6 NEW JERSEY 7 = » Fo 7 — | * pe ¢ : ae a am tal Se ey , o a z . tei .~. * Pry te ~ F i ih a : yr | wy x ' = * > Ss 4 1 0 . * a, A 5 c < ms * | ra 4 : \ : ES A ' vu i Mae Ac + Gein - th Materia Photographica A Dictionary of the Chemicals, Raw Materials, Developing Agents and Dyes used in Photography BY week DB. HITCHINS, Pu. D. F.R.P.S., F.R.M.S., F.C.S., F.PH.S.L. Member of Society of Motion Picture Engineers a PHILADELPHIA Frank V. CHAmpers, Publisher 636 FRANKLIN SQUARE - Sef RESTOR oo 5 ay, K CEL TONS EUS Cy on are aan Pr SENS SITD, BUS a rar Ra OS ESEOUNIV hea Pt aa CS a a Rh OOPS A373) coal ae eee ani Rb UO SEC TT jose arr el pen ae Ru eR UO he oe givin siwih' pe nln > Boece Sa WO SISSLER Fue 1 i tn cr rn Sc CE rR Pe a a ces eos Begg Se OO OE no eh Sa rr Si Ok Se Ag EWS lie A) ety oe rr Na OS OMELET oad sR ee a Sr “ULEEENURT' 5 4 5. 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Yb Sen, k= a re er ate Yt TNE ey a Zn Atomic Weight 175.0 24.32 99.93 200.6 96.0 144.3 6 MATERIA PHOTOGRAPHICA ABBREVIATIONS USED IN DESCRIBING MATERIALS A.P.—Average price A.W.—Atomic weight B.P.—Boiling point Der.— Derivation Fr.—French Ger.—German G.—Grade suitable for photographic use Ins.—Insoluble M.P.—Melting point M.W.—Molecular weight P.—Properties Sap.—Soluble in all proportions Sol.—Soluble Sp.G.—Specific Gravity Ss.—Slightly soluble Syn.—Synonym U.P.—wUses in photography C.P.—Chemically pure U.S.P.—United States Pharmacopzia owes: "NEWARK CAMERA GLUB 4 & BEWARK NDW JERSEY MATERIA PHOTOGRAPHICA 7 MATERIA PHOTOGRAPHICA ‘General Chemicals and Raw Materials ACETONE, (CH:;)2CO Fr. Acétone; Ger. Aceton Syn. Dimethyl-ketone, Ketopropane, Methylacetal, Prop- anone, Pyroacetic ether. M. W. 58: Sp. G. about 0.798°: M. P. 94.3°C: B. P. 56.48°C. Sol. in water, alcohol and ether. P. Colorless liquid, mint-like odor, highly volatile and inflammable. Should be kept in well stoppered bottles in a cool place. Der. By dry distillation of calcium acetate also as a by- product in the manufacture of butyl alcohol. Purified by rectification. ; G. Technical; U.S.P. (98% Acetone). Should not show more than a trace of acidity. U. P. Solvent for resins, collodion, nitrocellulose; used in manufacture of sheet celluloid, varnishes and film cements, can be used as a substitute for the alkali in pyro or hydroquinone developers. The acid amidol developer can be remarkably energized by the addition of from 3 to 5% acetone. ACETONE SULPHITE, NaHSOs (CH:;)2CO H.0 Fr. Acétone Sulfite; Ger. Acetonsulphit M. W. 162. Sol. in water; Ss. in alcohol. P. Fine white Powder. Der. Acetone combined with acid sodium sulphite. 8 MATERIA PHOTOGRAPHICA U. P. Substitute for sodium sulphite and the metabisulphites in development. 10 parts acetone sulphite are equal to 7.5 parts of potassium metabisulphite or 20 parts of dry sodium sulphite. _ As a preservative of pyro, % ounce of acetone sulphite is added for each ounce of pyro used. Keeps fixing baths clear and colorless. ACID ACETIC, HC.H:O, Fr. Acide Acétique; Ger. Essigsaure Syn. Acid methanecarboxylic, Vinegar acid, Purified Pyro- ligneous acid. Mew. 00° M..P216.7° CSB Pr lisa: Sol. in water, alcohol, ether, chloroform and glycerine. P. Colorless liquid, sour pungent smell, vapor inflammable, congeals at 15.65°C., Der. Prepared from wood by destructive distillation, also by the oxidation of dilute ethyl alcohol, governed by bacterial action. G. Two grades commonly used in photography, Glacial Acetic Acid, U.S.P. (99% acetic acid) Sp. G. about 1.065, congeals at about 12.8°C. hence the name glacial (or ice like) acetic acid. Commercial grade (28% acetic acid) Sp. G. 1.038; This strength acid can be easily prepared from the glacial acid by dilution with distilled water. Glacial acetic acid is a strong escharotic, if spilt on the skin should be washed off at once. ‘The impurities often found in acetic acids are sulphurous acid, tarry matters, hydrochloric or sulphuric acid. Samples which yield a precipitate when a drop of silver nitrate solution is added to a quarter of an ounce, or which discolor when the mixture is exposed to light, should be rejected. U. P. Preparation of acid fixing baths. As a clearing bath after ferrous oxalate development of bromide paper. Used in the uranium toning bath facilitates the penetration of the gelatine by the bath. Solvent for gelatine, celluloid, pyroxyline. Used in the manufacture of cellulose acetate. Preparation of gelatine substratum. MATERIA PHOTOGRAPHICA 9 ACID BENZOIC, C.H;COOH Fr. Acide Benzoique.; Ger. Benzoesaure Syn. Acid phenylformic. Bee) ee op. G. 1.2659: M. P. 121.25°C, B. P. 249.2°C. Sol. in alcohol and ether; Ss. in water. Freely soluble in chloroform or benzene. P. White voluminous crystalline plates or needles. Aromatic odor. Der. From gum benzoin by sublimation. Industrially, by the chlorination of toluol, heating this under pressure with milk of lime. The benzoic acid is distilled off by steam and crystallized. G. U.S.P. from benzoin. U. P. Has been used as a preservative in photographic emul- sions, used in toning baths and for the sizing and sur- facing of photographic paper. ACID BORIC, H;:BO; Fr. Acide Borique; Ger. Borsaure Syn. Acid boracic, Acid orthoboric. M. W. 62: Sp. G. 1.4347: M. P. 184°C. Sol. in water, alcohol, glycerine, and volatile oils. P. White shining scales or amorphous powder. Der. By the addition of hydrochloric or sulphuric acid to a solution of borax and crystallizing. G. U.S.P. crystal or powder. U. P. Used in pyro developers as a restrainer and to prevent stains, can also be used in the fixing bath as a stain pre- venter. A solution of 1 part boric acid in 30 parts of water acts as a stop bath, stopping development instantly. 10 MATERIA PHOTOGRAPHICA ACID CARBOLIC (Phenol), C,.H;OH Fr. Acide Phénique; Ger. Karbolsaure Syn. Phenic acid, Phenyl hydrate, Hydroxybenzene. M. W. 94: Sp. G. 1.0677: M. P. 42:5°C.> BaP iain ee Sol. in water, alcohol, ether, chloroform, glycerine and alkalis. P. White crystalline mass, turns pink or red if not pure, absorbs water from the air and liquefies, has sharp burn- ing taste and distinctive odor, strong corrosive poison. Der. By treating coal tar oil fraction, boiling between 170° and 230°C. with caustic soda to form phenolate. The solution is purified by removing the naphthalene, treated with acid to set the phenol free which is further purified by distillation. It can also be prepared by converting benzol into sulphonic acid and fusing the latter with caustic soda. On treating the sulphonate with acid, pure phenol is released. G. U.S.P. crystal or fused. U. P. Used as a preservative for photographic emulsions, gelatine solutions, and mountants. It is the starting point a many of the photographic chemicals, developers and yes. ACID CHROMIC (Anhydride), CrO; Fr. Acide Chromique; Ger. Chromsaure Anhydrid Syn. Chromium trioxide. M. W. 100: Sp.-G. 2:672°>M. Pr 19676 Sol. in water. P. Reddish brown crystals. Violently explodes when brought into contact with organic substances. Highly poisonous. Der. Hydrochloric or sulphuric acid added to a solution of sociGma bichromate and the product recovered by recrystal- ization. GaAs ea U. P. Principal use in process work in the fish glue process. Used in conjunction with sulphuric acid for clearing the fish glue image previous to etching, removing any scum from between the half-tone dots. MATERIA PHOTOGRAPHICA 11 ACID CITRIC, (CO:HCH:).C(OH)CO.H Fr. Acide Citrique; Ger. Citronensaure Syn. Acid oxytricarballylic. Beevee 2102 on. G, 1.542: M. P. 153°C, Sol. in water, alcohol and ether. P. Colorless, odorless crystals, with characteristic lemon flavor. Der. Crude citric acid is obtained from lemons or other citrus fruit, then neutralized with calcium carbonate and the lime salt dissociated with sulphuric acid. The product is then filtered, evaporated and recovered by crystalliza- tion. T'artaric acid is the most likely impurity to be expected. U.S.P. crystal or powder. G U. P. Citric acid can be used as a preservative in some developing solutions and in others acts as a restrainer. Can be used for making acid fixing baths and as a preser- vative in emulsions. 1 part citric acid to 100 of water is an excellent clearing bath for removing the yellow pyro stain from negatives. Used in the preparation of gelatino- citro-chloride printing-out paper. Citric acid can be used to replace acetic acid in pho- tographic solutions. 1 oz. of citric acid is equivalent to 2 ozs. of 28% acetic acid. Citric acid will replace glacial acetic acid weight for weight. ACID DIGALLIC (Tannin), CHO. Fr. Acide Tannique; Ger. Gerbsaure Syn. Acid gallotannic. M. W. 322: M. P. Decomposes at 210°C. Sol. in water and alcohol; Ss. in ether. P. Lustrous, faintly yellow amorphous powder. Der. Extracted from powdered gall nuts with water and alcohol, then evaporated and purified by crystallization. eer. 2 U. P. Principal use in process work as an ingredient in the etching solution for collotype plates acting as a hardener of the gelatine. Has been recommended as a hardening agent for prints and negatives, but is likely to give some stain. 12 MATERIA PHOTOGRAPHICA ACID FORMIC, HCOOH H.CO: Fr. Acide Formique; Ger. Ameisensaure Syn. Acid hydrogen carboxylic. M. W.° 46: Sp. G.1.2178: M. P)8.3% CBee aii Sol. in water, alcohol and ether. P. Colorless liquid, pungent odor, very strong caustic. Der. By dissociation of sodium formate with mineral acid, then by distillation and absorption in distilled water. Purified by rectification. Cay WES eke) U. P. Comparatively unimportant in photography. Is some- times used in process work instead of acetic acid for stripping of wet collodion negatives. Its disadvantage is, however, its dangerous caustic properties. ACID GALLIC, C.H:(OH);CO.H.H20 3:4:5 Fr. Acide Gallique; Ger. Gallussaure Syn. Acid Trioxybenzoic, Acid Trihydroxybenzoic. M. W. 188.06: Sp. G. 1.694: M. P. 220° to 240°C. Sol. in alcohol; Ss. in water and ether. P. Slightly yellow or colorless crystalline needles or prisms. Der. Obtained by fermentation from powdered galls or by boiling tannin with dilute acid or caustic soda. GU Sse: U. P. Not very much used in modern photography. In the early days of photography, was used as a developer for paper negatives. At the present time is occasionally used in the development of P. O. P., intensification of col- lodion and gelatine negatives, and as one of the ingredients in the ferrous citrate developer for chloride plates. Is used by lithographers for preparing the surface of zinc plates for printing. MATERIA PHOTOGRAPHICA 13 ACID HYDROBROMIC, HBr in Aqueous Solution Fr. Acide Bromhydrique; Ger. Bromwasserstoffsaure Syn. Hydrogen bromide, Bromhydric acid. bea eects op. Gr 1.38. Sol. in water. P. Faintly yellow or clear colorless liquid. Der. Made by passing hydrogen with bromine vapor over a warm platinum sponge which acts as a catalyzer and then collecting by absorption in water. G. U.S.P. (40% HBr.) U. P. Used in the production of some of the bromides used in photography. Sometimes added to emulsions as a preservative. Small additions of hydrobromic acid will cure fog in an emulsion, at the same time decreasing the emulsion speed. ACID HYDROCHLORIC, HCl Fr. Acide Chlorhydrique; Ger. Chlorwasserstoffsaure Syn. Muriatic acid, Hydrogen chloride. hie Wer s0.0; op, G. 1.16. Sol. in water, miscible in all proportions with alcohol and water. P. Clear, colorless or slightly yellow. Fuming pungent liquid, poisonous. Der. Usually made by the action of sulphuric acid on com- mon salt. Also as a by-product of the LeBlanc soda process. Sees (33% HCL) U. P. Generally used as a clearing bath for pyro stains and as a clearing bath in the platinotype process. Is used in connection with vanadium, iron and the copper toning processes. The addition of HC! to chloride emulsions increases speed, also tends to make such emulsions clean working and free from fog. 14 MATERIA PHOTOGRAPHICA ACID HYDROFLUORIC, HF Fr. Acide Fluorhydrique; Ger. Fluorwasserstoffsaure Syn. Hydrogen fluoride, Fluoric acid. M. W. 20. P. Clear, colorless fuming corrosive liquid. Very dangerous to handle. Dissolves the nails and produces terrible sores if allowed to come in contact with the skin. Der. Calcium fluoride is treated with sulphuric acid, the mixture distilled in a platinum retort. Hydrofluoric acid gas passes over and is dissolved in distilled water. G. Technical. 