we odbe od) Soe : ° erardsg ti , ei tga ste. e wae LPL CTE EP Pree Ne ge He McE. Knower *,* No book or pamphlet is to be removed from the Lab- ‘oratory without the permission of the Trustees. b SSheOO TOEO O AMIR IOHM/TalN PHOTOGRAPHIC FACTS AND FORMULAS zh PEO ah Ne a oa, Books on Photography Optics for Photographers, by Hans Harting, Ph. D. Translated by Frank R. Fraprie, S. M., F. R. P. S. 232 pages. Cloth, $2.50. Chemistry for Photographers, by William R. Flint. 2nd edition. 218 pages. Cloth, $2.50. ; Pictorial Composition in Photography, by Arthur Hammond. 234 pages, 49 illustrations. Cloth, $3.50. Photo-Engraving Primer, by Stephen H. Horgan. Cloth, $1.50. Cash from Your Camera. Edited by Frank R. Fraprie, S. M., F.R P. S. Paper, $1.00. Pictorial Landscape Photography, by the Photo Pictorialists of Buf- falo. 252 pages, 55 illustrations. Cloth, $4.00. Photographic Amusements, by Walter E. Woodbury. 9th edition. 128 pages, 100 illustrations. Cloth, $1.50. Practical Color Photography, by E. J. Wall, F. C. S., F. R. P. S. Cloth, $3.00. The Air Brush in Photography, by Geo. F. Stine. 143 pages, 45 illustrations. Cloth, $2.50. Bromoil Printing and Bromoil Transfer, by Dr. Emil Mayer. Translated by Frank R. Fraprie, S. M., F. Hi P. S. 199 pages. Cloth, $2.50. Practical Photography Series, each 50 cents in paper, $1.00 in cloth: 1. The Secret of Exposure. 2. Beginners’ Troubles. 3. How to Choose and Use a Lens. 4. How to Make Prints in Colors. 5. How to Make Enlargements. 6. How to Make Portraits. 7. How to Make Lantern Slides. 8. The Elements of Photography. 9. How to Retouch Negatives. 10. How to Make Good Prints. 11. Modern Development. ENGLISH IMPORTATIONS Photography Made Easy, as Easy as A B C, by R. Child Bayley. 264 pages. Paper, $1.50. The Barnet Book of Photography. Cloth, $2.00. Art of Retouching Negatives and Practical Directions for Finishing and Coloring Photographic Enlargements, by Robert Johnson, T. S. Bruce and Alfred Braithwaite. Boards, $2.50. Hieroglyphic or Greek Method of Life Drawing, by A. A. Braun. Boards, $7.50. Photograms of the Year. Paper, $2.50. Cloth, $3.50. Penrose’s Pictorial Annual. $4.00. Descriptive list on request. Published or Imported by American Photographic Publishing Co. 428 Newbury St., Boston 17, Massachusetts PHOTOGRAPHIC _, FACTS AND FORMULAS Bye | WALL, FC S)RiR Ps Associate Editor of “AMERICAN PHOTOGRAPHY” Author of “Practical Color Photography,” ete. AMERICAN PHOTOGRAPHIC PUBLISHING Co. Boston, Mass., U.S. A. 1924 Copyright, 1924, by AMERICAN PHOTOGRAPHIC PUBLISHING Entered at Stationers Hall Printed and bound in the U. 8. A. First edition, July, 1924 The Alpine Press, Boston, Mass., U. 8. A. Nags ge we JA 8 Ei Foreword Cp Piet N aes ta 5 The main idea kept in view in the compilation of this book has been to provide in condensed form working formulas and instructions for the various processes of photography. There must necessarily be errors of omission and commission, and the publishers will be grateful to any reader who, consulting its pages and failing to find what he requires, will at once communi- cate with them, in order that the omissions may be remedied in future editions. Forms for this purpose will be found at the end of the book. The formulas given have not been selected in hap- hazard fashion but, as far as possible, only from credit- able sources. Certain valuable information, received after the body of the book was made up into pages, will be found in the Appendix at page 376. Contents: Foreword . Contents : Studio and Workrcom Orthochromatic Photography Plate Backing Focus and Optics Exposure. Development Developers . Fixing and Clearing Intensification Eeducers- . Varnishes 7 Silver Printing Processes Printing-Out Papers Salted Paper Bromide Paper Developing-Out Papers f Toning Bromide and Gaslight Prints Sulphide Toning . The Carbon Process The Gum-Bichromate Process Vil Li 00 123 130 141 150 160 173 189 199 204 216 234 249 255 viii CONTENTS The Iron Processes Platinotype . Ozotype and Allied Processes Oil and Bromoil . Miscellaneous Printing Processes Mountants Stereoscopic Work Lantern Slides Enlarging Flashlights . Colour Photography Photomechanical Processes . Weights and Measures Chemical Tables . Appendix Index . 258 274 a 302 314 325 328 330 334 339 344 351 360 368 376 377 Hep Re Phe Gy Sie tet ee 2 q if 5 i “a 4 eS rit Ray LIBRARY | ax cane * 4 : iy oo ee my, Fein. ay ys, AO oe Ba” pl xg Rech, i ie Studio and Workroom ‘ WEIGHTS AND MeEasureEs.—It will be noted that formulas in this work are usually given both in metric and duodecimal (or British and U. S.) weights and measures. The metric weights and measures are not the exact equivalents of those in the other systems; but the ratio of the ingredients in each column is the same. Readers must therefore rigidly adhere to one or the other system, and not weigh out solids in grammes and measure liquids by ounces or a hopeless muddle will result. In all cases the conversion has been made on the assumption that photographic solutions are measured and not weighed out and, therefore, the ratios are based on a uniform bulk of 16 oz. or 7680 minims. In many cases fractional parts have been omitted or rounded off to the nearest practical quantity. In all cases, too, the quantities, 1000 ccm or 16 oz., mean that these should be the total bulk of the solution when made, unless otherwise stated. Therefore, it is advisable to dissolve the dry ingredients in some of the solvent and then make up to the given bulk. BackGrounpDs.—Cloth is the best material, and can gener- ally be obtained up to 96 inches in width. Calico, bleached or unbleached, can be obtained up to 72 inches wide; brown felt paper up to 60 inches. Small pieces of cardboard, about Y4 inch square, are required. Lay the stretcher or frame flat on the floor, and get a friend to hold the right-hand bottom corner of the material down to the corresponding corner of the frame, stretch the material quite taut, and nail down the top left-hand corner to the edge of the frame. Drive the tack or nail through a piece of cardboard and the material at 1 2 PHOTOGRAPHIC FACTS AND FORMULAS both corners. Then deal with the other corners in the same way. Then tack the center of the top and bottom edges, then the sides, pulling the material taut before putting in each nail. The result should be without any wrinkles. It must then be sized. For this rub one part of starch into a cream with three parts of water, and boil until a clear solution is formed. Apply this with a stiff brush to the material, and stand the frame on end to dry. To make the paint, use: Whiting 24 parts Powdered glue 8 parts Treacle (molasses ) 12 parts Water 160 parts Soak the glue in the water for some time, add the treacle and melt with heat, and stir in the whiting until a smooth cream is obtained. Divide into three parts. For colours, obtain the following dry water colour pigments: ivory black 2 parts, ultramarine 1 part, red ochre 1 part. Mix the three pigments together and divide into six equal parts; to one third of the glue solution add one part of the pigment, to another third of the glue add 2 parts of the pigment, and the remainder of the powder to the rest of the glue: this will give three dis- tempers of different shades. Commercial distemper powders, such as kalsomine, may be used. Alternatively, dry canvas may be tightly stretched on a wooden frame, then well wetted, a mixture of dextrine and colour sifted over the surface from a fine sieve, and the surface then worked over with a stiff brush. The colours used may be as above or any powder colour used for house decoration. The colours dry much lighter. For grey and black backgrounds, double size, which is used by paper- hangers, may be melted in a saucepan, slightly thinned down, and drop black and whiting, previously mixed to the required tint, added. Two coats should be given with a stiff brush, the STUDIO AND WORKROOM 3 second being applied with the brush strokes in opposite direc- tion to the first. PHOTOGRAPHING MacHiInery.— Bright parts may be dulled by painting over with a thin cream of white lead and turpentine, darkened by the admixture of lampblack to give a grey. Frequently, dabbing the surfaces with a lump of putty will be sufficient. | MEMORIAL STONES AND BrassEes.—These often present considerable trouble, but if the surfaces of the stones are swept clean and strong side lighting used, the lettering and carvings will be thrown up into better relief. Wetting the stone frequently brings out indistinct lettering. In the case of brasses, rubbing with whiting, avoiding any deposit in the letters, is useful, as is also side lighting. Rubbings, obtained by placing a sheet of paper over the brasses and rubbing with a soft pencil or charcoal, may also be used. | SILVERWARE.—Hollow ware may be filled with ice or very cold water; then in a warm damp room the outer surface will become dewed. Dabbing the surface with putty will also kill all reflections. Or the object may be placed inside a tunnel of tissue paper, so that the only light reaching it has to pass through the paper. GLASSWARE.—This may be treated like silver, or hollow vessels may be filled with a non-actinic solution. Cotns.—These may be smoked with burning magnesium ribbon, which leaves a delicate white film on their surfaces. Side lighting is preferable, so as to throw the figures, etc., into relief. An impression may be taken in fine plaster of Paris, and this photographed. Or the coins may be placed on a fine white calendered card, slightly dampened, with a backing of blotting or other soft paper, and passed through a copying or other press. This gives an intaglio of the coin, which, if lighted with a strong light from the bottom of the 4 PHOTOGRAPHIC FACTS AND FORMULAS design, will when viewed in the usual manner give the impres- sion of the relief of the original. OBJECTS UNDER GLass.—If it is desired to show the glass cover, give about one fourth of the whole exposure to the object with the glass in position; then remove the glass, and complete the exposure. To BLacken Woop.—Use: Borax 62.5 ¢ 1 oz. Glycerine 62.5 ccm 1 oz. Shellac 125 ¢ 2 OZ. Water 1000 ccm 16 oz. Boil until completely dissolved and add water to make up the original bulk, then add nigrosine WS, 125 g or 2 oz., stir until thoroughly dissolved, and paint the wood two or three times. ‘This is not as satisfactory as the following, in which the aniline black is chemically formed in the wood: Cupric chloride 70g 538 gr. Potassium bichromate 70g 538 gr. Hot water 1000 ccm 16 oz. The wood should be freed from grease, then painted with this solution and allowed to dry well, then painted with: Aniline hydrochloride 140 g 2% oz. Water 1000 ccm 16 oz. Allow to dry, wipe off any yellow powder that forms, and repaint with these solutions until black enough. As a rule, two coats are sufficient, as the colour deepens in a day or two. Then rub well with boiled linseed oil and leave to dry. To BLackeNn Brass.—Use: Copper nitrate 208 g 200 gr. Water 500 ccm loz Dissolve and add the following solution: Silver nitrate 208 g 200 gr. Water 500 ccm 1 oz. STUDIO AND WORKROOM 5 Clean the metal thoroughly, immerse in the mixture, and then heat; repeat if necessary. Or the following may be used: Copper carbonate 50 g 384 gr. Ammonia 25 ccm 192 min. Water 1000 ccm 16 oz. Clean the metal and immerse until black, then wipe dry and lacquer. This attacks soft solder. Solution of antimony (butter of antimony), brushed on, gives bronze colours. It ’ has been stated that boiling the metal in a solution of potas- sium sulphide (liver of sulphur) until sufficiently black, then rinsing, drying and smearing a little oil over it, gives better results than the above silver method. FIREPROOFING FABRICS.—Soak in: Alum 80g 7 8 oz. Ammonium carbonate 25) 3 24 02. Boric acid es 1Y, oz. Borax 1758 134 oz. Water 1000 ccm 100 oz. Or: Boric acid ie 200 gr. Ammonium phosphate 100 g 4 oz. Water — 1000 ccm AO oz. Or: Borax 150 ¢ tZloz. Magnesium sulphate PSs 9 oz. Water 1000 ccm 80 oz. Starch PASS 2/Oz. Boil the starch with the water and add the salts. Immerse the fabric until thoroughly soaked, then dry and iron. Ora strong. solution of aluminum acetate, sp. gr. 1.050, diluted with 40 times its volume of water, may be used. The material should be immersed for 24 hours and then dried in the shade. 6 PHOTOGRAPHIC FACTS AND FORMULAS FLEXIBLE LANTERN SCREEN.—TJTake: Glycerine 16 parts White glue 16 parts Zinc oxide 32 parts Hot water 10 parts All are to be weighed. Dissolve the glue in the hot water and add the zinc oxide, ground up with the glycerine. Apply hot to the screen. A screen 10 feet square requires about 160 ounces. To BrackEN ALUMINUM.—Clean perfectly free from grease by washing in soda solution, wash well, and immerse in: Ferrous sulphate 1 part Arsenious acid 1 part Hydrochloric acid 12 parts Water 12 parts When the colour is deep enough, dry with fine sawdust, and lacquer. This solution is intensely poisonous. BLACK FOR CAMERAS.—This may be used for wood or leather, inside or out: Nigrosine, spirit soluble 2.52 37 BF; Bismarck brown 0.65 g 10 gr. Denatured alcohol or methylated spirit 3.0 ccm 50 min. Aniline 29 ccm 1 oz. Heat the dyes with the alcohol until dissolved, and then add the aniline; apply with a brush and dry before the fire or in the sun. Or, for a dead matt varnish, lampblack may be rubbed up with gold size or shellac varnish, using as little of the liquid as possible; then thin down with turpentine. INK FoR BottLes.—The following formula gives a water- proof ink, and either black or white ink can be made by using lampblack or zinc white. STUDIO AND WORKROOM 7 Copal, powdered WAT 90 gr. Oil of lavender 1000 ccm 16 oz. Dissolve by heat and stir in, for black: Lampblack 12's Oar: Indigo 0.5¢ 4 gr, Or, for white: | Zinc white | 15g: iho: Apply with a fine brush. Mattinc GiLass.—Dissolve by heat: Sodium or potassium fluoride 4¢ 20 gr. Gelatine 4g 20 ger. Water 1000 ccm 1 oz. Coat on the glass and allow to set well and dry, then immerse in a 6 per cent solution of hydrochloric acid for 30 to 60 seconds, and dry without washing. The gelatine can be dis- solved off with hot water and a fine matt surface is obtained. Or the following may be used: A. Sodium fluoride 60 g 60 gr. Potassium sulphate 12¢ 12 er. Water 500 ccm az: B. Zine chloride l4¢g 14 gr. Hydrochloric acid 65 ccm 65 min. Water 500 ccm Loz: Mix in equal quantities just before use and apply with a quill pen or fine brush. In about 30 minutes a fine matt surface is obtained. Another plan, which is even more convenient, is to paint a square or rectangle with the above solution, when the whole surface will be matted. Titles may easily be writ- ten on the surface with a soft lead pencil, and can be easily removed at any time with rubber or soap and water. SUBSTITUTES FOR GrouND GLass.—Expose a dry plate to the light of a match at a distance of 3 feet, then develop until uniformly grey, fix and wash. Immerse the plate ina solu- 8 PHOTOGRAPHIC FACTS AND FORMULAS tion of iodine in potassium iodide, or a few drops of tincture of iodine in water, until the grey fog turns yellow; then rinse, immerse in weak ammonia water until it turns white, wash and dry. The longer the plate is developed in the first place, the more pronounced becomes the mattness. As a rule, this gives a surface that is only useful with a magnifier, the grain being too fine for ordinary visual work. Or the follow- ing may be used: Rice starch 20 parts Water glass 100 parts Water 200 parts The water glass is the ordinary commercial solution of sodium silicate of 1.3 sp. gr. Mix the above by first rubbing the starch up with the water and then adding the silicate. Level the glass and pour enough of the solution on to cover it, allow to dry, then coat with celluloid varnish. To CLEAN GLass.—Immerse the glass in the following: Potassium bichromate 50 g 1 oz. Sulphuric acid 25 ccm Y4 oz. Water 1000 ccm 20 oz. Immerse the glass and scrub with an old toothbrush or mop made by tying some rags on a stick, turning the glasses over with a stick, as the solution bites the fingers. Rinse in cold water, then in hot water and dry. Or make a thin cream of: Tripoli 500 g 8 oz. Denatured alcohol or methylated spirit 500 ccm 8 oz. Ammonia 500 ccm 8 oz. Rub well with a swab of cloth and polish with a clean cloth, finishing with filter paper. CEMENTS.—Melt rubber and shellac in equal parts on a sand bath and apply to the warm glass or metal. This is useful for cementing glass to glass, or glass to metal. Or STUDIO AND WORKROOM 2 glycerine and finely powdered litharge may be worked into a thick paste; the broken edges should be painted with glycerine, then the paste applied, and the articles bound to- gether with string and left for a day or two. Or zinc oxide should be worked into a stiff paste with a 15 per cent solution of zinc chloride. Or: Sulphur flowers 72 parts Pale resin 40 parts Shellac 10 parts Mastic 20 parts Crude lac 20 parts Barium sulphate 60 parts Melt the gums by heat and add the sulphur, stir well and then add the baryta. This must be melted each time before use. DIAMOND CEMENT.—Dissolve gelatine to saturation in glacial acetic acid. This must be melted on a water bath before use. DAMP-PROOF GLUE.—Cover some good glue with water and allow to soak for 12 hours, drain off the water, melt the glue by heat, and add one-fourth its volume of linseed oil. MarInE GLuE.—Dissolve india rubber shreds in benzole 1 part, shellac 2 parts; or ordinary cycle tyre cement may be used, one-fourth its volume of shellac added, and melted by heat. The vapour of this is very inflammable. Lioguip GLuE—This should not be used for mounting photographs : Fine glue 800 g 8 02. Water 1000 cem 10 oz. Allow to soak for 24 hours, then melt by heat, and add: Nitric acid, strong 175 ccm 134 oz. SILVERING GLass.—Brashear’s Process modified, as used at the Royal Observatory, Greenwich, England. The follow- 10 PHOTOGRAPHIC FACTS AND FORMULAS ing solutions are required: A. 10 per cent silver nitrate solu- tion; B. 25 per cent ammonia solution; C. 10 per cent caustic potash solution; D. reducing solution as follows: Sugar 90 g 690 gr. Nitric acid 4 ccm 30 min. Alcohol 175ccm 202z., 380 min. Water 1000 ccm 16 oz. To make this, dissolve the sugar and acid in the water, boil for 15 minutes, cool down, and add the alcohol. The longer this solution has been made, the better it works. The actual silvering bath is made up as follows: A solution 20 ccm 340 min. B solution (more or less) 10ccm 170 min. C solution 10 ccm 170 min. D solution 5 ccm 85 min. Distilled water 100ccm 302z., 250 min. To prepare the bath for about 700 square inches of glass surface, take 1200 ccm (42 oz., 112 min.) of A, and add B until the solution nearly clears up, which will take about 500 ccm (17 oz., 287 min.) ; then add C 600 ccm (21 oz., 56 min.). The mixture will again become thick; then add cautiously more B until the solution clears. It should now be a brown colour but transparent. Then add: Distilled water 6000 ccm 211 0z., 84 min. D solution 300ccm 100z., 268 min. The temperature should be from 18° to 21° C. (65° to 70° F.). With lower temperatures the D solution must be slightly increased. Too.low temperatures give too thin films, while with too high temperatures the silver film is too soft. The glass should be covered with water, and, if the solutions are mixed beforehand, the water should be poured off and the silvering liquid at once applied; but good results are obtained by pouring off the water, pouring on the D solution, STUDIO AND WORKROOM 11 rocking the dish, and then adding the silver-potash mixtures. The action begins at once, and in 2 or 3 minutes a light swab of absorbent cotton should be lightly drawn over the surface so as to prevent the heavy sediment from settling down. As the cotton becomes dirty, it should be thrown away and fresh used. When to stop the action depends entirely upon experi- ence; if too soon, the deposit is thin, and if too prolonged, it is thick and requires much polishing. Wash with distilled water, lightly swab with cotton, and allow to dry in a vertical position for at least an hour. Polishers are most satisfactorily made of the best chamois leather stretched over a ball of cotton. Two polishers are necessary. First go over the whole surface with a plain rubber with light circular strokes, dusting occasionally. Then rub a little rouge into the other pad, and polish in the same way. It has been stated that celluloid can be silvered with the above solution; or the celluloid may be immersed in the sugar solution and then the others added in succession. For the above process the old fashioned sugar candy is the best form of sugar to use; if this is not procurable, the best cane sugar must be used. Rk. E. Crowther gave a modification of this process in which caustic soda is used and which seems not to be so dependent on absolute purity of the chemicals. To make 100 ccm (3 oz., 250 min.) of solution, the following are required: I. 10 per cent solution of silver nitrate in distilled water; II. 7.25 per cent solution of caustic soda in distilled water; III. 28 to 30 per cent ammonia solution (strongest ammonia water) ; IV. Reducing solution—equal volumes of A and B, made as follows: A. Sugar, lump or whitecrystal 9g 150 gr. Distilled water 50 ccm 845 min. Nitric acid, c. p. 0.4 ccm 6 min. 12 PHOTOGRAPHIC FACTS AND FORMULAS Alcohol 17 ccm 285 min. Distilled water to 100ccm 30z., 250 min. B. Sugar 10g 165 gr. Distilled water 50 ccm 845 min. Tartaric acid, cryst. lg 15.4 gr. Boil for 5 minutes, cool and add: Alcohol 18 ccm 304 min. Distilled water to 100ccm 30z., 250 min. For every 100 ccm silvering solution take: 11 ccm solution I. (186 min.), remove 4 ccm (68 min.), and dilute with 15 ccm (250 min.) distilled water; add to the 7 ccm, while shaking, ammonia III., until just clear; then, while shaking, add 10 ccm (169 min.) solution II., and again, while shaking, add enough ammonia to just redissolve the precipitate. Finally, add the diluted 4 ccm of solution I., obtaining a sherry- coloured, opalescent liquid. Filter and dilute to 78 ccm (2 oz., 358 min.). Mix 11 ccm (186 min.) of IV. with 11 ccm distilled water, add to the sherry-coloured silver solu- tion, and pour immediately on the glass, which should be from 3° to 6° C. (5° to 10° F.) warmer than the solution. Rock vigorously, and silver for two and a half times the time observed from pouring on the mixed solutions until deposi- tion commences. Rinse twice in distilled water, swab under a tap, blot off the surface water, allow to dry half an hour in a warm place, and polish off the slight bloom. The Rochelle Salts Process——Two solutions are required for this: A. Silver nitrate 10¢g 77 gr. Distilled water 1000 ccm 16 oz. B. Silver nitrate 2g 15.4 gr. Rochelle salts 1.66 ¢ IZ ae Distilled water 1000 ccm 16 oz. In making this solution the water should be brought to a boil, STUDIO AND WORKROOM 13 and first the silver and then the Rochelle salts added, both being dissolved in as small a quantity of boiling distilled water as possible. Boiling should be continued for about 25 minutes, until a grey powder has collected at the bottom of the flask. The liquid should then be at once filtered until quite clear, and it may be necessary to repeat this three or four times. The longer the boiling the more rapid the deposition of the silver, and the more uniform it will be. Perfectly prepared solutions will keep for about a month. Equal volumes of the two solutions are mixed just before use. The Formaldehyde Process (Lumiére)—Clean the glass thoroughly with nitric acid, and wash well with distilled water. Pour on the surface a 25 per cent solution of alcohol and leave for a few minutes. Prepare the following solution, which must not be made until required for use: Formaldehyde, 40% solution 24 drops 24 drops Alcohol, 90% 24 ccm 407 min. Distilled water 24 ccm 407 min. Silver solution 48 ccm 812 min. This is sufficient for 1000 qcm (155 sq. in.), and the tempera- ture should be from 16° to 20° C. (60° to 68° F.). The silver solution is prepared as follows: Silver nitrate 10¢ 77 gr. _ Distilled water 100 ccm 2 oz. Add solution of ammonia drop by drop until the brown precipitate first formed is redissolved; but extreme care must be taken not to add too much ammonia. Then add: Silver nitrate Hey 505 15.4 gr. Distilled water 100 ccm 2. OZ. Then add sufficient water to make the total bulk 1000 ccm (16 oz.), and filter several times until quite clear. The glass should be drained from the alcohol bath and immediately covered with the silvering solution. The deposition begins in 14 PHOTOGRAPHIC FACTS AND FORMULAS about 90 seconds and will be complete in about 2 minutes. During the silvering, the bath should be gently rocked: to prevent striz. As soon as the liquid begins to become cloudy or show spicules of silver, it should be poured off and a second quantity of solution applied. Several coatings may be thus applied until the desired thickness is obtained. At the close of the operation the surface has a slightly reddish- — brown appearance. It should be washed with successive lots of distilled water and dried, standing it on white blotting paper. When the film is perfectly dry, it can be polished with a soft chamois, enclosing a pad of absorbent cotton and rouge; the rouge used for gold is the best. The alcohol is used to prevent the formation of a precipitate in the solution, and, if this forms, too much formaldehyde has been used. If too little formaldehyde be used, the film has a pronounced reddish-brown colour and is punctuated with numerous pin- holes. In all cases, the formaldehyde must only be added just before applying the mixture to the glass. If too high a temperature be used, the deposit forms too rapidly and be- comes powdery. For small mirrors, the glass may be placed in a dish of porcelain or glass, and the alcohol bath may be omitted. If, instead of using the silvered surface as the mirror, the glass side is used, then the silver coat should be covered with: Gum dammar 10¢ 77 gr. Bitumen of Judea (asphalt) 100g 770 gr. Red ochre 200 g 3, 1/3 on: Benzole 1000 ccm 16 oz. The ammoniacal solutions of silver are dangerous to keep in stock, as they may form fulminating silver which is explosive. LINE DRAWINGS FROM Prints.—Waterproof drawing ink should be used in drawing over any desired part of the print; then immerse it in: STUDIO AND WORKROOM Iodine 0.5 ¢ Potassium cyanide 0.03 g Water 1000 ccm 15 3.84 gr. 0.25 gr. 16 oz. Rub the cyanide up with the iodine, add first a very little water, and then make up to bulk. Or the following may be used: Thiocarbamide 15.5) 2 Nitric acid | 15.5 ccm Water ; 1000 ccm Os: Potassium bichromate 8g Sulphuric acid 12 ccm Water 1000 ccm Then wash well. 119 er. 119 min. 16 oz. 62 gr. 90 min. 16 oz. NEGATIVES Direct.—This method may be used for direct or enlarged prints on paper or plates. The image should be developed with: Amidol 6.25 g Sodium sulphite, dry 15.6¢ Ammonium bromide 475¢ Potassium metabisulphite 2¢ Water 1000 ccm 45 gr. 120/er. 36 gr. 15 gr. 16 oz. Development should be stopped when the image is seen through at the back of the plate. Wash for 5 minutes, back with a piece of wet black paper, and expose to daylight for 30 seconds or to 6 inches of magnesium ribbon held one foot from the plate. Bleach in: Potassium bichromate 29/316, Nitric acid 12 ccm Water 1000 ccm Then immerse in: Sodium sulphite, dry 95g Potassium metabisulphite 6.25 g 225.80. 90 min. 16 oz. 1¥4 oz. 45 gr. 16 PHOTOGRAPHIC FACTS AND FORMULAS Water 1000 ccm 16 oz. This clears the bichromate stain; after the plate has been well washed, develop in the developer given above without the bromide. Lioguip SAFELIGHTS.