarbonate. The print is then dyed in any of the dye solutions until the desired depth has been obtained, the high lights are cleared by placing the print in a weak acetic or hydrochloric acid solution. The print is then washed in running water and allowed to dry. 99 CHAPTER V. THE DIAZOTYPE PROCESS. There are several printing processes based on the peculiar property possessed by certain diazo compounds when exposed to light is decom- posed and by development will produce prints in a great range of colors or dyes. These colors vary with the particular developer used. In Europe several large concerns manufacturing table cloths and tapestries are using these processes for the designs found as borders. It is not used in photography as the process is somewhat difficult and the high lights are not altogether clear. But, however, it is interesting enough to ex- periment with, in the possibility that someone may find a simplified process. Green, Cross and Bevan. Jour. Soc. Chem. Ind. page 1001, 1890. A sheet of paper (or other surface as cloth, etc.) is impregnated with a diazo compound of Primuline and on exposure to the sun through a negative the following colors will be obtained on development with: Beta naphthol Red Beta naphthol disulphonic acid Maroon Phenol Y ellow Resorcinol Orange Pyrogallol Brown Para phenylenediamine Brown Alpha naphthylamine Purple Eikonogen Blue The sensitising solution consists of: Primuline 320 grains Water (hot) 20 ounces This is then steeped in the diazotising solution: Sodium nitrite 64 grains Hydrochloric acid 150 minims Water to 20 ounces 100 Transparencies and opals can be made by coating the cleaned surface with: Primuline 80 grains Gelatine 480 grains Alum . . 2 grains Water 50 ounces This process should be carried out in the dark and allowed to dry in a place free from dust. After it is thoroughly dried it is exposed to the light under a negative until the bare glass is colorless. Then wash thoroughly and develop in: For Red Tone. Beta naphthol 9/2 grains Sodium hydroxide 128 grains Water to .20 ounces For Purple Tones. Alpha napththylamine 190 grains I hydrochloric acid 1 ounce Water to 20 ounces For Blue Tones. Eikonogen . 125 grains Water to . 20 ounces For Brown Tones. Pyrogallol . 113 grains Water to . 20 ounces Wash well after development and dry. The high lights will be found to be blocked ; there is no method of clearing this as yet. Peer, in a communication to the Mulhouse Soc. describes the use of the following diazo sulphites to give the colors indicated: Aniline Orange Toludine e Orange Xylidine: Red Cumidine Red Benzidine Violet Tolidine Violet Dianisidine Blue Here are typical solutions used : 101 Peer, in a communication to the Mulhouse Soc. describes the use of the following diazo sulphites to give the colors indicatad: Aniline Orange Toludine Orange Xylidine Red Cumidine Red Benzidine Violet Tolidine Violet Dianisidine Blue Here are typical solutions used: ( 1 ) Sodium toluol diazosulphite 240 grains Beta naphthol 240 grains Sodium hydroxide 76 grains Water to 20 ounces (2) Sodium ditolyl tetrazosulphite 240 grains Para phenylenediamine 190 grains Water 20 ounces (3) Sodium ditolyl tetrazosulphite 240 grains Resorcinol 211 grains Sodium hydroxide 154 grains Water 20 ounces On the exposed parts an insoluble dye is formed, whilst on the unexposed parts the compounds remain colorless and is soluble in water. The print is fixed in a solution of hydrochloric acid. Andresen discovered in 1 894 another diazo printing process, the sensitiser is the diazo compound of alpha naphthylamine or Beta naph- thylamine, the former giving brownish grey images and the latter brownish red. If the print is treated with tetra azodiphenyl ether, violet images are obtained. Here is typical solution Andresen used: Alpha naphthylamine 220 grains Hydrochloric acid (sp. gr. 1.1 9).. 