52% HF. U. P. Its principal use in photography is for stripping films from glass plates; a 2 to 3% solution being used. It is also used in hyalography or photographic etching on glass. ACID LACTIC, CH:CH(OH)COOH Fr. Acide Lactique; Ger. Milchsaure Syn. Acid alpha-hydroxypropionic and acid ethylidenelactic. M. W. 90: Sp. G. 1.2485. Sol. in water, alcohol and ether. P. Yellow or colorless thick liquid. Der. Obtained very largely from sugar by the lactic ferment. G. .-U.S.P... 75% “Aacticsacid: U. P. Occasionally used in the preparation of silver lactate positive emulsions. Acts as a preservative for slow chloride emulsions and prevents fog. Is a useful preserva- tive for amidol developer in the proportion of 5cc. lactic acid to 1000cc. developer. A 3% solution can be used as a stop bath for arresting development. ACID NITRIC, HNO; Fr. Acide Nitrique; Ger. Salpeteraure Syn. Aqua fortis, Hydrogen nitrate, Acid azotic. M. W. . 63.022 Sp:G2l42 See a Sol. in water and alcohol. P. Transparent, colorless, fuming, suffocating, caustic and corrosive liquid. Causes very painful burns. Der. MATERIA PHOTOGRAPHICA 15 ea cbatcd by distillation from saltpetre and sulphuric aci U.S.P. U. P. Nitric acid is the principal ingredient in the nitration of cotton for nitrocellulose. Used as a preservative in pyro developer. Used in the production of silver nitrate and in some of the vanadium or iron toning baths. In process work, nitric acid is largely used as a mordant for etching zinc. ACID OXALIC, CO:.H.CO:H.2H:0 Fr. Acide Oxalique; Ger. Oxalsaure Bee et 0) op. G. 1.653: “M. P. 187°C. Sol. Pr. Der. in water, alcohol and ether. Transparent, colorless crystals; poisonous. Sodium carbonate, heated under pressure with carbon dioxide, produces sodium formate. This heated with sodium carbonate, yields sodium oxalate. A calcium salt is added to precipitate calcium oxalate which, when treated with sulphuric acid, gives oxalic acid. GP: G. U. P. Used in the sensitizing of platinotype paper. As a Syn. preservative for pyro developer. Used for making cor- rections on blue prints, as it dissolves the prussian blue image. Used in the preparation of ferrous oxalate developer. With some developers oxalic acid acts as a restrainer. ACID PHOSPHORIC, H;PO, Fr. Acide Phosphorique; Ger. Phosphorsaure Ortho-phosphoric acid. M. W. 98.06: Sp. G. 1.750: M. P. 38.6°C. Sol. £ Der. G. Miscible in all proportions with water and alcohol. Clear, colorless, syrupy liquid. Obtained by oxidizing white phosphorous, first in cake and then with nitric acid and evaporating the solution. U.S.P. 85 to 88% phosphoric acid. U. P. A 20% solution of phosphoric acid is frequently employed for acidulating platinum toning baths and in the preparation of silver phosphate emulsions. 16 MATERIA PHOTOGRAPHICA ACID PICRIC, C.H:(NO:-),;0H Fr. Acide Picrique; Ger. Pikrinsalpeters Syn. Acid picronitric, Trinitrophenol. MW, 8229.05 Sp Gal:/6/ aM eg) Sol. in water, alcohol and ether. P. Very poisonous and highly explosive, especially when in contact with metals or metallic oxides. Yellow crystals. Der. By the nitration of monochlorobenzol in presence of sulphuric acid. GaeU.o. U. P. Used in the preparation of nonhalation plates and is sometimes used for making color filters. ACID SALICYLIC, C,.H:(OH) (COOH) Fr. Acide Salicylique; Ger. Salicilsaure Syn. Acid ortho-hydroxybenzoic. MW, 138: Sp: G."1483 Meer 150 ee Sol. in alcohol and ether; Ss. in water. P. White crystals. Der. By the addition of hydrochloric acid to a solution of sodium salicylate, then by filtration and drying, purified by sublimation. Gi USP, U. P. Used as a preservative in emulsions and for the preservation of mounting paste. ACID SULPHURIC, H:.2SO, Fr. Acide Sulfurique; Ger. Schwefel Sdure Syn. Oil of vitriol. M. W. 98.09: Sp. G. 184: M. P. 1046°CA SBP zie 300) C. Sol. in water with evolution of heat. P. Strongly corrosive, dense, oily, liquid; colorless when pure. It is intensely corrosive and chars all organic matter which it comes in contact with. In mixing always aoe the acid slowly to the water, not the water to the acid. MATERIA PHOTOGRAPHICA 17 Der. Made by Chamber Process by roasting pyrites or sul- phur in specially designed furnaces, or by the catalytic process, the raw materials in this process being sulphur dioxide from pyrites, or sulphur and oxygen from the air to produce sulphur trioxide which is absorbed in water yielding sulphuric acid. The catalyzers most in use are spongy platinum and iron oxide. Purified by distillation. Cedi pea es U. P. Sometimes used as a preservative in pyro developer. Used in conjunction with nitric acid for the preparation of nitrocellulose. Is one of the ingredients in the various permanganate, persulphate, bichromate of potassium bleaching and reducing solutions. ACID SULPHUROUS, H:SO:; Fr. Acide Sulfureux. Ger. Schweflige Saure Syn. Sulphur dioxide, Sulphurous anhydride, Hydric sulphite. Nee Go sop. G. 1.025. Sol. in water. P. Colorless liquid with suffocating sulphur odor. Der. Pyrites are calcined and the gas absorbed in water, the liquor then concentrated by means of a still. Grobe (6% ); U. P. Sometimes used as a preservative for pyro developer and to acidify the fixing bath. It must be freshly pre- pared as on keeping it very quickly changes into sulphuric acid. AGAR-AGAR Fr. and Ger. Agar-Agar. Syn. Japanese gelatine, Chinese isinglass, Layor Carang. P. Transparent strips similar in appearance to shredded gelatine. Der. Agar-Agar is a gelatinous vegetable material made _ from several of the white sea weeds (gracilara lichenoides and eucheuma spinosum.) These sea weeds are found principally in the Pacific and Indian Oceans and the Japan Sea. Go U.S.P. 18 MATERIA PHOTOGRAPHICA U. P. Agar-Agar has been used at different times as a substitute for gelatine in emulsion-making. It is, how- ever, more difficult to melt than gelatine and a good deal harder to handle. It has been used as a substitute for arrowroot in the preparation of silver paper. In process work Agar-Agar is sometimes used as a substitute for fish glue in the process of preparing the resist for etch- ing. ALBUMEN Fr. Albumine. Ger. Albumen. P. Almost colorless gummy liquid, which dries to a pale yellow solid similar looking to many of the gums. Der. Is an exceedingly complex organic compound and is obtained from blood, milk or eggs. In photography, only the egg albumen is used. This is prepared by separating the fresh white of egg from the yolk, diluting with water, beating to a froth, filtering and evaporating. Albumen is coagulated by heat at 65.5° C. It is also coagulated by alcohol and most inorganic salts. It is easily decomposed and must be used directly after preparation, otherwise a preservative must be added. G. Technical. U. P. Used in the preparation of albumenized paper and various positive processes. In process work is used as a substratum, and is used in conjunction with potassium bichromate for sensitizing zinc plates in photo etching. Albumen also has the property of clarifying solutions of gelatine. ALCOHOL ETHYL, C:H;OH Fr. Alcool Ethylique. Ger. Aethylalkohol Syn. Grain alcohol, Fermentation alcohol, Cologne spirits, Spirits of wine, Ethyl hydrate. M. W. 46: Sp. G. .785: M. P—1123° C2 BaP) 7342 Sol. in water, methyl alcohol and ether. P. Colorless, volatile liquid, vinous odor. Der. Prepared by fermentation of the sugars derived from starch. G. Cologne spirits containing 95 to 96% alcohol. U. P. Used in the preparation of collodion and sometimes in the manufacture of celluloid; is frequently used as an addition to photographic emulsions, where it acts as a preservative. When present at the time of emulsification, has considerable influence on the formation of the silver halide grain, keeping it fine and uniform. MATERIA PHOTOGRAPHICA 19 ALCOHOL METHYL, CH;OH Fr. Alcool Méthylique. Ger. Methyl Alkohol Syn. Wood alcohol, Wood naphtha, Methyl hydrate, Colum- bian Spirits. PeeWee pp. G. .7913: M. P—978° C.: B. P. 66.78° C. Sol. in water, alcohol and ether. P. Colorless, volatile liquid, highly poisonous. Der. Obtained by the destructive distillation of wood. Puri- fied by rectification. Co S.P. U. P. One of the solvents frequently employed in the manu- facture of celluloid. Is an excellent solvent for resins. Is sometimes used to prepare very concentrated solutions of developers. Used for denaturing ethyl alcohol. Its use, in connection with photographic emulsions, is dangerous, as it produces fog. ALUM-AMMONIA, A1:(SO,)3(NHs)250.s.24H2O Fr. Alun dAmmoniaque. Ger. Ammoniakalaun Syn. Aluminum-Ammonium sulphate. M. W. 906: Sp. G. 1.645: M. P. 94.5° C. Sol. in water; Ins. in alcohol. P. Colorless crystals. Der. Obtained by crystallization from a mixture of aluminum and ammonium sulphates. Purified by recrystallization. G. U.S.P. (Lump, ground or powdered). U. P. Used in the preparation of acid fixing baths and sometimes as a hardener for gelatine. ALUM CHROME, K2SO.Cr2(SO.)3.24H20 Fr, Alun de Chrome. Ger. Chromalaun Syn. Chromium and potassium sulphate. M. W. 916. Sol. in water; Ins. in alcohol and ether. P. Violet colored crystals yielding a dichroic solution. Der. Obtained as a by-product in the manufacture of alizarine and several other dyes. G. Technical, crystal or powdered. 20 MATERIA PHOTOGRAPHICA U. P. Chrome alum is in general use as a hardener for photographic emulsions, the addition being made previous to coating. It is also used in the preparation of the chrome alum fixing bath. In process work, chrome alum is used as a hardening agent for gelatine and fish glue, and is used as an addition to the nitric acid bath for etch- ing enamel images on zinc with a view to preventing the image from becoming soft. ALUM, IRON, AMMONIA, FeNH.(SOs,)212H2O Fr. Alun de fer. Ger. Ammoniakeisenalaun Syn. Ammonio-ferric-sulphate, Iron ammonia sulphate. M. W. 962. Sol. in water; Ins, in alcohol. P. Lilac or violet efflorescent crystals. Der. Solutions of ferric sulphate and ammonium sulphate are mixed, then evaporated and crystallized, purified by recrystallization. Gre U.Sira U. P. Has been recommended for use in fixing baths, but is not satisfactory. Principal use in photography is in the making of ferric oxalate. ALUM POTASH, Al:(SO,)sK250..24H2O Fr. Alun de Potasse. Ger. Kalialaun Syn. Aluminum and potassium sulphate. M. W. 948: Sp. G. 1.7571: M. P. 105° G Sol. in water; Ins. in alcohol. P. White crystals. Der. By roasting alunite in special furnaces, afterwards leaching the mass and recovering the salt by crystalliza- tion. Gea ate U. P. Used in the preparation of hardening solutions for fixing baths. One of the ingredients of the hypo alum toning bath. Can be used as a clearing bath. In process work used in conjunction with dilute nitric acid for matting surface of zinc plates previous to coating with bichromated albumen. Is sometimes used for hardening are seal emulsions, but is not so suitable as chrome alum MATERIA PHOTOGRAPHICA 21 ALUMINU\M, Al Fr. and Ger. Aluminium Niemeyer 2s op. G 2.708: M. P. 657° C. Sol. in acids and alkalies; Ins. in water. P. Silvery ductile metal. Der. Obtained by electrolysis of the oxide in a bath of molten cryolite. G. Sheet and dust. U. P. Frequently used as one of the ingredients in flash- light powders. Very largely used for the construction of light hand cameras and for lens fittings. Used for the screen and plate-holders of process cameras, as it is not easily acted upon by silver nitrate solutions. Aluminum is now used as a substitute for the lithographic stone. ALUMINUM CHLORIDE, Al.Clc.12H:O Fr. Chlorure d’Alumine. Ger. Chloraluminium M. W. 483: M. P. 190° C. Sol. in water, ether and alcohol. P. Yellowish white crystalline or granular powder, very deliquescent. Der. Chlorine gas is passed over alumina in a heated tower, the product being recovered by sublimation. G. ‘Technical (must be kept in well stoppered bottles). U. P. Used in the gold and platinum toning baths. Has been recommended for hardening gelatine emulsions, but is not satisfactory. ALUMINUM SULPHATE, Al.