—Sometimes cells filled with liquid are used in front of the light, but they present no particular advantage. The following have been recommended : Deep orange (Farmer): Potassium bichromate 6 per cent solution in 3% inch thickness. - This is only suitable for ordinary plates. Or (Davenport) : Mandarin orange 20 g 154 gr. Water 1000 ccm 16 oz. Or (Wordsley) : Eosine 0.13 g 0.1 gr. Metanil yellow 3.2¢ 25 gr. Water 1000 ccm 16 oz. Or, for a darker filter: Eosine 04¢ 3 gr. Metanil yellow 2.6¢ 20 gr. Water 1000 ccm 16 oz. Or (Davenport) : New coccin 2¢g 15.4 gr. Water 1000 ccm 16 oz. For deep red in 1 inch thickness: Tartrazine 0.5 g 3.8 gr. Violet Dahlia BO 0.2 g 1.5 gr. Water 1000 ccm 16 oz. ors Naphthol yellow S lg 1 f oh: Violet Dahlia BO 0.18 ¢ 1.38 gr. Water 1000 ccm 16 oz. STUDIO AND WORKROOM 17 Liquid green filter: Acid green 0.6 g 4.6 er. Naphthol green 0.6 ¢g 4.6 ger. Partrazine _ hove PMS on. Water 1000 ccm 16 oz. The water in the above formulas is apt to evaporate, and this trouble may be overcome by using glycerine instead. Tartrazine 0.05 per cent solution absorbs to wave-length 510. Potassium bichromate 10 per cent solution absorbs to 550. The same solution plus 0.1 per cent of fuchsine to 620; with 0.2 of fuchsine to 630; with 0.5 per cent fuchsine to 635 ; with 0.2 per cent acid violet to 645. Tartrazine 0.05 per cent solution plus 0.02 per cent methyl violet to 660. Thick- ness of liquid in all cases 10 cm. For a green light with a liquid thickness of 214 cm, use: Blueish acid green 0.625 g 4.8 gr. Naphthol green 0.075 g 0.576 gr. Tartrazine 0.045 g 0.35 er. Water 1000 ccm 16 oz. In course of time, the water evaporates from the heat of the lamp. This can be obviated by using glycerine as the solvent instead of water. GLass SAFELIGHTS.—Coloured glasses, or glass coated with gelatine stained with dyes, are best for illumination of the darkroom. ‘The most satisfactory method of making the latter is to add a definite quantity of dye to a given quantity of gelatine solution and allow a definite quantity per area. Soft gelatine is the most suitable, and either a 6 or 8 per cent solution should be made. Weigh out the gelatine and cover with water, stir for about 5 minutes and pour the water off, and repeat this three times; finally, drain off as much water as possible, melt the gelatine in a water bath, and add enough water to make up to bulk. The temperature 18 PHOTOGRAPHIC FACTS AND FORMULAS should be about 60° C. (140° F.), and the dye added, prefer- ably, in solution. The glass should be levelled, the necessary quantity of the dyed gelatine coated on it, allowed to set and dried. Yellow screens, suitable for bromide papers and lantern slide work: - Tartrazine 8g 62 er. Gelatine solution, 8% 1000 ccm 16 oz. Allow 7 to 10 ccm to 100-qcem, or 750 to 1000 minims per 100 sq. in. Two such glasses should be bound up together. Orange: Rose Bengal 3g 23 er. Gelatine solution, 8% 1000 ccm 16 oz. Use the same quantity as above, and bind one of these red screens with one of the yellow tartrazine ones. Bright red: Xylene red 8g 62 gr. Gelatine solution, 8% 1000 ccm 16 oz. Use the same quantity and bind with one of the tartrazine screens. Deeper red: Crystal violet, 4% sol. 8 ccm 62 min. Gelatine, 8% 1000 ccm 16 oz. Use as above with a tartrazine screen. Bright red (Hubl): Fast red 5g | 384 er. Tartrazine 5¢g 3814 gr. Gelatine, 8% sol. 1000 ccm 16 oz. Allow 7 ccm per 100 qcm, or 750 minims per 100 sq. in. This cuts out all light to 600, and is safe for all ordinary plates. ; Deep red (Hubl): Crystal violet 1.65 g 12.7 er Cupric sulphate a. 25g 63 gr. STUDIO AND WORKROOM 19 Glacial acetic acid 16 drops 8 drops Gelatine, 6% sol. 1000 ccm 16 oz. Allow the same quantity as above, and bind up with one of the bright red screens. Or: Tartrazine 7.52 57'4 gr. Crystal violet 1515 2 120 gr. Cupric sulphate Lie 59D St: Glacial acetic acid 15 drops 8 drops Gelatine, 8% sol. — 1000 ccm 16 oz. Use the same quantity as above. This cuts out to 630 and is safe for orthochromatic plates. GREEN SAFELIGHTS.—These are used for panchromatic plates, and are occasionally adopted instead of the red, for with a green light it is possible to see better than with a faint red. Hiibl recommended a combination of filter blue with naphthol green, which is the only green dye that cuts out the extreme red. The blue was made into a stock solution of : Filter blue OMe 0.77 gr. Water 1000 ccm 16 oz. Ammonia 1 ccm LA or, For the screen use: Naphthol green 8g 61 gr. Blue solution as above 32 ccm YA oz. Gelatine, 8% sol. 1000 ccm 16 oz. Allow 7 ccm per 100 qcem, or 750 minims per 100 sq. in. Or (Lowy): New Bordeaux R BWVAS) (es 25/or: Tartrazine 6g 46 er. Light green S 9¢g 69 gr. Glycerine 50 ccm 384 min. Gelatine, 8% sol. 1000 ccm 16 oz. Allow about 10 ccm per 100 qcm, or 1000 minims per 100 sq. in. 20 PHOTOGRAPHIC FACTS AND FORMULAS Old fixed-out dry plates, or negatives freed from their images by reduction, may also be used by soaking in the above dye solutions minus the gelatine, that is, using water instead of the gelatine solution, for half an hour, then rinsing and drying. Or soak one plate in 3 per cent solution of naphthol yellow, and another in 0.9 per cent solution of methyl violet for half an hour, rinse, dry and bind together. | The following was suggested by Haberkorn: Gelatine 60 ¢ 460 er. Water 1000 ccm 16 oz. Soak for 30 minutes, melt on water bath, and add: Blueish acid green I5¢ li Siar: Then add: Tartrazine 0.18 g 13.8 gr. Naphthol green 0.4¢ 3.1 ee, Stir well and filter while hot. To every 100 qcm allow 7 ccm, or 750 minims per 100 sq. in. Bind two such screens together, and coat one with matt varnish, or use tissue paper between; a sheet of ground glass placed between the light and the screen absorbs some of the heat. NON-ACTINIC PAPER.—Soak the paper in: Tartrazine 10 ¢ iit. Rhodamine lg 7./ gr. Water), >) 500 ccm 8 oz. Alcohol 500 ccm 8 oz. The quantity of rhodamine may be increased at will, when a deeper coloured paper will be obtained. The above paper is safe for rapid ordinary plates. Translucent vegetable parch- ment paper was also suggested. This was to be immersed for 5 minutes in a warm 10 per cent solution of gelatine and dried, then stained up in one of the following baths: A, Tartrazine - 2 per cent solution B. Chrysoidine 0.1 per cent solution STUDIO AND WORKROOM 7 C. Blue carmine 1.0 per cent solution D. Methyl violet 0.1 per cent solution A gives a bright yellow paper, and one thickness is suitable for development papers. Two sheets of B and one of A are suitable for bromide papers and slow plates. Two of C and one of A are suitable for panchromatic plates, if not too bright a light be used; another A makes it safer. One of A and one of C may be used for ordinary and orthochromatic plates (Namias). ALCOHOL.—In several formulas “alcohol” is recommended as an ingredient, although under the prohibition act it is impossible for the average person in the United States to obtain this in any legal manner. In some cases ordinary denatured alcohol may be used, but in others as, for instance, the colour-sensitisi#e of plates, this is worse than useless because it has a very prejudicial effect on the emulsion. It is possible to obtain from chemical and bacteriological supply houses pure methyl alcohol under the names of Eagle methanol, or Columbian methanol or spirits, or methyl alco- hol C. P., and these may be substituted in nearly every case. Orthochromatic Photography WAVE-LENGTHS OF THE PRINCIPAL FRAUNHOFER LINES. Fraunhofer line Wave-length Colour A 7594 a 7186 Red B 6867 C 6563 Bright red D: 5896 Yellow-orange D, 5890 E 5270 Green b, 5184 b, BLS iy b, 5169 b, 5168 F 4861 Bright blue G 4308 Indigo blue g 4227 h 4101 Fi 3968 Violet i 3960 Violet K 3934 Ultra-violet L 3821-3816 Ultra-violet M 3728 Ultra-violet N 3581 Ultra-violet O 3441 Ultra-violet P. 3361 Ultra-violet QO 3287 Ultra-violet R 3180 Ultra-violet & 3100 Ultra-violet | al 3021 Ultra-violet U 2948 Ultra-violet 22 ORTHOCHROMATIC’ PHOTOGRAPHY. ZS The wave-lengths in the above table are those given by Rowland, and are usually employed, but for extreme accu- racy in spectroscopic work corrections must be used. The unit of measurement is Angstrom’s unit, one ten millionth of a millimeter or A. U. (called also tenth meter, t. m.), and only round numbers are given; thus, taking the red cadmium line, it would be called on the above plan 6438, while its correct measurement is 6438.4722. It is frequently the custom to employ other units, for instance, the millionth of a millimeter mp is used, or the thousandth of a millimeter p (pronounced mu). Thus the cadmium line may be expressed as: 6.4384722 x 10-° cm, or 0.64384722 p, or 643.84722 py or mp, or 6438.4722 A. U. or t. m. It is usual in photo- graphic literature to use the abbreviated A. U., as 6438 or the still briefer designation 644. The Greek lambda or A is used to designate the wave-length. It is very frequent also to designate a colour or position in the spectrum by such a term as D ¥% C, which means half way between the lines D and C; this would mean, taking 5893 as the mean wave-length of the D lines, that the stated position would be half the distance or difference of wave-lengths, thus C 6563 — 5893 = 670, then 670 divided by 2 plus 5893 = 6228, the designated wave-length. DISTRIBUTION OF COLOURS IN THE SPECTRUM.—Various tables of the distribution of the colours in the spectrum have been given, but the following compiled by Listing may be accepted as being typical: Colour Wave-length End 819 Deep red Middle 768 End 723 Red Middle 683 End 647 24 PHOTOGRAPHIC FACTS AND FORMULAS Orange Middle 614 End 585 Yellow Middle 559 End 534 Green Middle 512 End 491 Cyan blue Middle 473 i End 455 Indigo Middle 439 End 424 Violet Middle 409 End 396 Lavender Middle 384 End 372 ORTHOCHROMATISING PLATES.—Ordinary, or non-colour sensitive plates, may be orthochromatised by bathing in solu- tions of dyes. As a rule, such plates have a higher colour sensitivity than those coated with an emulsion to which the dye is added during the mixing, but they do not keep quite as well. . Blue-green and Green Sensitisers—Acridine orange NO, made by Leonhardt of Mithlheim, was the old dye used. A saturated alcoholic solution was made and diluted with water ; but this dye stains the gelatine so tenaciously that it cannot be removed except with an alcohol bath. It has been entirely replaced by pinaflavol (Hoechst) or the new dye dimethyl- styrylpyridine methiodide, suggested by Mills and Pope. This is used in an aqueous solution, 1:30,000 or 1:40,000, in which the plates are bathed for 3 minutes, rinsed and dried. This gives very even sensitiveness from the bright blue to the yellow at 560, then falling off rapidly to 620, and without the usual gap in the blue-green, characteristic of the eosine dyes. Green and Yellow Sensitisers—Erythrosine is the dye ORTHOCHROMATIC PHOTOGRAPHY 25 generally used. The extra blueish kind should be used in a 1:5000 aqueous solution with the addition of 0.5 per cent of ammonia. This gives a strong yellow, orange and green sensitiveness, but a marked want of sensitiveness in the blue- green. For this reason the new dyes mentioned above may be substituted with advantage, but the proportion of ammonia should be reduced to one-tenth. Green, Yellow and Orange Sensitisers—To obtain sensi- tiveness up to 620 to 640 in the orange, any of the following dyes may be used: isocol (Bayer), orthochrome T, pina- verdol (Hoechst), sensitol green (Ilford), or pinachrome (Hoechst). These should be used in about a 1: 50,000 solu- tion, with the addition of a little ammonia, not more than 0.01 per cent. The plates should be bathed for 3 or 4 minutes, then rinsed in alcohol, and dried as quickly as pos- sible. Instead of using ammonia in the bath, it is preferable to use about 0.02 per cent of borax, which does not tend to give so much fog. The dilute dye solutions have a tendency to deposit a flocculent precipitate, and this can be prevented by adding from 20 to 40 per cent of ethyl or methyl alcohol or acetone to the bath, but this method does not give such good colour sensitiveness as with aqueous solutions. A deep red safelight may be used until the plates are covered with the dye solution, and then the rest of the operations should be conducted in darkness, or a green safelight used. Panchromatic and Red Sensitisers—Pinacyanol (Hoechst) or sensitol red and sensitol violet (Ilford) may be used for red sensitising and panchromatic plates, the violet dyes giving the best all round results; though a mixture of orthochrome or sensitol green with the violet may be used, in the ratio of 2 of the former to 1 of the latter. The total strength of the bath should not be more than 1:75,000. Ammonia or borax should be used in the same way and the same precautions 26 PHOTOGRAPHIC FACTS AND FORMULAS taken as to the use of a green safelight. These dyes sensitise to about 720. For the extreme red and infra-red, dicyanine must be used. This does not sensitise for green at all, and great care must be taken in protecting the dye and its solution from light. Only perfectly clean glass dishes should be used for bath- ing plates; old porcelain dishes and metal tanks are to be avoided, as, in the former case, they are apt to contaminate the dye baths from traces of old solutions held in the cracks, and metals tend to reduce the dyes and cause fog. Home- bathed plates will not keep well, and the sooner they are used the better. The following method of hypersensitising plates gives extraordinary colour sensitivity and speed, but the plates will not keep more than about 36 hours. Three stock solutions of dyes are required: A. Pinaverdol lg 7.68 gr. Alcohol, 90° 1000 ccm 16 oz. B. Pinachrome 0.05 g 0.384 gr. Alcohol, 90° 1000 ccm 16 oz. C. Pinacyanol 0.05 g 0.384 gr. Alcohol, 90° 1000 ccm 16 oz. D. Solution A 405 ccm 634 oz. Solution B 405 ccm 634 oz. Solution C 210 ccm 3Y4 oz. If absolutely correct rendering of the colours is required, the ratios of these solutions may have to be altered slightly. It will be understood also that the English dyes, sensitol green and sensitol red, may be used instead of the pinaverdol and pinacyanol with equally satisfactory results. Stock dye solu- tion: E. Stock solution D 400 ccm 60z., 192 min. Alcohol 600 ccm 9o0z., 288 min. ORTHOCHROMATIC'! PHOTOGRAPHY 27 F. Silver chloride 2¢g 1.54 gr. Ammonia, 22° 80 ccm 61 min. Distilled water 920 ccm 16 oz. The ammonia should have a spose gravity of about 0.92. Sensitising bath: G. Solution E 100 ccm 1 z., 288 min. Solution F 100ccm 1 oz., 288 min. Alcohol, 22.5° 800 ccm 13 oz. This alcohol contains approximately 50 per cent water. The plates should be bathed at as low a temperature as possible, the dish rocked for 3 minutes, the plates rinsed for 1 minute, and then dried as rapidly as possible. It is possible to take snapshots with plates thus bathed in well-lighted rooms with a lens working at f: 4. Various formulas have been given for panchromatising plates, some of which are given here. As a rule, the fastest plates should not be used, as they are more liable to fog on keeping; and a clean working plate should be chosen. Wallace’s Bath— Pinacyanol 15/cen: 115 min. Pinaverdol 12 ccm 92 min. Homocol 12 ccm 92 min. Ammonia 35.7 ccm 270 min. Alcohol 410 ccm 634 oz. Water 590 ccm OY oz. Bathe for 4 minutes, rinse in alcohol for 30 seconds, dry. Sensitises to 720, without any gap in the blue-green. Dicyanine may be used instead of the homocol with slightly greater speed. Greenfield's Bath——This bath is specially intended for tank work, but the solution should not be used more than twice: Pinachrome 3 ccm 23 min. 28 PHOTOGRAPHIC FACTS AND FORMULAS Pinacyanol 2 ccm 15 min. Water 1000 ccm 16 oz. As all the isocyanines are decolourised by the carbonic acid dissolved in water, this bath would be rapidly decolourised, and in this state would not give such good results. A small addition of ammonia or borax is essential. In the above baths the dyes are used in 1: 1000 alcoholic stock solution. George's Formula.— Pinaverdol 13.75 ccm 105 min. Homocol 9ccm 69 min. Pinacyanol 11.5 ccm 88 min. Ammonia 68.75 ccm 528 min. Alcohol, 90% 376 ccm 6 oz. Water to 1000 ccm 16 oz. This bath is too strong in ammonia. The dyes in the above bath should be used in a 1: 2000 alcoholic stock solution. Monpillard’s Formula.— Pinacyanol or dicyanine 5 ccm 38 min. Homocol 5 ccm 38 min. Ammonia 0.1 ccm 0.77 min. Water 1000 ccm 16 oz. With dicyanine the sensitiveness extends to 750, with pina- cyanol to 680. Stock dye solution 1: 1000 alcohol. DESENSITISING PLATES.—Luppo-Cramer found that by bathing plates in certain dye solutions both ordinary and colour-sensitive plates could be desensitised after exposure and thus be worked in a bright orange or yellow light without fog. Phenosafranine in a 0.05 per cent solution may be used with one minute’s bathing in the dark, or 10 per cent of a 0.5 per cent solution may be added to the developer with equally good results. Other dyes of this class that act well are dimethylsafranine, amethyst violet, giroflé, safranine MN, phenosafranine and cresosafranine. Unfortunately, these ORTHOCHROMATIC PHOTOGRAPHY BS) dyes are very tenaciously retained by the gelatine and can only be discharged by a nitrite bath, such as: Sodium nitrite. lg 8 er. Hydrochloric acid 10 ccm 80 min. Water 1000 ccm 16 oz. or a 2 per cent alum solution with an equal volume of hydro- chloric acid. The Hoechst dye works have introduced two new dyes for the same purpose, pinakryptol and pinakryptol green; the latter is the more soluble of the two and may be used as a preliminary bath or added to the developer, but the strength should be only 1:5000. Neither of these dyes stain the gelatine so much as the safranines. Lumiére and Seyewetz have found that aurantia in a 1: 1000 solution acts as a good desensitiser, and also toluylene red. This desensi- tising process is also applicable to screen-plates. ORTHOCHROMATIC FILTERS.—Yellow filters are used to cut down the excessive blue and violet sensitiveness of colour- sensitised plates. The quantity of dye given is calculated in grams of the dry dye per square meter, or grains per 1000 square inches. It is advisable to dissolve the dyes in distilled water and add to the gelatine solution, previously prepared and filtered. To make the gelatine solution, immerse 125 g (614 gr.) soft gelatine in 500 ccm (8 oz.) distilled water, stir for 5 minutes, and pour off the water. Again add the same quantity of water, allow the gelatine to soak for 10 minutes with an occasional stir, and pour off. Repeat the operation, allowing the gelatine to soak for 15 minutes, and pour off the water. Drain out as much water as possible, then melt the gelatine on a water bath in the water that it has absorbed. Add sufficient distilled water to make the total bulk 1000 ccm (16 oz.), and filter through glass wool or well- oe tit absorbent cotton. Qs! 30 PHOTOGRAPHIC FACTS AND FORMULAS To make the dyed gelatine, the following quantities of filter yellow (Hoechst) should be used (Hubl) : No. 1. Filter yellow 0.5¢ 4.97 gr. No. 2. Filter yellow 10¢ 9.94 gr. No. 3. Filter yellow 20¢ 19.88 gr. No. 4. Filter yellow 3.4¢ 33.8 gr. No. 5. Tartrazine 3.0¢ 29.84 gr. The above quantities of dye should be dissolved in 50 to 100 ccm (384 to 768 min.) distilled water, and added to sufficient gelatine solution to make 700 ccm (15 oz., 435 min.) in all. This quantity should be coated on 1 qm or 1000 sq. in. of glass. The increase of exposure with these filters varies with the colour-sensitiveness of the plates used, but the following will be some guide: No. 1. Increase from ¥% to 2, according to plate. Can be used for instantaneous work and portraiture in the studio. No. 2. Increase from 2 to 6. Can be used for distant mountains and costume studies. Yellow reproduced the same tone as blue. No. 3. Increase from 6 to 8. Gives yellow much brighter than blue. No. 4. Increase from 4 to 12. Correct luminosity filter. No. 5. Increase from 4 to 15. Contrast filter. Reproduces blue like black, yellow like white. Suitable for cloud studies in which the sky is to be very dark, and furniture. Konig recommended the following quantities of filter yellow to the same areas as above: No. 1. Filter yellow 0.146 g 2.25 or. No. 2. Filter yellow 0.292 g 4.5 gr. No. 3. Filter yellow 0.594 ¢ 9.0 gr. No. 4. Filter yellow 1.167 g 18 gr. The increase in exposures should be 1.3, 1.7, 2, and 3 re- spectively. Plate Backing CARAMEL BacKING.—A non-actinic coating is applied to the back of glass plates to prevent halation, or the reflection of brightly lighted objects from the back surface of the glass. To be effective the backing must be in optical contact with the glass, and should theoretically be of the same refractive index. Caramel or burnt sugar does not dry, but a crystal caramel powder, which dries hard, is obtainable commercially. This can be made as follows: place some white sugar in a stewpan and heat over the gas, stirring continuously until it melts. The temperature will then rise very rapidly to 222° C. (430° F.). Continue heating for 15 minutes, stirring all the time; bubbles of gas will be given off and a clear red fluid formed, which gradually thickens. The heat should not be continued more than 5 minutes longer at this stage, or the product will be spoiled. Then pour out on a sheet of metal or slate, and it should set hard and brittle. Break up into small pieces, place in a wide-mouthed bottle, add water equal to one third the height of the fragments, and leave for three days. Add ten times the volume of wood or denatured alcohol or methylated spirit, and shake well two or three times in 24 hours. Pour off the alcohol, which extracts the sticky part, and add sufficient water to the residue to make a fairly thick liquid. This dries hard but brittle. If one eighth of the original mixture, before the addition of the alcohol, be added, it loses its brittleness. Instead of dissolving in water, it may be poured out in a flat dish, allowed to dry, and then powdered. A suitable backing mixture is: ot 32. PHOTOGRAPHIC FACTS AND FORMULAS Crystal caramel powder 500 g 5 oz. Gum arabic 250 ¢ 2 oz. Water 750 ccm 74 02. Or: Caramel powder 500 g 10 oz. Water 250 g 5 oz. Denatured aicohol (methylated spirit ) 150 ¢g 3 02. Mix and strain through muslin. Ordinary caramel or the above may be mixed with a thick gum arabic solution and burnt sienna or lampblack in equal weights. Or the follow- ing may be used: | Dextrine 50 g Y4 oz. Crystal caramel 200 g 1 oz. Ammonium chloride 4.5¢ 10 gr. Water 200 ccm 1 oz. Alcohol 200 ccm 1 oz. Glycerine 25 ccm 60 min. Work up into a stiff paste. | ASPHALT Bacxinc.—Dissolve powdered asphalt in ben- zole, chloroform or, preferably, carbon tetrachloride, to form a dark brown liquid. Apply with a brush. This dries very rapidly. Cornvu’s BacKInG.— Oil of cloves 6 parts Turpentine 7 parts Lampblack q.s. Use enough lampblack to form a stiff paste. This takes a long time to dry and has a very strong smell. STAINED COLLODIONS.— Aurine 45¢ 35 gr. Enamel collodion 1000 ccm 16 oz. PEATE, BACKING 33 Or; Nigrosine, spirit soluble 10¢g 77 gr. Pyroxyline 30 g 230 gr. Methyl alcohol 400 ccm 64 oz. Ether 600 ccm OY oz. Castor oil 60 ccm 460 min. Or: | Celluloid scraps 45 ¢ 350 gr. Nigrosine : 10g TI EE: Amy] acetate 250 ccm 4 oz. Acetone 750 ccm 1ioz. This takes some hours to dry. By replacing the amyl acetate with methyl alcohol, a much quicker drying mixture is obtained. These, like the asphalt backings, are sometimes difficult to remove, but friction with soap and water readily removes them. Brack Bacxinc.—For ordinary, non-colour-sensitive plates, the following may be used: Burnt sienna, paste 750 g 34 |b. Dextrine 63 g loz: Water 63 ccm 1 oz. Phenol (carbolic acid) 5 Cem 50 drops For panchromatic plates, use ivory sienna black instead of the burnt sienna. These pigments can be obtained from any colourman, ground in water. Mix the dextrine and water, heat until dissolved, and then work in the colour paste and the carbolic acid, which is merely added to prevent the stock from growing mouldy. CHREVETOTS BACKING.— White castile soap 60 g 46 er. Alcohol, 90° 1000 ccm 16 oz. Dissolve in a water bath and add: 34 PHOTOGRAPHIC FACTS AND FORMULAS Erythrosine 10g 77 gr. Aurine 8g 61 gr. Ivory black 8g 61 gr. This will dry in 10 minutes and can be readily removed with a, damp sponge. QUICK-DRYING Soap BACKING.— Soap f 45¢ 346 gr. Denatured alcohol (methylated spirit ) 1000 ccm 16 oz. Erythrosine l4¢ 107 gr. Aurine l4¢g 107 gr. Scrape the soap into fine powder or shavings, digest in the alcohol for a week with occasional shaking, add the dyes, and filter. BACKING SHEETS.—Black or red paper, gummed or coated with dextrine on one side, may be used, but is less efficient than any of the others. Sheets that can be repeatedly used may be made by coating cloth or paper with: Soft gelatine 1 part Water 2 parts Glycerine 1 part Soak the gelatine in the water and melt in a water bath; add the glycerine, then add lampblack, nigrosine, water soluble, or ared dyetocolour. Or printing-out paper may be exposed to light until dark, then washed, dried, soaked in glycerine, and squeegeed to the back of the plate. OxGALL (Boras) .— Oxgall, purified 1 part Gum arabic mucilage 4 parts Red or black water colour 1 part The water colour should be obtained in a tube ground up in water. This should be applied with a stiff brush, and a sheet of black celluloid or paper applied. Focus and Optics To FIND THE FocaL LENGTH oF A LENS.—Many methods have been suggested for finding the focal length, equivalent focus, or focus of a lens, and many of them require a knowl- edge of the position of the nodal point of emergence. This can be found by calculation, but it can also be determined by temporarily mounting the lens in a V-shaped groove on a small block of wood, so that the lens can be moved to and fro. Or take a large flat cork and drive a nail through the center, so that the cork will turn on this as an axis. Fasten the lens to the cork by a rubber band, and focus some very distant object, such as the sun or moon, on a piece of card or ground glass also temporarily held on a cork. When the image is quite sharp, rotate the lens, and, if the image moves, the nodal point of emergence of the lens is not over the point of rota- tion of the cork. The lens should be shifted to and fro and the image again focussed until it no longer moves with the rotation of the lens. Then the node of emergence is exactly over the axis of rotation, and this is the point from which the focal length should be measured. The following method is accurate and calls for measure- ments which are easily made. Focus a foot rule to a definite size, measure the distance between the rule and the image, and call this D. Then focus to a larger size, again measure the distance as before, and call this d. Then the following © formula will give the focus: d—D ( at) R*+1 r vie R being the ratio of image to object in the first case, and r 35 36 PHOTOGRAPHIC FACTS AND FORMULAS that in the second case. Example: D = 62.7 in.; d= 72.2 in.; R =4and r= 5; then 72.2 — 62.7 = 9.5; then (5 X 5+ 1) ~+5=—26/5 and (4X4+1)+4=17/4; then 26/5 — 17/4 = 19/20; and 9.5 ~ 19/20 = 10 in., the equivalent focus of the lens. Another Method:—This method can be carried out in any room. First focus on a very distant object, and mark the extension of the camera; then focus on a comparatively near object, that is to say, one in the length of an ordinary room, again mark the position of the camera, and call the distance between the two marks x. Again focus on a still nearer object, again measure the distance beyond the infinity mark, and call this distance y. Let B be the distance between the two objects, then the focus f = V~Bry+y—-x. Suppose the distance of one object is 144 in. and that of the other 96 in., then B = 144— 96 = 48. And suppose the extension of the camera beyond the infinity or distant mark for the object at 12 ft. was 1 in. and at 8 ft., 1% in., then f=V48XK1XK14=1%4%—1= V72=-%=v14=12. In this method, if the lens is moved in focussing, the distance between the object at the two positions, or B, must be ascer- tained by measuring from some part of the camera front. If, on the other hand, the focussing screen is moved and the lens remains stationary, we need only measure the distance between the two positions of the object. Another Method.—Set up a foot rule on a wall, and shift the camera until an image is obtained on the ground glass that is exactly the same size as the rule; naturally, how much of the rule is included depends on the size of the ground glass. Then measure the distance between the rule and the image, divide this by 4, and the result will be approximately the equivalent focus. Or set up the foot rule as in the previous method, and HOCUS, AND OETICS 37 make the image not more than one-fourth of the size of the object ; then make a negative of the foot rule, and, calling the distance between the rule and sensitive plate D and the ratio of reduction r, which can be found by measuring the length of the image on the negative and dividing into the length of the foot rule, then f = D X r+(r-+1)’*. Example: a rule of 150mm was found to give an image of 13.4mm, D was 800 mm, then rv = 150 + 13.4 = 11.19; then f = 800 x 11.19 — (11.19 -+ 1)? = 67.78 mm. Another Method.