152 grains Water (boiling) 5 ounces 102 This is stirred and allowed to cool, an evolution of gas will take place clhd a yellowish solution is formed which mu3b be filtered into an ice cold dish. Apply this to the surface and dry in the dark. Expose for 2 to 3 minutes under a negative in the sun and develop in a 1 0 to 20 per cent solution of fused sodium acetate and wash well and dry. Another process suggested by Andresen consists in the use of diazotised benzidine sulphate, which is made as follows: Pyridine (base) 110 grains Water (boiling) 10 ounces Then add Sulphuric acid 180 minims Water 180 minims Benzidine sulphate is formed and partially separates out. Cool this solution to about 1 1 0 deg. F and add ; Sodium nitrite 66 grains . Wafer 1 ounce in small quantities with continuous stirring. The benzidine sulphtete is dissolved and diazotised and dissolves. Filter the solution and pour into five times its volume of alcohol, which precipitates the diazo compound, filter out the precipitate and dissolve (without drying, as it explodes when dry) in: Water to 20 ounces The paper is sensitised in this cold solution for two minutes, dried in the dark and exposed under a positive or transparency and then developed in a 2 per cent solution of amido naphthol sulphbnic acid containing 2 per cent of sodium hydroxide. Deep blue images with pure whites are obtained. Lumiere and Seyewetz, in 1895, took up the study of the com- binations indicated by Feer in order to obtain simple mono chromes in blue, red and yellow so that they could be used in a three color process. The following are the solutions employed for the three primary colol-s: 103 YELLOW Diazo ortho toluidine sodium sulphite 2 grams Meta amidophenol 1 gram Water 100 grams The plate is steeped in this solution and dried. RED (A) Tetra azotolyl sodium sulphite. . . 1 gram Water 125 grams (B) Beta naphthylamine ether hydrochloride . . .125 grams Water 125 grams The plate is steeped first in “A” and then in “B” and dried. BLUE (A) Tetra azoethyl oxybenzidine sulphate 1 gram Water 125 grams (B) Alpha naphthylamine ether hydrochloride. . 2Yl grams Water 125 grams The material is steeped first in “A” then in “B” and dried. It is difficult to obtain a pure blue, but the mixture above gives a blue very slightly violet in shade. Schoen in 1 900, patented a process based on the property of amido salicylic acid and its derivitives to furnish diazo compounds transformed by the sunlight into red colors. Ortho amido salicylic acid is dissolved in dilute hydrochloric acid and this solution is treated w^ith its molecular equivalent of sodium nitrite. The diazotation product precipitates and is filtered off and washed. It is a yellow substance, soluble in water and alcohol and very soluble in alkalies. It turns rapidly to red under the action of the sunlight. The material to be coated is steeped in a solution of this product in dilute ammonium oi sodium hydroxide precisely neutralized. The material is then dried at the ordinary temperature in the dark and it is exposed under a negative until the print shows red. It is fixed by sijnply washing in water or some other solvent until the yellow tint of the untransformed product is com- pletely dissolved and disappears. The red print is fast to the sun light. 104 The product of the diazotation of amido salicylic acid in the state of an alkaline salt is still more sensitive to the sun and gives brighter tints. The diazo product of para brom amido salicylic acid is orange and is very stable in the dark. Under the action of the sun it gives a bright and very fast orange, which is fixed by simply washing in cold; water from three to five minutes. The diazo para nitro ortho amido salicylic acid is yellow, but it is too unchangeable in the sunlight to be of any practical value. All these colored products take different tints if they are treated with lime water or solutions of cobalt nitrate, ferric chloride or lead acetate. Gros, in 1901, took out a F rench patent for a process of obtaining photographic prints by means of a leuco base of the triphenylmethane color is regenerated under the action of the sunlight and their sensitive- ness can be increased by divers products, notably by the silver salts. As an example, the plate is impregnated with a 5 per cent solution of a leuco base of Fluorescein in ether. By exposure under a negative this gives a red positive. Ruff and Stein in 1901 find that the diazo derivitives so far pro- posed lack in snap and that the high lights are blocked. The processes are also difficult to prepare and work. They recommend in place of the unstable diazo carbazol the stable compound which it forms with certain metallic salts, principally with zific chloride. If, instead of using a positive, the