(SO,)3.18H20 Fr. Sulfate d’Alumine. Ger. Aluminiumsulfat Of very little importance in photography. This material is often erroneously called alum. 22 MATERIA PHOTOGRAPHICA ALUMINUM SULPHOCYANIDE, Al (CNS); Fr. Sulfocyanure d’Alumine. Ger. Aluminum-rhodanid Syn. Aluminum sulphocyanate, aluminum-rhodanide. M. W. 402. Sol. in water; Ins. in alcohol and ether. P. Yellowish powder, extremely deliquescent. Der. Aluminum cyanide is boiled with sulphur, the product being purified by crystallization. G. C.P. (must be kept in well stoppered bottles). U. P. Used as a preliminary bath for self-toning papers. Has been recommended in connection with gold toning bath, but is unsatisfactory. AMMONIA WATER, NH.OH Fr. Ammonique. Ger. Ammoniakwasser Syn. Ammonium hydrate, ammonium hydroxide. Sp. Gre (238%) 897 2Be Prssor Sol. in water. P. Colorless liquid with extremely irritating fumes. Should be kept in a cold place in well stoppered bottles. Der. Gas liquor from coke and gas manufacture is distilled, the volatile salts and ammonia being absorbed in sulphuric acid. This yields ammonium sulphate, which is heated, the ammonia distilled off and collected in water. Also made from waste animal matter. Goel e cove: U. P. Used as an accelerator in pyro developer. Also for blackening the mercury bleached image in intensification. Is used as an addition to the bichromate bath for sen- sitizing carbon tissue. Ammonia is used in emulsion making in the ammonia nitrate process in order to pro- duce exceedingly rapid emulsions. In process work is used as an addition to the bichromated albumen solution and also the fish glue solutions. MATERIA PHOTOGRAPHICA 23 AMMONIUM BICHROMATE (NH: ):Cr20O; Fr. Bichromate d’Ammoniaque. Ger. Ammoniumdichromat M. W. 252: Sp. G. 2.153. Sol. in water and alcohol. P. Yellow needles, explodes when in contact with many sub- stances. Der. Chromic acid acting on ammonium hydroxide followed by crystallization. Ge CP: U. P. Sometimes used for sensitizing carbon tissue, Gum bichromate, and in various photo-mechanical processes. Has greater sensitizing power than the potassium salt and in the carbon processes gives stronger pictures. In process work is used as a sensitizer for fish glue for print- ing half-tone images on copper and zinc. Ammonium bichromate is about twice as sensitive to light as is potassium bichromate. AMMONIUM BROMIDE, NH.Br. Fr. Bromure d’Ammonium. Ger. Bromammonium MW. 98: Sp: G. 2.327. Sol. in water, alcohol and ether. P. Colorless crystals. Der. Hydrobromic acid acting on ammonium hydroxide fol- lowed by crystallization. (see. P. granular. U. P. Can be used as a restrainer in place of the potassium salt, but must not be used with the caustic alkalies or carbonates, as ammonia would be set free. Largely used in emulsion-making, producing an emulsion with a little higher contrast than one made with potassium salt. 24 MATERIA PHOTOGRAPHICA AMMONIUM CARBONATE, (NH.) HCO;+ (NH,z) (NH:) CO, Fr. Carbonate d’Ammoniaque. Ger. Ammoniumkarbonat Syn. Hartshorn, rock ammonia. MAW 2c 57M APSO Sol. in water; decomposes in hot water. P. Colorless crystal plates, unstable in air, rapidly becoming converted to the bicarbonate. Der. Ammonium hydroxide heated with ammonium bicar- bonate. U.S.P. (cubes or powder). G. U. P. Can be used to replace ammonia water in some developing solutions, but must not be dissolved in hot water. Is frequently used to replace ammonia in the ammonia processes of emulsion making. AMMONIUM CHLORIDE, NH:.Cl Fr. Chlorure d’Ammoniaque. Ger. Chlorammonium Syn. Sal ammoniac. MW. 53:5: Sp. .G.-1.520: Sol. in water, alcohol and ammonium hydroxide. P. White crystals. Der. Ammonia salts acting on hydrochloric acid followed by crystallization. G. U.S.P. granular. U. P. Used in the salting of albumenized paper, its prin- cipal use, however, being in the preparation of chloride emulsions. ~ AMMONIUM CITRATE, (NH:):CsH;O, Fr, Citrate d’Ammoniaque. Ger. Ammoniumcitrate Very little used in photography. Occasionally used as restrainer with pyro developer. MATERIA PHOTOGRAPHICA 25 AMMONIUM FLUORIDE, NH.F Fr. Fluorure d’Ammonium. Ger. Fluorammon _ Very little used in photography, occasionally used for stripping negatives. Must be kept in wax-lined bottles. AMMONIUM HYPOSULPHITE, (NH).S:0s Fr. Hyposulphite d’Ammoniaque. Ger. Ammonthiosulfat Syn. Ammonium thiosulphate. Very little used in photography. In the earlier days was recommended as a substitute for the sodium salt. AMMONIUM IODIDE, NHI Fr. Iodure d’ Ammonium. Ger. Iodammon heyy. (145:°Sp. G. 2,501. Sol. in water and alcohol. P. White crystals. Der. Action of ammonium hydroxide on hydroiodic acid, fol- lowed by crystallization. Gaels f. granular. U. P. Is used in making iodized collodion and has been recommended for negative emulsions. It is unsatisfactory for fast gelatino-bromide emulsions because it is unstable and readily gives off iodine. AMMONIUM MOLYBDATE, (NH.)«Mo;,Ou4H:20 Fr. Molybdate d’Ammoniaque. Ger. Molybdansaures Ammonium M. W. 1236: Sp. G. 2.38-2.95. Sol. in water and acids. P. White crystalline powder readily decomposed by heat. Der. By the reaction of a solution of molybdic acid and ammonium hydroxide followed by crystallization. G. U.S.P. crystals. U. P. Used as an ingredient in P. O. P. emulsions to give greater contrast; has also been recommended as an addi- tion to chloride and bromide emulsions to increase con- trast and blacks. 26 MATERIA PHOTOGRAPHICA AMMONIUM NITRATE, NH.NO; Fr. Azotate d’Ammonium. Ger. Salpetersaures Ammon M. W. 80: Sp. G. 1.725: M. P. 153. Decomposes at 210° C. Sol. in water, alcohol and alkalies. P. Colorless crystals, explosive. Der. By the action of ammonium hydroxide on nitric acid. G US. Peeranilar: U. P. Sometimes used as a substitute for the potassium salt in flash-light mixtures; is one of the salts formed in emulsion-making by the double decomposition of ammo- nium bromide and silver nitrate. AMMONIUM OXALATE, (NH,)2C.0:H2O Fr, Oxalate d’Ammoniaque. Ger. Ammonoxalat Very little used in photography; finds occasional use in the preparation of ferric ammonio-oxalate. AMMONIUM PERSULPHATE, (NH,).S.0; Fr. Persulfate d’Ammoniaque. Ger. Ueberschwefelsaures Ammonium MiW. > 228: Sol. in water. P. White crystals. Der. By the electrolysis of a concentrated solution of ammonium sulphate followed by crystallization. GG, Prerystals: U. P. Its principal use is as a reducer, its valuable property being that it reduces the high-light detail more than the shadows. Has been suggested as a hypo eliminator. Sometimes used to remove developer stains and as an addition to the oxalate developer for platinotypes. Such an addition improves the quality of over-exposed platino- type prints. MATERIA PHOTOGRAPHICA 27 AMMONIUM PHOSPHATE (NH.)-HPO,: Fr. Phosphate d’Ammonium. Ger. Ammon-phosphat Syn. Ammonium diphosphate, Diammonium ortho-phosphate. Mew. 132: Sp. G. 1.619. Sol. in water; Ins. in alcohol. P. White crystals. Der. Reaction of ammonium hydroxide and phosphoric acid, followed by crystallization. Cece eranylar; U. P. Frequently used for fire-proofing fabrics for use around the studio and work-rooms, and used in making the slow silver phosphate emulsions. AMMONIUM SULPHOCYANIDE, NH.CNS Fr, Sulfocyanure d’Ammonium. Ger. Rhodanammonium. Syn. Ammonium sulphocyanate, Thiocyanate or rhodanide of ammonia. eee O op. op. G. 2.3312: M. P. 909° C.: B. P. Volatile at white heat. Sol. in water; Ins. in alcohol and ether. P. White, deliquescent, granular powder; alkaline reaction. Der. Obtained from wood ashes. GUS. P. U. P. Used as an accelerator in development. POTASSIUM CHLORATE, KCIO; Fr. Chlorate de Potasse. Ger. Chlorsaures Kalium. Syn. Chlorate of potash. Beye. op. G. 2.337: M. P. 357° C.: B. P. Decomposes at about 400° C., giving off oxygen. Sol. in water and alkalis; Ss. in alcohol. P. Transparent, colorless crystals or white powder; cooling saline taste; poisonous; must not be ground with sugar, sulphur or other combustible substances, may cause explosions. Der. By electrolyzing a hot poucca trated alkaline solution of potassium chloride. EO RSS ae U. P. Sometimes used in the sensitizer for platinotype paper to give brilliancy to the image. Its principal use, how- ever, being in flashlight mixtures. In process work, is used with hydrochloric acid as an etching solution for copper and steel, known as the Dutch mordant. 54 MATERIA PHOTOGRAPHICA POTASSIUM CHLORIDE, KCl Fr. Chlorure de Potasse. Ger. Chlorkalium. M. W. 74.5: Sp. G. 1.987: M. P. 772° C.: B. P. Decomposes at about 400° C. Sol. in water and alkalis; Ss. in alcohol; Ins. in absolute alcohol. P. Colorless or white crystals or powder; strong saline taste. Der. Prepared by neutralizing hydrochloric acid with potas- sium carbonate. G. Granular. U. P. Used in emulsion making. POTASSIUM CHLOROPLATINITE, K:,PtCh Fr. Chloroplatinite de Potassium. Ger. Platinchloruskalium. Syn. Chloroplatinite or platinochloride of potash. M. W. 413.4: Sp. G. 3.291. Sol. in water; Ins. in alcohol. P. Ruby-red, deliquescent crystals. Der. By adding potassium carbonate to a solution of chloro- platinous acid. G. Special photographic. U. P. Used in the platinotype process and as one of the ingredients of toning baths for silver prints. POTASSIUM CHROMATE, K.CrO, Fr. Chromate de Potasse. Ger. Chromsaures Kalium. Syn. Neutral or yellowish chromate of potash. M. W. ='194: Sp."G. 273198] MSs e/a Sol. in water; Ins. in alcohol. P. Yellow crystals. Der. By adding potassium carbonate to a solution of potas- sium bichromate and crystallizing. G. Technical. U. P. Sometimes used as a liquid light filter in sensitometry or three-color work. In process work, the chromate has been used as a sensitizer in place of bichromates, but is not as satisfactory. MATERIA PHOTOGRAPHICA 55 POTASSIUM CITRATE, K;C;.H;O,;,H.O Fr. Citrate de Potasse. Ger. Citronensaures Kalium. Syn. Tribasic citrate of potash. M. W. 342: Sp. G. 1.98: M. P. Decomposes when heated to about 230° C. Sol. in water and alcohol. P. Colorless or white crystals or powder; extremely deli- quescent. Der. By the action of citric acid on potassium carbonate. GPiU.S-P. U. P. Is used as a restrainer in alkaline development, and in several of the copper toning baths. Because of its deliquescent nature it is best to prepare this salt in solu- tion; the stronger the solution, the better it will keep; dilute solutions very soon grow a fungus. POTASSIUM CYANIDE, KCN Fr, Cyanure de Potassium. Ger, Cyankalium. Syn. Cyanide of potash, Cyanide. M. W. 65: Sp. G. 1.52: M. P. At red-heat.: B. P. At red- heat. Sol. in water, alcohol and glycerin. P. White, amorphous, deliquescent lumps or crystalline mass; faint odor of bitter almonds; extremely poisonous, do not handle with bare hands! Der. Prepared by fusing potassium ferrocyanide with potas- sium carbonate in an iron crucible. G. Pure granulated. U. P. Used as a fixing agent in collodion processes and sometimes as a clearing agent for bromide prints, also used in Monckhoven’s intensifier. In process work, is used for fixing wet collodion negatives and for cutting or reducing solution. Is also used in connection with electro- deposition and for degreasing articles previous to plating. 56 MATERIA PHOTOGRAPHICA POTASSIUM FERRIC OXALATE, Fe(C:0,)3sK33H:0 Fr. Oxalate Potassico-Ferrique. Ger Kalium-Ferri-Oxalat. M. W. 491. Sol. in water; Ins. in alcohol. P. Bright green crystals. Der. By acidulating potassium ferrous oxalate and exposing to light. 