—Focus on a near object, then move the object further away from the lens by a distance D, refocus, note the distance through which the focussing screen has been moved, and call this a2. Again move the object away from the lens another distance equal to the first distance D, and call the distance the focussing screen has moved 0, then © f=V2DXbXa(b+a)~+ (a—b). The lens must re- main stationary in this method. Let D=96,a—=2,b=—¥; Pei Vo DON 2) 2 2-2) (2) V 480 + 1.5 = 14.61. Another Method.—Reverse the lens in its flange, focus on infinity, or a very distant object, and call this distance b. Replace the lens in its ordinary position, and again focus on infinity. Now focus on a near object at a distance D, measure the extension of the camera beyond the infinity mark, and call this y; then f= V(D—b)y. Lett D=48, b=8, y= ¥,; then f= V (48— 8) 4 = 4.472. Pinhole Method—The focus can also be found by means of a pinhole. Focus on infinity with the lens, and measure the size of the image or make a negative. Then place a pinhole in the position of the lens, and produce an image of the distant object exactly the same size; the distance of the pinhole from the image is the focus. A simple thin lens may be used instead of the pinhole. Or, if a lens of known focus 38 PHOTOGRAPHIC FACTS AND FORMULAS is available, it is only necessary to measure the size of the two images, when both lenses are focussed on the same distant object, and the focal lengths are proportional to the sizes of the two images. A Geometrical Method.—Focus two distant objects, as 4 and B in Fig. 1, and let C and D be the images of these A ee objects; then f = h-~tan a, a being the angle between AC and BD. Measure the length h, the distance between the images of the two objects, and also CL, their distance from the lens; then f =h~(CD—~CL). Let CD or h=4 in. and CL = 8 in.; then f = 4~+(4-8) =8. Another Geometrical Method—At a distance a, at least 100 times the focus, set off at right angles to the axis of the lens two marks %4 a distant from the axis. The distance between the two images on the screen will be 14 f. Grubb’s Method—At each side of the focussing screen make a pencil mark equidistant from the center. Place the camera flat on a sheet of white paper in front of a window. Focus on a very distant object, so that its image falls exactly on one pencil mark. Then draw a pencil line along the side of the camera, using the edge of the camera as a straight edge. Shift the camera so as to bring the image of the same object on to the other pencil mark on the ground glass, and again draw a line along the side of the camera, using the same FOCUS AND OPTICS 39 side as before. Produce these two lines so that they meet in the point A, Fig. 2. Bisect the angle BAC by the line AD, 5 B y Cc Fig. 2 and draw a line EF at right angles to this line, equal to the separation of the pencil marks on the ground glass; the focal length is then AG. Smith's Method—T. Smith, of the National Physical Laboratory, London, has given another method of finding the equivalent focus of a lens, based on the focussing of the image of a distant object on the lens axis upon the ground glass of the camera, using first the complete lens and then each component separately. The optical rule that serves as a basis of the method is that the focus of a lens of focal length f is at a distance equal to fF ~ f’ from that of the combination of focal length F formed by placing in front of the first lens another of focal length f’. The method is carried out as follows: fit the complete lens to the camera, and focus sharply on a distant object. Mark the position of some part of the lens front or moving baseboard against a fixed part of the camera. Now remove the front combination, and again focus on the object, noting the distance d through which the lens front requires to be racked out; this distance is fF +f’ in which F is the focal length of the whole lens and f and f’ those of the combinations. Now focus again with the whole 40 PHOTOGRAPHIC FACTS AND FORMULAS lens on the same object, the lens being placed with the back combination to the front. Mark the position as before, then refocus after removing the front combination, really the back one now in front. The distance d’ between the two positions is f’F —f. Hence dd’ = F’, that is to say, by multiplying the two distances d and d’ together and extracting the square root, we get the focal length. Lockett’s Method—A. Lockett suggested the following method: First draw two short vertical lines at about the center of the focussing screen, exactly 1 inch apart and parallel with each other. Focus sharply on a far distant object, such as a remote church spire or factory chimney, and mark carefully on the camera baseboard the exact posi- tion of any convenient part of the moving lens front. This may be called the infinity mark. Now measure off 1 inch in advance of this mark, and rack out the camera until the same point of the front is against this l-inch mark. Fix up a foot rule at about the height of the lens, and move the whole camera to and fro, without any other adjustment, until the rule is in the sharpest possible focus at full aperture, and with the commencement or zero of the graduations coinciding with one of the pencil lines. Then the number of inches of the rule seen on the ground glass between the two pencil lines will be equal to the focal length of the lens. This method is based on the following reasoning: let F be the equivalent focus, and r the ratio or proportion between the size of the image and the object. Then the minor conjugate focus, or the distance from lens to ground glass, is F + F~r. When the camera front is set 1 inch from the infinity mark, then F —~r equals 1 inch and must also be equal to F ~ F; there- fore r equals F. It is not essential to adhere to the 1-inch extension, and a greater distance will eliminate errors in POCUS AND VOLES 41 measurement, but the distance between the marks on the ground glass must always be the same as the extension of the camera from the infinity mark. DEPTH OF Focus ScALE.—Decide what stops the scale is to be constructed for. Asa rule, it will be found sufficient to calculate for f:8, f: 16, f: 24, etc., as with larger apertures the scale becomes too confused, and one rarely uses a larger aperture than f:8 for snapshot work. Draw a scale each division of which is equal to one-hundredth of the aperture, this being the assumed diameter of the circle of confusion; if this degree of sharpness is not considered sufficient, one may adopt one-two-hundredth or smaller, but, obviously, the smaller the divisions the more confused the scale and the less value practically. Besides that, one cannot estimate the dis- tance of an object with sufficient accuracy for the smaller scales. Utilising the formula 100 < focus squared — ratio aperture (100 F* ~r), find the nearest points in focus. Mark off on the divided scale these distances, starting from the infinity point, as in Fig. 3. G 38 191 Ie 6 4 3% Fig. 3 Construct another scale of like dimensions and divisions, and mark off with the stop apertures only, starting in the center as in Fig. 4. F64 F32 F16 F8 F8 F16 F32 F64 Fig. 4 By placing Fig. 4 over Fig. 3 and sliding it along so that the arrow in the center marks the distance focussed on, one can at once read off under the stop numbers the distances which 42 PHOTOGRAPHIC FACTS AND FORMULAS will appear sharp in front of and behind the object focussed for. The following table shows the distances for a 6-inch lens starting with f:8, though in the scales only the nearest whole numbers are given: 100 K 62. f:8 = 450 in. — 37 ft. 6 in. 1000007’ f: 165 225 ta 00 Tea 100 « 6° =~ f:24 = 150 in. — 12 ft. 6 in. 100 & 6? + f:32 = 112Y in. — 9 ft. 4 in. 100 & 6? + f:40 = 90 in. — 7 ft. 6 in. FocussInc SCALE.—To construct a focussing scale, draw a line equal in length to the equivalent focus of the lens, mark off exactly the half, third, fourth, sixth, eighth, etc., and add 1 to each division; this will give a scale as below. Multiply the numbers below the line by the focus of the lens, and the result will be the distances in inches at which an object will be sharp, if the lens be placed at this point. To fix this scale to a camera, focus first on the clouds, or a very distant object, mark the baseboard at any convenient part of the camera front, and place B even with this mark, the scale extending, obviously, from this mark away from the rear of the camera. 3 4 5 79155 Fig. 5 DeptH oF Focus.—Welborne Piper suggests that, know- ing the hyperfocal distance for the stop in use and the distance of the object in sharp focus, if we divide the product of these two distances by their sum, the result will be the distance of the nearest object in focus; if their product is divided by their difference, the result is the distance of the farthest object in focus. Example: suppose we are focussing with a 6-inch lens on an object 10 ft. away, taking 1/100 in. as the circle of confusion. The depth constant for the lens is FOCUS) AND ORTIGS 43 100 X 6? = 3600 in. = 300 ft. The hyperfocal distance, which is always equal to the focal length multiplied by the diameter of the aperture, and divided by that of the circle of confusion, is therefore for a 6-inch lens at f:6, 300 +6 or 50 ft. When focussing on 10 ft., the near depth is (50 X 10) ~ (50-+ 10) —81/3 ft. The limit of far depth is (50 X 10) + (50 — 10) = 12% ft. When focussing on infinity, the nearest object in focus is at the hyperfocal distance, and depth extends from that point to infinity. When the hyperfocal distance is focussed on, the nearest object in focus is at half the hyperfocal distance, and the farthest at infinity, so that depth extends from half the hyperfocal distance to infinity. FocussING RULES FoR Hanp Cameras.—The following two simple rules may be useful to hand camera workers. 1. Applicable when the background is not very distant: Focus on a distance equal to twice the product of the greatest and shortest distances, divided by their sum. Example: Suppose the subject to be a street scene with a house 20 yards away, a man 5 yards away, and both are required to be sharp; then (20x 5) + (5+ 20) X2=8 yards. 2. Applicable when the background is infinity or very distant: Focus on a point just double the distance of the nearest point. Example: again suppose that the nearest point is 5 yards distant; then the point to focus on is 5 X 2 = 10 yards. The following rule may also be used: square the focal length of the lens in inches, multiply by 100, divide by the f number of the diaphragm, and then divide by 2. Example: Witthieaviens of 5. in. focus at #28; 5 xia 100 — 2500. 2500 — 8 = 312%, and 312% ~2—156 in. Then every- thing beyond 156 in. (13 ft.) will be in focus if this plane be focussed on. CoMBINING LEeNsEs.—To find the focal length of two lenses separated by a short distance, multiply the focal lengths 44 PHOTOGRAPHIC FACTS AND FORMULAS together, and divide by their sum less the distance of separa- tion. Let f’ and f’’ be the foci and d the separation of the two lenses; then the final focal length will be (f’ X f”) + (f’ + f’’ —d). Example: a 6-inch and an 8-inch lens are to be combined with a distance of separation of 1 inch; the focus will be (6 X 8) + (6+ 8—1) =48~13=—3¥Y. To find the focal length of a supplementary lens or magnifier to reduce or increase the focal length of a given lens, multiply the focal length F to be altered by the final focal length desired, and divide the product by the original focal length less the final focus. Example: it is desired to reduce the focal length of a 10-inch lens to 7 inches, then 10 XK 7 = 70, 10—7=3, and 70~—3—231/3. To reduce the focal length, positive or convex lenses must be used; to increase the focus, negative or concave lenses must be used; and, in this case, the focus of the lens to be added is prefixed by the minus sign in the formula. Example: to lengthen a 7-inch lens to 10 inches, 7 X 1070, and 7— (+10) =—3, therefore 70 ——3 = —23 1/3. A very simple rule to re- member as to the focus of a magnifier for reducing the focus, or, in other words, to take near objects close to the camera, is that the focus of the supplementary lens must be equal to the distance of the object. In this calculation the separation of the lenses has been neglected; to take this into considera- tion is a refinement that merely complicates calculations. Ratio APERTURE OF D1aPHRAGMS.—The ratio or effective aperture of the stops or diaphragms does not coincide with their actual diameters in consequence of the condensation of the light by the front lens component in compound lenses. To determine the correct ratio aperture, focus the lens for parallel rays, that is, for a very distant object; then replace the focussing screen with an opaque card, in the center of which is a pinhole. In a dark room place a light behind the FOCUS AND OPTICS 45 pinhole, and a circle of light will be found on the front glass of the lens; the diameter of this circle will be the true aper- ture of the stop, and dividing the focal length by this gives the true ratio aperture. As it is sometimes difficult to see the circle of light on the glass, the latter may be dusted with talc, which makes it more readily visible. Or a small piece of bromide paper may be cut and placed inside the cap of the lens, and a fairly long exposure given to the light passing through the pinhole and the lens. On development the diameter of the black circle is the diameter of the ratio aperture. Another method is to focus a bright spot of light at infinity or a great distance, and then move the focussing screen until the spot of light becomes a disk of any definite diameter, say, half an inch. Then the distance the focussing screen was moved divided by the diameter of the disk of light is the diameter of the ratio aperture. To find the diameter of the stops for a lens, the following approximate method may be adopted: Find the equivalent focus F of the lens, measure the distance between the two outer surfaces of the front and back lens, call this d; then the diameter of the stop f:x will be (F— Yd) +x. Example: focus of lens, 16 inches, distance between the surfaces or d, 2 inches; if the desired stop is f:8, then 16— (4% X 2) +=8= 16—1~— 8 — 1% inches, the diameter for f: 8. Piper’s TaBLeE oF ANGLES OF ViEw.—To find the angle included on any given plate, divide the diagonal of the plate by the equivalent focus of the lens. The quotient T is equal to twice the tangent of half the angle, but the value of the angle can be found very nearly from the following table: ii ais The angle Tides The angle less than is less than less than is less than 0.3 vee eZ 81° 0:35 20° 1.8 84° 46 PHOTOGRAPHIC FACTS AND FORMULAS If T is The angle less than is less than 0.4 25° 0.45 25" 0.5 Nn ae 0.55 fo 0.6 334° 0.65 36° 0.7 39° 0.75 414° 0.8 44° 0.85 4614° 0.9 4814° 0.95 sh ey 1.0 Bo. 1} 58° 12 G2" 1.3 66° 1.4 70° Site 74° 1.6 77° He as less than 1.9 2.0 2.1 The angle is less than 87° To determine the covering angle, the diameter is taken as equal to twice the distance from the principal axis of the lens to the farthest corner of the plate. angle, we take simply the diagonal of the plate as the diameter. The diagonals of ordinary plates and films are: 24,x3%....4.0 in. 24%x44%....49 in. $144x3%4....4.6 in, 3% x4%....5.3 in. 34% x5Y%....64 in. HOTS. th: MAE © Bee BE 434 x 614....8.0 in. 5 5 O72 8 10 16 20 To determine the view RA x 7% hes ean x10 m2 x 20 x 24 oa) Ola S30.) 0a 107 ae .. LZeuee RN Bs) cy. .. 200i. . ole ie FOCUS AND OFPMiIGsS 47 CoRRECTION FOR NON-ACHROMATIC (SPECTACLE) LENSES. —After focussing, the distance between the lens and plate must be decreased by approximately 1/40 the focal length of the lens, in the normal use of the lens when photographing distant objects. In portraiture, copying, etc., the correction is greater, as follows: Ratio of reduction Infin. 1/10 1/5 3/10 4/10 % 6/10 7/10 4/5 same Correction (% of ee focal length) 2 2.2 .2.4 2.6 Pee) eC) Pee 3.4 3.6 4 TELEPHOTO ForMULAS.—Let WM be the magnification, 1. e., the number of times the image produced by the complete lens is larger than that produced by the positive lens alone; F the focal length of the complete lens; f’ the focal length of the positive lens; f’’ the focal length of the negative lens; F the camera extension from negative lens to plate. To find the magnification M: Divide the camera extension by the focal length of the negative lens, and add 1, or M = (E = f’’) +1. To find the camera extension: Multiply the focal length of the negative lens by the magnification minus 1, or FE =f’ (M—1). The focal length of the whole lens for distant objects equals the focal length of the positive lens multiplied by the magnification, or F = Mf’. For near ob- jects when reducing N times, F = (mE + f’) + (mN +1), iawnicn a — ithe ratio, of |f’ to 7”, \1.\.e% F771) (Dall meyer ). Assume the same notation as above. The separation of the positive from the negative lens = (f’ —f”) + (f”+WM). Example: Suppose the positive lens has a focus of 7 in., the negative a focus of 3 in., what separation will be required for 4 magnifications? Ans—(7—3) + (3+4) =434. An alternative formula giving the separation necessary to obtain a telephoto combination of a desired focal length is (f’ — f’) +f G¢’ +F). Example: suppose the positive lens is 9 in. focus and the negative 4 in., what separation is required 48 PHOTOGRAPHIC FACTS AND FORMULAS to make the combined focus 16 in? Ans—(9—4)+9X (4—16)=5+9X %4%=—5+24%=7% in. Where a scale of magnification is marked, as on the ordinary type of adjustable mount, and another magnification is desired that is not marked, let M’ stand for any existing marked magnifi- cation, M” the magnification desired. Then f” kK (M’ — M’”) ~~ (M’ X M’”) will be the increase of separation re- quired. Example: Suppose a magnification of 5 be wanted, and the nearest mark is 3, the focus of the negative lens being 41%4. Then 4% X (5—3) + (5 X 3) = 4% X 2/15 = 3/5 in., which is the necessary extra separation readily measured from the existing mark for 3 magnifications. When the focus of the negative lens is not known, it is easy to find it from the distance between any two magnification marks on the mount. The rule is: multiply the two magnifications together and divide by their difference, multiplying the quo- tient by the distance D between the two marks; (M’ K M”) — (M’—M”) xD. Example: suppose the distance be- tween the marks 8 and 4 on a telephoto mount is % in., then (8 X 4) + (8—4) XK % = 32/4 X % = 6 in., which is the required focus (Lockett). PINHOLE Exposure.—The correct exposure is, with the small pinholes used in practice, always greater than that cal- culated on a basis of relative aperture ratios. The inverse square law cannot be applied in calculating relative exposures at varying plate distances from one and the same pinhole. Using a pinhole made with a No. 12 needle, the pinhole exposure factor by which the aperture ratio numbers must be multiplied varies from 1.6 to 1.42 as the plate distance diminishes from 254 to 128mm (Carnegie). Watkins finds that it is better to expose with a pinhole for 50 per cent longer than the exposure calculated on the ratio aperture, and gives the following table based on 1/40 instead FOCUS AND OERICS 49 of 1/60 inch, the numbers being called Watkins-Power, or W. P. Nos. Nearest Nearest Decimals vulgar needle Working W.P.Nos. of inch fractions size distance 1 .160 1/7 Sah EON HR saa Z O802 1/13 Bere bible cea 39 3 053 1/19 1 40 in 4 040 1/25 4 20 in 5 032 IW 5 14 in 6 027 1/38 i 10 in 7 023 1/44 8 8 in. 8 020 W/ 52 10 5 in. Multiply the W. P. No. of the aperture by the working distance from the plate. Use the result as the f number with which to calculate the exposure by table or meter. Whatever the calculated result is in seconds or fractions of a second, expose that same number of minutes or fractions of a minute. To find the best diameter of pinhole for a given extension of camera: divide the square root of the extension by 120. Example: extension = 11 in., square root of 11 = 3.316, and this divided by 120 — 0.0276 in. or approximately 1/36 in. To find the extension of camera for a given size hole, multiply the diameter of the hole by 120, and square the Recley) xataples diameter — 1/40) then 1/40)>< 120) — 3; and 3X 3 =9 in. CoNJUGATE Foc1.—The relative distances between the neg- ative and lens, and lens and image, for enlarging and reduc- ing, that is, copying in the camera or making lantern slides, can be found by the following simple rule: divide the longer side of the enlargement desired by the longer side of the negative, and the result will be the “times” of enlargement ; it should be noted that this is linear and not area enlargement. 50 PHOTOGRAPHIC FACTS AND FORMULAS Then multiply the focus of the lens by the times of enlarge- ment plus 1, and the result will be the distance between lens and sensitive surface. This distance divided by the times of enlargement will give the distance between the lens and nega- tive. Example: to find the distances for enlarging a 4x5 negative to 16 x 20, the times of enlargement — 20 — 5 = 4. Using a 6% in. focus lens, 6% & (4+ 1) = 32Y and 32% —4—8% in. The greater distance is called the major con- jugate focus and the lesser the minor conjugate. In reducing or copying, these distances are reversed, that is, the major conjugate or greater distance is between the subject and the lens and the minor between the lens and the sensitive surface. How To Care For High GRADE LENSES.—The lens should be capped when it is not in use. Avoid sudden and extreme temperature changes. The lens should not be exposed to acid fumes. Avoid placing or leaving lens where dampness or moisture may collect on it. Do not permit lens to fall, or subject it to a sudden jar. Occasional cleaning is not only advisable but necessary when dust, finger marks or moisture show on the lens surfaces. For this a camel’s hair brush and a clean, soft, linen cloth are desirable. Proceed as follows: Remove dust with camel’s hair brush. Breathe on lens surface, and with cloth wipe lightly with a circular move- ment. If finger or dust marks cannot be removed, rub the surface gently witha tuft of cotton moistened with clean warm water. Dry the surface with a piece of clean linen cloth. Under no circumstances use abrasives or any kind of polish- ing or cleaning material. Never use acids, alcohol, alcoholine or other solvents on the lens surfaces or on the mount. Only in extreme cases should lens elements be removed from their metal mounts to clean inner surfaces. When replacing same, see that they fit evenly and firmly in the mount. Exposure TIMING SHUTTER SPEEDS.—Using a pendulum for this purpose, the speed of the bob is in feet per second 2x gl( sin’ 2 sin’ S in which g = force of et at the eres of experiment, 32.2 being sufficiently approximate, ] = length of pendulum in feet, B the angular displacement from vertical of bob at its highest position, C the angular displacement from vertical of bob for position at which speed is required. From this a table can be calculated of the speeds of the bob over each 5 degrees of arc and also the total period of the pendulum (Collingridge). THE AMERICAN PHOTOGRAPHY EXPoSURE-TABLES.*— Find numbers for subject, stop, light, month and hour, and plate. Add them, refer to table (page 60), and give exposure indicated. When the exposure fails to correspond with speed marking on shutter, use the nearest shutter speed, preferably the lower. Subject.— Beam(omlyy) ane Cloudsy ick. .cialcie aeac ey acetate yy Sea views, snow scenes, distant landscape ............ 1 Open landscape with unimportant foreground ......... 2 Ewer celandscape with TOresround sik yoo uu ued 3 Landscape with dark foreground, groups in sunlight .... 4 SPReeR scenes, /DUidings SroUps {28.2 ee es 5 EGMeMES VTP SHAC es NL LV i 5) VMI irony 2 7 HTGOOTNPOTETAIES: sie. eS Re ge eat) 8 to 10 RESETS Me ey Ns A ON lay dle a (lds SU UMtMaM EN parla) 0 8 to 16 * Copyright, 1906 by F. Dundas Todd. Copyright, 1911, 1913, 1914, by F. R. Fraprie. Copyright, 1912, 1915, 1916, by American Photographic Publishing Co. oil 52 PHOTOGRAPHIC FACTS AND FORMULAS Stop.— 2.3 14 | 2.89 | 3.394 | 49 | 4.723 | 5.64 | 6.7 w02s!|oasT Fe Fe 13 | 14 i rl 19 | 38 | 16! | “8 49 | ‘eu | 256 re Light.— Intense sunlight (inky-black shadows) .............. 0 Bright sunlight (strong shadows) ...............0.. yy Paint shadow cast by sun... <2. 3. a bee ee 1 Dall (no shadows) «625.65. 556 06 snes hee 1% Very dull (whole sky very dark) ......5... eee 2 If sunlight falls over one shoulder, add 0; if straight across subject, add 1; if sun is ahead, add 2. When using back combination only of R. R. or symmetrical lens, add 2, unless actual f value of stop is known and used. LiGHT VALUES FoR VARIOUS LATITUDES.—The following tables show the value of the light for each hour of the day and month for various latitudes and are calculated for use with the American Photography Exposure Tables. For 60° N.; Southern Siberia, Southern Alaska, Northern Canada, Iceland, Norway, Sweden, and Northern Russia. 1 A og May Apr. Mar. Feb. Jan. MM June July Aug. Sept: Oct. “Nov: Wee: 12 0 0 hea | 1% 2 3 Bree 0 y% 1 bear 3 5 Oe y y% 1 1% 2 ~ 6 SAAS: y% 1 1% 2 3 s, 8 4 1 1% 2 2 5 “bans wy 2 3 5 B06 2 3 > SE 5 5 4 8 > Dec. Nov. Oct. Sept. Aug. July jae Jan. Feb. Mar.:. Apr: Mia ee EXPOSURE 53 The months for latitudes north of the equator are given at the top of the tables, while those for the southern hemisphere are below. For 53° N.; British Isles, Northern Germany, Southern Canada, and Southern Russia. JBN a ad May > Apr Manin Heb.) ) jan. MM jJune> July Aug, (Sept. Oct. Nov. | Dee. Bel 2 0 0. yy 1 PY) 2 3 es | 0 0 y% 1 2 3 + HOV -2Z 0 0 Y 1% 2% 4 5 SES: Y, yY 1 Z 3 5 7 8 4 1 1 1A) 2 ies Bei D 14% 2 24% (15 Bie Catan ¢ 2 3 5 eZ. 5 5 4 8 6 Dec. Nov. Oct: Sept, | Aug? July.) fume Jan. eb.) Mara Apr) (Miay, For 40° N.; Northern United States, Armenia, Spain, Italy, Turkey, Japan, Greece, Pekin, and Central China. JENN) bg May | Apr.) Mar.) Webs) )Jan! M M June July Aug. Sept. Oct. Nov. Dec. 2 0 0 0 y, Yak 1 JE Cae | 0 0 0 yy yY% 1 1 LOR 2 0 0 yy ye 4 1% 1% Or) 3 y, y, Mya e | 1 72 2 8 4 1 1 1 Z 2 3 4 TN AS 1 1% 3 4 5 5 5 6 6 Z 3 4 D7. 5 54 PHOTOGRAPHIC FACTS AND FORMULAS For 30° N.; Southern China, Southern United States, Northern Mexico, Northern Africa, Arabia, and Northern India. PANO viens tae May . Apr.)) Mars ihebs) haa MM June July “Aug: Sept.) Oct (Nev ie 12 y% 0 0 0 0 a | 0 0 0 0 0 ARE | BO 82 0 0 0 0 y% 1 i! DH hiiid 0 0 yy Ove 1% 2 8 4 yY 1 Ly ee 2% 3 Aas 14) 2 2Ye) hi + 3 SIN 0) 3 4 6 Dec. Nov. Oct. Sept. Aug: jai ae Jan. ‘Feb. Mar. Apr: tie For 30° S.; Southern Australia, Northern Argentina, Cape Colony, and Uruguay. For 23° N.; India, Mexico, Southern Egypt, ‘Central Arabia, Cuba, and Northern West Indies. 72 ME May \Aprt..:Mar. | Feb. jam M M June July Aug. Sept. Oct.) Mayes 12 ve YY Y% 0 0 0 4 Da sid 0 0 0 0 0 14 % LO} 12 0 0 0 0 yy eM EUAN: 7 y, y% 1 1 1 ly 8 4 1 1 1 1% 1% 2 2% AO 2 ys 2% 3 3% 4 7 By), 3 4 6 Dec. Nov. Oct. ‘Sept. Aug. Jily jaa Jan.) Heb. Mar. Apr. May For 23° S.; Northern Australia, Northern Chile, Bolivia, Madagascar, Rio Janeiro, and Transvaal. EXPOSURE a Tropics, 20° N. to 20° S.; Northern Brazil, Canal Zone, Central Africa, Ceylon, Borneo, Sumatra and Pacific Islands. JEN, SOU ag May Apr. MM Mame yy puly vase 12 0 0 —y, ga 0 0 0 Ou 2 0 Orewa ko oS 1 yy, yy, 8. 4 Aaa is 1 Fs) $ 3 2% Mar. Sept. —, 0 22 Feb. Jan. Ochi Nov.) Dee: 4 0 8) 0 0) 0) 0 0 0 Vay) iva viel 1 1 ly PAAR 3 PLATE SPEEDS.—The numbers in the first column indicate the exposure factors for use with the American Photography Exposure Tables. The letters in the last column are develop- The other columns contain factors for use with the Burroughs-Wellcome, Wat- kins, Wynne and Harvey exposure meters. ment speeds for Thermo Development. Amer Phot AS) 1050610 ERO OEE ae Bu anal Agta (Color plates .)5 ci. eo esis 0 ee Amsco Specdex: filmy .). ler. is cs ees te %4 AC Pe ME Wltra Speed | 2)... 50s ei ss 5 « a3 AP EA VIS YING (SICLETIEN TS 18 ors 6) cele stele % APSE WMENSpPeCtal TAaApId |). clsiei cies ose 1 PACHA VIC TITINY eilehe laters Caer NU eh dito . iL A. Edwards Ensign ............ 1 A. Edwards Ensign speedy ...... % Barnet Ordinary) 2). selec as see es 6 4 Barnet) Special rapid) 6.0.2 d. . ss 1% Barnet self-screen ..........00. al EMOTE GU SEAT) oe el aiavelevcle! aia chases %4 BAENeL) StUAIO SOO. es ui es eels wie 4 Barnet Studio 500 & Press ...... Wy Barnet Ult. rap. & SS ortho ...... Yy Barnet Studio 400 ortho ........ 