exposure is to be made under a negative the plate sensitised with 3-carbazol diazo sodium sul- phonate. In 1 906 La Moniteur Scientific published a patent granted to Meister, Lucius and Bruning, which consists of mixing a leuco base with compounds containing nitrogen and oxygen groups that are easily 105 eliminated by catalysers. As an example the following is recommended : Leucaniline 10 grams Alcohol 20 grams Ether 20 grams Collodion (4 per cent.) 50 grams This preparation is coated over the surface and dried in the dark. Expose to the sun under a negative, at the end of a few minutes ex- posure the print is colored red, this is fixed by washing in chloroform or carbon tetrachloride. The sensitiveness of the preparation can be in- creased by the addition of platinlc chloride and turpentine, and, accord- ing to the leuco base employed, prints of various colors are obtained. The leuco basic salts of the Malachite green series give green and blue tints and those of Flavaniline and Auramine give yellow prints. Damlanovich and Guglialmeth in 1 909, had the idea of beating albumen up with its own volume of water and filterering. The filtrate is then spread over the surface and dried slowly at the ordinary temp- erature, then sensitised in a cold solution of sodium nitrite in hydrochloric acid in the dark for several hours. The strength of the solution is 2 per cent. The prints thus treated are washed carefully and dried slowly in the dark. The albumen takes an intense yellow tint, unstable in the sun and in decomposing takes a pale green tint. Under the action of phenol in alkaline solution, or a phenolic amine in acid solution, this is transformed into a coloring matter with analogous properties to those obtained by coupling diazo compounds with the same phenols or amines. Baudisch in 1911, noted that when a fibrous material is impreg- nated with a solution of ammonium alpha, nitroso naphthyl hydroxyla- mine and steamed, the fibre takes a light yellow or dark brown color. If it is then exposed to the sun light this is turned to a fast red. The color is brighter if the steaming has been done in the presence of formic aldehyde. 106 A process using Indigo published in the bulletin of the Mulhouse Soc. is in the nature of a decoloration process. The following mixture is spread over the surface of the plate: Indigo salt 7.5 grains Sodium bisulphite 0.01 grains Sodium hydroxide 1.0 grains Gum water 300.0 grains Water 4.0 grains The fibre is then dried in the dark and exposed under a negative for an hour at the least. The exxposed parts turn yellow to begin with, then brown. The print is developed with sodium hydroxide of 1 5 deg. Be. at 60 deg. C. 107 CHAPTER VI. DIRECT POSITIVES. The production of positives instead of the usual negatives is of great importance to those practising with the Autochrome and similar color photographic processes. There are a number of methods in use for converting the negative into that of a positive, of these there are only two that give satisfactory results and are given herewith. Col. Waterhouse first described the use of thiocarbamide (CS (NH^) as having given satisfactory results. The formula he made use of is: Lithium carbonate 50 grains Sodium sulphite 50 grains Eikonogen 50 grains Thiocarbamide (saturated solution) 3 drops Water 10 ounces The negative appears as usual and then it apparently assumes a fog all over the surface, this is then exposed to diffused light and re- placed in the developer; after three or four minutes the positive image is clearly seen. This is then fixed and washed. 108 Recent exxperiments by Perley (Jour. Phys. Chem. vol. 1 3, page 649, 1 909) with thiocarbamide and Hydroquinone show better results. Herewith is the formula he made use of: (A) Water 20 ounces Sodium sulphite 126 grains Hydroquinone 21 grains (B) Water 20 ounces Sodium carbonate 126 grains Add 20 c. c. of a concentrated thiocarbamide solution to 25 c. c. of solution A and 25 c. c. of solution B. The tetra thiourea ammonium bromide recommended by Col. Waterhouse, but apparently not tried by Perley or other investigators, is very much superior to the plain thiourea, giving clearer and better positives. The following is the formula used: (A) Water 6% ounces Sodium sulphite 390 grains Hydroquinone 65 grains (B) Water 6J4 ounces Sodium