3 U. P. Used in Belitski’s reducer and in several iron printing processes. POTASSIUM FERRICYANIDE, K;Fe(CN),. Fr. Cyanoferride de Potassium. Ger, Ferrid-Cyan-Kalium. Syn. Ferricyanide of potash, Red prussiate of potash. M. W. 329: Sp. G. 1.8109: M. P. Decomposes when heated. Sol. in water; Ss. in alcohol. P. Bright-red, lustrous crystals, the crystals often become coated with a yellowish powder, this powder should be washed off before using. Poisonous. Der. Chlorine is passed into a solution of potassium ferro- cyanide, the ferricyanide separating out. G. Pure crystals. U. P. Used in several iron printing processes, but its prin- cipal use is in conjunction with hypo, forming Farmer’s reducer. In conjunction with potassium bromide is used for: bleaching bromide or gaslight prints previous to sulphiding. In process work, is one of the ingredients of the lead nitrate intensifier. MATERIA PHOTOGRAPHICA 57 POTASSIUM FERROCYANIDE, K.:Fe(CN).3H:O Fr. Cyanoferrure de Potassium. Ger. Ferrocyankalium. Syn. Ferrocyanide of potash, Yellow prussiate of potash. M. W. 422: M. P. Loses its water of crystallization when sees to 60° C.: B. P. Decomposes when heated to red- eat. Sol. in water; Ins. in alcohol, P. Lemon-yellow crystals or powder; effloresces on exposure tO air. Der. Obtained by fusing potassium carbonate with horn clippings, and stirring with an iron agitator. reer. U. P. Used as a developer in some iron printing processes. The addition of a small amount to pyro and hydro- quinone developers has been recommended as a means of lowering fog and giving greater density. A weak solu- tion is used as one of the test reagents for identifying iron and other metallic spots in paper raw stock. POTASSIUM FLUORIDE, KF2H:0 Fr. Fluorure de Potassium. Ger. Fluorkalium. Mew. 94> M.-P. 41° C. Sol. in water and hydrofluoric acid; Ins. in alcohol. P. White crystalline, deliquescent powder; sharp saline taste. Der. By saturation of hydrofluoric acid with potassium car- bonate. G. Technical. U. P. Used for stripping films from glass negatives. A five-minute immersion in a 2% solution with subsequent immersion in a 2% solution of sulphuric acid is sufficient. It keeps better than hydrofluoric acid and does not as strongly attack the skin, lungs or mucous membranes. 58 MATERIA PHOTOGRAPHICA POTASSIUM HYDRATE, KOH Fr. Potasse Caustique. Ger. Aetzkali. Syn. Caustic potash, Potassium hydroxide. M. W. 56: Sp. G. 2.044: M. P. 360.4° C.: B.°P. Sublimes when heated above melting point. Sol. in water and alcohol; Ss. in ether. P. White, deliquescent lumps or sticks. It readily attacks corks and glass stoppers, these should be waxed or paraffined. Must not be handled, as it is a very powerful escharotic inflicting severe burns upon the _ skin; poisonous. Der. Obtained by decomposing potassium carbonate with milk of lime. Gee U. P. Used as an accelerator in alkaline development. In process work, crude caustic potash is used for cleaning old negative glasses, and for taking the ink and resist off copper and zinc plates after etching. It is also used for cleaning articles previous to electro-plating. POTASSIUM IODIDE, KI Fr. Iodure de Potassium. Ger. Iodkali. Syn. Iodide of potash. M. W. 166: Sp. G. 3.123: M. P. 680° CS BSP i4z0 Sol. in water, alcohol and ether. P. White crystals, granules or powder; strong bitter saline taste. Der. A hot solution of potassium hydroxide is treated with iodine, evaporated to dryness, mixed with carbon and heated to redness. G. US U. P. Used in the preparation of the mercuric iodide intensifier. Used in emulsion making, particularly in conjunction with gelatino-bromide emulsions; has the property of reducing emulsion fog, increasing contrast, and giving increased density. The use of more than a small percentage, however, yields an emulsion which is slow in fixing. It is generally conceded that a complex double salt of bromo-iodide of silver is formed and is responsible for the particular character and photographic quality of bromo-iodide emulsions. A very small amount of a 1% solution added to a finished emulsion, enormously decreases its speed. Is also used in some of the more modern dye mordanting processes. MATERIA PHOTOGRAPHICA | 59 POTASSIUM METABISULPHITE, K.S.0O; Fr. Métabisulfite de Potassium. Ger, Kaliummetabisulfit. Syn. Metabisulphite of potash, Potassium pyrosulphite. M. W. 222. Ss. in water; Ins. in alcohol. P. Clear, transparent crystals; smelling of sulphurous acid gas. Der. By heating potassium bisulphite until it loses water. G. Granular photographic. U. P. Used as a preservative in developers, and for acidulat- ing hypo baths. Lately sodium metabisulphite has been introduced to take the place of the potassium salt. POTASSIUM NITRATE, KNO; Fr. Azotate de Potasse. Ger. Salpetersaures Kali. Syn. Nitrate of potash, Nitre, Saltpetre. M. W. 101: Sp. G. 2.1062: M. P. 337° C.: B. P. Decomposes with deflagration at about 400° C. Sol. in water; Ins. in alcohol and ether. P. Transparent, colorless or white crystalline powder or crystals; cooling, pungent, saline taste. Der. Sodium nitrate and potassium chloride in solution are evaporated until sodium chloride crystallizes out, then decanted and crystallized. GU.S-P. U. P. Used in the manufacture of pyroxyline and flash powders. Has been recommended as an addition to an emulsion to prevent fog. POTASSIUM OXALATE, K:C:0.H20 Fr. Oxalate Neutre de Potasse. Ger. Neutrales Oxalsaures Kali, Kaliumoxalat. _ Syn. Neutral oxalate of potash. M. W. 184: Sp. G. 2.08: M. P. Decomposes when heated. Sol. in water; Ins. in alcohol and ether. P. Colorless, transparent crystals. Der. Obtained by saturating acid oxalate of potash, or oxalic acid, with potassium carbonate. G. Photographic. U. P. Used in the ferrous oxalate developer, and as a developer for platinotypes. 60 MATERIA PHOTOGRAPHICA POTASSIUM PERCARBONATE, K.C,0,.H:O Fr. Percarbonate de Potasse. Ger. Kaliumpercarbonat. M. W. 216. Ss. in water. P. White, crystalline powder. Der. Obtained by electrolysis of potassium carbonate. G. Technical. U. P. Used as a hypo eliminator, and has been sold under many different trade names. POTASSIUM PERCHLORATE, KCl1O; Fr. Perchlorure de Potassium. Ger. Ueberchlorsaures Kali. M. W.. 138.5. Ss. in water; Ins. in alcohol. P. Colorless powder or rhombic crystals, G. ‘Technical. U. P. Used in flashlight mixtures. Should be mixed with the same precaution as potassium chlorate. POTASSIUM PERMANGANATE, KMnO, Fr. Permanganate de Potasse. Ger. Uebermangansaures Kali. Syn. Permanganate of potash. M. W. 158: Sp. G. 2.7032: M. P. Decomposes at 240° C. Sol. in water, sulphuric and acetic acids and alcohol. P. Dark purple crystals having a blue metallic sheen; sweetish, astringent taste. Der. Obtained by fusing manganese peroxide with potassium hydrate or nitrate. Le i) Re U. P. Used as a reducer for negatives, and when acidulated with sulphuric acid reduces the high-lights more than the shadows. Used as a neutral solution, it to all intents and purposes is an intensifier, as a manganese salt is precipi- tated on the silver image rendering it slightly non-actinic in color. Is used as the reverser in several screen plate color processes. Used as a test for the presence of hypo and as a hypo eliminator. In process work, a small amount of a 10% solution is used to rid the wet collodion silver bath of organic impurities. MATERIA PHOTOGRAPHICA 61 POTASSIUM PERSULPHATE, K:S.0; Fr. Persulphate de Potasse. Ger. Ueberschwefelsaures Kali. Syn. Persulphate of potash, Anthion. M. W. 270. M. P. Decomposes below 100° C. Sol. in water; Ins. in alcohol. P. White crystals. Der. By electrolysis of a saturated solution of potassium sulphate, G. Technical. U. P. Used as a hypo eliminator and has been sold under various trade names. May also be used as a reducer in place of ammonium persulphate and has the advantage that it is less likely to contain injurious impurities. POTASSIUM AND SODIUM TARTRATE, KNaC,H.0.4H.O . Sel de Seignette. Ger. Seignettesalz, Rochellesalz, Weinsaures Kalinatron. Syn. Rochelle or Seignette salts. Niet ep. 4s. 1.7/7; M. P..70°-80° C.:-B. P. Loses 4H-O at 215° C. Sol. in water; Ins. in alcohol. P. Colorless, transparent crystals or white powder. Der. Obtained by boiling together cream of tartar and sodium carbonate.- G. U.S.P. U. P. Used in printing-out emulsions to form silver tar- trate. POTASSIUM SULPHIDE, K:S8; Fr. Foie de Soufre. Ger. Schwefelkalium, Schwefelleber. Syn. Liver of sulphurated potash, Potassium trisulphide. M. W. 174: Sp. G. 1.805. Sol. in water, alcohol and glycerine; Ins. in ether. P. Deliquescent, red, crystalline mass; should be kept well stoppered. Der. Obtained by fusing sulphur and potassium carbonate. G. Technical. U. P. Used to precipitate the silver from waste photographic solutions, but recently has been almost entirely replaced by sodium sulphide for this purpose. 62 MATERIA PHOTOGRAPHICA POTASSIUM SULPHOCYANIDE, KCNS Fr. Sulfocyanure de Potassium. Ger, Rhodankalium, Schwefelcyankalium. . Syn. Potassium thiocyanate, Sulphocyanate, or Rhodanide. M. W.-.972 Sp. G: 1.906: MiP. 172.3° Ci Br eco neses at U0. Sol. in water, alcohol and acetone. P. Transparent, deliquescent crystals. Must be kept well stoppered. Der. By heating potassium cyanide with sulphur. G. Pure. U. P. Used in the sulphocyanide toning bath. Is a solvent for gelatine and therefore has been used in the develop- ment of over-exposed carbon prints. SILVER ACETATE, Ag(C.H:O2 Fr. Acétate d’Argent. Ger. Silberacetat. M. W. 167. Sol. in water; Ins. in alcohol. P. Fine white powder or crystals. Der. By adding an alkaline acetate to silver nitrate solution or by dissolving silver carbonate in glacial acetic acid. U. P. Has been recommended for use in printing-out papers, but it yields an image of poor quality and its sensitive- ness is about one-twentieth of that of silver chloride. SILVER AMMONIO-CARBONATE, Ag,CO:4NH:; Fr. Ammonio-Carbonate d’Argent. Ger. Kohlensaures Silberoxydammoniak. M. W. 229. Sol. in water and alcohol. P. Not found in the solid form. Der. Prepared by adding a solution of ammonium car- bonate to a solution of silver nitrate. U. P. Sometimes used in emulsion making, particularly in positive or lantern slide emulsions. MATERIA PHOTOGRAPHICA 63 SILVER AMMONIO-NITRATE, AgNO:2NH:; Fr. Ammonio-Nitrate d’Argent. Ger. Salpetersaures Silberoxydammoniak. Syn. Ammonio-oxide of silver. M. W. 204. Sol. in water and alcohol. P. Colorless needles, but rarely exists in the solid form, being formed in the ammonio-nitrate emulsion making processes. Der. By mixing a solution of ammonia with silver nitrate until the precipitate first formed is redissolved. U. P. A solution of silver ammonio-nitrate is sometimes used for sensitizing plain paper, but its principal use is in emulsion making to form silver bromide. Emulsions prepared by the ammonio-nitrate process do not have to s ripened by aot as ammonia takes the place of eat. SILVER BROMIDE, AgBr Fr. Bromure d’Argent. Ger. Bromsilber. Syn. Bromide of silver. Mie Weise. op. G. 6.473: M. P. 427° C.: B. P. Decomposes at -700°°C. Sol. in sodium thiosulphate, potassium bromide and potassium cyanide solutions; practically Ins, in water and ammon- ium hydroxide. P. Yellow amorphous powder. Der. Obtained by adding any soluble bromide to silver nitrate solution. In photography, it is always prepared in the presence of some vehicle which will suspend it in the form of an emulsion, and prevent it from forming coarse clots. U. P. Silver bromide is the basis of the modern gelatino- bromide emulsions, and is the most light sensitive silver salt. 64 MATERIA PHOTOGRAPHICA SILVER CARBONATE, Ag:CO; Fr. Carbonate d’Argent. Ger. Kohlensaures Silberoxyd. M. W. 276. Sol. in potassium cyanide, ammonia and sodium thiosulphate ; Ins. in water and alcohol, P. Yellow granular powder. Der. By adding an alkaline carbonate to silver nitrate solu- tion. U. P. Sometimes formed in the preparation of printing-out, gaslight and negative emulsions. SILVER CHLORIDE, AgCl Fr. Chlorure d’Argent. Ger. Chlorsilber. Syn. Chloride of silver, Horn silver, Muriate of silver. M.. W:.143.4> -SpoGwo Sele Me Pe 45h Sol. in sodium thiosulphate and potassium bromide solutions, concentrated sulphuric acid and ammonium hydroxide; practically Ins. in water. P. White granular powder, which darkens on exposure to light, finally turning black. Der. Obtained by adding a soluble chloride to silver nitrate solution. U. P. Formed in the preparation of printing-out emulsions and