34 APMC DE TESS esta HM pay ucie ave gia) % TBRON TCG a 3; Nd Bayyeg Ba hs aD Te ene Da es % TENDEPIOHYStH NBS spy Oa BA Ue 4 TEAS DICH OGY nnd Be a _IMA 1% PAM CHE teres ALL VARY Se Ment mB Tel ie 3 Carbine yrolly filmy ayes els 1 Central Colornon ..........2.«6 4 Central Pan. Ortho. Com ........ 4 GentralKComebwas coisa eka ots seve Central SHECiAw A cen Nee 1 Central Special XX ios atid Mae, % Wat. Wynne Har. 130 73 KE D HeOO SeQhtH TED} WnntneekoukeReER & 56 PHOTOGRAPHIC FACTS AND FORMULAS Amer. Phot. B.W. Wat. Wynne Har. TD. Central Excelall ....... a tahayer eel sie % 1/12 350 120 Cc Ss Cramer Contrast ..........ce0- A 9 3 32 35 M VVQ Cramer Slow Iso ....... Eek taste 5 1% 130 73 K MQ Cramer Com. & Com. Iso ........ 1% Ye 130 13.) mee MQ Cramer Spectrum & Trichrome ... 2 1/3 90 60) LE MQ Cramer Anchor & med. Iso. ...... 2 1/3 90 60 G.H MQ EWamMer RAN OL XL! . 2).) 0) s)s)0s o\2jnles\e 1% 1/6 130 TS) ue Ss Cramer Inst. Iso & Iso. Port. .... 1 1/6 180 86 E MQ Cramer Crown. Post .........-- 1 1/6 180 86 E Ss Cramer Speed-o-krome .......... 1 Ej6 (180 86 E Ss Cramer FS peed. i)..') seo 0's 2 «20% Ne 1% 250 100 D Ss Criterion Process ...........-- Mea e! 4 3 32 35 M Q Criterion Ordinary ....... 5) areata’ 4 % 65 iy Ay = | Q Criterion Iso ordinary .......... 2 1/3 90 60) at M Criterion Extra rapid ........... 2 1/3 90 GO) MS Criterion Extra rapid Iso ........ 1% % 130 72 #G M Oriferion Roll film. ...... 2016... 1 1/6 (180 87 vs Mrsterion | Cine SLM | ies oid 'e01nen oe 1% uy 130 72 MQ Criterion Special Extra Rap. .... Lk f6) NESS 87 VS Criterion Portrait ........... ya 1 1/6: ‘2380 87 MS Criterion Hnelite ........++-+0-. % As/i2 350. t2e vs Eastman Process film ....... se 9 3 32 35 L MQ Eastman Cine Pos. film ........ A 9 3 32 35 MQ Eastman Rapid plate ........... 1% % 130 72 MS Eastman Extra rapid plate ...... 1 1/6 180 87 MS Eastman Spl. ultra rapid ....... : 1 % 180 87 MS ASEAN EEG) o's Lie n\el be nd aie ete lee 1 4% «180 87 MS Eastman Super-sensitive plate ... % 1/12 350 120 vs Eastman Par-speed Port. Film ... % \% 250 100: DB MS Eastman Cine neg. ord. ......... 1 1/6 180 87 8 Eastman Cine neg. sup. speed .... % % 250 £100 vs Eastman Cine neg. pan. ....... eh ee i 130 72 MS Eastman Sup. Speed Port film .... % 1/12 350 120 B vs Eastman Commercial ............ 4 2/3 65 52 H M Eastman Commercial ortho ...... i iy 180 ST) va MQ Bam: Process (ec ok! Gok wlohe 5 1% 65 52 M Q Gem Universal Slow ............ a 1 32 35 M MQ Kem) WMIVEreaE oss esc is, op wie tere Bene 4 % 65 i | M PCIE MIS es9 Eh hs Ren i eS AEA 2 u% 90 60° Ss EHR SUTICON cis 55 aaeicien “A 8 1% % 130 STi ts Q Gem Ultra rap. studio .......... 1 1/6 180 87 et s Gem Noskrene & Sp. Rap. ...... ds Nfe 1/6 180 B71 ae Ss em Cet oar j,°.% is /ct eee cle ale 1 1/6 180 37 M “CHEER ET ES Fa a ES, ha 1 1/6 180 BT ce M Rarereeh SRGONN: FARTING 61s ba) GS) a gaes tain emis ee 1 % 180 87 Vs Gem portrait & Salon Iso ........ % %y 250 a s Roped oid label: 5-12 cst c\ninln sien teeie % 1/12 350 120 s Gem Salon XX & Iso ........... % 1/16.) 500." 43 vs end (Salon Mili!) 20). !s.2 ds e's Sele es % % 250 87 s Gevaert Ortho Process .......... 9 2 32 35 M M Gevaert Ordinary .............. 4 2/3 65 52.) MQ Gevaert Ortho antihalo ......... L % 180 87 MQ Gevaert Filtered ortho .......... 1% % 130 on ee MS Gevaert Spec. rapid ............ 1 LG) a BO 87° MQ Gevaert Orthochrome ........... a 1/6 180 BT >. a MQ Gevaert Special sensitive ........ % % 250 100 D Vs EXPOSURE Amer Phot Bae Gevaert Sensima ...........26... y% 1/12 Gevaert Sensima ortho .......... yy 1/12 Gevaert Cine film) ei. ese oo y, Goerz Tenax Ultra rap .......... % ¥%, Goerz Tenax Ultra Iso ......... - & yy, GoerzRenax Bx.) Taps... .6 56s %, yy Goerz Tenax Ex. rap. Iso ....... 4 a2 VA Goerz Tenax Ex. Iso antihalo .... 1% VA Coerzgbenax) fm! . cise c.s 3 ses sis )e 1% 4, Crpiexa roll) Amy, sie cre ss lelal cis 410) 1 1/6 Grifin Com. & Prof. 125 ........ D) 1/3 Griffin Com. & Prof. 250 ....... 5 1 1/6 Griffin Com. & Prof. 375 ..... cod | OA VA Gritinwself ortho i. c.6 2 sec 5 8 1 1/6 Gari vGraMMes o/c Cie On Ome 4 1 Hammer Slow ortho ........... 5 Lug 1 EAMHIET ASL! ais) «| alesis) <=) ~-- 1% 1 Hammer Ortho non-hal. ......... 1% 1 Hammer Ortho extra fast ....... 1% 14 Hammer Aurora extra fast ...... 1% % Hammer Postal & extra fast .... 1 1/6 Hammer Special extra fast ..... Bas A IZ Hauff ortho anti-hal ............ 1% 1/3 Marty L A WATE! Veayeyielle iielisl siieliei's/o/she ie) ile 1% yy, ait xt. (rap. Ortho ..).../.. «.'s - 1% 1/6 laut Witra, rapid. os 276. e)6 os os g le 1/12 MfGrdeePTrOCESS 9 aie chavelulic dois ose a/e 9 2 titordivap. (Proc. Panic... s/sleio 6 <3 2 1/3 MLford TV alE-GONE 6.6 oc iaicisie sc escleie 4% 1 HI fordG Ordinaryiers «sie ckeveese olake ec. 3 2/3 EEFOrd PEMPTeSS! ho .).) 6's sysie oo sie)s s Sis 4 i HiordsHmpress film. <.6.5)5:.).... 2, 1/3 ford i@hromatic: 5.10. 6s. sie ecae 1% y%, ford (Special rapid@ <0... 6.6... 6 1 1/6 Iiford Special rapid film ........ 1 1/6 Ilford Screened chromatic ....... 1 1/6 Mion CON filly oy. Soe seieieccia otis ««'s %, % iford (Spee. rap. Pan. so6 <6. s<. iy % Hitord) Auto-SCTreen —\s)5.0.6) 66 a;60 + 2,6! yy % Ilford Rapid chromatic .......... 34 ¥% iiiford Se oR. xt. ‘Sen... 56 3. dates 1/12 Kifordi Zenith 400) 3 686) ciesle stele «5 yy 1/12 Miford (Zenith) film) 2:5 .c40)sse/ce « a) SA % MNEOR AME PESSY sates: crc Nolske oon aise. ale y% 1/12 Miiford MONAT CHG 6.655. 8 oc lets tess 60. yy, 1/12 ilford: Zenith) 650 <5 656d. s 8 y, 1/16 Ilford Zenith Ex-Sen. film ....... y% 1/12 MTOrd son AMG hee. verses oeskhe sie iy, 1/16 ilmeworth Ordinary 62.5.3... 4 y% Illingworth Med. & Ortho med. ... 2 4 Illingworth Pan. Process ........ 4. 1 Illingworth Sp. rapid ...... Sea 1 1/6 Illingworth Non screen .......... 1 1/6 Wat. Wynne Har. nee 500 143) D 500 143 &E M 90 60 MQ 250 100 Vs 250 100 S 250 100 MS 130 72 MS 130 72 M 130 72 MS 180 87 VS 90 60 M 180 87 MS 250 100 VS 180 87 MS 180 87 MS 180 87 MS 250 100 vs 65 BON VQ 130 gon) di VQ 120 70 MQ 120 70 M 130 7 D M 130 RO) anke MS 180 Se yin M 250 100 D MS 120 70 M 130 72 M 130 72 MS 350 120 Vs 32 35 M Q 90 73 VVQ 65 gE Q 65 SN | VQ 65 Bo en M 90 63 VQ 130 72 M 180 87 MS 180 87 MS 180 87 MQ 250 100 MS 350 120 F Q 350 120 M 250 100 MQ 350.1120) E MS 350 120 E MS 250 100 MS 350) 20.) Ss 350 120 D Ss 5000) 145 6 MS 350 120 vs 500 143 MS 65 Gene f VQ 90 60 HI Q.vQ 65 52 VVQ 180 Su) G MQ 180 87 G VQ 58 PHOTOGRAPHIC FACTS AND FORMULAS Amer. Phot. Illingworth roll film Pack ......- 1 Illingworth Panchro fast ........ % Illingworth High rapidity ....... % Illingworth Ultra rapid ......... % Illingworth Studio fast ...... als ibie) Nahe Bilin work ISEB 6/63) e'5\s6 0! e eo % Illingworth Studio ex. fast ...... % Illingworth Super Fleet ......... % Illingworth Ortho fast ..... ie ve aag i) ae Imperial Process ...... pe ielelalaehete 9 Imperial Process Pan. .......ce. 4 Imperial Landscape Day witeie tela 6 Imperial Fine grain Ord. ..... eu 6 MAO EEIAUOMAG e ts\= so leiai'el el siiavelisi esas a es Imperial Sovereign ......... RCSA Hs ie Tmperial Spec. Tap)... 0s esekesce) Ve Imperial Spec. rap ortho ..... Seth Viale Imperial Non-filter ......... A ANE 1 imperial Roll) film) {/). 26/2320) .\6 0 % Imperial Panchro A ..... ARS Lees acl 1 Imperial Panchro B ..... Se ee AR Imperial Special sen. ......... sh Imperial Special sen. ortho ..... eA Imperial S. S. Press & Lata LN dae Imperial 8S. S. S. Press..... 4 Si ae Imperial Eclipse ......... nM Be YY Imperial Eclipse soft,ortho,orthosoft % Jougla Rose label & ortho A ..... 1 JouglapUntensivies sie\elevs sleeves jereie = « 1 Jougla Ortho By Oe sees 1 Jougla Pan. Process ..... AO aa 1% Jougla Blue band & Prof. ........ 1 Jougla Green label ......... Rhee le) pH INeNe: Jougla) Maive. Pamd, siete.) sie elers ere % Kodak Speed film ......... Bis ates) oa: Kodak film pack ....... 2.000 GNIS Ze Kodak) cut film! rev.) .). s)0 20's. $ ‘ 4 Kodak super speed ..... os lehaleite yy Lumiére Blue label ........ milena vol ehh ee ye Lumiére Simplex, anti-hal. ...... 1% Bumiere) Ortho PA. (Be in peice uiieisne il Mumrere Ortho Cr) ss elabeliewialeyeve le ab Lumiére Pan. Procédé .......... 1 Lumiére Reproduction .......... 2 Lumiére Pelliculaire .......... -. LY Lumiére Instantanée ............ 1% Lumiére panchromatic .......... 1 Lumiére Extra rapide ........... 1% Lumiére Grande instantanée ..... if Lumiére Portrait instantanée .... 1 iamiere (Maxaman 2)6 0) Siyeieseve oiaeers ania MAA TET OE COLEMAN ei sc) )e Wikis wiateumie ciate y% Lumiére Autochrome ....... 7%-8% Lumiére Plavik film ............ 1% iuamiere, Cine filmy eo foea aye ee ee 1% Lumiére N. C. Speed film ...... Ae 1 B.W. Wat. Wynne Har. T.D. iy 180 87 M % 250 100 E Q 1 250i... LOO ae MQ 17 12)() 850i! 12 ieee MS 1/12 350 120 E VS 1/12 350 120 D M 1/16 500 143 G VS 1/16) 500» 143) °D Ss 1/16) ' 850\,\.\/ 1207) 1 M 2 32 35 M Q 1 65 Ey MQ 1% 45 43 MQ 1 45 43 K VVQ 2/3 65 52 I VVQ A 130 72 A Q 1/6 180 87.) et Q 1/6 180 87 G MQ 1/6 180 87 G VvQ % 250 100 E M 1% 180 87 F VVQ 16: 350) (Oia VQ % 250 100 F M % 250 100 F VQ 1/12) :350) ei vs 1/16 500 143 vs 1/16 500 143 Cc Ss 1/16 500 143 Cc MS Mu 180 87 M % 180 87 F VS A 180 87 G M % 130 72 M 1/6 180 87 MS % 250: 100 MS 1/12 3850 143 MS % 250 100 D Ss 14% 250 100 D Ss 1% 250 100 D Ss 1/12. |. 850%) AO eae vs u% 130 72 G M Yu 130 72 M % 180 87 Q % 180 87 Q % 180 87 Q % 90 60 MQ % 130 72 MS % 130 72 MQ 1/6 180 87 VQ ¥% 130 72 MQ % 180 87 MQ % 180 87 M 1 250 100 M 1/16 500 143 B VS 6 15 Q uy 130 87 MQ 1% 180 87 M % 250 100 Ss +. = Slee © ae EXPOSURE Amer Phot Lumiére Sigma ortho film ....... 1 Marion Process ..... SeWareltoiatealeirene 9 Marion Fine grain ..... avait aware 3 6 MEariOn yy OTGINATY, "\/)s\s/s\s)cecs vie « «6 5 4 JUED ROT, STEROL RO AAS OAS DIG HEN ACHOROIGIG 3% Marion Inst. & Tso) occ... 606 3. ae 1 Marion Brilliant ....... eVeterelet eves 34 Marion Record & Iso Record ..... % MITT a Sehielejsielies sien re PEE Oe USA UE 7a Marion Portrait) 2/0... (3.6/5.6 Bier svaniet we WHEN Ey UN ons See Deiane tal He idles Mawson Photomech. ......2cceee 9 Mawson Castle ..... efalelcrsl chia clic elle 4 Mawson Felixi ..... satisheheveisiererare 1 Mawson Gladiator ..... ACN a A Mawson Ortho A & Pan. ........ 1% Mawson Wizard ........ sitelania ite SAGA Mawson \VictOry, |... .< c. 6 ateyoranells 1 Mawson Super Gladiator ........ % New Record, ext. fast .......... % Novex ext. speedy ....... sielslareleneui Sid ING WMexXHOTTHO! 2). /)6\'s: e166 6 soo cds 1 Novex ortho studio ....... EN ARR A Novex Max. speed ..... OP CRS L Ma ee Paget Color plate .......... abo 5 TARO by ONO eS 8 Ale evs: aheltanclapavelemeveitee 2 WUE EWPROREN fc Sic 6 Rveraeuen Sige WDE Paget process Pan. ....... so000K 2 Baset Ss. ih. Ortho ......: bidaswaae BA Paget S. R. & Ortho S. R. ...... 1 ROL ETO fe MC's Keke iss sere) stave. ee 1 Paget Ortho ext. Spec. rap. ..... % Paget Port. & extra S. R......... % PASE t ror. eXbe Es) ‘slelsicisicleeisie ce. Ye OG Mr OMAN sts) severe Wiel io esto ere.s 1 UEC OMKOLEHO) cic ayiieleieeicig esate 1 Paget Pan. ord. ...... US ANSE ea We Paget Hurricane ..... He SAGs Sicha Rajan Ordinary... 32. 3.0% 6 Cora ooloni aie Rajar S. R. & Iso N. S. ...... ate 1 Rajar roll film ...... araielahenetaherais aL Hajar Wltrsa, (Tsp. 400) \o cscs eel a!) KH ajar lta rapsO50)) oe... ces. U6 Seed Process ......:.. SWelrey atlesie! abeine 9 Seed Panchro ...... APRESS Epa Da Sarah: PAST I WSs aA Sr aWsHatohehelele tela etin ae Seed Ortho L...... Bralaitaiciletetcisle eiokh Lute Seed 26x & Non-hal. ..... auavenee ere ite\ia: Seed Gabby MATE SOM. te siete eke s eis) UA Seed Graflex ./....... taivarivieyetastaues lh ay Standard imp. Ports) 08os. sek) 3K Standard Postcard ..... sdoséoga ) SA Standard Orthonon & Poly. ...... % Standard Ext. Imperial ......... % Stanley Commercial ............ 4 UAE EVOL IIRT)\lalolalaielsilelals s\elie/e/ ere.) Sy . Wynne Har. ASD): 87 Ss 35 H 43 M Q 43 I MQ 100 F MQ 87 G M 100 F MS 143 CO VS.S 100 MS 72 M 72 MQ 35 Q 52 af VS 87 G M 100 E Ss 72 F.G MS.VS 100 HK MS 87 E s 120 VS 100 M 100 F Ss 87 F M 100 E MS 120 D NS) 21 60 MS 72 H MS 60 M 100 Ss 87 G NS) 87 E SS} 120 Vs 120 aD) NS) 120 H VS 87 VS 100 MS 72 MS 143 C Ss 52 I Q 87 EF M 87 EF MS 100 E M 120 M 35 L Q 72 J MQ 72 H MQ 2: E M 100 E M 120 D MS 142 C VS 100 M 100 H Q 100 E M 100 E MS 52 181 Q 100 E MS 60 PHOTOGRAPHIC FACTS AND FORMULAS Amer Phot LUG AEY VERIRIR ENN eV Sian) elles on) bi fos! pla 1 Wellington Film ..........20.2. 1 Wellington Ortho Process ....... 9 Wellington Ordinary ..........- 4 Wellington Speedy Portrait ...... 1 Wellington Extra Speedy ........ 4 Wellington Iso speedy & Anti-scr. . 1 Wellington Studio anti-screen .... Wellington Press & Spec. extra speed. 1% Wellington Xtreme .........2.06 yy Wellington super Xtreme ......-. % Wratten Panchros|) .(...:s sc «s/ei0 ls» « 1% Wratten Panchro. Process ....... 5 Wratten Panchro. M ........... 5 " B.W. Wat. Wynne Har. T.D. 1/ 86 6 180 vs 160.) 180. i, 86 M 1 32 85 MM. Swe % 90 60 Q 1/6 180 86 @G M 16) 2500) (AER ae M 1/6. 180. “seu M 1/16 500 143 E MS 1/12, 350. «12098 Ss 1/12) 350 .; 2200s Ss 1/16 500’, 142 ae vs 16.) G80 yee MS Me i ee 1e GB yoo Exposure.—The following table shows the exposure cor- responding to the number found by adding the five factors. Bian) a8 Ny ag ———_—_— |] | | |] fe ———— D an he 2A +f : 10: x 135 or 153 § cf SY Ss — | Ef | | 30 2314) 24% | 24ry Bae |) S658 aes 303 ee EXPOSURE 61 CoNTINENTAL PLATE SPEEDS.—In the following table the speeds given are those usually accepted on the continent of Europe and are “degrees Scheiner.”’ A few plates, other than those of German make, are also included. These degrees are compared with those of other speed marking systems in a table on another page. AZa, (Coie leoo WSpN iin Sa Mannie RNC eR Se) th aol ah aie ie 16.5 Pa NOM LSOlar <). o. 6 <4 sso oes Malate alae as 125 eae nTomio TsOrapid. ..5.4). . «sie ce el aero mite ee 17 AvP a. [Eg ai 7h 0) (6 ibe nea ane AE rs Pn. 17 BWeeeemMa TTI PACKS ee ehh oak Vo the ale are ara ate 15:5 PePHmCONG (a ei oe kas «alae ete ee eee sas ere nee 15:5 EMSEMUOIOR) Flaten cj. ee Wii dca eos bs ea, eee ee eines 15 2.518) USOIEN eens Hs AR a AUPE Pohak oun ei Ae AU al 1255 PE MUSOTA DIC Wey ee kkk a eae hk Ouivie Minune ae 17 Poco rthochrom [solar 06. .3 ee eae. 125 2o8s, SPEC Ci Nase Ree a OEIC res nese acm Le 15.5 FMT EI SE Ie ooo cid ata sa hsm o argie ck a cuhebaned ena eis vera ae 155 PM OMO ICS ya sa) ee ae SE A 17 apollo NteeVIGIER 2252). 42). sss chao emotes 20 Bayemivollvand ivmi pack) io... 6.00 es a 15.5 eROMaaMeAnGSeApe Yo)... seid sa soe suineesa ea aeta es 12.5 Hp eT atten OUMOTIA Eis) e5 64) 5 5s oa, a 2 acl ale ayn eletenetainees 14 Penola Wiltra- Record Ks ee eee P55 Benpuna, Wiltta-wecord Ws... see a eee a 17 Welmnmicubiier abel Me i OY i VR Vee 15.5 Salome yellow labeliorthon.:. ci. oe eee 14 Colonia. yellow labeluortho antihal. 22). 395. 205.2 2): 125 Coloma GredWabel nie. eke se ca be ee 125 LSA TTe iT) TEL TEC ed EN (Ss) Oe. SOL OS 14 SASH OGE NO oak cy ya ssa 4 ag A RIS Ge 12.5 J SISLIUGEN To SNC ON otra te Oa Pee” es A fe 12.5 JEEVES Si: SES Ga a ieee rere Nepal 50 tau NA Mae 17 62 PHOTOGRAPHIC FACTS AND FORMULAS Loe hick! cepa: OU) aan ie mn M Cp mn GUHA Hraah Carnie MeL uuneny b! 15.5 Masumian) eed 26 bol) sk. ae REN ah Le Ne eae 125 APAStAN CRM 27. js). (bios « She ROM Lene et 14 Petra OPO see ae a 125 Pam COLNE (6804 sic 66k we boa 6 aes GO a 14 Potwree Giarattie,.\.....< ¢'s's «sels adden ee ne 14 Magwee ortho, antihal. |. 4 .)6se.)yiea eee eee 14 Pewee) SPeCIAl i... '.o)4 ak sled Wala oe 12.5 Miwee)Witra: rapid | iz deed ic ae eee Ly, Hisenberger Extra, Rapid...) 1.6.4. /2. 14 Misenberger Color )..).. 2 ee 14 Hisenberger Ortho antihal ...)55. 64 2.0), 02 ee 14 Bisenberger, Reform )).)...)./440 25 66 004, a 12.5 Pisenberger | Ultra rapid) cio yi.s 6 17 Revo) Vderar apie se. is 544 66 dian a.8 5 ae 17 Biko Ultrarapid antihal. 0.00... 440. 029 2h 14 Miko Uiltrarapid ortho). ).).3ed . sd sinless 15.5 Bike Ultrarapid ortho ‘antihal.:.). 600) Joyo ee 14 Ension, Filmpack & Roll film). 5. 00../203.5, 0 17 Hrrtee Yellow, label. fio i/o0 das Weac age ee 15.5 Prrtee lilac labels cio k oa ois ta eee ee 17 rttee white label. 2.0 4. isc ede ee ee 15,5 Clock Pidelitas 36.) ie sks apenas ala) ie 14 Gidek’ Bona oo 2 ses i ee Oe ee 14 Goerz roll film and fittn pack so). 2 ae 155 Gintleminot: Radio-brom)\. 0000s joel eee 18.5 Gritlemmot Radio-Helaig 0.0 Ai ee a a 20 Haake High speed portrait(ya ic Se ek, 17 danone Normal io. .)5 0b ee ON el ea 14.5 Haake landscape and, Process) Von. o uae eee 16 Pisce OPO oe ly Plage ixtia: rapid 0 SUMO aut al 17 Frau Orthochrom extra rapido. oe 17 EXPOSURE 63 Pecan Orhochrond. amtinaly Li a i lta 7, Tol gili7e TOUTE a aR STU a eee IBY OH /AA LICH Us Og Ea ap) fet seit ONG CAG eV cls so ciel d a, SNS A AMERY LUE) 20:5 SDECNGE (RCO OreS rau AD Al RN a Ue MEM e En ONAN ae nig 19 fener MN TALIS OAETICY (15. 5 a aioe Dials el ahaa MeV ara 5 Retemlamooy Genlaiian |... 5). wd. euieon ETC didiati ay 12 HeMeeraleeUO ONE AN 4. sc (ee ane o/iclalohh ae ile uanan Ea Pate NV al lene alin ay) 16 ficranco) Ultra ortho, & Antihal) once ee 15 emenco Nizam) Ni ee 16 Ptemanco) Ortho-Vigor antihal. . se ene 15 Piewanco) Wuzo.orthochrom antihal 0.2420. 13 ilemlance) Wirot,,orthochrom antihal 220 os. 3h Helis O NO TOEESS os 0 Ala ae RL ah 2 iewanco Germania transparency ./))44).))5 0) 1 terete MULT OLATOG LIM) (1 oc a: Wal hic a a CHAU naira) 15.5 alter ly POET ASE APG ii oie 6 adja elle ce SERGE eg 17, Peer OPNATA FAI. sea ese UN 155 Been OLA DOREAG) |... sd es eine EE 14 Bleed Jorna ce ortho antihaly i 1001) 6 Ta ea 14 15 zl an) Nore ag at ah 0 eee ae Me UG NITE, 14 lege Ee ressoplan )tilmpack, jo...) eyale ys velaln lee 17 eRe MMIN CHOTA G ie) Syst s 6 6 Gs Albee hele Gi a Re 11 leiden WMA AIO Sees Na Gey Un IO 18.5 MermiGen WE tra rapids coo sy eA ao) 14 ReGen anti ee kU Un AN En Alsat is 14 Meamlidcalrortio Gc antihnal a) 6. ok aeRO N Ne 14 LCE) LLU Sac SEE See eam UVES eM 125 122, Mig sobace hay) eae Hm esenen ENE 0/0. SU RN 14 MCCUE ayaa Ck) el UE ana 25 Meee (MES sobteea APUG (8) io) UG A eRe I 17, Her OlraSOrdo MC UNO Nau 14 Hoel AMARESE REE a) ANU A AON ga) 7, 64 PHOTOGRAPHIC FACTS AND FORMULAS Thora Wersatile i/o RU a ae 18.5 Teora Cente ee SRO ee eee 18.5 Poperial etashlight |. 60.00 y Saal ee ee ea 18.5 Enerial Ortho spec. ‘sen. .'. 2. 2 ee eee 17 imperial Ortho spec.\rapid). ..... o. 2 heen eee 15.5 Tiaperialy Special. sensitive). 0.0 a0 Va 17 Nahe Sipurd ord, all sorts;.). 60.2, 24.0005 ve een 15 faut) Sieard ext. all sorts... 552,02). Grose ene ee 18 Want Blue’ seal. 0. bee ek ee a ae 2 15 jane Blue seal ortho } 23). 0.) 0.400. eo 15 falir ‘Red label, A, B,C, Di: a). 2000.0 02 16.5 Karschten’ Reform red label .'.. 2 006. A eee 11 Kirschten Extra rapid yellow label ,........ 2.3 14.5 Karschten Extra ‘rapid'antihal, ........'.45.4. 73 14.5 Kirschten Extra rapid orthochrom °..'. 3270, age 14.5 Rossenten, Ultra Rapid)... 0 soci. eee ts ee Kraco Eootra ‘tapid |). 3); os... ec} ae es ee 15.5 WOGACG) OLED ae 68 ee ald os dab see 2 Re 155 Kraco oreo antihal ss) 2.) seis oils le io b's Ce ee 12.5 Kranseder Reform (i) oes cee oe eed se ale 12 Kranseder ortho. moment. .3. 00... ee 155 Kranseder ortho. slow :. 4.66). boos ee os ok ee 10.5 Kranseder Bromsilber extra rapid)... ... 5:42 Nseee 17.5 Kranseder Bromsilber antihal 0. ......2s. 2ceee eee 11.5 Kranseder Bromsilber extra.rich :.......... (25 15.5 icanseder’ Imperial (000000). OO ee 18.5 iKranseder MunchenerAerial.’,\.): 3) 05.2 seo 16 Weonar) Green! label ya hs ee 12.5 Memmar ASOT es oe bb eek ia ole Ra a ie el 9.5 Peeanar nen. labels.) 2 eee ne Oe 14 Meanar ortho, & antihal 23), sas cin eae ele Gave 12.5 . WELL oOo CO aM ONAN DO MPESER MRNA EA 15.5 EXPOSURE 65 EE DOGO ATE soi a oy) oi 5c olntetanatal ates Mista lelteyoen 14. RE ET ACEADIO A eA iet ek ahd 17 Met OLEMOtOM Sc amtilaa ls 66/5) elie Gisteeeaiaein eats ee 155 SPER IOLENO: ANE) ANEIMAL! ee cc 2)g So Miran aides ween eis toh a 12.5 ee RENE CAA Naan ee A RS ASUS RCIA Ua ERA 12:5 repre y NER ie te aii oS EU 0a MN A 17 ieomibers: Elochrom i005... 0... 00ers oe Laer eat, 14 Memmens Mlochrom antihal. ol. 0 ele a 12,5 Wmanene xtra rapid Lea. 6 5 oy ee ey uroruiaa te maleate 1.5 ombers andscape & Repro. oi.) aa esos: 9.5 Menntnecoeleinait oc. Ll NS ey aie 8 Ny Byes TESS jo ieiph 99 05 (4 Uh AVM Rae MPa URIS IN oie MHL IAL a Sy 17 Piece SEUSIEIVE 0 4. Uk Sail Me 15:5 Meter VOMbHO ey anitinal so ce eet 14.5 Peter Onbnonextha rapid 05.40) vid tisayinein we aia 17 Heiman Me ae oe eA UR IE RAN 15.5 PMO SAVvORPMOV cc atatinal s/o eo ae Vay ale 14 MAUR MAT LETT VSP GS ccs els cloak yl aaah a Gna aU een ES aay 15.5 emmeosanvecllow Mabel. acai OUST vat lane 12.5 RPMIIne SOTA ane ee te UN ee an ie UE a 17 Monty OSA 1) ie ys) Ailes oo anal io ish oh alia Al ailad VHotaaP eA Au IZA MeO nCOule COATER ee csi algs es Meals Cn le Race One £5:5 PE Merato ERAT A PEG 1 ei 8 as es al SLU a ae NA UG 17 Pete PUETA TAL oie ie a is C8 cia) ee Nar ae 11 Mima ntaa atin ii eG AO ee 12.5 Lu Ss0) TET Rers 70) A Mia en a aR AD NSN EO Sub ANA 14 AM uESAO NG ACN AS a SL Mee AU pace RCSL) CN 18.5 pec Niesativel Paper s/o)... 5.2 ae Bea 10 Te Sie" VEST CE OU OAM GL NASA ReaaS Mpg RMAC CAVA TT 14 eR EA Ss TOMISHDeI HN 2) Siclu taht in arehe ana ean tC) 15:5 eRe erOtON TEC A yuu Oa UA 14 CREE CHOU STCCE C00 ig t1 4a tio oie One Mia Nie 15.5 PeCIMEZ SCE SETISON (se) r a sg yu are, w'cjela oe ME NCC Ue 17 66 PHOTOGRAPHIC FACTS AND FORMULAS Reruts Perscanto 6 Oke ae OO eee 14 Pecutz Silver, coside )0..4 22 2 Ue ce een a keke eae 125 Rene tin packs... 5 Gals bee Re eae 14 remo fiimipack Speed) ie ok vei ve 15.5 Baers loxtra irapids .40 yee Ue SR Ok eM ace ee 155 Seems Color iiss kate hk keke aie e ce en 14 Sachs Antihalation 220005)... ce C ee es ee 12.5 Bachs /Antihalation ‘Color i)iuii40 fy isis cee ee 11 Senlenssner’ Blue label 2...) 6 0.4.05) eee 17 Schleussner' Yellow label 20.0 00.00.05. ize Schleussner Yellow label Instantaneous ............ 17 Selleussner Inialos.)..0/. sss aie se os neler 15.5 Scehleussner ‘Orthochrom \. ....)..06.. oe 15:5 Schleussner Red label .. 2)... 03:0... sias =o» el 18.5 Sehleussner Viridin’)..'..)..)00 Jc. i er 17 Schleussner A inalo so. .6 ssa. ea ee 17 Spock Mxtrarapid) tis oe eee a 17 Siock, Orda yy) te kiss sua we elle os 14 Pathot Errtee Special rapid 's.2.0... 503 2 16.5 Talbot Prrtee ‘Ortho :& antihal 2.0...) 5. 15 Talbot 'Errtee Extra sensitive .. 2 ......%.2snn eee 16.5 Palbot Errtee, Ultra, rapid... oi... nasa ale eee 20.5 Unger & Hoffmann ‘Verax normal...) 4040 eee i7. Wnger & Hoffman Kromal) oo. 0403 17 Waeer &/Hottman Verax rapid) ince SMa Angi 38° 20 Unger; & Hoffman’ Verax' rapid with Star. ).0a. ee 20.5 Unger & Hoffmann Verax’ Bromide’)... 0.y sak ee 18 Wager & Hotimann’ Verax)Isokromid:s 0.1.0) Soe 18 Wager & Hoffmann Verax ‘Vransparency ') 2.7 seme 7 Nyecstendorp:.& ‘Webner Reds e 2G 18.5 Westendorp & Wehner (Greeniiu i003. fii ee 14 Westendorp) & Wehner Color 123.00 0040084) ee 17 EXPOSURE 67 “ic cHDURCOT2 TBD ete aa 0 6 Un Re DU 18 a I A 14 Pramiet Color: antihalo is.) ie ae alee! lst ove) a oh 14 Penmmortae antinalo. sy). cs Ui acanye aie Gee eels cls 255 “hs IDIRYOVE MOU Rez Ata SS eRe SSE V8) 113 0h AA Ab Ace 20 BROMIDE PAPER SPEEDS (BURROUGHS-WELLCOME ) .— EMSS EAT (ers a etal oes oa A) ae eh necd + Pameitioecarlh CrayOn: isu sd scoala ole: ~ Barnet Ordinary, Platino-matt, Cream Crayon ...... ly reg eeM hier MONSUCL: in). cfs a aa) Ge ee Z pemeeeT CEM NEL OMA Hy Ay ils shoe) a vol ester gel Tere ee eee 6 SERNCE MeN CMON Vii sole. eae Se ee i ae 6 “so TERI NUS LEN ONG LI a a TN een aS CAN 6 Pree OT CITMAL Yi yc). cae, s/o. cs cia: aden stevie ol ve) ollevetis ole; reves 12 Memecmren tattoo hye sh eh ne 2 Macedon) i latino-matt, Rough’ . 3025) .shad 6 ecomlal nST ON Ne ds a OY Geb ae ee eae 48 Rae Ey OTTER so) 6 5). s) 5 ale ds ey Gah eater en oe 2 Be at He io ale ie ON a Mae ee 10 ETDS IN Ose 00) eS Apa ee em parece sy ee ey AS oa ee Wl 1 PEereT CTV OROUS or oie c oleh oie iss os ana + DP ETOSE TERE AU ee a ninU suena D rennin celts he KE 010) 24 eatgt REL IME ete M cee Ooh ala) J05 sas oo cha hit sR ara 2 Bonds (all varieties, except as. below) ...../...... 5: 3 Mnowamncapic: Contrasty oe ea a Gale we ee Z Weer OGCIMary “OUTIACE 1) 3... 6.55 ceive ney awe 6 2s ETE ROOE LDN EA a MRO na Sn Aart Fda 2 Mimpemalrrlatino-miatt’ 06). oc bs oe ae one ee 1 EG oniardetiet OG GINA 2/5) 6) 0s eas oo Us Se 1 CETTE TAG ee ieee ee Rene Re UR i) SNAG nL 2 a AN eH aa eo nny a 16 2 SSRUTT EIS TEC CNA ee REO MOIR pnt SINE) Cag 64 Mora Cove ee AV as 6 yay he ee eA ly Kodak Rapid (Platino-matt, Permanent) ........... ly 68 PHOTOGRAPHIC FACTS AND FORMULAS Kodak Contrast (Platino-matt, Permanent) ........ 4 Veli ei raivey 0s, ALAA ELEANOR SOMA NPA SHALL) 2) 6 Salk | Nalco), Velvet iii Ue SON yeni 3 Beiter) 03) a 24 [SC cals) SW ee RM LION GOORIN AC yf) Ty 3 BO OSES VALEZAS). ci) 53s +) sje ip eleyoip ce Meena ee eee 24 Maryavaite, Normal |. oc ied eck alesis ae eens ake ane ee 8 Pyrite: Rapid ii). sieeve. Rai at ee oe ly, Simeieres A COR De oi NC ee 5 Pierre, Be bee ee CGN Git eek ets ence ene nee 2 RO ee ee ae ee eee ee a ata Noll tele ia er 6 AVEO CP Eelam Uae ea iui aia la Sade ee 2 PB Nessie eich ae i vss ita ib Lee ae iy Lo 1y% ah EE) OE ae AME ERO MNUAAUM RINDI AUR iy COC 6 BAPTA ei SN a Al lea alia tat pl tghie ada aati et err 6 Standard Bromide & P. Mui C.ii.\u 00.60. na 2 Wellanotom i 22 lial lee bale aes eee 1% Wellington BiB viiieleek Wik Ue bie Hess Ss oie eae 6 SASIAIAE PraEr St ci a)sh a Wa On! NN approximately 64 LANTERN PLATES.— PSOE a ae Oe ON 15 Barn eE ee 0 hal er 6 Cramer: Lantern, Transparency |.\0 24a 0 ee 3 HEARN oie he Ee ee ie ee Rie lee eat 6 Bae se Ca WON ON 12 Reta Flach se in a ae te We NAM eS 28 a 10 tamamer, Yellow label oo eee Cee Oe ane coe 3 farmer, VW ite label) 202i Pee WV ee 2 Moone (Special 2 Uo eS Os 5 Peerial Special one Ae BAR oo Re + Raapertan) DIO Woe oa a 8 Da alec see aie le ie mie ee eee ee ie ole 8 MG a UA a oe Ok aC MRR MERC STR 6 EXPOSURE 69 wemrene lransparency, Black iy Wie vislec hess o\6 aa) « 8 LATE CUNY CL oa IE A enn eT SUT i RN Mia uta 25 PPT PA SEY MUNIN a) dal fis ooh 4 Alb Ai aie tamara a eT VeRaNeN sta aE ablsia tego 10 Pinion (Chloro-bromide. oo iy ea eas an = Perret Vic CG he Sk SAM te vd LIA 32 Merion Gelatine-chioride |... 012 COMM a UAT al ol 32 WARS OTA oh ial 4) aay ee edat Sie i ck Gla S ROMAN a NREL SIMS NY Nat UU 0 Vale = Rete ENACT eS By UA ly Pasay (SI Let sane OMT CH An SN OM WW Beet WOOK WU ransparency . 1.) dies espe ees 3 IPSEC CURIA NGS ae Ae SAMAR Suh Ue CoS OEY Ie 10 oval otandand black ie oy Oe a ue nN ais em) el ie 8 SSO SANA EE SmI STOO RU Aa NS ATAU Aa 3 SiZinCley ec Resa beh ills MUR en aN USMS atu 3 SAMOA G COMO GN CL oho ICS ut eT a Ae oe 4 EPMO a iy Lk aL GS TAU eT Ani A 1 Be eter eM en eS ACN ga LU AUS RE UE i 20 In these tables the paper or plate with a factor number of 6 requires twice the exposure of one with a factor of 3, under like conditions. COMPARISON OF PLATE SPEEDS.—Unfortunately, no com- mon agreement has been arrived at as to the marking of plate speeds, but the following table gives the usually accepted ratios between the various systems: wa 5 “4 i ea ow Hal E 2 fa E a Be pa 5.4 8 17 8 8 c me 100 7, 10 20 Hae 9 b 80 9 SNe, 6 ONS cau vA OTN 65 11 LOLS 25-5 4 10 ] 43 50 14 Bi) 20 10.50 (20 ae ag 17:5 26 32 3 ot 3 49 30 70 PHOTOGRAPHIC FACTS AND FORMULAS f Se hide Se ei E B Ao ar 20 34 OF, 2 12 4 Be 23 28 42 40 t3 5 54 17 38 2). AR) a a a ees 14 45 66 52 1 15 7 60 11 56 82 58 2/3 16 8 63 9 70 103 64 Hs 17 9 66 Zz 88 130 72 y, 18 10 69 55 105 154 79 anh 19 a 42 4 140 206 90 73 20 ‘7 15 3. 5 257, 100 Y% fA 13 78 2.6 228 300 115 al 22 14 80 2 280 410 128 1/6 23 15 84 1.6 350 575 144 1/8 24 16 88 1.3 455 670 164 War 25 17 92 1 560 825 ISO) hf 12 26 18 95 8 700 1030 204 ae 27 19 98 6 875 1280 228 ae 28 20 100 5 To convert Hurter & Driffield into the Watkins system: Multiply the H. & D. numbers by 50 and divide by 34. To convert Wynne into Watkins: Multiply the square root of Watkins numbers by 6.4. To convert Wynne into H.& D.: Multiply the square root of Wynne’s numbers by 7.7. This table gives an approximation of the connection be- tween the various systems of determining plate speeds. But absolute reliance can not be placed upon it as there is no standard system and plate manufacturers differ as to their use of the Hurter & Driffield (H. & D.) method, therefore, these speeds, as advertised by various makers, are not comparable. EXPOSURE 71 It should be recognized that the figures given are for use with particular exposure systems and will yield good well- exposed negatives. The character of the same may not agree with individual opinions, and in this case higher or lower numbers should be used until with a given developer the desired character of negative is obtained. All plates have more or less latitude and, therefore, considerable variation in exposure may be given and good negatives be still obtained. EFFECT OF THE STOP APERTURE.