carbonate 830 grains (C) Water 34 ounces Tetra thiourea ammonium bromide 15.5 grains For use take one part A, one part B and two parts C. With the exception of the temperature, the development is the same as for other negatives. The temperature is absolutely essential to the successful working of the process. The limits are 59 to 64 deg. F ; and they must be strictly adhered to. The corresponding chloride, however, appears to be better still and works without a restrainer (potassium bromide) . The iodide is not satisfactory. , 109 Satisfactory postitives were obtained with an Adurol developer containing a rather large amount of alkali, but with Amidol the results were unsatisfactory. The effect of Metol is very peculiar. A small amount of it added to the regular Hydroquinone developer increases very much the density of the negative image. Hybrides generally result, although by decreasing the exposure very much and developing for a short time, some rather poor positives would be obtained. All these compounds were prepared according to the directions of Reynolds (Jour. Chem. Soc. vol. 59, page 384, 1891), The manufacturers of the Autochrome plates advocate the follow- ing: Potassium permanganate 18 grains Sodium bisulphite 1 ounce Water 20 ounces The method of precedure is the same as with thiocarbamide salts. CHAPTER VII. RECOVERY OF SILVER FROM HYPO. ^The largest use of silver at the present day is in photography. It IS natural that a considerable amount should find its way into silver refining and sweeps trade. It may be said, however, that a smaller per- centage is obtained from photographers than should be produced for the reason that many photographers make no attempt to save their solu- tion, but throw them away regularly. This fact is quite true of a large percentage of those who work with dry plates and films, and especially those who do developing for the amateur trade, as they are not familiar with the method of saving the silver or disposing of it after saving it. With the old wet-plate process, photographers were compelled to save their silver wastes, for the reason that it amounted to a very large quan- tity and was of a character that could readily be reclaimed. The v/et- plate process is now used only to a limited extent and is almost confined to the photo-engravers’ trade; practically every professional photo- grapher now employs the dry plates which have, as every one knows, been the cause of the present popularity and enormous growth of both professional and amateur photography. Had it not been for the advent of dry plates the art of photography would never have been what it is today. The methods for recovering the silver from photographers’ solu- tions herein given apply only to dry-plate work, as the wet-plate process is used so rarely that it is unnecessary to consider it as a factor in the matter of silver saving when carried out according to the method here- with described. “Hypo” Solutions the Only Ones Worth Saving The modern photographer, who uses dry plates, has quite a number of solutions, but the principal ones are the two following: 1 . The developer. , 2. The fixing solutions. The other solutions are of little importance as they are seldom used and contain no silver. These solutions are generally employed ibr reduction or intensification of the silver image on the plate and cannot be considered. The developer is the solution used to bring up the image on the exposed dry plate and contains no silver when fresh and unused. After using, it contains traces of silver, but not of sufficient quantity to warrant saving. The developer, therefore, is of no value and should not be saved. After the developer has brought out the image on the dry plate there still remains the bromide of silver that has not been acted upon by the light during the exposure of the plate through the lens in ttie camera. 