positive emulsions. The higher the proportion of silver chloride in an emulsion, the shorter the gradation scale. SILVER CHROMATE, Ag.CrO, Fr. Chromate d’Argent. Ger. Silberchromat. McAW. wood: Sol. in ammonia and sodium thiosulphate; Ins. in water, alcohol and ether, P. Red amorphous powder. Der. Obtained by adding potassium chromate to silver nitrate solution. U. P. The formation of a small amount of this salt in a printing-out emulsion reduces the scale of gradation, making a more contrasty paper suitable for weak nega- tives. MATERIA PHOTOGRAPHICA 65 SILVER CITRATE, AgC.H;O, Fr. Citrate d’Argent. Ger. Silbercitrate, Citronensaures Silberoxyd. Syn. Citrate of silver. M. W. 297. Sol. in ammonia, sodium thiosulphate and _ potassium cyanide; Ins. in water, alcohol and ether. P. Curdy white powder. Der. Obtained by adding an alkaline citrate to silver nitrate solution. U. P. When formed in small proportions in printing-out emulsions, has a definite influence on the keeping quality of the paper—seemingly it has a preservative effect. Formed in silver chloride gaslight emulsions, it tends to increase contrast and reduce fog. SILVER CYANIDE, AgCN Fr. Cyanure d’Argent. Ger. Silbercyanid. M. W. 134: Sp. G. 3.95: M. P. Decomposes when heated. Sol. in ammonia, potassium cyanide and sodium thiosulphate solutions; Ins. in water, alcohol and ether. P. White powder which darkens on exposure to light; very poisonous. Der. Obtained by adding an alkaline cyanide to a solution of silver nitrate. U. P. Formed in the preparation of the blackening solution in Monckhoven’s intensifier. SILVER IODIDE, Agl Fr. Iodure d’Argent. Ger. Iodsilber. Bie op. G, 5.6/5: M. P. 556° C. Sol. in potassium cyanide and sodium thiosulphate solutions. Ins. in water, ammonia, alcohol and ether. P. Pale yellow powder, darkening on exposure to light. Der. Obtained by adding a soluble iodide to silver nitrate solution. U. P. Silver Iodide is sometimes formed in small propor- tions in gelatino-bromide emulsions, tending to restrain fog during digestion and produces greater sensitiveness (see Potassium Iodide). Silver Iodide is also employed in the wet plate process. The negative silver bath for sensitizing wet collodion plates should be saturated with silver iodide before using. 66 MATERIA PHOTOGRAPHICA SILVER NITRATE, AgNO; Fr. Azotate d’Argent. re Silbernitrat, Salpetersaures ilber. M. W. 170: Sp. G. 4.352: M. P. 218° C.: B. P. Decomposes. Sol. in water, ether and glycerine; Ss. in alcohol. P. Colorless, rhombic plates. Is not in itself sensitive to light, but is very easily reduced to the metallic state in the presence of organic materials: as the skin, paper or gelatine. Der. Silver is dissolved in dilute nitric acid, the solution evaporated. G. Pure crystals, photographic. U. P. Silver Nitrate is the salt from which are made all the sensitive materials of photography in which silver is used. In process work, is occasionally used in the ae bath for steel plates. SILVER PHOSPHATE, Ag;POs Fr. Phosphate d’Argent. Ger. Silberphosphat. Syn. Normal silver orthophosphat. M. W.. 419: Sp:-G. 7.320: Me Po Sol. in ammonia, potassium cyanide and sodium thiosulphate solutions, and organic acids; Ins, in water, alcohol and ether. P. Heavy yellow powder; turns brown when heated, or on exposure to light. Der. Obtained by adding phosphoric acid to silver nitrate solution. U. P. When formed in small proportions in printing-out emulsions, gives a long scale of gradation suitable for soft prints from hard negatives; acts very similarly when formed in silver chloride gaslight emulsions. MATERIA PHOTOGRAPHICA 67 SILVER SULPHIDE, Ag:S Fr. Sulfure d’Argent. Ger. Silbersulfid. M. W. 248: Sp. G. 6.85-7.32: M. P. 842° C.: B. P. Decom- poses. Sol. in concentrated sulphuric and nitric acids; Ins. in water and alcohol. P. A brownish-black powder. Der. Obtained by mixing an alkaline sulphide with silver nitrate solution. Also formed when liver of sulphur is added to old hypo baths. U. P. Silver sulphide is the salt formed when gaslight or bromide prints are sepia toned in the sulphide bath. SODIUM ACETATE, NaC,H;0.3H2O Fr. Acétate de Soude. Ger. Essigsaures Natron. Syn. Acetate of soda. Bee tao 9p. cx. LA: M. P. 58° C. Sol. in water; Ss. in alcohol. P. Colorless, transparent, efflorescent crystals. Der. Prepared by neutralizing acetic acid with sodium car- bonate. G. U.S.P. Granulated. U. P. Used in the gold toning bath. Double fused sodium acetate is sometimes used, having a slight alkaline reaction, makes the toning bath work more quickly. It is also more free of organic impurities. 68 MATERIA PHOTOGRAPHICA SODIUM BICHROMATE, Na:Cr.0,2H:O Fr. Bichromate de Soude. Ger. Doppelt Chromsaures Natron. Syn. Dichromate of soda, Acid sodium chromate. M. W. 298: Sp. G: 2.52: M. RB. Losés 2he@aapenn ee B. P. Decomposes. Sol. in water; Ins. in alcohol. P. Red, deliquescent, crystalline fragments. Der. Obtained in similar manner to potassium salt. (QV.) G. Technical. U. P. Used in the same manner and for the same purposes as the potassium salt. One part of potassium bichromate is equivalent to 1.10 parts of sodium bichromate. In proc- ess work, is sometimes used to replace the ammonium and potassium salts for sensitizing, but its deliquescent nature is a disadvantage. SODIUM BISULPHITE, NaHSO: Fr, Bisulfite de Soude. Ger. Saures Schwefeligsaures Natron, Natrium Bisulfit. Syn. Acid sulphite of soda. M. W. 104: Sp. G. 1.48: M. P. Decomposes. Sol. in water; Ins. in alcohol. P. White crystalline powder; faint sulphurous odor. Der. Prepared by passing sulphurous acid gas through car- bonate of soda solution. G. U.S.P. or special photographic. U. P. Used for acidulating and preserving fixing baths supplying both the sulphite and acid necessary. For preparing neutral sulphite solution which is cee used as a preservative for pyro developer. Can be sub- stituted weight for weight for potassium metabisulphite. For photographic purposes, sodium bisulphite should be free from iron. MATERIA PHOTOGRAPHICA 69 SODIUM BORATE, Na.B.0,10H.O Fr. Borate de Soude. Ger. Borax, Borsaures Natron. Syn. Borax, Sodium tetraborate, Pyroborate, Biborate. M. W. 382: M. P. Red-heat. Sol. in water and glycerine; Ins, in alcohol. P. White crystals or powder. Der. Obtained from the native borax, or by neutralization of native boric acid. eer Uo. U. P. Used in gold toning baths, and as an accelerator with hydroquinone and eikonogen developers. Can be used as a restrainer with the metol-hydroquinone developer for gaslight papers, and produces a print having a warm brownish-black. SODIUM CARBONATE, Na:CO;10H:O (cryst): Na.Cos (dry) Fr. Carbonate de Soude. Ger. Soda, Kohlensaures Natron, Natriumcarbonat. Syn. Soda, Washing soda, Carbonate of soda. Mower coo. op. G. 1446; M. P. Loses 5H:0 at 12.5° C., and mee at oF. C.: B. P, 106°C. Sol. in water and glycerine; Ins. in alcohol. P. Colorless crystals or white powder; strong alkaline taste; effloresces in alr. Der. Obtained by converting salt into sodium sulphate, and then decomposing the latter by roasting with limestone and coal. Sag ech ge U. P. Sodium carbonate is the principal alkali used for developers; in addition to the crystal form there is a grade known as “dry powder” which is extensively used For all practical work, 37 parts of the dry powder are equivalent to 100 of the crystals. 70 MATERIA PHOTOGRAPHICA SODIUM CHLORIDE, NaCl Fr. Chlorure de Soude, Selmarin. Ger. Chlornatrium, Sal Gemmae. Syn. Muriate or chloride of soda, Salt, Common table-salt. M. W. 58.5: Sp. G. 2:16): M. P) 804 Pee Sol. in water; practically Ins. in alcohol; Ins. in concentrated hydrochloric acid. P. Colorless, transparent crystals or white, crystalline powder. Der. Obtained native or by purification from sea water. ks. J OLS U. P. Used in the preparation of chloride emulsions. Also acts as a restrainer, but is weaker than the alkaline bromides. SODIUM CITRATE, 2Na;C.H;O;7.11H2O Fr. Citrate de Soude. Ger. Citronensaures Natron. Syn. Citrate of soda, Neutral citrate of soda. M. W. 714: M. P. Loses 11H.O at 150° C.: B. P. Decom- poses. Sol. in water; Ss. in alcohol. P. White crystals or granular powder; pleasant acid taste; very deliquescent. Der. Obtained by neutralizing citric acid with sodium car- bonate. Cry U. P. Used as a preservative in albumen papers, also to form silver citrate in printing-out emulsions. Is also used as a restrainer in development. MATERIA PHOTOGRAPHICA 71 SODIUM HYDRATE (Caustic), NaOH Fr. Soude Caustique. Ger. Aetznatron. Syn. Caustic soda, Sodium hydroxide. Pew. a0. Sp. G. 2.13: M. P. 318° C.: B. P, White heat. Sol. in water, alcohol and glycerine. P. White, deliquescent pieces, lumps or sticks; crystalline fracture. Keep well stoppered, absorbs water and carbon dioxide from the air. Should not be handled with the fingers. Der. Obtained by decomposing sodium carbonate with lime. USP. U. P. Used as an accelerator in development. Most gen- erally used with low energy developers, as hydroquinon, etc: SODIUM NITRATE, NaNO; Fr. Azotate de Soude. Ger. Salpetersaures Natron. Syn. Cubic, Chili, or Soda nitre or Saltpetre. Meo sp G. 220/: M. P. 316° C.: B, P. Decomposes. Sol. in water and glycerine; Ss. in alcohol. P. Colorless, transparent crystals. Der. Found native. G. U-S-P. U. P. Not often used in photography, although it is credited with imparting a brownish-black tone to developed silver images. SODIUM NITRITE, NaNO, Fr. Azotite de Soude. Ger. Salpetrigsaures Natron. Syn. Nitrite of soda. oe eooe op. G. 2.157) M. P. 213° C.: B. P. Decomposes. Sol. in water; Ss. in alcohol and ether. P. Slightly yellowish or white crystals. Der. Prepared by fusing the nitrate or neutralizing nitrous acid. ARTS U. P. Used in the diazotype process and in the preparation of photometer paper. 72 MATERIA PHOTOGRAPHICA SODIUM NITROPRUSSIDE NasFe(CN)s(NO)2H:0 | Fr. Nitroprussiate de Soude. Ger. Nitroprussidnatrium. Syn. Sodium nitroprussiate. M. W. 298: Sp. G. 1.6803. Sol. in water and alcohol. P. Ruby-red, transparent crystals. Der. Sodium ferrocyanide solution is treated with nitric acid. G. Pure. U. P. Is one of the most light sensitive iron salts, and is sometimes used in iron printing processes. SODIUM OXALATE, Na:C.0, Fr. Oxalate de Soude. Ger. Oxalsaures Natron. Syn. Oxalate of soda. M. W. 134. ' Sol. in water; Ins. in alcohol. P. White, crystalline powder; poisonous. Der. By neutralizing an oxalic acid solution with sodium carbonate. G. Pure. U. P. Not often used because of its low solubility; is, how- ever, sometimes used in the platinotype process. SODIUM PHOSPHATE, Na:HPO,12H2O0 Fr. Phosphate de Soude. Ger. Phosphorsaures Natron. Syn. Disodium phosphate, Disodium orth-phosphate. M. W. 358: Sp..G. 1.5235: M. P. 35° Co: BY Piosestieee? ate 00sec. Sol. in water; Ins. in alcohol. P. Colorless, transparent crystals. Der. By treating calcium phosphate with carbonate of soda. (SU See. U. P. Used in gold toning baths and sometimes in connec- tion with silver chloride emulsions. MATERIA PHOTOGRAPHICA 73 SODIUM SILICATE, Na:SiO; Fr. Silicate de Soude. Ger. Natronwasserglas. Syn. Soluble glass, Soda water-glass. Bee i242 M. P._1018° C. Sol. in water and alkalis; Ins. in alcohol and acids. P. White to gray-white lumps or powder. Also obtainable in a commercial form as a syrupy yellowish liquid. Der. Silica, calcined soda and coal are heated together in a crucible, the mass when cold, is extracted with water, followed by evaporation of the water. G. Usually bought in the grade known as “Technical solu- tion.” U. P. Used principally in process work, either alone or with albumen to form a substratum for coating collotype print- ing plates. SODIUM SULPHANTIMONIATE, Na;SbS8.9H:O Fr. Sulfoantimoniate de Soude, Sel de Schlippe. Ger. Schlippesche Salz. Syn. Schlippe’s salt, Sodium thioantimonate. M. W. 479. Sol. in water. P. Colorless or yellow crystals. Der. Obtained by boiling sulphide of antimony, milk of lime and sodium carbonate. G. Pure. U. P. Used for blackening negatives after bleaching with mercuric chloride, and sometimes used for toning bromide prints. SODIUM SULPHATE, Na.S0O.10H:O Fr. Sulfate de Soude. Ger. Schwefelsaures Natron. Syn. Glauber’s salt. Mi Ws Sen. Sol. in water; Ins. in alcohol. P. Colorless, efflorescent crystals. Der. Is yielded as a by-product in the salt cake process. G. Technical. U. P. Finds considerable use in the preparation of barium sulphate for surface coating photographic raw paper stock. 