—The relative exposures are as the squares of the aperture of the stops or diaphragms. For instance, if the exposure with stop f:8 is 5 seconds, with f: 16 it is not twice as much, but 4 times; because, according to the above rule, 8° — 64 and 16° — 256. Therefore, the exposures are as 64:256, or as 1:4. This applies to all lenses irrespective of their focal lengths. VARIATION OF F VALuES.—When copying and enlarging, the lens is not working at its equivalent focus, the actual working focus being more or less increased; therefore the values of the stops are altered. Mr. Alfred Watkins gives the following table which shows the necessary variation of the exposure due to the alteration of the f value of the stop: Lantern slide making Thin Neg. Medium Dense Neg. Neg. Copying Black and Photograph Coloured White Object 15 times focus from lens 4 y, 1 i H 1M ee ati. ¥ Vay VA SUA f: CRihhtae yy 1 2 eK, I au 2% “* i tetas 4 ly 3 Bi oa Aru 1 Zz 4 (Copying same size) 72 PHOTOGRAPHIC FACTS AND FORMULAS The numbers in the table are multipliers of the calculated exposure. VARIATION OF ENLARGING EXPOSURES FROM THEORETI- cAL.—Mr. Watkins also gives the table for enlarging: Enlarging Diameters Thin Neg. Medium Neg. Dense Neg. Equal size 1 os a ly, ly 3 6 2 2 44 o 2% gS 6 12 3 4 8 16 + 6% 12yY% 25 y 9 18 36 These numbers are multipliers, as in the last table. The numbers of diameters of enlargement are found by dividing the length of one side of the enlargement by the length of the same side of the negative. THe EFrrect oF ALTITUDE ON ExposuRE.—Variations in exposure due to variations in altitude, or distance above sea level, are negligible in ordinary work, that is to say, unless the altitude exceeds 5000 ft., when three-quarters of the cal- culated exposure should be given. Over 10,000 ft., half the regular time would be sufficient. This is for near objects. Panoramic views from mountain tops require panchromatic plates and special filters to cut out haze, as in aerial exposures. SHUTTER SPEEDS FoR Movinec Opjects.—The following are approximately the slowest speeds of the shutter which will give a sharp image. The object is assumed to be 25 feet distant from the lens and to move diagonally across the field of the lens: eople walking ini streetiseenesi isi Sisal cajewn 1/10 sec. Animals and people walking slowly ............ LAL People walking three miles per hour ........... 1/50) \* EXPOSURE 73 meeple walkine four miles per hour) )4/20 2.2). LA LOO 3: Mebicles/at eight miles per howe yyy. nee Ufa tis) Ovi Preineles at tenjnatles per Hour) ie) P2005, Remicles atitwelve miles per hour sinensis). L250) 05 Bicycle and horse races ....... Se De eR CUAL 1/500) .5, LE Gioky lini lrken Ns A OE NE HI OA L/600));; matomopile and fast horse races. 3652990 ove P/TOOO If the object is at 50 feet distance, twice the exposure can be given; at 100 feet, four times as much. The longer the focus of the lens the shorter must be the exposure, and the more nearly the object moves at right angles to the axis of the lens, the shorter the exposure. EXPOSURES FOR INTERIORS.—Cover the camera and head with the focussing cloth, and wait until the eyes are accus- tomed to the dull light. Stop down until detail can barely be seen in the deepest shadow in which full detail is required. Note the stop, and consult the following table for the ex- posure at f: 16 of a plate or film classed as 1% A. P.: Stop noted Exposure at f: 16 ace 56 minutes ifavalk 28 minutes ale 14 minutes eee 7 minutes eo 314 minutes ~f:45 134 minutes f : 64 52 seconds For other stops or plates, calculate from the known speeds, remembering that each step in plate speed represents 50 per cent, whereas each listed stop represents 100 per cent varia- tion. NicHtT PHoTocraPpHY.—Exposure suggested for trial at f:8 with ortho plates of speed 1% A. P.: ited Sao wi Widows) \\.).)3)2\5 4/5 Wisi) ee ants 1 minute 74. PHOTOGRAPHIC FACTS AND FORMULAS Phemenerbed sot dames | eo) age da aii le eles eins eine 2 minutes Ooen streets with arc lamps! -y agai 3 minutes Open streets with wet roadway or snow ....... 2 minutes REIGSE) SUNCEE SCENES |) 2) ay/s 4500) 4: 0le lanes Re A a 6 minutes Close street with wet roadway or snow ........ 4 minutes Stop APERTURE SYSTEMS.—Various systems have been suggested from time to time for numbering the diaphragms or stops, but practically only two have survived. In the one, and the more general, the F or ratio system, the effective aperture is expressed as a fraction of the equivalent focus, thus as F: 8, F/8 or f: 8, which means that the aperture of the stop is one eighth of the equivalent focus. The other system is based on f:4 as unity, and the stops are merely numbered in fractions and multiples of this. The following table shows the relation of the two systems, the latter being known as the U. S. system, or the Uniform System numbers: D.S.Ne:, U.S. Net gee 1/16 iin ° f:1.414 i F216 16 Rie 4 f222.02 32 f:2.828 yy, f:28 49 fe 0.562 fise 64 f:4 1 reno) 81 eA 1.56 f:40 100 Fo.000 2 f:45.25 has 726 2.25 F256 196 Ror 3.06 f :64 256 Ate: 4 fire 306.25 Fey 5.06 f :80 400 enles, 6.25 f:90.5 512 “ee 8 f:100 625 Stolze proposed f:10 as unit, and Dallmeyer (s35)- The Paris Congress also adopted f: 10 as the unit. Zeiss adopted EXPOSURE 75 f: 100 as unity, so that the larger stops were marked with the relative luminosity, which gave as a fraction the relative exposures; for instance, f:6.3 was 256, and the exposure compared to that for f:100 was 1/256. All these systems have practically fallen into disuse in England and America, the ratio system alone being used. Exposure Meters.—The Watkins, Wynne, Imperial, and Beck meters are based on the measurement of the actinic power of the light by the darkening of a sensitive paper to a standard tint. Scales bearing the f: x value of the diaphragm and speed of the plate are brought into coincidence, and the exposure is then read off against the time taken by the paper to darken. | These meters should be exposed to the light falling upon the shadiest part of the subject in which full detail is re- quired. If there is no important shadow, test the direct sun- light. If there is any important shadow, face the meter to the sky and not to the sun, or use the shadow of the body. To judge the matching of the tint, hold the meter at arm’s length and observe through half-closed eyes, and note the time when the paper is neither lighter nor darker than the tint. An absolute match is not required. MAKING PAPER FoR ExposurE METERS.—In order to make a paper suitable for these meters, bromide paper should be immersed in the darkroom for 5 minutes in a 2.5 to 5 per cent solution of potassium metabisulphite or sodium nitrite, rinsed and dried. The tint caused by the action of light varies with the paper ; but a test should be made by burning 2 grains of magnesium ribbon, coiled into a spiral, at a distance of 434 inches. The tint thus obtained will correspond to the correct exposure for a plate of Watkins’ speed 1 exposed at f: 8, midday in June sunlight. The colour should be matched with water colour. Development | FacTorIAL DEVELOPMENT (Watkins).—There is practi- cally a fixed relation between the time of appearance of the image and the total time of development to obtain a given density, degree of contrast, or gamma of a negative, which holds good for all variations of strength, amount of alkali, bromide, or temperature, within reasonable limits. This 1s known as the factorial or time development method. The total time of development divided by the “time of appearance” of the first signs of the image, exclusive of the sky in lands- scape work, or a white collar in a portrait, gives what is known as the “factor” of the developer. The following table gives the factors for various developers for a normal neg- ative : Adurol 5 Kodak portrait 18 Amidol 10 Metol 30 Azol 30 Metol-hydrochinon 14 Certinal 30 Ortol 10 Diogen 12 Paramidophenol 16 Edinol 20 Pyrocatechin 10 Eikonogen 9 Pyro-metol , Glycin-potash 12 Metoquinone 30 Glycin-soda 8 Rodinal 30 Hydrochinon with bromide 5 Synthol 30 Imogen-sulphite 6 The following are the factors for pyro-soda or pyro- potash: 76 DEVELOPMENT 7/7 Pyro Bromide Factor Pyro Bromide Factor gr. peroz. gr. vi OZ. 9 gr. per oz. 0 18 2 y 5) 2 0 12 3 % 4¥ 3 0 10 4 1 4 4 0 8 8 2 3% 5 0 6Y% Estimated factors for American pyro-soda developers: Seed A. B. C., no bromide 11 Seed pyro, no bromide 11 Stanley, no bromide 10 Cramer, maximum strength 6% Cramer, minimum strength 11 Hammer, no bromide 11 Eastman, no bromide b2 Should the negatives obtained by the use of the above factors seem too thin, the factors must be increased; if the negatives are too dense, the factors should be decreased. The factor for a combined developer with the reducing agents in equal ratios is the mean of the two; for instance: (Pyro = 6+ metol = 30) —2=— 18 If the developing agents are in different ratios, the factor for each is multiplied by the number of parts, and the sum of the factors divided by the number of parts of developer agents used. For instance, pyro 4 parts plus metol 2 parts: 64 — 24 and\30) <2 —— G0 24+ 60—84and 4+2=— 6 then 84 — 6 = 14 the factor required. THERMO-DEVELOPMENT (Watkins)—While the normal temperature for development is assumed to be 18° C. (65° F.), it is not always convenient or possible to obtain this temperature exactly, and, as the rapidity of development is increased with a rise of temperature, and decreased with a colder solution, allowance must be made for the change of 78 PHOTOGRAPHIC FACTS AND FORMULAS temperature. The variation in time of development due to changes in temperature of the solutions is known as the “tem- perature co-efficient,” and is calculated for 10° C. (18° F.). In practice it will be found convenient to draw up a table for a developer for every 2 degrees rise or fall, which is not a difficult matter, as one can use the developer factor and a table of logarithms. Expose a plate on a landscape, including a portion of the sky, and cut into two, or make two exposures. It is necessary to have means for warming up the dish, devel- oper and graduate, and also a thermometer must be handy. The warming apparatus need be nothing elaborate, a deep baking tin or a large developing dish. Fill this with water at about 32° C. (90° F.), and place the dish, graduate and developer in it. As soon as the developer has reached the desired temperature, which for convenience may be 24° C. (75° F.), and should not be above 27° C. (80° F.), place the plate in the dish, flood with the developer, and note the time; watch carefully for the first appearance of the image, and again note the time. The plate is no longer any use and may be thrown away. It is really advisable to place the plate in the dish at the same time as this is floated on the warm water, so that the plate itself may be raised in temperature. It can be easily covered with an opaque card to protect it from light. Then treat the second plate in the same way, only this time use the developer cold, and note the time of appear- ance exactly as before. If the difference in the temperatures of the two developers is exactly 10° C., the temperature co- efficient is found at once by subtracting the logarithm of the lesser time of appearance from the logarithm of the greater — time. Should there be a greater or less difference in the temperatures than 10 degrees, subtract the logarithm of the lesser time from that of the greater time, and divide by the difference of temperatures. The result will be the log. factor DEVELOPMENT 79 by which a table can be drawn up for the developer used. An example will make this clear. Suppose that we have a developer which we know from practical trial gives just the negative which we want with a factor of 10. Suppose that we make the above-described trial with a developer at 90° C. (48° F.) and 20° C. (68° F.), and with the lower tempera- ture it took 50 seconds for the first appearance of the image, and at the higher temperature 22 seconds; then from a table of logarithms we find that the log. of 50 is 1.699 and that for 22 is 1.342, then: log. 50 = 1.699 logs 22 — 1342 0.357 Now the difference between the two temperatures was 20 —9 = 11, therefore 0.357 — 11 — 0.0324, which is the logarithm of the difference in time of development for 1° C. or the log. factor. As we know that the developer has a factor of 10, therefore, if the time of appearance at 9° C. was 50 seconds, the total time of development will be 50 * 10 = 500 seconds. Then, if we want to find the time of develop- ment for 10° C., we subtract the log. factor 0.0324 from the log. of 50, and multiply by the factor to find the correct time of development. Thus log. of 50 = 1.699 — 0.0324 — 1.6666; from a table of logs. we find that this is the log. of 46.4, and, multiplying by the factor 10, we have 464 seconds as the result, instead of 500 at 9 degrees. If the temperature is lower, then we add the log. factor; thus, assuming that the temperature has dropped 2 degrees to 7° C., then log. 50 = 1.699 + (0.0324 & 2) = 1.699 + 0.0688 = 1.7638; from our table we find this to be the log. of 58.05, and again, using our factor, we have 58.05 & 10 — 580.5 seconds as the correct duration of development at the lower temperature. The 80 PHOTOGRAPHIC FACTS AND FORMULAS following are a few temperature co-efficients that have been determined (Watkins) : Pyro-soda, without bromide (Watkins) 1.5 Pyro-soda, with bromide (Watkins) 1.9 Pyro-soda (H. & D.) without bromide 1.48 Pyro-soda, Kodak powders .......... 12 Pyro-soda tabloid (B. & W.) ........ 245 Pyro-soda tabloid, ford formula .... 2.04 Rodinal, Azol, Victol, Certinal ....... 1.9 Metol-hydrochinion) .).05 6.) ieee aides 19 Metol-hydrochinon tabloid ........... 1.86 C5 [fest o RARER HO MOTTE PEE MTSE 8 rN 12705) OMEN ORD MAME DU EATING 1 8 1.84 EAC MRONT, 1 /2S010 Cho tae La a Una a 2.20 Paramidaphenol 3) inl Cue ss eieiaua eae 2.4 aU GV (8 6, DUAR O Ra ADHERE a ALO AOR) 2.06 Fg 5) (A RTI re DMI SRN EG 2.06 STAND DEVELOPMENT.—This is a method of development in which a dilute developer is used in an upright grooved tank, in which the plates are placed and left for a given time. In the early days, it was put forward as a cure for every error in exposure, and the solutions used were so dilute that from 12 to 24 hours were required to obtain normal negatives. The only advantages of stand development are that the grain of the negatives is fine and the results uniform, if the devel- oper be frequently agitated, and no visual examination is re- quired or possible. It has been stated that the duration of development with the diluted solutions can be calculated from their dilution, that is to say, a developer that is diluted 5 times will require 5 times as long in the tank, but this is only true of one or two developers. Wratten & Wainwright found by careful photometric measurements, that the increase in time depends to a great extent on the quantity of air dissolved in DEVELOPMENT 81 the water used. In the case of rodinal it was found that a plate which required 3 minutes development with a 1:20 solution, when the latter was diluted to 1: 200, did not require 30 minutes, but 42, with air-free distilled water; with ordi- nary distilled water 46 minutes, and with tap water 52 min- utes. Pyro-soda and glycin seem to be the only developers that are not affected by the water, but a pyro developer diluted ten times requires fifteen times normal to obtain the same results. Stand development is not economical, as most ~ commercial tanks require a large amount of solution, which is, as a rule, so oxidised at the end of development as to be useless for a second time. The following are some of the developers recommended for this method. Pyro-soda (Wratten & Wainwright) — A. Sodium sulphite, dry 5) 3 oz. Pyrogallol 1.66 g 1 oz. Sulphuric acid 0.21 ccm 1 dr. Water 1000 ccm 600 oz. B. Sodium carbonate, cryst. 10g 6 oz. Water 1000 ccm 600 oz. Mix in equal parts. Glycin (Wratten & Wainwright ).— Glycin 0.833 g Y, oz. Sodium sulphite, dry 125\2 34 OZ. Potassium carbonate 4.16 ¢ 2Y4 oz. Water 1000 ccm 600 oz. Glycin (Bothamley) — Glycin 3¢g 46 gr. Sodium sulphite, dry js) 23 gr. Water 2000 ccm 70 oz. Time 1 hour at 18° C. (65° F.). 82 PHOTOGRAPHIC FACTS AND FORMULAS Pyrocatechin (Bothamley).— A. Pyrocatechin 10g Sodium sulphite, dry 40 ¢ Water 500 ccm B. Sodium carbonate, cryst. 100 g Water 500 ccm Time, 1 hour at' 18°C, (65°) F:). Pyro-soda (Claudy).— Sodium sulphite 3.9¢ Sodium carbonate 2.6¢ Pyro 13g Water 1000 ccm Pyro-soda (Harris).— Pyro lg Sodium sulphite, dry 3g Sodium carbonate, cryst. 12 ¢ Potassium metabisulphite 6.5 ¢ Water 1000 ccm Time, 10 to 15 minutes at 16° C. (60° F.). Pyro-soda (Munkman).— A. Pyro 100 g Potassium metabisulphite 25g Water 1000 ccm B. Sodium sulphite, dry 100 g Sodium carbonate, cryst. 100 g Water 2000 ccm For use, mix 1 part A, 1 part B and 8 parts water. Time: 25 minutes at 18° to 21° C. (65° to 70° F.); 30 minutes at 15° to 18°. C. (60° to 65° F.) ; 40 minutes at 13; toto (55° to 60° F.) ; 50 minutes at 10° to 13° C. (50° toga Bae If the developer be used at half the above strength, the times will be: 50 minutes, 1 hour, 80 minutes, and 100 minutes respectively for the above temperatures. 154 er. 616 gr. 174 oz. 3% oz. 174 oz. 90 gr. 60 er. 30 gr. 48 oz. 20 gr. 60 gr. 240 er. 130 gr. 40 oz. 1 oz. Y4 oz. 10 oz. 1 oz. 1 oz. 20 oz. DEVELOPMENT 83 Rodinal (Munkman).—Dilution 1:100. Sodium sulphite, dry, in 244 per cent solution may be used instead of water to dilute the developer : Temperature Development in minutes Cent. Fahr. Portrait Architecture Landscape 22; Apa 14 194 27% 21 TO ic 15 20% 28 2/3 20 68 Ate 21y4 30 19 66 17 22% alit/3 18 64 18 23% 5212/3 17 62 19 244 34 15:5 60 20 25% S5nh/3 14.5 58 21 26% 36 2/3 13:5 56 22 274 38 2S 54 Zo 28% 39 1/3 Metol-glycin (Jeffcott).— Metol 0.88 g 40 er. Glycin 0.44 g 20 gr. Sodium sulphite, dry 16¢g 75 gr. Potassium carbonate 6.52 300 gr. Hot water 1000 ccm 96 oz. Adurol (Mortimer ).— Sodium sulphite, dry 200 g 4 oz. Potassium carbonate 300 g 6 oz. Water 1000 ccm 20 oz. When dissolved add: Adurol 50 g 1 oz. Dilute 1:20; time, 10 minutes at 18° C. (65° F.). Edinol.— Edinol 45¢ 45 gr. Sodium sulphite, dry 2a 4 oz. Potassium carbonate 44¢ 1 oz. ‘Water 1000 ccm 20 oz. 84 PHOTOGRAPHIC FACTS AND FORMULAS Edinol-H ydrochinon.— Edinol Hydrochinon Sodium sulphite, dry Potassium carbonate Sodium carbonate, cryst. Caustic soda Potassium bromide Water 1000 ccm Pyro for lantern slides (Mortumer ).— Pyrogallol Sodium sulphite, dry Sulphuric acid Acetone Water Ze 3.25 g 0.5 ccm b:2 ccm 1000 ccm Time, 5 to 10 minutes at 18° C. (65° F.). Amuidol (Harris).— Sodium sulphite, dry Potassium metabisulphite Potassium bromide Amidol Water Amidol Sodium sulphite, dry Caustic soda lye, 27% Potassium bromide Water Time, 2 to 3 hours. Glycin.— Glycin Sodium sulphite, dry Potassium carbonate 13g 5.2¢ 0.52 g 2.6¢ 1000 ccm O0.5¢ 76 gr. 76 gr. 1842 gr. 307 gr. 307 gr. 61 gr. 15 gr. 32 OZ: 44 er. 66 gr. 10 min. 24 min. 42 oz. 250 er. 100 gr. 10 gr. 50 gr. 40 oz. 15 gr. 90 gr. 145 min. 75 ee. 32 oz. 30.7 gr. 76.8 gr. 153.8 gr. DEVELOPMENT 85 Potassium bromide 0.05 g 0.768 gr. Water 1000 ccm 32 oz. CoMBINED DEVELOPING AND Frx1nc.—This process fre- quently crops up and numerous formulas have been given for its use. The following are arranged in chronological order and the later ones do give some sort of satisfactory negatives. Punnett.— A. Potassium metabisulphite 2¢ 35 28: Ortol 32g 5215 en) Water | 400 ccm 10 oz. B. Caustic soda 4g 60 gr. Potassium bromide 4¢ 60 gr. Water 500 ccm 16 oz. C. Hypo 25¢g 1 oz. Water 500 ccm 20 oz. For use mix 1 part A, 1 part B, and 2 parts water. Hanneke.— A. Sodium sulphite, dry 200 g 1536 gr. Caustic potash 93 g /14 gr. Pyrocatechin 93 g 714 gr. Water 1000 cem — 16 oz. B. Hypo 200 g 3/5 Oz: Water 1000 ccm 16 oz. For use mix 12 parts A, 20 parts B, and 30 parts water. Baker.— Hydrochinon Vhs) 124 5/5/28) Potassium metabisulphite I5 g {i5/er. Caustic potash 50 g 384 gr. Hypo 200 g 8) WAS) Od. Water 1000 ccm 16 oz. Or: Edinol : | Tea 57 Dian: 86 PHOTOGRAPHIC FACTS AND FORMULAS Sodium carbonate, cryst. 50 g Sodium sulphite, dry 25g Hypo 200 g Water 1000 ccm Or: Hypo 30 g Potassium metabisulphite 40 ¢g Sodium carbonate, cryst. 120 g Potassium bromide lg Water 1000 ccm Add 2 per cent edinol just before use. Pigg. — Pyrogallol 15¢ Amidol 15¢ Sodium sulphite, sat. sol. 240 ccm Sodium carbonate, sat. sol. 480 ccm Potassium cyanide, sat. sol. 240 ccm Crémier.— Amidol 10¢g Sodium sulphite, dry 50 g Hypo 125¢ Water 1000 ccm Raymond.— Hydrochinon 8g Metol 4¢ Sodium sulphite, dry 30 g Sodium carbonate, cryst. 80 g Hypo 6g Water 1000 ccm Crémier, for lantern slide work.— Sodium sulphite, dry I5¢ Hydrochinon 2.52 Caustic soda 15g 384 gr. 192 gr. 3 1/5iez: 16 oz. 230 gr. 307 gr. 920 gr. 7.7 gf. 16 oz. 11.5 gr. 11.5 gr. 4 oz. 8 oz. 4 oz. 77 gr. 384 gr. 2 oz. 16 oz. 61 gr. 30.7 gr. 230 gr. 614 gr. 46 gr. 16 oz. 115 gr. 19.2 gr. 115 or: DEVELOPMENT 87 Potassium bromide Se IS er. Water 1000 cem 16 oz. The actual developer is 4 parts of the above, 8 parts water, and 2% parts of 20 per cent solution of hypo. Haysede.— Sodium sulphite, dry 20 g 154 gr. Hypo 320 g 2457 gr. Sodium carbonate, cryst. 10¢ 77 gr. Potassium bromide — 10g 77 gr. Hydrochinon 25 ¢ 192 gr. Ammonia, 28% sol. 10 ccm 77 min. Water 1000 ccm 16 oz. E.W— Hydrochinon 12'5\¢ 96 gr. Sodium sulphite, dry 50 g 384 gr. Sodium carbonate, cryst. 100 g 770 gr. Hypo 200 g Sil/S.0z: Ammonia 50 ccm 384 min. Water 1000 ccm 16 oz. Otsuki & Sudzukit.— A. Metoquinone ) 6g 36 gr. Sodium sulphite, dry 30 g 180 gr. Water 600 ccm 12 oz. B. Hypo 60 g 576 gr. Caustic soda 5g 48 gr. Water 400 ccm 8 Oz. Mix in equal volumes just before use. Bunel.— Amidol 5g 38.5 gr. Sodium sulphite, dry 30 g 230 gr. Acetone 80 ccm 614 min. Hypo 50 g 385 gr. Water 1000 ccm 16 oz. 88 PHOTOGRAPHIC FACTS AND FORMULAS Namtas.— Metol Sodium sulphite, dry Hydrochinon Caustic soda Hypo Water 1000 ccm 11.5 gr. 230 gr. 34 gr. 38.5 gr. 460 gr. 16 oz. DEVELOPERS FOR DEEP TANKS FOR COMMERCIAL FINISH- ERS.—Eastman Kodak Tank A B C Pyro formulas: A. Sodium bisulphite Or potassium metabisulphite Pyrogallol Potassium bromide Water to B. Sodium sulphite, dry Water to C. Sodium carbonate, dry Water to 9g 9g 60 g lg 1000 ccm 105 ¢g 1000 ccm 75g 1000 ccm 140 gr. 140 gr. 2 oz. 16 gr. 32 oz. 3¥Y oz. 32 oz. 2Y4 oz. 32 oz. Take 5¥% oz. each of A, B and C and add water to make one gallon (162 ccm to make 3785 ccm). Time of development about 12 minutes at 65° F. (18° C.). Portrait Super Speed film requires about 10 to 15 per cent longer development than other film. Metol-Pyro tank developer: A. Sodium bisulphite Metol Pyrogallol Potassium bromide Water to B. Sodium sulphite, dry Water to C. Sodium carbonate, dry Water to 150 ¢ 1000 ccm 75g 1000 ccm Y oz. Y oz. 1 oz. 60 gr. 32 oz. 5 oz: 32 oz. 2Y4 oz. 32 OZ. DEVELOPMENT 89 Take 8 oz. each of A, B and C and add water to make one gallon (237 ccm to 3785 ccm). Time of development at 65° F. (18° C.) from 9 to 12 minutes. This developer can be repeatedly used if kept up to its normal strength. For strengthening use 2 oz. each of A, B and C to each 8 oz. of water (59 ccm to 237 ccm). Metol-Hydrochinon tank developer: Warm water | 4000 ccm 1 gal. Metol I2¢ 170 gr. Sodium sulphite, dry 360 g 12 oz. Sodium bisulphite Le V4 oz. Hydrochinon 2215/2; 34 Oz. Sodium carbonate, dry 45¢ 1YZ oz. Potassium bromide 6g 95 gr. Cold water to 16 liters 4 gal. Time of development at 65° F. (18° C.) from 10 to 14 minutes. Strengthening solution: Water 4000 ccm 1 gal. Metol 6g 85 er. Sodium sulphite, dry 180 g 6 oz. Sodium bisulphite SHS) ie 55.g8: Hydrochinon I2¢g 170 gr. Potassium bromide 2g 45 er. Water to 8000 ccm 2 gal. To give this stock solution greater keeping quality, the sodium carbonate should not be added until the strengthening solution is used. For use dissolve 14 oz. sodium carbonate in 16 oz. of the above solution (15 g in 473 ccm), and add to the tank Tank developer for Ansco Speedex roll film: Igal.tank 10-gal. tank A. Warm water SZ a2: 2 gal. Metol 22 gr. Y oz. 90 PHOTOGRAPHIC FACTS AND FORMULAS Sodium sulphite, dry 34 OZ. 74 02. Hydrochinon 90 gr. 2 OZ. Sodium bisulphite Y, oz. 5 oz. Potassium bromide 5 gr. 50 gr. Sodium carbonate, dry hiez. 10 oz. Cold water to 2 qt. OY, gal. B. Cold water 16 oz. YZ gal. Pyrogallol 45 ger. 1 oz. Add B to A and develop 15 to 20 minutes at 65° F., accord- ing to density desired. For each degree below 65° F., one minute should be added to the time of development chosen. For each degree above 65° F., one minute should be sub- tracted from the chosen development time, provided the bath is fairly fresh. Renewer : Water 32 oz. 2 gal. Metol 22 gr. 4 oz. Sodium sulphite, dry 2/5 oz. 4 oz. Hydrochinon 45 gr. 1 oz. Sodium bisulphite Y4 oz. 2Y4 02. Sodium carbonate, dry 2/5) az. 4 oz. The renewer is added from time to time to keep the developer even with the top of the tank and at the same time to freshen up the solution. A fresh bath should, however, be mixed up every two or three weeks at least, according to the number of rolls developed in the old solution. Developers Acrot.—The Eastman name for amidol, which see. ApuroL.—This is either bromhydrochinon (Schering) or chlorhydrochinon (Hauff), gives softer negatives than hydrochinon, and is less affected by temperature: A. Sodium sulphite, dry 125s 2 oz. Adurol 16.6 g 128 gr. Water 1000 ccm 16 oz. B. Sodium carbonate, cryst. 350 g 534 Oz. Water | 1000 ccm 16 oz. Mix 3 parts A with 2 parts B. A. Adurol 20 g 154 gr. Potassium metabisulphite 20 g 154 gr. Water 1000 ccm 16 oz. B. Caustic soda 75g 576 gr. Potassium bromide 2¢g 15 gr. Water 1000 ccm 16 oz. Mix in equal volumes. A. Adurol 20 g 154 gr. Sodium sulphite, dry 80 g 615 gr. Water 1000 ccm 16 oz. B. Potassium carbonate 125 ¢ Z'O2: Water 1000 ccm 16 oz. For studio and instantaneous work mix in equal volumes. For time exposures and landscape work mix equal volumes A, B, and water. AmipoLt.—A stable amidol developer (Namias) : Sodium sulphite, dry 215 192 gr. Amidol 5g 38 gr. Ot 92 PHOTOGRAPHIC FACTS AND FORMULAS Metol lg 7./ gr. Potassium bromide 2g 15.4 gr. Water 1000 ccm 16 oz. The metol exerts a protective action for the amidol. Desalme has suggested as a preservative stannous tartrate, which is made as follows: Stannous chloride 50 g 384 gr. Tartaric acid 70g 538 gr. Boiling water _ 350 ccm 5Y4 oz. To this add the following solution: Sodium carbonate, dry 55/5 422 gr. Warm water 300 ccm 5.02: Filter the mixture and make up to 1000 ccm (16 0z.). Make the amidol developer stock as follows: Amidol IS g 115 gr. Sodium sulphite, dry Ste 422 gr. Stannous tartrate, as above 100ccm 768 min. Water 1000 ccm 16 oz. For use dilute with 2 parts of water and add 3 per cent of sodium bisulphite lye. This stannous tartrate solution may also be successfully used with other developing agents. An- other method of making the stannous tartrate solution is as follows: Stannous chloride 10g 77 gr. Tartaric acid I5¢g 115 gr. Water 50 ccm 1 oz. And add: Sodium carbonate 25g 192 gr. Water 250 ccm 5 oz. Filter and make up the bulk to 1000 ccm (16 oz.). Glycollic and lactic acids have also been recommended as preservatives and act well: DEVELOPERS oS Sodium sulphite, dry 31.25 ¢ Y/ oz. Amidol 6:3) 2 48 gr. Potassium bromide 14g 10 gr. Glycollic acid 1.4 ccm 10 min. Water 1000 ccm 16 oz. Or: Sodium sulphite, dry 30 g 230 gr. Amidol Sig 38.5 gr. Lactic acid 5 ccm 40 min. Water 1000 ccm 16 oz. Alkaline amidol (Valenta). Sodium sulphite, dry I5¢g PS ox: Amidol 5g 38%4 gr. Caustic soda lg 7.7 gr. Water 1000 ccm 16 oz. This keeps quite clear during development and does not stain. Amidol is sold by the Eastman Kodak Co. under the name Acrol. Amupot-Pyro.—The following is recommended as having all the good properties of amidol and yet giving an image of the same colour as pyro: Potassium metabisulphite lg 8 gr. Sodium sulphite, dry 42¢ 336 gr. Amidol 5g AO er. Pyrogallol 28 16 gr. Potassium bromide lg 8 gr. Water 1000 ccm 16 oz. To this is added just before use: Caustic soda lg 8 gr. Water 1000 ccm 16 oz. This can be used for plates and papers without staining. The Watkins factor 1s 10. 94 PHOTOGRAPHIC FACTS AND FORMULAS | DiocEN.—Generally used in one solution: Sodium sulphite, dry 150 '¢ 2 02: 5/72 ee Diogen 75.