1 he portions of the plate that have been acted upon by the light are reduced by the developer and are converted into metallic silver, which constitutes the image. The portions unacted upon by the light are not reduced by the developer and thus remain as bromide of silver. When the developing process is completed the dry plate must be “fixed,” and this consists of soaking it in a solution of hyposulphite of soda, as it is usually called “hypo.” This material has the property of dissolving the bromide of silver, but does not dissolve the black metallic silver formed as the image by the developer. In this manner, 112 therefore, all the silver unacted upon by the light, and which is in the form of bromide of silver ig dissolved from the plate, leaving untouched the black reduced silver comprising the image. (The plate, of course, is coated with gelatine remains on the surface of the glass.) A glass negative, therefore, that has been developed and fixed, as well as washed and dried, contains the image in the form of silver imbedded in thej gelatine. The “fixing solution” or that used to dissolve the unacted-upon bromide of silver from the plate, is the only one that contains sufficient silver to be worth saving. This fact should be impressed upon photo- graphers, many of whom save all solutions, so that only the fixing bath will be retained. If this is done the operations are somewhat simplified. What the hypo solution is The so-called “hypo” solution, used for dissolving the bromide of silver on the dry plate that has been unacted upon by the light, consists of a nearly saturated solution of hyposulphite of soda (sodium thiosul- phate) in water. It is frequently used alone, but more often contains alum. The alum is used in connection with it to harden the gelatin on the glass and prevent it frilling at the edges. The use of alum is now extensive and nearly all photographers employ it. In addition to the alum (either ordinary alum or chromic alum may be used) small quantities of acetic acid, sulphuric acid, sulphate of soda, oxalic acid or other weak acids are employed to render the solution slightly acid. The principal ingredient, however, is the hyposulphite of soda, and it is this substance which dissolves the bromide of silver. It is customary for photographers to use their hypo solutions until nearly “exxhausted,” so to speak, or until they work slowly. They are then discarded and new ones made up. 113 Recovering the Silver from the “Hypo" Solution As the hypo solution is the only one used by photographers which contains sufficient silver to pay for treatment, it is upon this, therefore, that we must concentrate our attenion. The removal of he silver is simple. The first thing to do is to render the hypo solution slightly alkaline by the addition of a little carbonate of soda solution. Add just enough to make slightly alkaline. In other words, red litmus paper should turn blue when wet with it. Now add a little solution of liver of sulphur in water to this hypo solution and allow it to stand in a warm place for a short time. The liver of sulphur will precipitate immediately, but takes a few minutes to form, and if warmed the formation takes place more rapidly. Its formation can be seen by the presence of black flocks of sulphite off silver, which settle down to the bottom of the vessel. When the top of the solution is clear, add some more of liver of sulphur solution and see if a sufficient quantity has been adde'd to precipitate all the silver. If not, add more. The idea is to avoid adding too large an excess of the liver of sulphur, although a moderate excess is not harmful. When enough liver of sulphur has been added to precipitate, or “throw down,” all of the silver in the hypo solution the whole should be allowed to stand in a warm place for about an hour to give it an oppor- tunity to settle. tA the end of this time the black sulphide of silver will be found on the bottom of the vessel. The clear solution at the top, should be tested with liver of sulphur to make sure there is no silver left, and if this is the case it may be siphoned off and thrown away. The sulphide of silver on the bottom should be washed off with water, by stirring up with clear water and then allowed to settle. The clear liquid is again siphoned or poured off and the washing operation repeated. This may be carried on several times, and the whole poured onto a filter paper in a large glass funnel and the silver sulphide filtered out. While on the filter it should be washed several times with clear water. If everything has been done well there is obtained a mass of fairly pure sulphide of silver in the moist state. This should be dried. Pure sulphide of silver contains 87.09 per cnt. of mtallic silver. If