74 MATERIA PHOTOGRAPHICA SODIUM SULPHIDE, Na.S9H.O Fr, Sulfure de Soude. Ger. Natrimsulfid. Syn. Sulphide of soda. M. W. 240: Sp. G. 1.856. © Sol. in water; Ss. in alcohol; Ins. in ether. P. Yellow or brick-red lumps. Deliquescent, must be kept well stoppered. Der. Prepared by fusing sodium carbonate with sulphur. G. Technical. U. P. Used for the sulphide toning of bromide and gaslight prints. Sodium sulphide should not be kept near sensitive materials as it is likely to fog them and bring about deterioration. In process work, a three to five per cent. solution is used as the blackening agent in the intensifica- tion of wet collodion negatives; for this purpose it is better than ammonium sulphide. SODIUM SULPHITE, Na2SOs;7H.2O(cryst) NazSos(dry) Fr. Sulfite de Soude. Ger. Natriumsulfid. Syn. Sulphite of soda. M. W.:.252: Sp. GG. 1:5939: Mo Poses 7H.0 atclo0. 32 B. Po Decompases. Sol. in water; Ins. in alcohol. P. White crystals or powder. The crystals are efflorescent, becoming readily oxidized to sulphate. Der. Prepared by passing sulphurous acid gas over moistened sodium carbonate. G. U.S.P. Crystals or Dry Powder. U. P. Sodium sulphite is a vigorous absorbent of oxygen, therefore it is used as a preservative of developing agents. It is one of the constituents of the acid fixing bath. The _. dry powder form, which is now almost universally used in - photography, is twice as strong in sulphite as the crystalline. . MATERIA PHOTOGRAPHICA 75 SODIUM THIOSULPHATE, Na:.S:.0;5H:.O Fr. Hyposulfite de Soude. Ger, Fixirnatron, Unterschwefligsaures Natron. Syn. Sodium hyposulphite. M. W. 248: Sp. G. 1.729: M. P. 48° C.: B. P. Decomposes. Sol. in water and oil of turpentine; Ins. in alcohol. P. White, transparent crystals. Der. The crude sulphide liquors resulting from the Le Blanc soda process are exposed to air and oxidized, yielding calcium thiosulphate. This solution is boiled with sodium sulphate and subsequently crystallized. G. Technical. U. P. Its principal use is in the preparation of fixing baths for films, plates and papers. It is one of the ingredients of Farmer’s ferricyanide-hypo reducer. SODIUM VANADATE, Na:VOs,. Fr. Vanadate de Soude. Ger. Natriumvanadat. Syn. Sodium orthovanadat. M. W. 184: M. P. 866° C. Sol. in water; Ins. in alcohol. P. White, crystalline powder. Der. By solution of ammonium vanadate in sodium hydroxide solution and crystallization. U. P. Sometimes used to increase the contrast of printing- out emulsions. STARCH, C;HwOs Fr. Amidon. Ger. Starke. Sp. G. 1.499-1.513: M. P. Does not melt: B. P. Decomposes and chars. Ins. in cold water, alcohol and ether. Makes a jelly with hot water. P. White, amorphous powder. Starch when heated to about 204° C. is converted into dextrine. Der. From corn, maze, rice, potatoes, arrow root, etc. U. P. Used in the preparation of photographic mountants, and also for sizing photographic paper. Is sometimes used as a matting agent, being added to emulsions to dull the surface. 76 MATERIA PHOTOGRAPHICA STRONTIUM BROMIDE, SrBr.6H:O Fr. Bromure de Strontium. Ger. Strontiumbromid. Syn. Bromide of strontia. M. W. 355.5. Sol. in water; Ss. in alcohol, P. Colorless crystals. Der. Prepared by neutralizing hydrobromic acid with stron- tium hydrate. Gy eULRStP: U. P. Sometimes used in collodion emulsions to increase contrast. The anhydrous salt, SrBr2, is sometimes used and occurs as a white deliquescent powder. oe STRONTIUM CHLORIDE, SrCl.6H,O(crystals) SrCl.(dry) Fr. Chlorure de Strontium. Ger. Strontiumchlorid. Syn. Chloride of strontia. M. W. 266.5: Sp. G. 1.964: M. P. Loses 6H.2O at 112° C. Sol. in water and alcohol. P. White needles. Der. Calcium chloride is fused with sodium carbonate, the yield extracted with water, concentrated and crystallized. GC US. U. P. Used in the preparation of chloride emulsions, yielding more contrast and a shorter scale. The anhydrous salt, SrCl:, occurring as a white powder is sometimes used. STRONTIUM IODIDE, SrI.6H.O Fr. Iodure de Strontium. Ger. Strontiumiodid., Syn. Iodide of strontia. M. W. 449: Sp. G. 4.415. Sol. in water, alcohol and ether. P. Yellowish, granular powder. Der. By treating strontium carbonate with hydriodic acid. G. U.S.P. Fused. U. P. Uses, the same as for strontium bromide. (QV.) MATERIA PHOTOGRAPHICA 77 THIOCARBAMIDE, CS(NH:). Fr. Sulfo-urée, Sulfocarbamide. Ger. Thiocarbamid, Sulfoharnstoff. Syn. Sulphourea, Thiourea. M. W. 76: Sp. G. 1.406: M. P. 180° C.: B. P. Sublimes in vacuo at 150°-160° C. Sol. in cold water, ammonium sulphocyanide solution and ether; Ins, in cold alcohol. P. White, lustrous crystals. Der. Obtained by heating ammonium sulphocyanide for sev- eral hours at a temperature of 161° C. U. P. Used in the gold toning bath and has been suggested as an addition to eikonogen developer to produce reversal. Thiocarbamide can also be used for clearing yellow stains from prints and plates. THIOSINAMINE, CS(NH:)NHC;H; Fr. Sulfophenylurée. Ger. Thiosinamin Allylsulfoharnstoff. Syn. Allyl sulphocarbamide, Allyl sulphourea. M. W. 116. Sol. in alcohol and ether; Ss. in water. P. Colorless crystals; garlic odor. Der. Prepared by the action of ammonia and alcohol on allyl sulphocyanate (oil of mustard). U. P. Has been tried as a fixing agent, but is not nearly as energetic as hypo. TIN (Stannous) CHLORIDE, SnCl.2H20 Fr. Chlorure d’Etain. Ger. Stannochlorid. Syn. Tin protochloride or dichloride, Tin salt. hee yee on. G, 2./):.M. P.37.7° C.:-B. PB. Decomposes: Sol. in water and alcohol. P. White crystals. Der. Prepared by the action of hydrochloric acid on tin. G. Technical crystals. U. P. Can be used as a blackening agent after bleaching with mercuric chloride. 78 MATERIA PHOTOGRAPHICA URANIUM CHLORIDE, UO.CI1.H:O Fr. Chlorure d’Urane. Ger. Uranylchlorid. Syn. Uranyl chloride or oxychloride. M. W. 361. Sol. in water and alcohol. P. Deliquescent, greenish-yellow flakes; poisonous. Der. GS by dissolving uranic oxide in hydrochloric acid. U. P. Sometimes used as a sensitive salt for printing-out paper, and added to a chloride emulsion increases con- trast. URANIUM NITRATE, UO.(NOs3):6H:O Fr. Azotate d’Urane. Ger. Uranylsalpetersaure. Syn. Uranyl nitrate, Uranium oxynitrate. M. W. 504:-Sp. G. 2.807: M;-P. 602° Cos Bier Sol in water, alcohol and ether. Poisonous. P. Yellow, rhombic crystals; efflorescent, greenish color by reflected light. Der. Prepared by dissolving uranic oxide in nitric acid. Go s-U-S:Pi U. P. Used in printing-out emulsions and with potassium ferricyanide in the toning of bromide prints and intensi- fication of negatives. Used in conjunction with silver nitrate in the preparation of uranium silver papers for gaslight printing. Also used in the uranium mercuro- uranotype and the platino-uranotype processes. VANADIUM CHLORIDE, 2V0.4HCI13H:.O Fr. Chloure de Vanade. Ger. Chlorvandium. Syn. Hypovanadic-hydrochloride, Divanadyl-tetrachloride. M. Wt 306: Sp. tae Sol. in water and alcohol. P. Dark green syrupy mass; poisonous. Der. Prepared by dissolving vanadic anhydride in hydro- chloric acid. U. P. Used for imparting a green tone to bromide prints, and is one of the ingredients of the Donisthorpe dye printing process. Lumiére, in 1894, introduced a van- adium printing paper in which a gelatinized paper was sensitized with a mixture of vanadium chloride in alcohol and water, printed under a positive transparency and subsequently treated with paramidophenol. MATERIA PHOTOGRAPHICA 79 ZINC BROMIDE, ZnMr. Fr. Bromure de Zinc. Ger. Zinkbromid. heey orezzo op. G. 4219: M. P. 394° C.: B. P. 650° C. Sol. in water, alcohol and ether. P White, hygroscopic, crystalline powder. Der. Prepared by dissolving zinc carbonate in hydrobromic acid. Goro. U. P. Used in the preparation of collodion emulsions. ZINC CHLORIDE, ZnCl. Fr. Chlorure de Zinc. Ger. Zinkchlorid. Mew is0- Sp. G. 291: M. P. 262° C:.: B. P 730° C. Sol. in water, alcohol and ether. P. White, granular, deliquescent crystals; poisonous. Keep well stoppered. Der. By the action of hydrochloric acid on zinc, with sub- sequent crystallization. 53: U. P. Used in the preparation of collodion emulsions. ZINC IODIDE, ZnI, Fr. Iodure de Zinc. Ger. Zinkiodid. Mow. 319: Sp. G. 4.696: M. P. 446° C.: B. P. 624° C. Sol. in water, alcohol and ether. P. White, deliquescent powder. Keep well stoppered. Der. Prepared by dissolving zinc oxide in iodic acid. Se De oe U. P. Used in the preparation of collodion emulsions. 80 MATERIA PHOTOGRAPHICA DEVELOPERS There are upwards of three hundred (300) known photographic developing agents, most of them are, how- ever, of purely laboratory interest. Some have become obsolete and many are no longer manufactured, therefore, only the developing agents in current use will be described in this section: Developers obtained from Monohydric Phenols: sou PARAMIDOPHENOL, CoHs (1: 4) NH; Obtained by reducing para-nitrophenol with tin and hydrochloric acid. Occurs in colorless crystals with an M. P. of 184° C., also forms a crystalline hydrochloride. “Rodinal,” the concentrated liquid developer, contains para-amidophenol-hydrochloride. There is a solid form known as Unal. MONO-METHYL-PARAMIDO-PHENOL, C.H.(OH) (NHCHs) 1:4 Obtained by methylating paramidophenol, and more recently by the direct synthesis of methylamine and hydroquinone. Elon or “Metol” is the sulphate and is also known as Rhodol, Adne, Satrapol, Genol, etc. Elon or Metol in conjunction with hydroquinone is one of the best known developers. It also works well in conjunction with pyro. DI-AMIDO-PHENOL, CsH;s(OH)(NH:)(NH:2)1:2:4 Obtained by reducing 1:2:4 dinitrophenol with tin and hydrochloric acid, forms salts with sulphuric and hydro- chloric acids. “Amidol” can be either the sulphate or chloride, and is one of the best developers for bromide and gaslight MATERIA PHOTOGRAPHICA 81 papers. It does not keep very well in solution. Recently, methods of prolonging the life of Amidol solutions have been suggested by the addition of a small amount of lactic acid or a small proportion of metol. Amidol and Acetone sulphite form a powerful developer. PARA-AMIDO-SALIGENIN, CoH3(CH:0H)(OH)(NH:2)1: 2:3 Occurs as an easily soluble white powder, somewhat similar in properties to Amidol, with the advantage of allowing the preparation of very concentrated solutions. “Eidinol,’ made by Bayer, is the trade name of this material. It combines well with hydroquinone and acetone sulphite. /ONa(1) ee ENE, CHG (4) | CesHs.NHs The sodium salt can be used in a manner similar to Rodinol. Is sold as “Diphenal.” PARA-OXY-PHENYL-GLYCOCOLL, CsH.:(OH) (NH.CH2.CO:H)1: 4 Obtained by heating paramidophenol with monochloracetic acid in aqueous solution. ‘‘Glycin” is the trade name for this preparation. It gives a very pure black image and solutions keep well. Used principally for stand develop- ment, owing to the fact that it does not produce chemical fog with prolonged development. METHYL-ORTHO-AMIDO-PHENOL, C.H.(OH) (NHCH;)1 2 One molecule of hydroquinone with two molecules of methylorthoamidophenol forms the basis of “Ortol.” 82 MATERIA PHOTOGRAPHICA The following two naphthalene compounds are used as developers: SODIUM AMIDO-BETA-NAPHTHOL-MONO- SULPHONIC ACID, Ci.H;(OH) (NH:2)(SO;Na) Occurs in tabular crystals, white or slightly violet tinted. Is frequently sold blended with potassium metabisulphite. Is known commercially as ‘“Fikonogen.” Eikonogen is a useful developer for plates which have received short exposure, and works very well in conjunction with hydroquinone. SODIUM AMIDO-NAPHTHOL-DI-SULPHONATE, CyHi(N H2) (OH) (SO;Na)2 A yellowish powder, frequently combined with meta- bisulphite as a preservative. This body forms the basis of the developer “Diogen.’ Diogen gives negatives of a good pure black color having good gradation; not very susceptible to bromide. Developers obtained from Dihydric Phenols: PARA-DI-OXY-BENZINE, C;H:(OH):l: 4 The best preparation occurs as almost white crystals or needles obtained by _ recrystallizing the commercial product in the presence of SOx Is known commercially as “Hydroquinone.” Hydroquinone alone gives strong, hard negatives of a bluish-black tone and is quite opposed to Metol in performance, as with Hydroquinone the shadow detail does not come up until the high lights have acquired considerable density; in other words, it produces density rather than detail, which makes it of value in combination with the softer working Metol. Can be successfully used with Edinol and Fikonogen. MONOCHLOR and MONO-BROM-HYDRO- QUINONE, Ce.H:C1(OH)>. and C.HsBr(OH). The Monochlor is prepared by leading Chlorine gas through Hydroquinone dissolved in benzol, while the Monobrom is obtained by adding a solution of bromine in benzol to a Hydroquinone benzol solution, subsequently evaporating the benzol and crystallizing from ligrion. Commercially these bodies are known as “Adurol,” the monobrom being the product of Schering, and the mono- MATERIA PHOTOGRAPHICA 83 chlor, the product of Hauff. Adurol in performance comes between Hydroquinone and the rapid types of developers, such as Metol and Rodinal. Solutions are not readily oxidized and may be repeatedly used. PYROCATECHOL, C.H:(OH)21: 2 Occurs as a white crystalline powder, something like Hydroquinone in appearance. Is soluble in alcohol, ether and water. Does not keep well in solution. If a 5% solu- tion of borax be used as restrainer, very good brown-black tones may be obtained by direct development on gaslight and bromide paper. It is also sold under the name of “Kachin.” RESORCIN, C.H:i(OH).1: 3 Is in itself of no use as a developer, but two Amido derivatives from excellent developers. “Diamido Resorcin,” CesH2(NH:2)2(OH)2 and “Triamido Resorcin.” Diamido Resorcin Hydrochloride is sold as “Dianine,” is a fawn colored powder working similarly to Amidol, needing only soda sulphite to produce an energetic developer. ‘Triamido Resorcin Hydrochloride is sold as ‘“Reducin.” Developers obtained from Trihydric Phenols: PYROGALLOL, C.H;:(OH)s1: 2:3 Familiarly known as “Pyrogallic Acid” or “Pyro,” a fine, very light, white powder which oxidizes very quickly in solution. Produces negatives of a yellowish color unless sodium sulphite is used. It also stains the fingers. Used in conjunction with Metol and Hydroquinone forms an excellent tank developer, and with Metol an excellent developer for portrait negatives. The accelerators used with Pyro can be Ammonia, Sodium Carbonate, Potassium Carbonate or Acetone. PINAKOL P Is a good developer made by substituting in the Pyro potash developer the alkali by half the equivalent amount of sodium amidoacetate. This developer works more rapidly than ordinary pyro, gives clearer negatives and does not stain the fingers. 84 MATERIA PHOTOGRAPHICA DYES Of the several hundred known dyes for color sensitiz- ing, desensitizing safe lights, mordanting processes, and the preparation of light filters, but comparatively few are really useful and practical in performance. Only those which have found continued and successful application in photographic processes will be dealt with: SENSITIZING DYES For Orthochromatic Emulsions: ERYTHROSIN is most generally used for ortho- chromatizing silver bromide emulsions. It sensitizes for yellow and green. EOSIN is also used for orthochromatizing but does not give as great a sensitiveness as Erythrosin, and is more likely to produce fog in the emulsion. The usual practice when orthochromatizing emulsions with either of these two dyes is to add them to the emul- sion during the course of manufacture instead of bathing. MONO-BROM-FLUORESCEIN is also used as a yellow-green sensitizer for silver bromide. In the preparation of the so-called self-screened emul- sions a yellow dye is incorporated with the emulsion and acts as though a yellow filter were employed upon the lens, usually this result is obtained by adding to the emul- sion a small amount of Filter Yellow K. With both Erythrosin and Eosin the sensitizing effect is greatly increased by using them in conjunction with ammonia. For Panchromatizing Emulsions: For Panchromatizing it is usual to employ two or more dyes to secure the desired result. MATERIA PHOTOGRAPHICA 85 CYANINES CYANIN, a blue dye, is very useful as a sensitizer for silver bromide where a panchromatic effect is desired. It confers a sensitiveness to yellow, orange and red rays with a minimum of sensitiveness between E and F. Its chief disadvantage is a tendency to produce fog, and it has been almost entirely replaced by the Isocyanines. DICYANIN sensitizes silver bromide emulsions as far as the red line A, with minimum sensitiveness between E and F. The prepared plates, however, do not keep very well. ISOCYANINES ETHYL RED, which occurs as green crystals, soluble in water and alcohol, sensitizes bromide emulsions with fair uniformity from violet to red with a small minimum in the green. It does not, however, sensitize very far into the red end. ORTHOCHROME—T is an excellent sensitizer for green, yellow, orange and red, diminishing the general sensitiveness but very little, and has no tendency to fog the emulsion. PINACYANOL. This is one of a new class of dyes which gives great sensitiveness to yellow, orange and red. Is particularly useful in the preparation of plates for three-color photography, for recording the blue sensation. Pinacyanol does not sensitize for green and so the plates may be developed in dark green light (F line) without danger of fog. Pinacyanol may be added to an emulsion during the process of manufacture, or may be used to bathe the finished plates or films. PINACHROM sensitizes bromide emulsions up to the line B, producing plates which render dark red extremely well; does not tend to produce emulsion fog and the finished plates will keep for a long time. This dye can either be added to the emulsion or the finished plates may be bathed. 86 MATERIA PHOTOGRAPHICA PINACHROM VIOLET has one great advantage over Pinacyanol: in that it combines with the green sen- sitizers with less danger of fog and influence on the keep- ing quality of the finished plates. Pinachrom Violet sen- sitizes almost to line B. Can be added to the emulsion or used for bathing the finished plates. PINAVERDOL is excellent for conferring green sensitiveness, and may be added to the emulsion or used for bathing the finished plate. PINAFLAVOL is the newest sensitizer for green and combines much better with Pinacyanol than does Pinaver- dol. Can be added to the emulsions or used for bathing the finished plates. Confers no red sensitiveness. In Panchromatizing it is always found that there are definite maxima and minima of sensitiveness and recently the addition of Auramine has been suggested to the pan- chromatizing dyes as a means of securing a more uniform panchromatic effect. It is only necessary to use a very small amount of this dye. KRYPTOCYANINE sensitizes very strongly for red and has only recently been introduced. It gives a maximum sensitiveness at wave length 770; confers no green sensitiveness. Other sensitizers of this class for the deep red which have recently been introduced, are: Beta-naphtha-cyanole, which sensitizes with a strong maxi- mum in the deep red at wave length 690, and also sen- sitizes for green but less so than Pinacyanol. Acetamino- cyanole, when added to an emulsion yields a maximum sensitiveness at wave length 730, can also be used for bathing the finished plates. During the war Pinacyanol and Pinaverdol were synthesized in this country at the Color Laboratory at the Bureau of Chemistry at Washington, and were also prepared in England by Prof. Pope, under the names of Sensitol Red and Sensitol Green; both the English and American dyes were in every way equal to the German product. MATERIA PHOTOGRAPHICA 87 DESENSITIZING DYES Recently Ltuppo-Cramer discovered the desensitizing action of the Azo dye known as Phenosafranine, and also of other dyes of the same class on ordinary and pan- chromatic plates. A further application of the use of Phenosafranine is the use of the substance in very small amounts for development under ruby or orange light of great brilliancy, so that even a very sensitive plate or even orthochromatic plates may be developed under the direct rays of the dark-room light. It has been found that 10 cc. of a 100,000 solution of Phenosafranine added to 100 cc. of any desired developer permits of the safe development without risk of fog, even in a very bright ruby light. In addition to Phenosafranine the following dyes of the Safranine class possess valuable desensitizing properties: Di-methyl-pheno-safranine. Tetra-methyl-safranine. Tolu-safranine (ordinary safranine). Methyl-tolu-safranine (Safranine MN). Dimethyl-benzoxylyl-safranine (Giroflé). Tetra-ethyl-phenosafranine (Amethyst violet). Creso-safranine. Naphtho-phenosafranine. Ethyl-dimethyl-etho-safranine (Fast neutral violet D). The following bodies also exert a strong desensitizing action: Toluylene red, 1: 1,000 solution; immersion for 4 minutes. Aurantia (ammonium salt), 1: 1,000 solution. Picric Acid, 1 per cent. solution. Indian Yellow, 2 per 1,000 solution. Crysoidine, 1: 2,000 solution. Diamidophenol, 1 per cent. solution. Apomorphine hydrochloride, 1 per 1,000 solution. Neutral potass chromate, 2 per cent. solution. Plates may also be desensitized with Potassium Iodide according to Freund’s method. This method is not very satisfactory. FILTER DYES Recently Hnatek has given a very complete collection of dyes and their applications for filter-making that cover the whole of the spectrum and are applicable to all classes of photographic work where contrast or compensating filters and safe lights are necessary: MATERIA PHOTOGRAPHICA 88 000Z Wosy pet yRom ‘Wd 000Z Wor} por “ws 0089 Wolf pol ‘wis 0% “99 0'z 99 OT “299 OT ‘29 07 99 0? 99 07Z a) 0? 99 07? ‘09 Cl ‘09 OT wee oe 538) 07? ‘090 OT 72/2) OT Oe) OT 8) o'¢ ‘O99 OT 0c OT 07 OT 0c Ov 0c OT oT OT oe 0° OT 0c 0¢ ie QUIZEIJIC T, d pel isey useid [OoyVYydeN UIZEI}IC T UISOD YSIMOT[I A useIs JoyyYydeN aSuUeIO JURIIG usd13 [OYyWYdeN DUIZEIYIL T, S usa13 JY SIT useIs [oyyyden O ulmeiny on[q jus9}eg MO][IA VUTTOUTYD d p ONyq ouspAyyayy UISOD YSIMO]]I A JO[OIA S UUeUJ OPT SLINA SINOULSONYV 0001 INOdV AO NOISSINSNVAL V HLIM SYALIIA ‘Vv (q) (®) (q) (®) (q) (2) (q) (2) (q) (2) (q) (2) (q) (2) 0069-006 0099-0095 00S9-00SS 00r9-002S 006S-008r 009S-00SP O08P-F91OLA O06P7-F91O1A © 8 9 v cc c b oe | 89 MATERIA PHOTOGRAPHICA 0c Lett ots 22 0089 Woy por yeom 000Z Wost pot 000Z tory par ANS ANS ANS maNC N wer Noo mari 5 ee cee oe | ‘ me N Soe A oe | N Om SS 9S SS SN SoH CSS CoN CSS mN ee ee ee Oe OOM Se Oe ta NAN usd1d joyyYydeNn QUIZEIPIV T, qd pest sey use18 joyuyydeN DUIZEIVIC I, [esusgq 93sSo0y UISOD YSIMOTIIX useIs [oyuIYydeN DUIZEIVIC T qf uses prioy usa13 [oyuyyden QUIZEILIC T, p An] q sus AQP, OQ urweiny aq 9 enq Hea M Moyo J09TY d p anyq euatAyjow uIsod YsIn[g € p ONq susAYra I UISOD YSIMO]]I ‘Nl “V 006 OL 00S (q) (2) (q) (®) 0099-0009 009r-008S 00£9-009S 00ZS-O0TS 00SS-008r OOTS-OSbhr 009b-006¢ 00Srh-006¢ WOU AO NOISSINSNVAL V HLIM SHALTIA “& ot +! Al aa ‘OL MATERIA PHOTOGRAPHICA Q00Z Wosy por jurey “WS KT 99 YZ use13 jueNitg (4) ts) T1290 1 02 MoOTJaA snizepy (2) 10 ms GT ‘99 CT enjq yuazeq (q) 000L Woy pat yurey “US QT “99 Op moyjas sniyzep (®) 0025-0025 “br ‘ths OF OD Oe use18 jouiydeN (q) ws 07 99 Or asueio juellitg (&) Q0rs-00ZS ‘€2 OOTL Wosy pot jurey “WB (EG “99 YC anyq yue}eq (4) ms 07 99 OT auizeqyiey, (@) O0ss-OS0S zz 00Z9 Wor pet jure} “WB (YZ 9D YT 9 aniq NexIV (4) ms Q'¢ 99 O'S MOTJEA TOuIYdeN (%) CO0ZS-006F ‘IZ 0099 Wor} pot jurey “WS CT 99 CT aq 9 enq Neary (4) ms 07 99 02 moyjad fouyydeN (8) O0S-008r “02 WS. TN 2 Se ae JB[OIA UeI}UI5 (9) NIBP A[tiey “is jz 30 OZ usei18d joyuyydeN (q) ws 0g 99 OY moras urjoury) (%) O08r-00Zr “61 Q0S9 Wo1y por “WB GT 99 OF JOJOLA ueTUAL (q) ws 07 99 OZ MoyeA UTOUTy (B®) 008r-009F ‘8I QOL Worl por yRaM "WB Op 99 Oh V eniq yuaieg (q) EB Te 990 Sl uysos, -ysinjg (8) OS0v-Oszr ZT ‘Nn ‘v 00S OL 002 NOYA AO NOISSINSNVAL V HLIM SAALTII 91 tH NAN ONAN ° MATERIA PHOTOGRAPHICA to MNT tt Seo SSN ON SOOO CONN CS OSS SOO oeo SoM oN COS ONS CS SSD CSS So Ah ee I oe | Nr onjq juszeq (q) QUIZEIJIL T, qd pet yseyq (®e) P?4-0069 use13 [Aye (q) QUIZEIPIL, CG per yseq (8) pes-0gZ9 JOJOIA S uUeWIJOFZ (q) UINN09 MIN (2) P24-00S9 JOJOIA URT}UaD) (q) use13 [oyuyydeNn uI9909 MAN (®) — 0089-009 usei13 jouyydeN dUuIzesyIey (q) xneapiog (®) (099-0019 use13 jouyyden (q) UIN909 MON (®) 0SP9-0S6S onyq uI1eg useis jouyydeN (q) uI9909 MEN (®) 0009-0025 onjq jusjeg use13 jouiydeN (q) esueIO WRITIIIg (2) 008S-00bS 92 MATERIA PHOTOGRAPHICA The dyes were made up into stock solutions of the following strengths: 0.4-100 Acid green. 