¢ 102, 196 er: Potassium carbonate 375 g 6 oz. Water 1000 ccm 16 oz. Mix 1 part with 4 parts water. EDINOL.—One solution: Potassium metabisulphite 300g +40z., 384 gr. Water 500 ccm 8 oz. Dissolve and add: Edinol 100g _ 1oz., 318 gr. Then add: Caustic potash 220g 30z., 249 gr. Water 1000 ccm 16 oz. Mix 1 part with 10 to 20 parts water. One solution with carbonate: Sodium sulphite, dry 50 g 384 gr. Edinol 50 g 384 gr. Sodium carbonate, dry 2S 96 gr. Water 1000 ccm 16 oz. Mix 1 part with 5 to 10 parts water. The sodium carbonate may be replaced by potassium carbonate 15¢g (1l5gr.), when the developer acts more rapidly. Gives very clean negatives. Two solution: A. Edinol 10g 77 gr. Sodium sulphite, dry 100 g 770 gr. Water 1000 ccm 16 oz. B. Sodium carbonate, dry 5 per cent solution or Potassium carbonate 5 per cent solution Mix in equal volumes. The potash works more rapidly and gives denser negatives. DEVELOPERS 95 Stock solution for Hammer Plates: Sodium sulphite 125 ¢ 24 02. Edinol 10g 96 gr. Sodium carbonate 50 g hoz! Water 1000 ccm 20 oz. For use mix with an equal volume of water. EIKONOGEN.—-A slow acting soft developer: A. Sodium sulphite, dry 67 g 514 gr. Eikonogen 16.6 g 128 gr. Water 1000 ccm 16 oz. B. Sodium carbonate, dry 75g 576 gr. Water 1000 ccm 16 oz. Mix 3 parts A with 1 part B. A more rapid acting developer can be made by replacing the soda by an equivalent weight of potassium carbonate, namely 98 g (752 gr.). One solution: Sodium sulphite, dry 60 g 460 er. Potassium carbonate 50 g 384 gr. Eikonogen 30 g 230 gr. Boiling water 1000 ccm 16 oz. Keeps well. For use mix with an equal volume of water. ErLon.—Another name for Metol, under which heading the Eastman Elon formulas may be found. FERROUS OXALATE.—The use of this developer has been completely abandoned, mainly because plates are actually slower when developed with it than with the organic devel- opers, and also because of the deposition of calcium oxalate and basic iron salts in the gelatine film. On the other hand, it has the great advantage of giving an image composed of nothing but pure silver which is a neutral colour, that is, without selective absorption, and is, therefore, valuable in certain photochemical investigations. Ferrous oxalate is a yellow stable powder, insoluble in water, which can be pre- 96 PHOTOGRAPHIC FACTS AND FORMULAS pared by mixing ferrous sulphate with oxalic acid or a soluble oxalate, as follows: Ferrous sulphate 278 parts Water 500 parts Dissolve and add: Potassium oxalate, neutral 184 parts Water 500 parts Mix the two solutions, filter and wash the precipitate with four or five lots of distilled water, and dry. The result should be 180 parts of ferrous oxalate. Oxalic acid 126 parts may be used instead of the potassium salt. Ferrous oxalate is soluble in excess of neutral potassium oxalate, or other alkaline oxalate. It is obvious that the developer may be pre- pared in two ways: either by dissolving the dry salt in oxalate solution, or by adding ferrous sulphate solution to excess of an alkaline oxalate, when it will remain in solution. Potas- sium oxalate is used in preference to the corresponding ammonium and sodium oxalates, because it is more soluble. Consequently, it will dissolve more of the ferrous oxalate, which is the active agent in development. The strongest developer can be made as follows: Potassium oxalate 500 g 8 oz. Water 1000 ccm 16 oz. Boil and add: Ferrous oxalate, dry 100 g 1 3/5 oz. Allow to cool slightly and immediately bottle. This practi- cally forms a saturated solution of ferrous oxalate. This method is not so convenient as using separate solutions, for which the following stock solutions are required: A. Ferrous sulphate 330 g 5% oz. Water 1000 ccm 16 oz. Sulphuric acid l ccm 7 min. DEVELOPERS oF, The iron salt should preferably be pure, and, if covered at all with whitish or yellowish powder, a little excess should be allowed in weighing out. The crystals are to be placed in a flask, covered with water, well stirred, and the water poured off. Then the acid should be added to about three-fourths of the water, the salt dissolved, and the bulk made up with the remainder of the water. As this solution readily oxidises on exposure to the air, it is better to keep it in small bottles, and fill them right up to the cork: B. Potassium oxalate SIO 4. OZ. Hot water 1000 ccm 16 oz. For use add 1 part of A to 4 parts of B. The usual strength is 1:3, but this is apt to deposit the insoluble ferrous oxalate. If the order of mixing is reversed, the insoluble iron salt is at once precipitated, as there is no excess of oxalate to dissolve it. With this developer the image appears in from 10 to 30 seconds and is complete in 2 to 5 minutes. Potassium bromide, may, of course, be added as restrainer. As an accelerator a few drops of weak hypo solution may be used, about 10 drops of a 1: 200 solution to 100 ccm or 4 drops to the ounce; but this is apt to give fog. Modifications have been suggested mainly for use with gelatino-chloride lantern plates, and, by suitably prolonging the exposure and modifying the developer, any tone can be obtained from black to red. For black or purple tones the following may be used: A. Potassium citrate, neutral 450 g LAL Oz: Potassium oxalate, neutral ize 784 gr. Water 1000 ccm 16 oz. B. Ferrous sulphate 200 g o/ aoz. Water 1000 ccm 16 oz. Mix in equal parts. 98 PHOTOGRAPHIC FACTS AND FORMULAS I. Potassium oxalate 125 ¢ 2 oz. Potassium citrate 42¢ Y, oz. Water 1000 ccm 16 oz. This gives cold tones. II. Citric acid 333 g 51/3 a, Ammonium carbonate 250 g 4 oz. Water 1000 ccm 16 oz. Gives warm tones. III. Citric acid 500 g 8 oz. Ammonium carbonate 166 g 2 2/3 ae. Water 1000 ccm 16 oz. Gives extra warm tones. IV. Ferrous sulphate 333 g 5 1/3 02: Sulphuric acid 12.5 ccm 96 min. Water 1000 ccm 16 oz. For use add 1 part of IV to 3 parts of I, II, or III. Another modification is: Citric acid 250 g 4 oz. Magnesium carbonate 157 g 24 02. Water 1000 ccm 16 oz. This can be used instead of I, II, or III given above. Should any calcium oxalate be precipitated in the gelatine, a weak hydrochloric acid bath, about 1 per cent, will remove the precipitate. Giycin.—This is a slow-working very clean developer giving images of a neutral grey colour, and is very suitable for stand development. Glycin paste (Hibl).— Sodium sulphite, dry 125 ¢ 1% oz. Warm water 400 ccm 4 oz. Glycin 100 g 1 oz. DEVELOPERS oe Mix well and add gradually: Potassium carbonate 500 g 5 oz. Water to make 750 ccm 7Y OZ. Carbonic acid is given off and a thin cream formed, which must be well shaken and mixed with 12 times its volume of water before use. Glycin-soda.— Glycin I5¢ 115 gr. Sodium sulphite, dry S7:5)S 288 gr. Sodium carbonate, dry Soh fss 422 er. Water 1000 ccm 16 oz. Glycin-potash (Hubl).— Potassium metabisulphite 175g 202z., 384 gr. Caustic potash 175g 20z., 384 gr. Glycin 120 g O22 et: Water 1000 ccm 16 oz. Mix 1 part with 25 parts water. HyprRocHINON.—One solution: Sodium sulphite, dry 37.5 g 288 gr. Hydrochinon 10g 77 ot. Sodium carbonate, cryst. 150 g 1152 or: Hot water 1000 ccm 16 oz. Two solution: A. Hydrochinon 25¢ 192 gr. Sodium sulphite, dry 50 g 384 gr. Water 1000 ccm 16 oz. B. Potassium carbonate 10 per cent solution Mix 2 parts A with 1 part B. One solution: Hydrochinon l5¢ [f5,er. Sodium sulphite, dry 150 ¢ 1152 gr. Formaldehyde 20 ccm 154 min. Water 1000 ccm 16 oz. 100 PHOTOGRAPHIC FACTS AND FORMULAS Especially suitable for black and white line work. The fol- lowing also is excellent for the same purpose: A. Hydrochinon 8.5 ¢g Potassium metabisulphite 8.5¢g Potassium bromide 2.0¢ Water 1000 ccm B. Caustic potash I7 g Water 1000 ccm Mix in equal parts. 65 gr. 65 gr. 16 gr. 16 oz. 131 gr. 16 oz. For very fine grained images, add 50 to 300g (384 gr. to 514 0z.) of ammonium chloride to every liter (160z.) of normal hydrochinon developer. Rapid acting, soft-working developer (Lainer) : A. Hydrochinon 10¢g Sodium sulphite, dry 20 g Potassium ferrocyanide 120 g Water 1000 ccm B. Caustic potash 50 g Water 1000 ccm 77 gr. 154 gr. 922 gr. 16 oz. 384 gr. 16 oz. For use mix 10 parts A with 1 part B. Development will be completed in about one minute. If caustic soda is used, the ferrocyanide may be reduced to one-fifth. For general use it is better to mix the developer with an equal volume of water. One solution developer (Lainer) : Sodium sulphite, dry 752g Hydrochinon 50 g Potassium ferrocyanide 175 ¢ Caustic potash 165 g Water 1000 ccm For use dilute with 4 parts of water. 576 gr. 384 er. 1344 gr. 1267 gr. 16 oz. For Eastman Motion Picture Film, Negative and Pos- itive.— DEVELOPERS 101 Hydrochinon 390 g 13 oz. Sodium sulphite, dry 2000 g 4 Ib. Sodium carbonate, dry 2000 g 4 Ib. Potassium bromide 90 g SiOz: Water AO litres 1280 oz. Temperature 65° to 68° F. For film developed on drum add to above 45g (1% 0z.) potassium bromide and develop at 2° FE. Cramer’s Contrast Developer for Line Work.— A. Hydrochinon 45 ¢ 1Y, oz. Sodium sulphite, dry 30 g 1 oz. Sulphuric acid 4 ccm 60 min. Water 1000 ccm 32 oz. B. Sodium carbonate, dry 30 g oz: Potassium carbonate 90 g 3 02. Potassium bromide 8g 120 gr. Sodium sulphite, dry 90 g 3 OZ. Water 1000 ccm 32 02. For use mix in equal volumes. Develop for 6 to 10 minutes. Temperature 21° C. (70° F.). This may also be used for X-ray and lantern plates. KopELon.—Paramidophenol hydrochloride is sold by the _Eastman Kodak Co. under this name, especially for use with developing papers, under which heading formulas may be found. Metot.—A very rapid developer, rarely used alone, but generally in combination with hydrochinon or pyrogallol. Also marketed by the Eastman Kodak Co. under the name Elon. Motol is another synonym. Metol-potash.— A. Metol 10g To Sodium sulphite, dry 50 g 384 gr. Water 1000 ccm 16 oz. 102 PHOTOGRAPHIC FACTS AND FORMULAS B. Potassium carbonate 100 g 1 oz. Water 1000 ccm 10 oz. Mix 3 parts A with 1 part B. Metol-soda.—Replace the potassium carbonate in B by Sodium carbonate, dry 50 g 384 gr. For use mix A and B in equal volumes. One solution: Metol I5¢g fdisk Sodium sulphite, dry 60 g 460 er. Sodium carbonate, dry 75g 576 gr. Potassium bromide 15g 11 S.er, Water 1000 ccm OO For studio work mix with an equal volume of water. landscape work mix I part with 2 parts water. Metol poisoning (Beers)—The hands should be dipped into a saturated solution of paraffine in gasoline (petrol) before using metol. Less severe forms of the trouble can be treated with: Carbolic acid 21g 160 ger. Powdered calamine aloe 240 gr. Zinc oxide 63 g 480 gr. Glycerine 65 ccm 1 oz. Lime water 250 ccm 4 oz. Rose water to 1000 ccm 16 oz. Rub the zinc and calamine into a smooth paste with the glycerine, and add the carbolic acid and the rest of the © waters. This may be applied during the day. The following should be applied at night: Salicylic acid lg 15 gr. Boric acid 4g 60 gr. Starch powder 8g 120 er. Zinc oxide 4g 60 gr. Petrolatum 329 1 oz. DEVELOPERS 103 Flexible coliodion should be applied to all cracks during the day. Metol-hydrochinon (Cramer) — Ee Nletol,) . 2g 30 gr. Hydrochinon 6g 90 gr. Sodium sulphite, dry 30 g 1 oz. Water 750 ccm 25/02: B. Sodium carbonate, dry Lig, YY oz. Water 750 ccm 25 Oz: For use mix in equal volumes. Ansco Metol-Hydrochinon.— Metol 1.56 ¢ 48 gr. Hydrochinon 0.78 g 24 er. Sodum sulphite, dry Og 280 ger. Sodium carbonate, dry 6g 180 gr. Potassium bromide 0.39 g i2er, Water 1000 ccm 64 oz. Pine. 5 or 6 minutes at 18° C.. (657 F.). M. Q. Eastman Motion Picture Film, Negative & Post- tive.— Elon (metol) I2¢ 180 gr. Sodium sulphite, dry 1590 g SlbV Sez: Hydrochinon 240 ¢ 8 oz. Potassium bromide 36.2, Waz'63 ex. Sodium carbonate, dry 750 g 1 lb., 9 oz. Citric acid 28 g 400 gr. Potassium metabisulphite 60 g Zioz Water 40 liters 1280 oz. Michiperatine 657) Hi (1s* C.). Eastman Portrait & Commercial Films.—Metol-hydro- chinon tank formula.— Elon (metol) 1 O:8)e 170 gr. Sodium sulphite, dry 23:9) 2 12 oz. 104 PHOTOGRAPHIC FACTS AND FORMULAS Sodium bisulphite Og Y4 oz. Hydrochinon tog 34 OZ. Sodium carbonate, dry 3g LY oz. Potassium bromide 0.4 g 95 gr. Water to 1000 ccm 512 07 Temperature 18° C. (65° F.). Development from 10 to 14 minutes. The following strengthening solution may be used to keep the volume and strength up to standard: Elon (metol) 0.75 ¢ 85 gr. Sodium sulphite, dry 23.52 6 oz. Sodium bisulphite 0.5 ¢ 55 gr. Hydrochinon 15g 170 gr. Potassium bromide 0.4¢ 45 gr. Water to 1000 ccm 256 oz. To give this stock solution greater keeping quality, the sodium carbonate is not added until the strengthening solution is used. For use dissolve 1 part of sodium carbonate, dry, in 32 parts of the above solution. Standard Postcard Plates.— Elon (metol) a2 Y, oz. Sodium sulphite, dry 31.25'5 4 oz. Hydrochinon 782 1 oz. Sodium carbonate, dry 47g © 6 oz. Potassium bromide 195 g 4 oz. Water 1000 ccm 128 oz. For use mix with an equal volume of water. Stanley Plates—For these plates the following metol- hydrochinon developer is recommended : Elon (metol) roe Ma 30 gr. Sodium sulphite, dry S125 4 oz. Hydrochinon 3.9¢ 30 gr. Sodium carbonate, dry 15.625 g V4 OZ. Water 1000 ccm 16 oz. For use mix 1 part with 7 parts water, and use at 65° F. Seed Graflex Plates—Contrast Developer.— DEVELOPERS A. Elon (metol) 3.9¢ Sodium sulphite, dry 47g Hydrochinon 7.82 Potassium bromide 6.5 g Water . 1000 ccm B. Sodimm carbonate, dry § 312.5 ¢ Water 1000 ccm For use mix 3 parts A, 1 part B, 2 parts water. Metol-Hydrochinon-Pyro.— A. Elon (metol) DI Sodium sulphite, dry 31252 Hydrochinon 8.5¢g Sodium carbonate, dry 52 ¢ Water 1000 ccm B. Sodium bisulphite (or potassium metabisulphite) 9.2¢ Potassium bromide 2.6¢ Pyrogallol 62752 Water 1000 ccm For use mix 8 parts A and 1 part B. Seed Plates.— A. Elon (metol) | 4¢ Sodium sulphite, dry Sa) Hydrochinon 4g Potassium bromide Ze Water 1000 ccm B. Sodium carbonate, dry 94¢ Water 1000 ccm 60 gr. LY oz. 120 ger. 50 gr. 32 oz. 5 oz. 16 oz. Si am 1 oz. 130 gr. 800 gr. 3Z)0z: 70 gr. 20 gr. 1 oz. 16 oz. 120 gr. 2 oz. 120 er. 60 gr. 64 oz. LY, oz. 16 oz. 105 For tray developer, use A 4 parts, B 1 part, water 4 parts. 106 PHOTOGRAPHIC FACTS AND FORMULAS Eastman X-Ray Film.— ; Elon (metol) 2/72 40 er. Sodium sulphite, dry 120 g 4 oz. Hydrochinon llg 160 gr. Sodium carbonate, dry 60 g 2 Oz. Potassium bromide ZL e 32 gr. Water 1200 ccm 40 oz. The above is for tray development ; for tank, use: Elon (metol) 42g 1loz.,240 gr. Sodium sulphite, dry 2040 g 68 oz. Hydrochinon 185g 60z2., 96 gr. Sodium carbonate, dry 1020 g 34 oz. Potassium bromide 36 g 550 gr. Water to 22000 ccm 6 gal. Hammer Postal Plate—Stock solutions : 1. Metol 2/72 165 gr. Hydrochinon 10g LY, oz. Sodium sulphite 38 g 6 oz. Water 1000 ccm 128 oz. 2. Sodium carbonate 78g 10 oz. Water 1000 ccm 128 oz. For use mix equal parts of Nos. 1 and 2. One solution developer : Metol 0.15 g 22Y4 gr. Hydrochinon 0.30 g 45 gr. Sodium sulphite 12 ¢ 34 OZ. Sodium carbonate 4g Y4 oz. Potassium bromide 0.4¢ 6 gr. Water 1000 ccm 32 oz. For use mix with an equal volume of water. Rexo Film.—Dissolve the chemicals in the following order : Metol b25'¢ | 20 gr. Sodium sulphite, dry 14g Y, oz. DEVELOPERS 107 Hydrochinon 4g 60 gr. Sodium carbonate, dry 21g 34 OZ. Potassium bromide lg 15 gr. Witter) (1; 1150 ccm 40 oz. Neou.—This is a fine, white, crystalline powder, insoluble in water except in the presence of caustic alkali, which should be very pure, so that the manufacturers recommend only the use of Hauff alkali, which may be obtained either in solid form or in solution, in connection with this developer. The alkaline solution is prepared as follows: Hauff alkali (caustic soda) 400 ccm Z0Z: Water 1000 ccm 5 oz. The developing solution is compounded as follows. For tray development; time, three to five minutes: Water 1000 ccm 16 oz. Sodium sulphite, anhydrous 5g 40 er. Neol lye solution, as above 20ccm E/3) Oz. Neol 4¢g Silver. In case of over-exposure 10 to 20 drops of 10 per cent potas- sium bromide solution may be added. For tank development, 15 to 20 minutes: Water 100 liters Zeal. Sodium sulphite, anhydrous 300g 10 oz. Neol lye solution 1200 g 40 oz. Neol 200 g 634 oz. Potassium bromide, 10% sol. 15 ccm VY oz. Neol is claimed to work free from fog and therefore to be excellent for underexposed negatives. OrtoLt.—A molecular compound of two molecules of metol with one of hydrochinon: A. Potassium metabisulphite 75S 53:7) 20. Ortol 158 115) en: Water 1000 ccm 16 oz. 108 PHOTOGRAPHIC FACTS AND FORMULAS B. Sodium carbonate, dry 60 g 460 gr. Sodium sulphite, dry 90 g 690 gr. Potassium bromide 15g 11.5 gr. Hypo 0.5 ¢g 3.8 gr. Water 1000 ccm 16 oz. The same weight of potassium carbonate may be used instead of the soda. Mix 1 part A, 1 part B, and 1 part water; for a more rapid developer mix A and B in equal volumes. Stock solutions for Hammer plates: L. Ortol 21g 160 gr. Water 1000 ccm 16 oz. 2. Sodium carbonate 3lg 240 gr. Sodium sulphite 15.5 ¢ 120 gr. Water 1000 ccm 16 oz. For use take: No. 1 solution 125 ccm 1 oz. No. 2 solution 125 ccm 1 oz. Water 750 ccm 6 oz. PARAMIDOPHENOL.—One solution: Paramidophenol hydrochloride 4g 31 gr. Sodium sulphite, dry 40g 310 gr. Sodium carbonate, dry 40 ¢ 310 gr. Water 1000 ccm 16 oz. Ready for use. Does not keep so well as in separate solutions. A. Paramidophenol hydrochloride 20¢ 154 gr. Water 1000 ccm 16 oz. B. Sodium sulphite, dry 60 g 460 er. Potassium carbonate 120 g 920 gr. Water 2000 ccm 32 oz. Mix 1 part A with 2 parts B. More suitable for papers and transparencies than negatives. One solution, similar to rodinal (Ermen) : Water 625 ccm 11 oz. DEVELOPERS 109 Boil, allow to cool for 5 minutes, and add a few crystals of potassium metabisulphite; then add: Paramidophenol hydrochloride 50¢ 385 gr. Potassium metabisulphite 150))))2\0z)) 192) er: Stir until dissolved. Then make a solution of : Caustic soda 215i g 3Y oz. Water 500 ccm 834 oz. and add with constant stirring about 340 to 350 ccm (6 oz.) to the paramidophenol solution. At first a precipitate of the paramidophenol base is formed, but, as more caustic soda is added, this dissolves. Enough soda solution should be added to nearly dissolve the precipitate; then add: Water to inake 1000 ccm 16 oz. Bottle and allow to cool. Should any paramidophenol crys- tallise out, more soda must be added to nearly dissolve it. It is very important to leave some undissolved. For use mix 1 part with 10 parts water with some bromide for plates, and with 40 parts water for papers. Liquid developers consisting of paramidophenol and an alkali are marketed under such names as rodinal, azol, activol, citol, paranol, paramol, certinal, kalogen, etc. PARAPHENYLENDIAMINE, for fine-grained images (Lumi- ére & Seyewetz).—The following gives a finer grain image than most developers: Paraphenylendiamine 10g VANES: Sodium sulphite, dry 60 g 460 er. Water 1000 ccm 16 oz. PYROCATECHIN OR Kacuin.—Also called Elconal. A. Pyrocatechin lg 8 gr. Water 1000 ccm 16 oz. B. Potassium carbonate 200 g fez: Water 1000 ccm D OZ: For use mix 10 parts A with 1 part B. Gives brownish 110 PHOTOGRAPHIC FACTS AND FORMULAS images, suitable for transparencies. The developer can only be used once, as it spoils rapidly. Pyrocatechin-Potash._— A. Pyrocatechin 200g 302z., 224 gr. Sodium sulphite, dry 400 g 7 OZ. Water 1000 ccm 16 oz. B. Potassium carbonate 120 g 922 gr. Water 1000 ccm 16 oz. For use mix in equal parts. One solution: Potassium metabisulphite 100 g 2 Oz. Potassium carbonate 150 g 3 0z. Water 400 ccm 8 oz. Mix in a mortar and add: Pyrocatechin 350 g 7 Oz. This forms a thick cream which must be stored in well-corked bottles. Mix 1 part with 20 parts of water. Rapid one-solution developer (Ellon) — Sodium sulphite, dry 250 g 4 oz. Caustic soda 35 g 269 gr. Pyrocatechin 50 ¢ 384 er. Water 1000 ccm 16 oz. Mix 1 part with 15 parts of water. Two-solution (V ogel) — A. Sodium sulphite, dry 50 g 384 gr. Pyrocatechin 20 g 154 gr. Water 1000 ccm 16 oz. B. Caustic soda l4¢ 108 gr. Water 1000 ccm 16 oz. Mix 1 part A, 1 part B with 4 parts water. Pyrocatechin-acetone (Hanneke).— Pyrocatechin 10g 77 gr. DEVELOPERS 111 Sodium sulphite, dry l2¢g 92 gr. Water 1000 ccm 16 oz. Mix just before use 12 parts with 1 part acetone. PyYROGALLOL.—Pyro-ammonia was once the favorite de- veloper, but is rarely used now on account of its variability, due to the evaporation of the ammonia: A. Sodium sulphite, dry 50 g 384 gr. Sulphuric acid 6 drops 3 drops Pyrogallol : 14g 107.5 gr. Water 500 ccm 8 oz. B. Potassium bromide 10 per cent solution C. Ammonia, sp. gr. 0.91 200 ccm 4 oz. Water 1000 ccm 20 oz. For use mix 5 parts A, 1 part B, 5 parts C, and 50 parts water. Pyro-glycerine (Edwards ).— A. Pyrogallol 40 g 1 oz. Glycerine 40 ccm 1 oz. Denatured alcohol (methylated spirit) 250 ccm 6% oz. B. Potassium bromide I5¢ 65 gr. Ammonia 40 ccm 1 oz. Glycerine 40 ccm 1 oz. Water 250 ccm 6% oz. For use mix 1 part A, 1 part B, and 30 parts water. For great contrasts, suitable for black and white line work or photomechanical or process plates (Mawson) : A. Pyrogallol LS} 54 gr. Ammonium bromide 7g 54 gr. Potassium metabisulphite 7g 54 gr. Water 1000 ccm 16 oz. B. Ammonia, sp. gr. 0.91 21 ccm 160 min. Water 1000 ccm 16 oz. For use, mix in equal volumes. 112 PHOTOGRAPHIC FACTS AND FORMULAS P yro-Soda.— A. Sodium sulphite, dry 50 g 1 oz. Sulphuric acid 6 ccm 3 drops Pyrogallol l4g 122 gr. Water 500 ccm 10 oz. B. Sodium carbonate, cryst. 50 g 1 oz. Water 500 ccm 10 oz. For use mix in equal volumes. The “B. J”? Pyro-Soda.—Specially recommended by the British Journal of Photography. It keeps well and does not stain: A. Pyrogallol 16.6 g 1 oz. Sodium sulphite, dry 66g 4 oz. Potassium metabisulphite 16.6 g 1 oz. Hot water 1000 ccm 60 oz. Mix the sulphite and metabisulphite dry, and add to half the water ; boil for one minute, add the pyro, then the remainder of the water, and cool. B. Sodium carbonate, cryst. 200 g 12'oz. Water 1000 ccm 60 oz. For use mix 1 part A, 1 part B and 2 parts water. Hurter & Driffield Standard Developer Recommended for plate testing: Pyrogallol 8 parts Sodium carbonate, cryst. 40 parts Sodium sulphite, cryst. 40 parts Water 1000 parts Pyro-Caustic (Valenta) —A very rapid stainless developer, acting very much like metol: A. Sodium sulphite, dry 80 g 615 gr. Pyrogallol 25¢ 192 gr. Water 1000 ccm 16 oz. DEVELOPERS 113 B. Caustic potash 1l.5¢ 88.3 gr. (or Caustic soda) 8.5 g 65.3 gr. Water 1000 ccm 16 oz. For use mix | part A, 1 part B and 1 part water. Pyro-Acetone (Lumiere) — A. Pyrogallol 100 g 768 gr. Sodium sulphite, dry 200 g 1536 gr. Water 1000 ccm 16 oz. Potassium metabisulphite must not be used, nor must acid be added. For use mix A 8 parts, acetone 8 parts and water 100 parts. Pyro-Potash (Beach) — A. Pyrogallol 100 g 1 oz. Sodium sulphite, dry 200 g Zoz: Sulphurous acid 400 ccm 4 oz. Hot water 500 ccm Doz Dissolve the sulphite; when cold add the acid, and then the pyro. B. Potassium carbonate Joo) 8 HE oVOZ Sodium sulphite, dry lilg 1 oz. Hot water 1000 ccm 10 oz. For use mix 1 part A, 2 parts B and 16 parts water. Cramer's Pyro Tank Developer.— Sodium bisulphite 19.5¢ 2Y4 02. Sodium sulphite, dry 19iSie 24 02. Hot water 500 ccm 64 oz. Dissolve and boil for 5 minutes; then add: Pyrogallol 15.512 2 02. Sodium carbonate, dry 27 3Y oz. Cold water 500 ccm 64 oz. To keep up to original strength and bulk, add equal volumes of the following (A and B) after each day’s working: 114 PHOTOGRAPHIC FACTS AND FORMULAS A. Sodium bisulphite 39 g 24 oz. Sodium sulphite, dry 39 g 24 02. Hot water 1000 ccm 64 oz. Boil for 5 minutes and add when cool: Pyrogallol 3l¢g 2 02, B. Sodium carbonate, dry 62.5 g 4 oz. Water | 1000 ccm 64 oz. Potassium metabisulphite must not be substituted for the bisulphite in the above formulas. . Pyro-soda developer for Cramer plates.— A. Sodium bisulphite 5g 75 gr. Pyrogallol 30 ¢ 1 oz. Water 480 ccm 16 oz. B. Sodium sulphite, dry 60 g 2 02. Water 480 ccm 16 oz. C. Sodium carbonate, dry 30 g 1 oz. Water 480 ccm 16 oz. For tray use: Solution A 100 ccm 1 oz. Solution B ; 100 ccm ez. Solution C 100 ccm 1 'o7. Water 800 ccm 8 02. For tank use: Solution A 250 ccm 214 02. Solution B 350 ccm 314 oz. Solution C 250 ccm 2Y4 oz. Water 5800 ccm 58 oz. Temperature 65° F. Time 20 minutes. Cramer’s Pyro-Acetone.—Stock pyro solution: Sodium bisulphite B,20'2 25 gr. Pyrogallol 62.5 ¢g 1 oz. Sodium sulphite, dry 182 g 234 02. Water 1000 ccm 16 oz. DEVELOPERS us For tray, use: Stock pyro solution 72 ccm, acetone 24 ccm, water 928 ccm; or pyro solution 1 oz., acetone 3 drams, water 14 oz. For tank, use: Pyro solution 21.5 ccm, acetone 12.5 ccm, water 1000 ccm; or pyro solution 1%4 oz., acetone 5 drams, water 58 oz. ) Temperature 21° C. (70° F.) Time 30 minutes. Ansco Pyro-Soda.— ~ 1. Potassium metabisulphite 16.3 g 250 gr. Sodium sulphite, dry 62.5 g Zi0z! Pyrogallol 16.3 g 250 gr. Water 1000 ccm 32:02. 2. Sodium carbonate, dry 70g 24 oz. Water 1000 ccm 32 oz. For use mix No. 1, 1 part, No. 2, 1 part, water, 2 parts. Time of development 5 minutes at 18° C. (65° F.). Kodak Film Pack Pyro formula.— Pyrogallol ig THAD eh Sodium sulphite, dry 5g 60 gr. Sodium carbonate, dry 6.5¢ Paony. Water 1000 ccm 2707: Temperature 18° C. (65° F.). Develop for 20 minutes. For Eastman N-C & Autographic Film— A. Pyrogallol SANs hoz. Sulphuric acid, c. p. 3 ccm 20 min. Water. 1000 ccm 28 oz. B. Sodium sulphite, dry 107 g JIOZ: Sodium carbonate, dry FASS 202: Water 1000 ccm 23) Oz. For use mix 1 part A, 1 part B, 8 parts water. For Seed and Stanley Plates—For tray developer: 116 PHOTOGRAPHIC FACTS AND FORMULAS A. Sodium or potassium bisulphite 11.7 g Pyrogallol 62.5¢ Water 1000 ccm B. Sodium sulphite, dry 94¢g Water 1000 ccm C. Sodium carbonate, dry 782 Water 1000 ccm For use mix 1 part A, 1 part B, 1 part C, For tank developer : A. Sodium or potassium bisulphite 9g Potassium bromide 0.9¢ Pyrogallol 62.5 ¢ Water 1000 ccm B. Sodium sulphite, dry 109 g Water 1000 ccm C. Sodium carbonate, dry 78g Water 1000 ccm For use mix A solution 36 ccm B solution 36 ccm C solution 36 ccm Water to 1000 ccm Temperature 65° F. Develop 15 minutes. For Seed 30 and Graflex plates use: A solution 47 ccm B solution 47 ccm C solution 47 ccm Water to 1000 ccm Temperature 65° F. Develop 15 minutes. 90 gr. 1 oz. 16 oz. 1¥4 oz. 16 oz. 1% oz. 16 oz. and 7 parts water. 70 gr. 7 eae 1 oz. 16 oz. 134 oz. 16 oz. 1% oz. 16 oz. 4¥4 oz. 4¥4 oz. 4¥4 oz. 128 oz. 6 oz. 6 oz. 6 oz. 128 oz. Pyro-Acetone for Hammer Plates——Stock solutions: 1. Sodium sulphite 129 ¢g Water 1000 ccm Hydrometer test, 75°. 3 02. 23% oz. DEVELOPERS 2. Pyrogallol Oxalic acid Water For use, take: No. 1 solution No. 2 solution Acetone Water Pyro for Hammer Plates—Stock solutions: 1. Sodium sulphite Water Hydrometer test, 80°. 2. Sodium carbonate Water Hydrometer test, 40°. 3. Potassium metabisulphite Pyrogallol Water For tray take: No. 1 solution No. 2 solution No. 3 solution Water (winter ) Water (summer ) For tank take: No. 1 solution No. 2 solution No. 3 solution Water 62.5 g zg 1000 ccm 118 ccm 59 ccm 29.5 ccm 588 ccm 156 g 1000 ccm 782g 1000 ccm 7.82 62.5 ¢ 1000 ccm 30 ccm 30 ccm 30 ccm 360 ccm 480 ccm 43 ccm 43 ccm 43 ccm 870 ccm 111¥ oz. 117 Bromide potassium, saturated solution, 0.2 ccm, 12 drops. Develop 12 minutes at 65° F. Rexo Film—Make the following solution: 118 PHOTOGRAPHIC FACTS AND FORMULAS Pyrogallol 28 g 1 oz. Oxalic acid 0.5¢ 8 gr. Water 225 ccm 8 oz. For use make the following solutions, Nos. 1 and 2 and mix equal parts: 1. Pyro solution as above 56 ccm 2 oz. Water 500 ccm 18 oz. 2. Sodium sulphite, dry 28g 1 oz. Sodium carbonate, dry l4g YZ 02. Water 560 ccm 20 oz. Tank developer: No. 1 solution 56 ccm 2 oz. No. 2 solution 56 ccm 2 oz. For 15 minute development add 225 ccm (8 oz.) of water at (57) Fe For 30 minute development add 560 ccm (20 oz.) of water at 650 i, For Wratten Panchromatic Plates.— A. Sodium or potassium bisulphite 6g 90 gr. Pyrogallol 30 g 1 oz. Water 500 ccm 16 oz. B. Sodium sulphite, dry 45¢ LY, oz. Water 500 ccm 16 oz. C. Sodium carbonate, dry 37.5 g 1% oz. Water 500 ccm 16 oz. For tray development, mix 1 part A, 1 part B, 1 part C, and 7 parts water. For tank development, mix 1 part A, 1 part B, 1 part C, and 25 parts water, to which add for every 500 parts, 2 parts of 1 per cent solution of potassium bromide. The times for development for the above tray and tank de- velopers are: © DEVELOPERS Temperature Tray 10g) 12 min. oo) (E. 6 min. SORE. 3 min. B, C, but 12 parts water. Tank jhe: 36 min. 18 min. 9 min. For Standard Plates—The stock solutions are as above. To develop Standard Extra, Imperial Portrait, Thermic, or Polychrome plates, use 1 part A, 1 part B, 1 part C, 7 parts water. For Orthonon plates use the same proportions of A, For tank developer for Standard Plates, use the same form- ula as for Seed plates, except for the Standard Polychrome, for which the formula is: A solution B solution C solution Water Temperature 65° F. Develop 15 minutes. 