one desires to reduce this to metallic silver, the best way is to dissolve it in diluted nitric acid, filter off the sulphur that separates, and precipitate the metallic silver by means of copper, sheet or wire. Such a procedure, however, is not advisable, as the sulphide of silver is always salable and is readily purchased by silver smelters and refiners. They do not, however, as a rule, like to purchase the hypo solution, for the reason that it usually does not contain sufficient silver in the manne^r described, therefore, the silver sulphide obtained, even when wet, is so rich that it will pay transportation to a long distance. The operation of precipitating is so simple that photographers can do it at frequent inter- vals and gradually accumulate the sulphide of silver, so that when it has reached a sufficient amount it can be sold to silver smelters. Or, if it is not desired to sell it, the silver can be reduced as previously mentioned. It will, it is believed, be found preferable to sell the sulphide of silver, for the reason that there is no use for either metallic silver or nitrate of silver in the photographic studio when dry plates are employed. 115 CHAPTER VIII. PHOTOGRAPHIC BRONZE AND PLASTER PLAQUES. In 1861 M. Willeme was successful in making plaster casts in relief from photographic negatives. To carry out this process a series of cameras was required as well as various devices such as pantographs to make the impression in the plaster. This process fell into oblivion, inasmuch as it depended too much on the skill of the photograph-sculptor for the best results. Other attempts were made, and these again proved a fialure. Eventually the well-known swelling property of so-called “bichromated gelatine” was adopted. The process involved is quite simple, and consists of eight succes- sive steps in the production of a photograph in bas-relief, either in plaster- of-paris or in copper. These are as follows: 1 . Secure a good sharp negative (of a head) in profile. 2. Make a print in the bichromated gelatine. 3. Swell (or develop) this latter plate. 4. Mordant roharden the image. 5. Make a plaster negative or impression. 6. From this latter secure a duplicate in wax. 7. Coat with graphite. 8. Electroplate with copper. 1 16 making the gelatine plate. Use an enameled iron pot and into it place V/i ounces of Nelson's soft gelatine, 1 0 ounces water (distilled) , and 6 drops glycerine. Allow the mass to stand until the gelatine swells and becomes soft. Then heat the pot (preferably in a water bath) until the mass dissolves, taking care, however, that the temperature does not exceed 120 deg. F. When the mass is entirely dissolved add 1 50 grains of potassium bichromate and 75 grains of ammonium bichromate, stirring thoroughly and keeping the solution at 1 20 deg. F. Then filter it through muslin into a glass graduate that has been heated to 1 30 deg. F. All this must be done in a dark room, using only a ruby lamp for light. In the meantime a piece of glass about 5 by 7 inches in sizQ and inch thick is ca’refeully cleaned and warmed; this plate is coated with the gelatine solution. Great caie must be taken that the coating is not put on in streaks and does not run over the edges. The gelatine- coated plate is then placed in a dark room or box and allowed to dry. The temperature of the room must be about 95 deg. F. The best results are obtained with plates coated at the rate of three ounces to each plate. Leave the plates to age for three days. Secure a good, sharp photographic negative, preferably one of a head in profile, and expose the gelatine-coated plate through this for about fifteen minutes to direct sunlight or for one hour to ordinary dif- fused daylight. After exposure remove the plate from the printing-frame, and place it face up in a dish of clean, cool water. The gelatine will mediately begin to swell. The parts of the gelatine film that have not been acted upon by light wall absorb water and swell up. The other parts, which correspond to the transparent portion of the negative and which have been acted upon by light, have become insoluble and will not be affected by the water, so that they remain at their original level. The progress of the swelling can be ascertained both visually and by feeling with the tip of the finger. Should the