0.5-100 Brilliant orange, martius yellow, brilliant green, methyl green, methylene blue, toluidin blue, gentian violet. 1-100 Fast red, D. Bordeaux, rose bengal, naphthol yellow, chinolin yellow, rapid filter yellow K, auramin, naphthol green, light green, alkali blue, patent blue, Hof- mann’s violet. 2-100. New coccin, eosin, tartrazine. The second column gives the band of transmission of the filter, the fourth gives the number of cubic centi- meters that should be added to 7 cc. of 12 per cent. solu- tion of gelatin, and this is the quantity that should be coated on 100 square centimeters of glass. The fifth column gives the quantity of dry dye in grams per square meter, according to Huebl, which is called the density of the dye. The last column gives useful data as to the transmis- sion of the red end of the spectrum, which for visual work is negligible, but for photographic work must be taken into consideration, when panchromatic plates are used. Filters 9, 29 and 32 are rather dark, that is to say, they exert some absorption of the region that they gen- erally transmit; 10, 17, 28 and 31 are less dark, but still do not transmit to the full the wave lengths given. It is obvious that by combination of two or more filters almost monochromatic filters can be obtained, but in all cases the resultant filters are very dark. The signs (a) and (b) mean that the dyed gelatine must be coated on two separate glasses and that they can- not be mixed. MATERIA PHOTOGRAPHICA 93 For the preparation of orthochromatic filters similar to the K series, Filter Yellow K is the dye used. A filter about equivalent to K2 can be prepared as follows: MOPITEIMOPSGIULION Asc lees un eee ele es 6% LORE? NPE can «gn rr 1 to 200 sol. (Rapid Filter Yellow) For Orthochromatic Emulsions: selatnersoiition «...0s.0 6.5. e5 eco s 120 cc. RE MER ONITIOU S252 c Sina win tees cae ss oes 66° cc: et eM ce. 5s She vGeieidiw owes x 6. Gc: Use 7 cc. of dyed gelatine to 1 sq. decimeter plate sur- face and use two of the coated glasses cemented together, or use 14 cc. dyed gelatine to 1 sq. decimeter and cement to a plain glass. Lighter or darker filters may of course be obtained by decreasing or increasing the amount of dye. Filter Yellow K aes be replaced by the English dye (Ilford Ltd.) Filter Yellow A. FILTERS FOR THREE COLOR WORK. Stock Solutions: Blue— OL! AE 4 grams SO Aes er aU Cr: PT Atia LCehico ACI ...2 0.60. hres 5 or 6 drops Green— UPS IS ee Og ce | 1 gram ee OO WW ya is ce 81s eos ein 1 gram Lo NST Se er 100 ce, Red— mecaeiiter Red To... i. scenes 5 grams ails cr ne a 8% a8 oes we Z00R ec: Dyed Gelatine— PROMS ONITIO Rie sons «ek Sine nie os en os 20. cc, Geélatine ‘Solution 6%...........«. 100 cc. 7 ccs, to 100 sq. cm. Cement two of each filter together. 94 MATERIA PHOTOGRAPHICA DARK ROOM FILTERS—BASED ON 16 C. P. LAMP For use with Developing Papers: Transmits 515 to 800 TLartrazine:..20). 2. .veo0 eo eee 0.8 grams Gelatine ‘Sol'6%73 720. eee 60.0 cc. _ Coated on a glass 8 x 10. Bind two together with onion skin paper between. For Bromide Papers and Lantern Plates: Transmits 575 to 800 Glass No. 1— Gelatine Sol?.6%.. 283.4. ee 60.0 cc. ‘Tartrazine #48 ss oer ee eee 0.8 grams Glass No. 2— Gelatine Sol. (6% <... : os. oi. ccn eee 60.0 cc. Rose’ Bengal... cg. 2553 eee eee 0.3 grams Bind 1 and 2 with tissue—8 x 10 glass. Rapid Ordinary Plate Transmits 620 to 800 Glass No. 1—8 x 10 Gelatine Sol. 6%... . 2502 ec. 60.0 cc. Tartrazine 6.5.9 3k 4 eee 0.8 grams Glass No. 2— Gelatine’ Sol. 6%... cs sas se ae 60.0 cc. Xylene Rede G2. ... °° | py Da ef SS fs a ee NS be fp Se Se a Se ae | Sa | |e et | pe ee ef ee ee ee ee eee _ furnish you anywhere, at any time, a soft, powerful light ‘and on groups, banquets and interiors, the Victor Flash Powder “The Light That’s Always Available’’ A majority of your negatives are made indoors, and daylight seldom strongly or uniformly lights any interior, and never permits the instantaneous exposures necessary to prevent movement and secure desired animation of your subjects. You can, however, easily overcome this handicap by using Victor Flash Powder as your exposure-light. It will which you can regulate in volume and direction to exactly suit the character and requirements of your subjects. All your exposures with Victor Flash Powder are in- stantaneous, enabling you to unfailingly catch desired expressions and poses of even the most active subjects. The amount of illumination you secure is merely a matter of the quantity of Victor Powder you use. For portrait work, 3 to 10 grains is sufficient, amount required is surprisingly small. Secure a supply now, that you may con- stantly have it on hand to assist you. Is supplied in four grades to meet all requirements, viz.: Normal, Extra Fast, Soft } and Portrait. Normal is most satisfactory | for general use. We manufacture a complete line of Hand Flashlamps, Flash Bags and Studio Flash Cabinets, description of which will be gladly sent on request. JAMES H. SMITH @ SONS CO. 3529 Cottage Grove Ave. CHICAGO, ILLINOIS eee ————E———————————— lo eee 2) Be] Be) Be] Be) Be) netensbamiaeninalnelacta ae telialedleclemicc In no other photographic magazine can you find so much plain and practical information as in THE MAGAZINE LE LUXE FOR ALL PHOTOGRAPHERS HE pictorial reproductions in THE CAMERA are by the best workers in America and abroad. Every issue is a veritable work of art. If you want a print criticised or are puzzled about a working formula, just ask THE CAMERA—it is at your service. THE CAMERA is for sale by dealers at 20 cents per — copy or $2.00 per year by subscription. If your dealer cannot show you a sample copy, send five 2-cent stamps to the publisher for one. FRANK V. CHAMBERS Corner Seventh and Race Streets PHILADELPHIA (4) G4 Gd Be] Ge] Bd G4) Gel Ge) Ge Gd] Be) Ge] BS) Gd Ge GS) BS) G4] G4] Be) Be] Be Ge) 2] Be] Be G4] 52] BS] Ge) G4] Be] BA Be] Bel Be) Bel Bel Bd] Bel Be] G4) GE] G4) 4] BE Bl Ge] Bd G4) Be] G4) Be] Gel Be] G4] Bei GE] G4) BE] 54] G4) BE] BE BEI BE) Be) G¢] Be] Be] Be) Be) Be) Fe] G€) Ge] Be) Be) Be) Be) G€] Bel Ee] Bel Bel Bd) Ge) Bel Bel Bel Be] Gel be] Gel Bel Gel Ge] (24) Be) 56) Be] 134] Ge] Ge] Ge) G4) G4) 64) Be] 4] Be) Be] Ge) Be] Be] Be] Be) G4] Bel Bel G4 4] Be) BFi BA] BE Bal Bd Bel Ge] Be] Be] Ba] Be] Be) QPeeeeeeer rrr rere err rere reer Ve + THERE’S A GRADE Beinee VERY PURPOSE O matter what the need, there’s a grade and surface of HALOID QUALITY PAPER with which to meet it. The most exacting studios, the busiest finishers and commercial photographers, all find in the HALOID line, solution to their paper problem. Briefly classified the HALOID grades are these: Haloid Portraya for portraits in warm black. Haloid Enlarging Portraya for prints by enlargement that es- cape the “‘enlarged”’ appearance. Haloid Outline Special Very thin tough stock. For fur- niture and other commercial prints. Will not crack when folded. A unique product. Haloid Parchment Antique A unigue portrait paper of ‘*hand-made”’ appearance. Haloid Industro A remarkably effective paper for popular-priced portraits. Haloid Press Bromide A fast and very contrasty bro- mide paper. Single and Double Weight Glossy. Haloid Fine-Fabric Linen (buff or white) Fine-textured linen papers for de luxe portraits. Haloid Art-Proof P. O. P. papers of unequalled guality for proofing. Haloid Rito Non-abrasive papers of wide latitude for finishing and com- mercial work. Now made in four degrees of contrast. THE HALOID COMPANY, Rochester, N. Y. NEW YORK OFFICE: 225 Fifth Avenue CHICAGO OFFICE: 68 W. Washington Street BOSTON OFFICE: IOI Tremont Street, at Bromfield San Francisco Agent: A. H. MUHL, 143 Second Street Los Angeles Agent: A. H. MUHL, 643 S. Olive Street MERCK’S Photographic Developers FOR PROFESSIONAL AND AMATEUR PHOTOGRAPHERS Photol (Monomethyl-Paramido- Phenol Sulphate) Widely used in developing negatives, Velox and other developing-out papers. Hydroquinone Beautiful, light, needlelike crystals. Particularly use- ful in developing papers, and in motion picture work. Acid Pyrogallic Finest detail in lights and shades. Most perfect printing negatives. Price list on request MERCK & CO. St. Louis New York Montreal Works at Rahway, N. J. THERE IS A CRAMER PLATE FOR EVERY NEED 25 BRANDS OF UNEQUALLED QUALITY Sao? CONY 9D Write for a copy of our “Manual.” | It briefly describes all 25 brands and is full of useful information. COA DSS GC aed G. CRAMER DRY PLATE COMPANY NEW YORK ST. LOUIS CHICAGO PHOS SEH SP SESH ESS SPIN SESS SOS! OPH EMO OLIN SLIH OLN SPIN OLLI SLOP SPSL OLS PLIN SLO SPONSE PS (SSO SSS SPONSES SSC SSS SESH See 116 % 0 | RO 1 Sea + | RE | Gee | RED NEES | MD 1 | Coa | ecimey 6 1 emai | | Gt + OSE | | MD | | CRE 1 + Moen 1 | MRE + | Come) | tained) Masi: + AD 1 | Com 4 em ++ Comal 1 The News of the Photographic World— may be brought to your desk every Wednesday of the year through the pages of the IBULLETIN ~ OF] IPHOTOGRAPHY| It keeps you enlightened on | every-day progress—tells you | what the rest of the world is doing in photography—and | gives you the news most es- sential, most interesting and | most vital to your business. PUBLISHED EXCLUSIVELY PORSTHE PROFESSIONAL PHOTOGERAR A. Subscription price, $2.00 per year, postpaid BULLETIN OF PHOTOGRAPHY FRANK V. CHAMBERS, PustisHER 636 FRANKLIN SQUARE, PHILADELPHIA WOULD YOU LIKE A 3A Se PSC Sweieweteoe ete 6 4 CERIO 4 ORE 6 ENED | KRRIE 4 6 AER | | PR 1 RE | HOEY | m6 SH | HSS + GE | | AD + 1 Em | GE Den | SRD 1 + OY se W OLLENSAK LENSES JUST A FEW OF THE MANY POPULAR TYPES —for all-round studio use and Graflex as well as home portraiture, the Series II Velostigmat 4.5 is ideally suited. It capably handles bust and child portraits, full figures and groups, and is adaptable to commercial work, copying, enlarging, etc. —for delightful soft-focus effects nothing compares with the Verito Diffused Focus f4. This versatile objective gives as much or as little diffusion as may be desired by simply turning the diaphragm ring, Long focus rear element. —for portraiture and baby pictures the Vitax Portrait 3.8 stands supreme. Its improved Petzval formula helps to produce life-like portraits with beautiful modeling. Its extreme speed permits snap shots in the studio. —for commercial and view work we recommend the new Series Ia Velostigmat f6.3--f7.7. This is a wonderful triple-convertible anastigmat. Its long-focus single elements are also fully corrected and ‘ aid in obtaining telephoto effects, better perspective and larger images. —for wide-angle photographs we offer the Series III Velostigmat. It has the unusual speed of f9.5 and an angle of 90 degrees. A truly valuable addition to any equipment. If you wish descriptive catalog of the complete Wollensak line of lenses and shutters, write to the WOLLENSAK OPTICAL COMPANY ~- Rochester, New York i i ?, ? =D ie ° IWENTIETH CENTURY PHOTOGRAPHY THE WILLSON WAY Willson Apparatus Solves The Profit Problem WILLSON MAGAZINE CAMERA Capacity, 1,100 exposures at one loading GROUP PICTURES FROM ORIGINAL NEGATIVES LARGE PICTURES FROM SMALL NEGATIVES IDENTIFICATION Write for Catalog _WILLSON AUTOMATIC PRINTER | VICAM PHOTO APPLIANCE CORPORATION 1224 BELMONT AVENUE, PHILADELPHIA, PA. 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