54.6 ccm 54.6 ccm 54.6 ccm 1000 ccm 3 Oz. 3 oz. S'Oz. 55 oz: For Eastman Portrait, Commercial, Commercial Ortho & Commercial Panchromatic Films.—The formulas for the tray developer are the same as for the Wratten Panchromatic plates. For the tank developer the same formulas are used, in the following proportions: A solution B solution C solution Water to Pyro-M etol.— A. Pyrogallol Metol Potassium metabisulphite Potassium bromide Water 43 ccm 43 ccm 43 ccm 1000 ccm Sle 1000 ccm 5Y4 oz. 54 oz. 5Y4 oz. 128 oz. 64 gr. 54 gr. 144 gr. 24 gr. 16 oz. 120 PHOTOGRAPHIC FACTS AND FORMULAS B. Sodium carbonate, cryst. 156 g 24 02. Water 1000 ccm 16 oz. Mix in equal volumes. For Hammer Plates.—Stock solutions : 1. Sodium sulphite 156 g 2Y4 oz. Water 1000 ccm 16 oz. 2. Sodium carbonate 782 1% oz. Water 1000 ccm 16 oz. 3. Potassium metabisulphite 78¢ 60 gr. Metol 15.6¢g V4 oz. Pyrogallol 46.8 g 34 OZ. Potassium bromide 39 ¢ 30 gr. Water 1000 ccm 16 oz. For tank take: No. 1 solution 41 ccm 5% oz. No. 2 solution 41 ccm 514 oz. No. 3 solution 41 ccm 514 02. Water 877 ccm 112% oz Develop 10 minutes at 65° F. For tray development: 4. Pyrogallol 37 g 1 oz. Metol 46g 60 gr. Water 1000 ccm 27 02. Solution No. 2 as above Solution No. 3 as above For use take: No. 4 solution 100 ccm 1 oz. No. 2 solution 100 ccm 1 oz. No. 3 solution 100 ccm 1 oz. Water 800 to 1200 ccm 8 to 12 oz. Pyro-Metol Tank & Tray Developer for Eastman Portratt & Commercial Films.— DEVELOPERS 12h A. Sodium bisulphite 15.52 V4 oz. Elon (metol) 15:5'¢ V4 oz. Pyrogallol 62:52 Loz: Potassium bromide 4g 60 gr. Water 1000 ccm 32 OZ: B. Sodium sulphite, dry 156 ¢ 5/0Z: Water | 1000 ccm 57) OZ! C. Sodium carbonate, dry 78g 2Y4 oz. Water 1000 ccm SZ 02. For tank development mix 2 parts each of A, B, and C with 32 parts water. Temperature 18° C. (65° F.). Develop- ment from 9 to 12 minutes. This may be used repeatedly if kept up to normal strength. For strengthening add 2 parts each of A, B, and C to 8 parts water. For tray development mix 2 parts each of A, B, and C with 16 parts water. Cramer's Pyro-Metol Developer.— A. Metol 30 g 1 oz. Sodium bisulphite lg iSite oh Pyrogallol 10g YZ oz. Water 600 ccm 30 oz. B. Sodium sulphite, dry 120 g 4 oz. Water 600 ccm 30 oz. C. Sodium carbonate, dry 120g 4 oz. Water 600 ccm 30 oz. For use mix: Solution A 10 ccm YZ oz. Solution B 10 ccm YZ oz. Solution C 10 ccm Y, oz. Water 200 to 300cem = 10 to 15 oz. B and C may be mixed together and keep well in one solu- tion, which should be diluted for use with from 6 to 10 parts of water. ! . Fixing and Clearing Fixinc.—The rapidity with which plates, films, and papers fix is dependent on the strength of the bath, its temperature, and the degree of exhaustion or previous use. A 40 to 45 per cent solution of hypo:is the strongest bath that should be used and is the most rapid in action. Plain, alkaline, acid, or acid and alum baths may be used. The first two are generally used for printing-out papers, and the latter for plates, film, and developed papers. In all cases, the temperature should be maintained about normal, 18° C. (65° F.). A bath should not be used too long, as the more it is used, the greater its saturation in silver salts, therefore, the longer it will take to fix properly and the greater the chance for the formation of insoluble, transparent silver salts which are difficult to wash out. The easiest way to make a solution is to tie the hypo crystals up in a cloth or piece of Canton flannel, and suspend in a vessel of hot water. This obviates any necessity for filtering the solution. Plain bath.— Hypo 400 g 64 oz. Hot water to 1000 ccm 16 oz. Alkaline bath—Generally used for silver printing-out images : Hypo 125¢ 24 oz. Sodium carbonate, dry 7g Y4 oz. Salt iis V4 oz. Water 1000 ccm 16 oz. Sodium sulphite, dry, may be substituted for the carbonate. 123 124 PHOTOGRAPHIC FACTS AND FORMULAS Acid bath— Hypo 150g 2Y4 oz. Potassium metabisulphite 25g 4 oz. Water 1000 ccm 16 oz. This is about the correct strength for papers; for negative work the hypo should be increased to 400 g (614 oz.). An equally efficient bath is made as follows: Hypo 400 g 64 oz. Citric acid 30 g 230 gr. Sodium sulphite, dry 35,2 270 gr. Hot water to 1000 ccm 16 oz. Dissolve the hypo in half the water and the acid and sulphite in one-fourth, mix the solutions and make up to bulk. Acid-alum bath.—The following is typical of the formulas recommended by plate and film makers: Hypo 250 g 16 oz. Water 1000 ccm 64 oz. Dissolve and add: } Sodium sulphite, dry 31g YZ oz. Acetic acid, No. 8 186 g 3 0Z. Alum Sle 4 oz. Water 312 ccm 5 oz. Dissolve the chemicals in this order. Some paper makers recommend the same bath, but with double the quantity of sulphite and alum, for developed prints. Acid-chrome alum bath.— Sodium sulphite, dry 45 ¢ 34 ox Water 100 ccm LY oz. Stir well and add: Glacial acetic acid 20 ccm 154 min. Then add to the following, after the hypo is dissolved: Hypo 400 g 6¥4 oz. Hot water 600 ccm 9 oz. FIXING AND CLEARING 125 Finally, add: Chrome alum 20 g 154 gr. Hot water 50 ccm 34 Oz. Make the total bulk up to 1000 ccm or 16 oz. Rapid ammonia fixing bath.—It is frequently recommended to add ammonium chloride to the fixing bath on the supposi- tion that ammonium hyposulphite is formed, that this fixes quicker, and is washed out more easily. If a 20 per cent solu- tion of hypo is used, the addition of from 2% to 5 per cent of ammonium chloride increases the rapidity of fixing. With a 40 per cent solution, it has no effect. The addition of 10 per cent of ammonia water to a 20 per cent solution of hypo acts as quickly as the ammonium chloride. ReEsIDUES.—To precipitate metallic silver from old hypo baths, from 6 to 8 g per liter (420 to 560 grains per gallon) of sodium hydrosulphite, Na,S,O,, should be added, with about half the quantity of caustic soda, and the bath heated to boiling to decompose excess of hydrosulphite. This treat- ment regenerates the hypo, and the bath can be used again. Addition of a saturated solution of sulphurated potash, the so-called liver of sulphur, may be used for precipitating the silver from old hypo baths. This should be done out of doors, as sulphuretted hydrogen is evolved. The mixture should be well stirred and the silver sulphide allowed to settle down; then some of the clear supernatant liquid should be collected in a graduate, and tested with a drop or two of liver of sulphur solution. A deep brown colour or blackish precipitate shows the presence of silver in solution, and then more sulphur compound should be added. A much more cleanly precipitant is zinc. This can be used either in scrap or mossy form. The liquid should be well stirred and allowed to settle; this operation should be re- peated three times at intervals of 24 hours. The clear liquid 126 PHOTOGRAPHIC FACTS AND FORMULAS may be tested as suggested above. About three days is suffi- cient, as a rule, to throw down the whole of the silver. One of the best methods of regaining the silver is to procure a sheet of brass, not too thin, and place in the barrel or jar at an angle, so that both sides are presented to the liquid. After about 48 hours, the whole of the silver will be precipitated in the metallic form on the brass and can usually be removed by bending a corner sharply two or three times, when the silver will spring off. The brass can then be put back into the vessel and allowed to remain another 24 or 48 hours, when practically the last trace of silver will be ex- tracted. This thin coat is difficult to remove and may be left on until the next batch of residues is to be treated. Paper and print clippings and waste prints should be burnt, and the ashes collected and mixed with the silver sulphide from the old fixing baths. Platinum Residues——The developer and acid fixing baths from the platinotype process should be collected and prefer- ably boiled down to about one-fourth the volume. Then some saturated solution of ferrous sulphate should be added, the mixture boiled for an hour, and the platinum filtered out. Gold baths.—Old gold toning baths may be treated in the same way as the platinum solutions, after acidulating with hydrochloric acid. It does not pay a photographer to refine his own residues. All the silver residues should be mixed together, and the gold and platinum kept separate, and sent to a refiner, who will allow market value of the metals minus a small charge for refining. Hypo ELImMInators.—It is an open question whether the use of chemicals to destroy the last traces of hyposulphite of soda and the hyposulphites of silver is justifiable if perma- nency of results be the aim. Their action is probably in most FIXING AND CLEARING 127 cases to convert these salts into tetrathionates ; and, as a nega- tive or print can be practically freed from hypo in half an hour by proper washing, their use is only allowable in cases of great pressure of time or shortage of fresh water. The fol- lowing have been recommended. Zinc hypochlorite (Hart).— Chloride of lime 10g 77 gr. Water 500 ccm 8 oz. Rub the lime into a cream with a little water; then add the rest of the water, and add to: Zinc sulphate 20 g 154 gr. Water 500 ccm 8 oz. Shake well and filter or allow to stand until the precipitate subsides, and decant the supernatant liquid. For use dilute with 9 parts of water; immerse the negatives or prints for about 3 minutes, and then briefly wash and dry. Sodium or potassium hypochlorites may be made and used in the same way, employing the alkaline carbonates instead of the zinc salt. Potassium permanganate, in 1 per cent solution, may also be used, enough being added to water to give a pink tinge, and the negatives bathed in the solution until the colour is no longer discharged, repeated baths being used. Potassium percarbonate in 1 per cent solution has also been sold com- mercially as Hypax or Hypono. Sodium perborate can be used in the same way. Potassium or ammonium persulphate in 1 per cent solution, made alkaline with ammonia, may also be used. The former has been sold as Thioxydant, Anthion, etc. A 5 per cent solution of hydrogen peroxide may also be used. HARDENING BatHs.—Sometimes used for negatives and prints in hot weather. Thorough washing so as to eliminate all hypo must precede these baths: 128 PHOTOGRAPHIC FACTS AND FORMULAS A. Alum 10 per cent solution, or B. Chrome alum 2 per cent solution, or C. Formaldehyde 10 per cent solution With the last bath, freedom from hypo is not so essential. Practically, the use of these baths has been rendered obsolete by the use of the chrome alum fixing baths. CLEARING Batus.—These baths are not much used at the present day when the use of sulphite and the newer developers prevents the staining of the gelatine, which was so prone to occur in the early days of the gelatine plate, when plain pyrogallol developer was used. The well-washed negatives may be immersed in: Potassium permanganate lg Ai eu Water 1000 ccm 16 oz. for 5 minutes, then rinsed in water and immersed in a 1 per cent solution of potassium metabisulphite, or sodium bisul- phite, or in: Alum 200 g 3 Oz: Citric acid 65 g 1 oz Water 1000 ccm 16 oz Or: Alum 50 g 34 Oz Citric acid 50 g 34 OZ Ferrous sulphate 150 ¢g 214 oz Water 1000 ccm 16 oz Or: Chrome alum 25g 192 gr Sodium bisulphite 100 g 770 gr Water 1000 ccm 16 oz (Dr: Thiocarbamide 20 g 154 gr Citric acid 10g 77 gr Water 1000 ccm 16 oz FIXING AND CLEARING 129 Dichroic, red or green fog, is practically unknown at the present day, but it was very prevalent in the early days of dry plate work, and showed itself mainly in the shadows as a more or less deep red colour by transmitted light, which was green by reflected light. The remedy for this (Abney) is to bleach the negative in: Ferric chloride 24¢ 184 gr. Potassium bromide 18g 138 gr. Water 1000 ccm 16 oz. Wash well and then redevelop. ALUMS AS HARDENING AGENTS.— Potash alum 6 parts Ammonia alum 5.6 parts Aluminum sulphate 4.2 parts Aluminum chloride, anhydrous 1.6 parts Aluminum nitrate 4.5 parts Chrome alum 2 parts The above quantities will render 100 parts of dry gelatine insoluble in hot water. Basic chrome alum is the most effective agent. This is made as follows: Chrome alum 100 g 768 gr. Hot water 800 ccm 12 oz: When dissolved, add: Ammonia quant. suff. to form a slight permanent precipitate after stirring well; then filter, and make bulk to 1000 ccm, or 16 oz. Intensification Tue Mercury INTENSIFIER.—This is probably the most generally used of all intensifiers. The silver image is treated with mercuric chloride or bromide until bleached, then washed, and blackened by various reagents. The mercuric halide solution is sensitive to light and should be kept in the dark. It is extremely poisonous when taken internally, but the absorption by the skin, even in the case of cuts and abra- sions, is practically harmless. Make up the following mer- cury solution: Mercuric chloride 20 g 154 gr. Salt 20 g 154 er. or Ammonium chloride 20 g 154 er. or Hydrochloric acid 3 ccm 23 min. or Potassium bromide 20 g 154 er. Water 1000 ccm 16 oz. The purpose of these additions is to increase the solubility of the mercury salt, and the bromide gives greater increase of density than the others. The plate to be intensified should be perfectly free from hypo, and if dry, soaked in water for 10 minutes, and then immersed in the mercury solution until the image seen from the back is white; on no account should the action be stopped before this point is reached. It should then be well washed in water acidulated with hydrochloric acid, 1: 300; about 5 minutes soaking in six successive baths may be used; then, after washing in running water for 10 minutes, it may be blackened. The acid bath removes the mercury salt, which is tenaciously held by the gelatine, and might otherwise give rise to stains. This acid treatment may be avoided by the use of the following bleach: 130 INTENSIFICATION ey Mercuric chloride 20 ¢ 154 gr. Ammonium chloride NS OieqyZ)oz., 192 an; Hydrochloric acid 10 ¢g 47 St. Water 1000 ccm 16 oz. The large proportion of the ammonium chloride is said to facilitate the removal of the mercury salt. The blackening may be effected with one of the following reagents : A. Ferrous oxalate developer, using 1 part of iron sulphate solution to 6 of oxalate; B. Amidol developer. Other developing agents with sul- phite may be used; C. Sodium sulphite, 5 per cent solution of the anhydrous or 10 per cent solution of the hydrated salt; D. Ammonia, 10 per cent solution of the strongest am- monia water. The bromide bleach does not give such satis- factory results with this as the chloride; KE. Silver-potassio-cyanide (Monckhoven). ‘This is pre- pared from: I. Silver nitrate 20 g 154 ger. Water 500 ccm 8 Oz. II. Potassium cyanide 20g 154 gr. Water 500 ccm 8 oz. Add three-fourths of I to II and shake thoroughly; a thick curdy white precipitate will be thrown down, which dissolves on shaking. If a perfectly clear solution is obtained, add more [ until, after shaking and allowing to stand with occa- sional agitation for 10 minutes, there is a permanent white precipitate. The quantity of silver required depends on the strength of the cyanide, which varies considerably; in any case, a permanent deposit must be formed, even by adding more silver than above stated. This method of mixing is better than adding the cyanide to the silver. If the negatives 132 PHOTOGRAPHIC FACTS AND FORMULAS are allowed to remain too long in this solution, they are reduced ; F. Mercuric-iodo-cyanide (Eder) : Potassium cyanide 5g 38 gr. Potassium iodide 252 19 gr. Mercuric chloride 25'2 19 gr. Water 1000 ccm 16 oz. The bleached image first turns yellowish, then dark brown, and, if the plate be removed at this stage, it will generally be too dense for practical purposes; if the action is allowed to continue longer, the image turns a lighter brown and becomes more transparent ; - G. Schlippe’s salt or sodium sulphantimoniate : Schlippe’s salt 25¢ 192 gr. Ammonia 10 ccm 77 min. Water 1000 ccm 16 oz. Make just before use and filter. Gives a brownish-red image which is too dense for ordinary work. This is useful for restoring negatives intensified with mercury, which have faded with course of time; H. Sodium sulphide 10¢g 77 gr. Water 1000 ccm 16 oz. Usually gives too much intensification for ordinary work; I. Formalin with caustic soda has been recommended for blackening the bleached images, but presents no advantage; J. Stannous tartrate (Helain) : Stannous chloride 20 g 154 gr. Tartaric acid 20g 154 er. Water 1000 ccm 16 oz. This has also no special features to recommend it. Practically, it may be said that, assuming the original den- sity of the negative to be 1, the intensification given by A, B, C, E will be 2, by D about 2.5. Repeated bleaching with” INTENSIFICATION 133 _ mercury and development with ferrous oxalate will give any desired degree of increase. Mercuric Iodide (Edwards, Lumiére, etc.)—As originally recommended by Edwards, this was a solution of mercuric iodide in excess of iodide and hypo, as follows: Mercuric chloride I2¢ 97 sr. Water 650 ccm 10 oz. Dissolve and add: Potassium iodide 33 g 253 er. Water 100 ccm 2 oz. And, finally: Hypo 27 g 207 gr. Water 250 ccm 4 oz. MM. Lumiére suggested: Mercuric iodide 10g 77 gr. Sodium sulphite, dry 100 g 770 gr. Water 1000 ccm 16 oz. This is an improvement on the first formula. The negatives assume a dark brown colour, but the image is not stable and soon turns yellow. It is advisable, therefore, to treat the darkened image with a developer, which renders it per- manent. Welborne Piper proposed the following: A. Mercuric chloride 50 g 384 gr. Hot water LOO cena: 16 oz. B. Potassium iodide 50 g 384 gr. Cold water 250 ccm 4 oz. Add B to A gradually, shaking after each addition until the solution becomes clear, and, if necessary, heating. After all B has been added and the solution is clear, allow to cool and filter out any red precipitate formed. The negatives should be bleached in this solution, washed and treated with sodium sulphite or ammonia, or redeveloped, and well washed. Mercuric Sulphocyanide (Agfa)—This was patented in 134 PHOTOGRAPHIC FACTS AND FORMULAS Germany by the Aktiengesellschaft f. Anilinfabrikation. A similarly acting solution can be made as follows: Mercuric chloride 187 g 3/02: Hot water 750 ccm 12 oz. Add: Ammonium sulphocyanide 225 ¢ 3 0z., Z02'ee Water 250 ccm 4 oz. For use dilute 1 part with 10 parts of water. The negative turns black at once; but, if left too long, the intensification is reduced. The images are not stable unless a developer is applied. THE CHROMIUM INTENSIFIER (Eder, Welborne Piper and Carnegie)—This method of intensification has deservedly received considerable attention, being less liable to stain and much less poisonous than many others. The negatives need not be absolutely free from hypo, as the bleaching bath oxidises this, though, if much hypo be present, it may be necessary to apply the bleaching bath twice. Two stock solutions are required: I. Potassium bichromate 50 g 384 gr. Water 1000 ccm 16 oz. II. Hydrochloric acid, pure 100 ccm lL oz. Water 1000 ccm 10 oz. The bleaching baths are: A B c Stock solution I 32 64 64 parts Stock solution IT 3 16 64 parts Water 128 fe RO 32 parts Immerse the negative in the solution until the image on the glass side appears bleached, then wash until the yellow stain is removed, and develop with amidol in white light. Other developers may be used, without bromide, but the image requires exposure to diffused daylight, and they are less a INTENSE ICA TON 135 satisfactory. A gives the strongest and C the least intensifi- cation. The process may be repeated as often as required. As a variant the following may be used: Chromic acid 2.5/2 197 or Sale: 235) o 197 on: Water 1000 ccm 16 oz. The procedure described above should be followed. The acid and salt may be kept in stock solutions, say 10 per cent, and mixed as required. A convenient form of a dry salt, the chlorochromate, may be prepared as follows (Lumiére & Seyewetz) : Ammonium bichromate 82¢ 1265 gr. Hydrochloric acid, spon. 116 364 ccm 12 oz., 160 min. Place the acid in an evaporating dish, add the ammonium salt, and evaporate until dry. The result will be 100¢ (1543 gr.) of ammonium chlorochromate, which may be kept in a dry state or in a 10 per cent solution by dissolving in 1000 ccm (32 oz.) distilled water. Of this, 30 ccm (210 min.) should be diluted to 1000 ccm (16 oz.) to form a convenient bleacher. The equivalent weights of the potassium salt may be used, that is, 100 g or 1543 gr. THE CoOPPER-SILVER INTENSIFIER.—This intensifier is par- ticularly valuable for black and white or line negatives, and gives great intensification. The bleaching solution is pre- pared from: I. Cupric sulphate ll5¢g 2 oz. Hot water 500 ccm Sioz) II. Potassium bromide 1S) & 2 OZ. Hot water 500 ccm 8 oz. Mix and allow to cool. The negative should be bleached in this, washed no longer than 2 minutes, and blackened in: Silver nitrate 10 per cent solution 136 PHOTOGRAPHIC FACTS AND FORMULAS If still greater density be required, the negative should be well washed after bleaching and redeveloped with any ordinary developer, the silver treatment being omitted. Or, after washing, the negative may be blackened with a 0.5 per cent solution of sodium sulphide. As an improvement on the silver nitrate, which may cause stains, Namias recommends silver oxalate. To prepare this, take: Silver nitrate 10g 77 gr. Water 100 ccm 2 02: Dissolve, and add: Potassium oxalate, neutral 6g 46 gr. Water 50 ccm 1 og: Allow the silver oxalate to settle down, decant the water, and add the precipitate to 1000 ccm (16 oz.) water. Shake the solution every time before applying to the bleached negative. The process is applicable to papers as well as plates, and it is advisable to subsequently immerse in a 10 per cent solution of hypo for a few minutes and wash well. Tue Copper-T1n INTENSIFIER.—In this the final image consists of a mixture of tin and silver compounds, and the intensification is due to a great extent to the non-actinic colour of the deposit, which is a warm brown. Bleach the negative in: Cupric chloride 30 g 230 gr. Hydrochloric acid 3 ccm 23 min. Water 1000 ccm 16 oz. Wash thoroughly and immerse in the following: Stannous chloride 40¢g 307 gr. Water 400 ccm 4 oz. To which is added: Caustic soda 30 g 230 gr. Water 100 ccm 1 oz. INTENSIFICATION 137 This should be added cautiously to the tin solution, with con- stant stirring, so that the precipitate first formed is not quite cleared up. The solution should then be filtered, and the bulk made up to 1000 ccm (16 oz.) with water. A variation of this method is to treat the bleached image with a 5 per cent solution of caustic soda, wash, and then with 10 per cent of — stannous chloride. The cupric chloride may be replaced by: Cupric sulphate _ 44¢ 34 gr. Salt 20.8 g 160 gr. Hot water 1000 ccm 16 oz. Mix and allow to cool before use. CopPpER FERROCYANIDE INTENSIFIER.—This is very rarely used, and is apt to give too great intensification. The degree of increase depends on the duration of the action of the bath and the consequent warmth of colour. Two stock solutions are required : 1. Cupric sulphate Al Xs 54 gr. Potassium citrate, neutral 28 g 215 ger. Water 1000 ccm 16 oz. II. Potassium ferricyanide 6g 46 gr. Potassium citrate, neutral 28g Z215er: Water 1000 ccm 16 oz. Mix in equal quantities just before use. No. II solution must be kept in the dark. A variation of this is to mix the two solutions and to add enough strong ammonia to form a clear solution. THe URANIUM INTENSIFIER.—Except for extremely thin and flat negatives, this is not to be recommended. The degree of intensification depends upon the ratio of the uranium to the ferricyanide: I. Uranium nitrate 100 g 768 gr. Glacial acetic acid 40 ccm 300 min. Water 1000 ccm 16 oz. 138 PHOTOGRAPHIC FACTS AND FORMULAS II. Potassium ferricyanide 40g 307 gr. Potassium oxalate 10¢g 77 gr. Glacial acetic acid 40 ccm 300 min. Water 1000 ccm 16 oz. If mixed in equal volumes, a reddish brown image is ob- tained; 1 part I and 2 parts II give a reddish image; 5 parts I and 1 part II give a brown. The colour is also dependent to some extent on the duration of the action of each bath. The negatives should be washed in a 2 per cent solution of citric acid, or 1 per cent oxalic or glacial acetic acid. If plain water be used, about five changes at intervals of 5 minutes are enough. Prolonged washing in running water will com- pletely remove the intensification, generally first in patches. Tue Leap INTENSIFIER.—This gives very great intensifi- cation and is only suitable for black and white line work: Lead nitrate 46¢ 353 gr. Potassium ferricyanide 70g 537 gr. Glacial acetic acid 20 ccm 154 min. Water 1000 ccm 16 oz. This will keep in the dark. The lead salts are rather tena- ciously retained by the gelatine; it is advisable to immerse the negatives in a 5 per cent solution of nitric acid for 5 minutes, and then wash. If the negative be subsequently developed, rather less intensification is given. By applying a 10 per cent solution of chromic acid to the bleached negative, an orange image is obtained, which is very non-actinic, and the lines remain clear. Treatment with a 2 per cent sodium sulphide solution gives the greatest increase. QUINONE INTENSIFIER (Lumiére)—This has not come into general use, and the intensification is practically depen- dent on a change of colour of the image into a more non- actinic one; but some compound of silver and bromine is present. INTENSIFICATION 139 A. Quinone 5g 38 gr. Potassium bromide 25) 2 192 gr. Water 1000 ccm 16 oz. Or: B. Sodiumquinone sulphonate 10g 77 ox: Potassium bromide 25 ¢ 1 Zion: Water 1000 ccm 16 oz. The negative after treatment may look muddy. It should be briefly rinsed with water, and immersed in a 10 per cent solution of ammonia. The colour given by A is reddish brown, by B yellowish brown. Ammonia, with short action, gives great intensification, both images becoming dark brown; after 10 minutes’ action, the original colours are again formed with less intensification. The carbonates of sodium and potassium also turn the images brown, giving also great in- tensification. Hypo reduces the image without altering the colour of plates treated with A, but with B the final colour is a reddish-yellow. Sulphites or bisulphites convert the image of A into a greenish-brown; in the case of B, into a dark brown. An amidol developer acts like sulphite on A, but gives yellowish-black images with B. Bromo-Iop1pE oF Copper (Jenney).— Cupric sulphate 37.5 288 gr. Water 500 ccm 8 oz. When dissolved, add: Potassium iodide og 69 gr. Potassium bromide 23g LL eK. Water 500 ccm 8 oz. A slight precipitate of copper iodide is formed, which should be filtered out. The negative should be immersed in the solu- tion until bleached to a bright yellow colour, which takes from 5 to 15 minutes, and then well washed and immersed in a saturated solution of sodium sulphite to which a few 140 PHOTOGRAPHIC FACTS AND FORMULAS grains of silver nitrate have been added. This gives a brown- ish-black image. By applying a hydrochinon developer, a reddish image is obtained, and rodinal gives a brown. After intensification, the negative or print should be well washed in water. Both bleaching and redevelopment should be car- ried out in bright daylight. This is very rarely used and presents no particular advantages. Dye INTENSIFICATION.—Partially bleach the images in: Potassium ferricyanide 0.34 g Ammonium bichromate 0.068 g Glacial acetic acid 8.5 ccm Water 1000 ccm Then wash, and immerse in: Victoria green 0.26 g Safranin 0.52 g Glacial acetic acid 8.5 ccm Water 1000 ccm 2:5 gt. 0.5 gr. 64 min. 16 oz. 1.25 gr. 2.5 gr. 64 min. 16 oz. Dye for 30 to 120 seconds and wash for 5 minutes. zen we = = Reducers PoTASSIO-FERRIC OXALATE (Belitzski)—A very conveni- ent reducer, which may be kept as a stock solution in the dark, and repeatedly used until it turns yellow, which is a sign of exhaustion: . Potassium ferric oxalate 50 g 384 gr. Water 1000 ccm 16 oz. Dissolve, and add: Sodium sulphite, dry 20 g 154 gr. This forms a blood red solution, to which should be added: Oxalic acid, cryst. I5¢ 115 gr. Shake the solution until a bright green colour is formed, free from any tinge of yellow; then pour off from any undissolved crystals, and add: Hypo 250 g 4 oz. Shake until dissolved. It is preferable to soak the negative in water before apply- ing the reducer. Thorough washing should follow the reduc- tion. Instead of the potassium ferric oxalate, the following may be used: Ferric chloride 32:52 500 gr. Neutral potassium oxalate 62.5 ¢ 950 gr. This will make the above quantity of potassium ferric oxalate, and the potassium chloride formed is negligible. The reducer tends to attack the shadows more than the high-lights, there- fore, increases contrasts. HyYpocHLoritE AND ALumM (Debenham).