swelling be allowed to proceed too far, the edges of the lines will absorb water, and in the finished print the surface will be con- vex. If not swelled sufficiently the relief will be shallow and the lines slightly concave. When it is judged that the relief is sufficient, remove the plate from the dish, and, after washing under the tap, place it in another dish containing a hardening solution made up of 36 ounces water, ]/2 ounce chrome alum, and ounce citric acid. After remain- ing in htis solution from three to five minutes, remove the plate and wash it thoroughly. Lay the plate on a level slab, and place iron bars ^2 inch in thickness about one inch from the edges of the glass and parrellel with them. The bars should be well greased with lard or oil to prevent the plaster sub- sequently used from adhering to them. - THE PLASTER CAST. Now prepare the plaster-of-Paris (grade XXX) by pouring a lit- tle water into a basin and adding the plaster until it is the consistency of treacle. To this add a handful of powdered alum. It is best to' pass the plaster through a fine sieve to remove any large or rough par- ticles of foreign matter. The mixture should be well worked up with a wooden spoon, or stirred, and this should be done rapidly, or the plaster will set during the operation. As soon as it is mixed, carefully pour the plaster upon the swelled gelatine print until the space between the bars is completely filled and is rather higher than the bars, care being taken to avoid air bubbles. It should be pressed down with a large shallow spoon or spatula. When the plaster begins to set, scrape the surface level with a straight-edge resting on the bars, and when set hard insert the edge of a knife beneath one end to push the glass and cast apart, removing the irons and trim- ming the edges. It is a matter of experience to determine how long to leave the plaster before lifting it from the gelatine print. By pressing 118 the finger on the back the time can be judged. When it takes some pressure to make an impression the cast may be considered ready to lift. Thus is produced a negative in plaster, from which a copy is to be made in wax. Copying in wax is done by removing the moisture from the face of the plaster negative with the aid of a cloth or sponge. The plaster negative is then laid flat and the iron bars again laid in the same position as when the plaster-of-paris was molded. Now pour upon this negative to the height of ^/i inch 8 ounces beeswax, 32 ounces paraffin, and 6 ounces rosin. When this has congealed or hardened separate it with a knife. Now give the wax print, or positive, a surface of fine graphite, and place it in a shallow basin, leaving in it a concentrated solution of copper sulphate. Sprinkle upon the surface of the wax image some fine iron filings. A fine copper film will immediately form on the surface of the graphite. Wash in running water and copper plate in the usual manner. It must not be supposed that this process is to become a competitor of the sculptor, but it is really intended to be a valuable aid to him. It may be commercially used for making signs, medals, cameos, brooches, and architectural pieces. 119 IMPORTATION OF DEVELOPERS. Norton. Department of Commerce report on importation of de- velopers and dye sensitizers for the fiscal year 1913-1914. Compound Pounds Value Para nitrophenol 4780 $ 770 Para amidophenol 10631 1684 hydrochloride 652 189 Para phenylenediamine . . . 11088 3414 Metol 10582 13658 Ortho amidophenol 625 223 Diamidophenol 441 391 Pyrogallol 23615 20476 Hydroquinone 66596 25140 Pinacyanol 40 Pinachrome 30 120 ' NAME AND SUBJECT INDEX PAGE Acetone 95, 96 Acridine orange 96 red B 96 Adurol 59, 74, no Alpha chlor ethyl aceto acetate 96 naphthol 95 trichlor 95 Alum 77, 89 Alpha naphthylamine 1 00, 1 02 ether hydrochloride 104 Amidol 60, 68, 71, 72, 74, 89, 110 Amido naphthol sulphonic acid 103 salicylic acid 104 Ammonia 85, 92 Ammonium alum 99 bichromate 117 bromide 79 carbonate 91, 98 chloride 78 citrate * 98 Molybdate 87 Persulphate 81, 82 sulphide . 85 sulphocyanide 80, 92 Andresen ^ 92, 1 03 Aniline ^91 blue 97 121 PAGE Arsenic acid 90 Autochrome 110 Auramine 96, 106 Barium sulphide 85 Baudisch 106 Beeswax 119 Beta naphthol 1 00, 1 02 disulphonic acid 100 ether hydrochloride 104 naphthylamine 104 Benzidine 101 sulphate 103 Bichromated gelatine 116 Bismarck brown 96 Bleaching 77 with the ferricyanides 79 and intensification 76 Boric acid 92, 97 Brewster 68 Brilliant green 96 Brougham 80 Bronze plaqiKS 116 Calcium chromate 84 Calomel 78 Carnegie 83 Ceric sulphate ^ 84 Chromic acid 79, 99 Chromium 81, 83, 84 dioxide 83, Chrysoidine 96 Cobalt chloride 93 Compound tones 99 122 PAGE Copper lie bromide sulphate . .82. 87, 91. 92, 97, 98 Crabtree Cros Crystal violet Cumidine Cupric chloride Damianovich Deck Desalme Developers, importation of 120 Developing 59 Developers alkaline factors of Diamine 61 Diamond green 96 Dianisidine 101 Diazo carbazol sodium sulphonate 105 ortho toluidine sodium sulphonate. . . 104 Diazotype process 100 Dichroic veil 76 Dimethyl para phenylenediamine . 95 Diphenal 61 Direct positives 108 Duratol 61 Dye toning 96 Eastman Kodak Co 70 Edinol 60, 74 Eikonogen . .61, 62, 74, 100, 108 Emerald green 96 Factor of combined developers 75 123 PAGE Factorial development 7-3 Factor six 75 Farmer’s reducer 80, 81 Feer 101, 103 Ferric ammonium citrate 93 oxalate 94 sulphate 99 chloride 93, 94, 95 Ferrous oxalate 86, 93 Fischer 95 Flavaniline 106 Fluorecein 105 Formaline 77 Fuchsine 96, 98 Gear 80 Gelatine ....... . 117 Gentian violet 97 Glycin 62, 63, 74 Gold chloride 92 Graphite 119 Green dyes 96 Guglialmeth 1 06 Guinea green 94 Flardening 77 Homolka 96 Hunter 81 Hydramine 63 Hydroquinone . .63, 64, 69, 74, 75, 80, 84, 109, 110, 120 Hypo 76, 78, 80, 82, 86, 89, 92, 93, 97, 98, 1 1 2, 114 test for 77 recovery of silver from Ill Importation of developers 120 124 Irdigo salt . . . IntensificalHon . Iodine PAGE green Ives Janus green Lead nitrate sulphate Liesegang Leucaniline Lithium carbonate Lumiere - Magenta Malachite Mazo Meister, Lucius and Bruning Mercurous chloride Mercury chloride iodide Meta amidophenol Methylene blue green Methyl glycin violet Metol 64, Metoqoinone Miller Mono ethyl naphthoquione ether . . . , ethyl para phenylenediamine . . Monomet Mulhouse Soc Namias 107 77, 80 80 96 99 96 82, 83 97 67 106 108 64, 84, 103 96 96, 106 97 105 78 78, 79, 94 78, 79 104 97 96 _ 63 97 65, 66, 74, 75, 80, 110, 120 ; 64, 74 98 96 95 65 107 81, 97 125 PAGE Naphthoquinone ether, monoethyl 96 Norton 120 Ortol 65, 74, 120 Oxalic acid ‘ 93, 94, 99 Para amidophenol 65, 66, 67, 74, 120 Paraffin 119 Para phenylenediamine 68, 95, 100, 120 dimethyl 95 monoethyl 95 Perley 109 Phenol 100 Phenosafranine 96 Phenyl hydrazine 67 hydroxylamine 68 Pinachrome 120 Pinacyanol 120 Piper 83 Plaster 119 cast 118 Potassium bichromate 83, 90, 94, 99, 1 17 bromide 79 cyanide 97 ferricyanide 79, 80, 83, 91, 92, 93, 94, 98, 99 iodide 78, 79, 80, 94, 97 permanganate 77, 80, 81, 82, 92, 110 sulphide 85 Primuline 100 Pyridine 103 Pyrocatechin 69, 74 Pyramidol 68 Pyrogallol 60, 61, 65, 69, 70, 71, 120 acetone 70 soda 70, 100 factor of 74 Quinoline red 96 Red dyes 96 Reducer, Farmer’s 80 Reducin 71 126 Resorcinol Reynolds Rhodamine B Rodinal how it is made Ruff Safranine Salicylic acid, amido Schlippe’s salt Schoen Selenium sepia tones with arsenic acid selenium sulphiding hypo-alum. Schlippe’s salt .... Seyewetz Silver iodide nitrate sulphide recovery of, from hypo Sodium chloride citrate ditolyl diazosulphite tetrazosulphite . ... nitrite phosphate stannite sulphate sulphide sulphite Stannous chloride Stein . Synthol Tauleigne Tetra azoethyl oxybenzidine sulphate azotolyl sodium sulphite .... thiourea ammonium boromide . 127 PAGE 100 , 102 100 96 61 , 65 , 67 , 71 , 72 , 74 71 105 96 104 87 , 89 104 90 90 90 88 , 92 89 89 103 98 86 115 Ill 82 , 92 92 102 102 100 , 103 79 90 97 85 , 89 , 90 79 , 85 90 105 72 ,97 104 104 109 PAGE Thiocarbamide Thioindoxyl carboKylic acid Thionin blue Tolidine Toluidine blue Tone compound crimson blue . . . brown . green maroon orange purple red sepia violet yellow Toning with dyes Trichlor alpha naphthol . . Traube Turkey blue Uranium nitrate Vanadium chloride Valenta Victoria blue green Von Hubl Waterhouse Watkins Wax, bees Yellow dyes Xylene red Xylidine 76 , 108 , 109 95 97 .• 101 101 97 98 92 93 , 95 . 100 , 101 , 103 , 104 90 . 91 , 100 , 101 , 102 94 , 95 100 94 . 100 100 , 101 91 , 92 , 95 , 100 , 101 , 102 , 104 88 , 89 . 90 101 94 , 96 , 100 , 104 88 96 95 98 97 87 , 91 94 63 97 96 62 '... 108 , 109 73 119 96 96 101 128 ^'3 Sii