—An excellent reducer, which can be locally used by immersing the negative in the solution and rubbing any part with a pad of absorbent cotton : 141 142 PHOTOGRAPHIC FACTS AND FORMULAS Chloride of lime 6g 46 er. Make into a paste with a little water, and add to: Sodium carbonate, dry 4.5¢ 34 er. Water 250 ccm 4 oz. Shake thoroughly, filter, and wash the filter with successive portions of water to make the total bulk of the filtrate 1000 ccm (16 oz.), then add: Chrome alum 4¢g 30 gr. Immerse the negative and rock the dish for a few minutes; then gently pass a pad of absorbent cotton, well wetted, over the surface. BICHROMATE.— Potassium bichromate 20 g 154 gr. Sulphuric acid 40 ccm 308 min. Water 1000 ccm 16 oz. Dissolve the bichromate, and add the acid. This has nothing particular to recommend it, and requires rather long washing to remove the yellow stain from the negative. PERMANGANATE (Namias).— Potassium permanganate 0.5 g 4 gr. Sulphuric acid 10 ccm 77 min. Water 1000 ccm 16 oz. It is preferable to mix this just before use, or stock solutions can be prepared by dissolving the permanganate in half the water, and the acid in the other half; the stock permanganate solution must be kept in the dark. This reducer acts evenly and can be used for prints as well as negatives. Should any brown stains appear, they may be removed by immersing the plates or prints in: Sodium sulphite, dry 75g 576 gr. Oxalic acid 30 g 230 gr. Water 1000 ccm 16 oz. Wash well after this bath. REDUCERS 143 IopIpDE AND Hypo (Lainer).—An extremely slow acting reducer, which is useful in the case of negatives generally fogged: Potassium iodide 10g 77 gr. Hypo 250 g 4 oz. Water 1000 ccm 16 oz. The negative should be immersed in this solution for from 8 to 10 hours, or until the desired reduction is attained, then well washed. Prints may also be reduced in the same way. Ceric SULPHATE (Lumiére).— Sulphuric acid 4 ccm 30 min. Water 200 ccm 3 0z. Add: i Ceric sulphate 10g TE Sik: Stir until dissolved, then add: ; Water to 1000 ccm 16 oz. For use mix 1 part with 9 parts of water. This reduces the contrasts, and the negatives should be well soaked in water prior to immersion in the solution. For overexposed dense negatives, mix the above stock solution with an equal volume of water, and immerse the negative dry; care must be exer- cised, as the action is very rapid. There is no liability to stain, and the solution may be used still more dilute for prints. Iopo-CYANIDE.—Extremely poisonous, but clean acting: Iodine 6g 46 er. Potassium iodide 18g 138 gr. Water 30 ccm Y oz. Rub the iodine and the iodide together in a mortar or graduate with a glass rod, add the water, and stir until complete solu- tion is obtained; then add: Water 970 ccm 154 oz. Potassium cyanide lg 7.7 gr. 144 PHOTOGRAPHIC FACTS AND FORMULAS This forms an excellent non-staining reducer for developed prints if diluted with 10 times its volume of water. MeERcuRY AND CYANIDE (Eder).—An extremely poisonous but non-staining reducer: Mercuric chloride 2.5¢ 19 gr. Water 1000 ccm 16 oz. Dissolve, and add: Potassium iodide 2.08 19 gr. Red mercuric iodide is precipitated, which is dissolved by the addition of : Potassium iodide | 5g 38 gr. This acts rapidly. It is suitable for developed prints if diluted with 10 parts of water. A variant of this is to replace the iodide with a like quantity of sodium carbonate crystals. Cupric CHLORIDE (Spiller) — A. Alum 100 g 134 oz. Cupric chloride 100 g 134 oz. Salt 200 g 34 oz. Hot water 1000 ccm 16 oz. Dissolve, and filter when cold. B. Saturated solution of salt. For use mix in equal volumes. When the negative is nearly sufficiently reduced, wash. This cannot be recommended, as the reducing action continues too much during the washing. A variation of the above (Fourtier) has been suggested: Cupric sulphate 5g 38 gr. Water 100 ccm 2 Gn. Dissolve, and add solution of potassium carbonate until no further precipitate is formed. Collect the precipitate on a filter, wash with several changes of water, and then dissolve in: Hydrochloric acid q. S. | Water 25 ccm YZ 02. REDUCERS 145 Enough acid should be used to dissolve the precipitate. To the clear solution add: Ammonia q.S. This forms a deep blue, clear solution to which should finally be added: Hypo 5¢g 38 gr. Water to 1000 ccm 16 oz. This is said to be particularly useful for local reduction of prints. The print should be well soaked in water, placed face up on a sheet of giass, and the reducer applied with a pad of absorbent cotton. The action is at once stopped by well washing with water. This has been but little used in practice, and the method of making is a roundabout way of making cupric chloride. An easier way would be to mix: Cupric sulphate 5) g 38 gr. Salt 2.35 g 18 gr. Water 100 ccm 2 02. then add enough ammonia to form a clear solution. Ferric chloride and sulphate either alone or with citric acid have been recommended as reducers; but they are extremely liable to stain the gelatine by the deposition of basic iron salts and should not be used. Hypo AND FERRICYANIDE (Farmer ).—This is prepared as wanted by adding a little 10 per cent solution of potassium ferricyanide to a 20 per cent plain solution of hypo. The quantity of ferricyanide to be added depends on the result desired; the weaker the solution, the more even the action, that is to say, the less the shadows are attacked. A pale yellow coloured mixture is best. The colour of the solution rapidly disappears in use, and this is a sign of exhaustion. A fresh mixture should be applied rather than allow an old one to act. The action of this bath is the conversion of some of 146 PHOTOGRAPHIC FACTS AND FORMULAS the silver into silver ferrocyanide, which dissolves in the hypo. Homolka suggested as a stable reducer: Potassium ferricyanide 50 g 384 gr. Sodium amido-acetate 200g 30z., 224 gr. Water 1000 ccm 16 oz. For use dilute with from 5 to 10 parts of water, and, when the desired reduction is attained, immerse the negative in an acid fixing bath. Another modification of Farmer’s reducer is the following (Haddon), which has the advantage of keeping well: Potassium ferricyanide 10g ve ie Ammonium sulphocyanide 20 g 154 gr. Water 1000 ccm 16 oz. The negative should be soaked in water before immersion. AMMONIUM PERSULPHATE.—The particular value of this reducer is that it attacks the densest parts of a negative more than the shadows, thus considerably reducing contrasts; but its action is much complicated by intentional or accidental additions, such as acid, chlorides, and iron salts, which may occur by keeping the solution or the use of ordinary tap water. A 5 per cent solution in distilled water should be made, and allowed to stand for 3 to 4 hours, or 15 ccm (105 min.) of 10 per cent solution of sulphuric acid, or 1 ccm (8 min.) of 5 per cent solution of ammonia iron alum added per liter (16 oz.). The following solution has been advised (Bennett), and can be kept for a considerable time in stock: Ammonium persulphate 125 ¢ 2 oz. Sodium sulphite, dry 10g 77 gr. Sulphuric acid 10 g 77 min. Water 1000 ccm 16 oz. For use dilute with from 4 to 8 parts of water, according to REDUCERS 147 the rapidity of action desired. Immersion in a 5 per cent solution of sodium sulphite has been recommended as a stop bath, but this is liable to cause red stains. The best plan is to wash rapidly. The following mixture (Puddy) acts on the shadows be- fore the high-lights: Ammonium persulphate 50 g 384 gr. Ammonium sulphocyanide 25 g 192 er. Water 1000 ccm 16 oz. The following solution acts on all densities nearly alike: A. Potassium permanganate 0.25 g 1.92 gr. Sulphuric acid, 10% solution 15 ccm 115 min. Water 1000 ccm 16 oz. B. Ammonium persulphate 25'e 192 gr. Water 1000 ccm 16 oz. For use mix 1 part A with 3 parts B. The separate solutions keep well, but should not be mixed until required. The time of reduction varies from 1 to 3 minutes, and greater control is obtained by diluting the mixture with an equal volume of water. As soon as the desired reduction is reached, immerse the negative in a 1 per cent solution of potassium metabisul- phite for 5 minutes, and wash. QUINONE REDUCER (Lumiére).—This acts like ammonium persulphate, that is, reduces the high-lights more than the shadows: Quinone 5g 38 gr. Sulphuric acid 20 ccm 154 min. Water 1000 ccm 16 oz. As soon as the desired reduction is reached, the plate should be immersed in a 2 per cent solution of sodium bisulphite, washed, and dried. Harmonisinc Harsu Necatives.—This method of re- ducing the over-dense parts of negatives has been replaced by 148 PHOTOGRAPHIC FACTS AND FORMULAS the use of the persulphate, but it is still valuable. The nega- tive should be immersed in: Hydrochloric acid 25 ccm 192 min. Potassium bichromate 8g 61 gr. Alum 40¢g 307 gr. Water 1000 ccm 16 oz. Leave until bleached through to the glass, then thoroughly wash until all traces of yellow disappear. lt should then be developed with a slow acting developer, such as hydrochinon, about one-fourth the usual strength, and development con- tinued until, on examination of the negative from the glass side, it is seen that the shadows and half tones are fully developed, while the high lights still show white silver chlo- ride. The negatives should then be fixed and washed. This method is also useful for halated negatives. The following modified bleacher may be used: Chromic acid 5g 38 gr. Potassium bromide 10g 77 gr. Water 1000 ccm 16 oz. The method of using is as above, or, to hasten the removal of the yellow stain, apply a 2.5 per cent solution of potassium metabisulphite or sodium bisulphite. MECHANICAL Repuction.—This is a method but little practiced and rather dangerous, except in expert hands. It consists in local attrition of the gelatine, preferably with a chamois leather moistened with denatured alcohol (methylated spirit). Another abrasive has also been suggested (Baskett), and consists of a mixture of equal parts of terebene, olive oil, and metal polish. This is also used with chamois leather, and acts more quickly than the alcohol. After its use, the negative should be rubbed two or three times with benzol to remove the grease. Some commercial metal polishes may be used without any admixture, but, after shaking well, should be t for a minute or two for the coarser particles © Ni AP Kin 5) 4 Varnishes VARNISHES.—The increasing use of bromide and develop- ment papers instead of printing-out papers, and, in a minor degree, the general adoption of films by amateur workers, has rendered less obligatory the use of negative varnishes for the protection of the gelatine surface. In the case of celluloid films, it is obvious that the solvents used in the varnishes must not attack the celluloid; therefore, the aqueous varnishes are preferred, though they do not give so much protection as the others. Varnishes may be classified as “hot” and “cold” varnishes, the former being applied to a heated negative, while the latter may be applied to the cold negative. In the first case, the negatives should be warmed in front of a fire or over a gas or spirit burner until the glass is as hot as the back of the hand can comfortably bear. Hot VARNISHES.— Orange shellac 752g 576 gr. Gum sandarac 75g 576 gr. Alcohol, 96% 1000 ccm 16 oz. Castor oil 2 ccm 15 min. Allow the mixture to stand with frequent shaking until the resins have dissolved; then filter. There is frequently some trouble in clarifying varnishes, as the fine insoluble particles will not easily filter out. The remedy is to add about 2 per cent by weight of some inert powder, such as finely powdered pumice stone or tripoli, shake well, and filter. Another formula: Orange shellac 50 g 384 gr. Gum elemi I5¢g 115 gr. Alcohol 1000 ccm 16 oz. 150 Or: VARNISHES Gum mastic 8g Ether 250 ccm Gasoline 750 ccm 151 61 gr. 5 oz. Th oz: Not advisable, as the vapours are very explosive when mixed with air. Another: Gum sandarac 100 g Camphor 10g Venice turpentine: 10g Oil of lavender 20 ccm Alcohol 1000 cem Or: Orange shellac 200 g Gum sandarac 50 g Gum mastic 5g Gum dammar 5g Castor oil 5 ccm Alcohol 1000 ccm CoLp VARNISHES.—Aqueous shellac house) : Orange shellac 80 g Borax 20g Sodium carbonate, cryst. 20 g Glycerine 5 ccm Water 1000 ccm 768 gr. 77 gr. 77 gr. 154 min. 16 oz. 1536 gr. 384 gr. 38 gr. 38 gr. 38 min. 16 oz. varnish (Water- 614 gr. 154 gr. 154 gr. 38 gr. 16 oz. Dissolve the borax and soda in half the water, add the shellac, and boil until dissolved; then add the glycerine and enough water to make the total bulk, and filter when cold. @r: Bleached shellac 100 g Borax 25¢ Sodium carbonate, cryst. 6g 3/5) 0z: 192 gr. 46 gr. 152 PHOTOGRAPHIC FACTS AND FORMULAS Glycerine 3ccm 23 min. Water 1000 ccm 16 oz. The method of making is as above. Or: Bleached shellac 150 B00 2a haa Alcohol 300 ccm 5. 1/3/02, Dissolve, and add: Ammonia 225 ccm 4 oz. Glycerine 7 ccm 54 min. Warm water 1000 ccm 16 oz. The above are particularly suitable for films. When using bleached shellac, it is essential to procure freshly bleached lac, or that which has been kept under water, as, when exposed to the air, this loses its solubility to a great extent. Dichlor- hydrin is an excellent solvent for bleached shellac, when warmed, but this varnish cannot be used for films, as it dis- solves the celluloid. An excellent varnish (Valenta) is made as follows: Gum dammar 75g 576 gr. or Gum mastic 60 g 460 gr. Carbon tetrachloride 1000 ccm 16 oz. If the mastic is used, it is necessary to heat to obtain perfect solution. Both varnishes give hard surfaces, which take retouching well. Epichlorhydrin and dichlorhydrin have also been recom- mended (Valenta) as solvents for varnishes, but have found little use. The following are suitable formulas: Copal 20 g 154 er. Epichlorhydrin 70 ccm 1 oz. Digest on a water bath until dissolved, and add: Alcohol 770 ccm 11 oz. Epichlorhydrin 160 ccm 4 oz. Then filter. This gives a very hard film that dries quickly, VARNISHES | 1s) may be used either as a hot or cold varnish, and takes the retouching pencil well. MatTr VARNISHES.—These are generally used on the backs of negatives either to hold back certain parts in printing, or to facilitate working up with pencil or crayon: Gum sandarac, powdered 53 g 400 gr. Gum dammar l6g 120 gr. Ether 700 ccm 11% oz. Allow to stand with frequent shaking until dissolved, then filter, and add: Benzol 300 ccm 434 oz. and: Alcohol lto5ccm 7to 35 min. The quantity of alcohol determines to some extent the fine- ness of the matt grain. The following may also be used: Gum sandarac, powdered 722 504 gr. Ether 715 ccm 114 oz. Shake until dissolved, filter, and add: Toluol 285 ccm 44 oz. This does not give such fine grain as the former. For celluloid negatives the above varnishes with alcohol- ether solvents are not suitable, as the latter attacks the base. The following is suitable: Amber 25, 192 gr. Benzol 1000 ccm 16 oz. The amber should be added in fine pieces, and the mixture digested in a warm place for two or three days, with occa- sional shaking, until the resin dissolves, then filter. There is frequently trouble when making varnishes, from the gums and resins compacting into a solid mass at the bot- tom of the bottle. This may be avoided to a great extent by using a wide-mouth bottle and suspending the resins in a little bag of fine muslin at the top of the liquid. As the resins 154 PHOTOGRAPHIC FACTS AND FORMULAS dissolve, the solution sinks to the bottom of the bottle, and fresh solvent takes its place. This also frequently obviates the necessity of filtering. Another plan is to mix the resins with coarse glass grains or beads, about half the size of a grain of wheat. DEVARNISHING NEGATIVES.—Sometimes it becomes neces- sary to remove the varnish from negatives and this usually can be accomplished by soaking in strong alcohol, and then using gentle friction with a pad of absorbent cotton. It is preferable to use only just enough alcohol to cover the surface of the negative, and to apply two or three successive alcohol baths. A more energetic solvent is a 2 per cent solution of caustic potash, or soda, or ammonia in alcohol, which may be used for the first bath, and then followed by clean alcohol. PRINT VARNISH.—Sometimes used for brightening up matt surface papers: Gum sandarac 110¢g 134 oz. Benzol 400 ccm 6% oz. Acetone 400 ccm 64 oz. Alcohol, 90% 200 ccm 3 oz. Or Gum dammar 60 g 1 oz. Ether 500 ccm 8 oz. Benzol 500 ccm 8 oz. These may either be applied with a brush locally to the shadows or the prints floated face downwards on the varnish. BLack VARNISH.— Shellac 200 g 3 1/50, Denatured alcohol 1000 ccm 16 oz. Aniline black, spirit soluble I5¢ 115 gr. ALCOHOLIC CoLD VARNISHES (V alenta).— Gum sandarac 180 g 1382 gr. Alcohol, 96% ~ 1000 ccm 16 oz. VARNISHES 159 Oil of lavender 10 ccm 77 min. Or: Gum sandarac 100 g 768 gr. Benzol - 400 ccm 6Y4 oz. Acetone 400 ccm 6Y, oz. Alcohol, 96% 200 ccm 3% oz. CELLULOID OR ZAPON VARNISH.— Pyroxyline or celluloid scraps 20g 154 gr. Amy]l acetate 1000 ccm 16 oz. Allow to stand for some time with frequent shaking until solution take place, and then allow to stand three or four days to settle. This takes a very long time to dry. Or: Pyroxyline or celluloid scraps 12¢ oF are Amyl acetate 400 ccm 6 oz. Benzol 400 ccm 6 oz. Acetone 200 ccm S02! This is also suitable for prints. A 5 per cent solution of pyroxyline in equal volumes of amyl acetate and alcohol can be used to protect metal work, can be applied either with a brush or spray, and is quite invisible ; sometimes butyl acetate is used instead of the amyl compound. Greater adhesion is obtained with the following : Pyroxyline 3751S 288 gr. Shellac 37.58 288 er. Amy] acetate 500 ccm 8 oz. Benzol 250 ccm 4 oz. Methy! alcohol 250 ccm 4 oz. The film thus obtained is not so lasting as the plain pyroxyline varnish. Black varnish may be made by incorporating lamp black, when the varnish will be more or less matt, or by the use of spirit-soluble nigrosine, when glossy surfaces will be obtained. Any coloured varnish may be made by dissolving oil-soluble aniline dyes in the solvents. 156 PHOTOGRAPHIC FACTS AND FORMULAS CRYSTAL VARNISHES.—TLhese are sometimes used for lan- tern slides and transparencies: Gum dammar 125 ¢ 2 oz. Benzol 1000 ccm 16 oz. Or: Fused amber 125 ¢ 2 oz. Chloroform 1000 ccm 16 oz. Cor: Fused amber 200 g 3 0Z: Gum sandarac 300 g 4Y4 oz. Gum elemi 50 g 384 gr. Alcohol 1000 ccm 16 oz. Camphor 6g 46 er. RETOUCHING VARNISHES.—Since the gelatine film, as well as many of the varnishes, will not take kindly to the retouch- ing pencil, it is customary to apply locally a retouching varnish or medium which leaves a surface with a slight tooth. These should be applied in very small quantities, a drop or two, gently rubbed with a circular motion with the finger tip over the part to be retouched, and then allowed to dry: Gum dammar 20 g 96 gr. Turpentine, refined 100 ccm Loz: Or: Powdered resin 12.5.2 60 gr. Turpentine, refined 100 ccm 1 oz. 6ors Gum dammar 6.6 g 32 oe: Turpentine, refined 50 ccm YZ oz. Benzol 50 ccm 4 oz. Oil of lavender 50 drops 10 drops Or: Gum dammar 20 g 154 gr. Venice turpentine 10g 77 gr. VARNISHES 157 Turpentine 1000 ccm 16 oz. Nitrobenzol 100ccm_ 1 0z., 288 min. ReEtToucHING Mepium.— Pure American turpentine 43ccm 1Y4 oz. Oil of spike 14.2 ccm YZ oz. Pale resin 28.3 g 1 oz. Raw linseed oil 0.5 ccm 8 min. Terebene 1.2 ccm 20 min. -Amyl acetate 7 ccm Y4 oz. If the solution is too thick, dilute with turpentine. Apply as little as possible with the finger tip. BLocKkinc-ouT MEepIumM.— Gum sandarac 500 g 8 oz. Denatured alcohol 1000 ccm 16 oz. Dissolve by allowing to stand in a warm place with constant stirring, carefully decant from the residue, and add lamp black to give a suitable consistency. FIXATIVE FOR CRAYON OR PASTEL WorkK.—This also forms a good varnish for prints: Mastic 8.3 g 64 gr. Amy] acetate 500 ccm 8 oz. Dissolve with constant stirring, allow to stand some hours to settle, and mix with: Celluloid Pe 18.5 gr. Amy] acetate 500 ccm 8 oz. This should be applied with a spray diffuser. STRIPPING Fitms.—The film can be easily stripped from negatives by one of the following processes. First, lay the negative face up on a smooth support, and cut right through the gelatine down to the glass with a sharp knife, about one- eighth of an inch from the edges. Then level the plate, and pour on it a little of the following solution: Glycerine 37.5 ccm 288 min. 158 PHOTOGRAPHIC FACTS AND FORMULAS Water 37.5 ccm 288 min. Hydrofluoric acid 37.5 ccm 288 min. Denatured alcohol to 1000 ccm 16 oz. Spread the solution with a brush or spill of paper, and allow to soak for about 5 minutes. Then try and strip the narrow cut edges; if these can be easily removed, the work may be proceeded with; if not, the plate should be left a little longer. When the film is loose, as shown by the above test, pour off the liquid carefully, taking care not to let the film slip. Pour on some of the above solution without the acid, leave for 2 or 3 minutes, and then drain this off. Gently place a piece of smooth waxed paper or thin celluloid over the negative, and lightly squeegee into contact; on lifting the paper, the film will be removed with it, and can be transferred to another support. Great care must be taken in the use of the above solution, as it attacks the fingers and all glass. It is better either to make up the stock solution without the hydrofluoric acid and add this just before use, or to omit the acid alto- gether, and use instead: Sodium fluoride 30 g 230 gr. or Potassium fluoride 44¢ 337 gr. Add just before use: Nitric acid 75 ccm 576 min. If the gelatine skin is to be kept as a film, it should first be coated rather thickly with enamel collodion, made as follows: Pyroxyline 30 g 230 gr. Alcohol 500 ccm 8 oz. Ether 500 ccm 8 oz. Castor oil 20 ccm 154 min. Allow to dry thoroughly before applying the stripping fluid. In order to obviate the use of the fluorides, the following may also be used with success: Potassium carbonate 100 g 770 gr. VARNISHES 159 Formaldehyde 100 ccm 770 min. Glycerine 100 ccm 770 min. Denatured alcohol (meth. spirit ) 300 ccm 434 oz. Water to 1000 ccm 16 oz. The carbonate should be dissolved in the glycerine, and the water and other ingredients added... This solution is rather slower than the hydrofluoric acid; it can be used in a dish and allowed to act for 20 to 30 minutes. When the film proves to be loosened, pour off the solution, replace with a mixture of 4 parts of alcohol and 6 parts water, and leave for 5 to 10 minutes; then lift the plate out, drain, and strip the film as outlined above. Silver Printing Processes CoLLoDIO-CHLORIDE PRINTING-OUT EmMuLsion.—The va- rious formulas have been calculated for a total bulk of 1000 ccm (16 oz.). The correct method of making the emul- sion is to prepare the collodion by dissolving the pyroxyline in the alcohol and ether, by first pouring the former on to the pyroxyline and shaking until it is thoroughly saturated, and then adding the ether. Absolute alcohol should be used, and pure methyl alcohol may replace ordinary ethyl alcohol, but the alcohol must be free from pyridine bases, which cause dis- coloration of the coated paper. As little water as possible should be used to dissolve the chlorides, acid, and silver, and such solutions should be mixed with alcohol prior to addition to the collodion. It is often necessary to allow the raw col- lodion to stand for some time for any impurities or undis- solved fibers to settle down; but the best results are obtained with the specially prepared pyroxylines, sold under the name of celloidin or pyralin. The best chlorides are those of strontium and lithium, and only the crystalline salt of stron- tium should be used. The lithium chloride should be weighed out and dissolved in alcohol as soon as purchased, so as to make a 10 per cent solution, as it is very hygroscopic and absorbs varying quantities of moisture. These two chlorides are the most satisfactory in practice. Taking a typical formula (Hanneke), the following is the best method of mixing: Pyroxyline 26 g 200 gr. Alcohol 565 ccm 9 oz. Ether 425 ccm 634 oz. 160 SEVER PRINTING PROCHS SHS 161 Add 500 cem (8 0z.) alcohol to the pyroxylin, and shake well ; then add the ether. Lithium chloride, cryst. 3g 23 gr. Citric acid 5g 38.5 gr. Water 5 ccm 38 min. Dissolve by the aid of heat, and add: Alcohol 30 ccm 230 min. Then add to the collodion gradually with continual shaking, so as not to precipitate any of the pyroxyline: Silver nitrate 24 ¢ 184 er. Water 30 ccm 230 min. Glycerine 7 ccm 54 min. Heat gently until the silver dissolves, and add: Alcohol So cen 270 min. If any silver is thrown out in crystals, gently heat until dis- solved, and add gradually while hot in small quantities to the salted collodion, shaking well after each addition. Allow to stand to ripen, and then coat. The longer the emulsion stands. the faster the printing and the softer the gradation of the prints. The following formulas are those of the leading experimenters and should be compounded on the above lines. Niederstadt.— Pyroxyline 28 g PANS) (oy Alcohol 630 ccm 10 oz. Ether 350 ccm 534 oz. Citric acid PA dUS) 16.5 gr. Lithium chloride, cryst. Zula, lorem: Glycerine 7 ccm 54 min. Silver nitrate 20 g 154 gr. Water 10 ccm 77 min. Geldmacher.— Pyroxyline 258 192 gr. Alcohol 590 ccm 9% oz. 162 PHOTOGRAPHIC FACTS AND FORMULAS Ether 400 ccm 64 oz Citric acid 5g 38.5 gr Strontium chloride, cryst. 5g 38.5 gr Silver nitrate 20 g 154 gr Castor oil 4 ccm 31 min Water 20 ccm 154 min. When castor oil is advised, which is used to keep the paper supple and prevent it from cracking, it should be mixed with an equal volume of alcohol before adding to the emulsion, and should be added last. Wall.— Pyroxyline Alcohol Ether Citric acid Lithium citrate Lithium chloride, cryst. Strontium chloride, cryst. Silver nitrate Water Glycerine Monckhoven.— Pyroxyline Alcohol Ether Citric acid Magnesium chloride, cryst. 3.1¢g Silver nitrate Water Ammonia Add the ammonia to the solution of citric acid. This was specially recommended for transparencies. 20 g 154 gr. 535 ccm 84 oz. 400 ccm 6Y4 oz. 2.52 19 gr. 2:5\¢ 19 gr. 2.5¢g 19 gr. BW 19 gr. 20 g 154 gr. 20 ccm 154 min. 1 ccm 8 min. I5¢g 115 gr. 662ccm 100z., 388 min. 500 ccm 8 oz. l.lg 8Y4 gr. 24 gr. 10g 77 gr. 10 ccm 77 min. 0.6 ccm 5 min. SILVER PRINTING PROCESSES V alenta.— Pyroxyline Alcohol Ether Citric acid Lithium chloride, cryst. Strontium chloride, cryst. Silver nitrate Water Glycerine Belhttzski— Pyroxyline Alcohol Ether Citric acid Lithium chloride, dry Strontium chloride, cryst. Silver nitrate Water Glycerine V ollenbruch— Pyroxyline Alcohol Ether Citric acid Lithium chloride, cryst. Strontium chloride, cryst. Silver nitrate Water Glycerine Anon.— Pyroxyline Alcohol 20 g 154 gr. 500 ccm 8 oz. 500 ccm 8 oz. 17g 13 gr. l7¢g 13 gr. 34¢ 26 gr. L9¢ 58 ger. 20 ccm 154 min. 2 ccm 16 min. 22 2 169 gr. 600 ccm 9oz., 388 min. 400 ccm 64 oz. 22g, 169 gr. 1 25\¢ OY gr. 375g 29 er. 22.3 g 171 gr. 15 ccm 115 min. 20 ccm 154 min. 24¢g 184 gr. 500 ccm 8 oz. 500 ccm 8 oz. 8g 62 gr. 2¢g 15.5 gr. 4¢ 31 gr. 28 g 214.5 gr. 34 ccm 260 min. 13 ccm 100 min. 8.33 g 65 gr. 500 ccm 8 oz. 163 Ether Citric acid Calcium chloride, cryst. Silver nitrate Pyroxyline Alcohol Ether Citric acid Zinc chloride Silver nitrate Water Glycerine Bolton— Pyroxyline Alcohol Ether Citric acid Lithium chloride, cryst. Silver nitrate Hanneke.— Pyroxyline Alcohol Ether Citric acid Calcium chloride, cryst. Silver nitrate Water Glycerine Castor oil Hanneke.— Pyroxyline 500 ccm 8 oz. Pies WY 2g 16 gr. 10.5 ¢ 81 gr. one 269 gr. 17.6¢ 135 of: 565 ccm 9 oz. 424 ccm 7 02: 13g 10 gr. 3.6 ¢ 2734 gr. 17.6¢ 135 gr. 10 ccm 77 min. 2ccm 15 min. 23¢ 177 gr. 490 ccm 7 0z., 400 min. 490 ccm 7 o0z., 400 min. 4¢ 31 gr. 8g 62 er. 18¢ 138 gr. 24.82 19t or. 540 ccm 8Y4 oz. 460 ccm 74 oz. as 38 er. 4¢ 31's. 25.2 192 gr. 34 ccm 260 min. 5 ccm 38 min. 5 ccm 38 min. 26g 200 gr. 164 PHOTOGRAPHIC FACTS AND FORMULAS Specially recommended for transparencies. Moss.— SEVER PRIN TING PROCESSES Alcohol Ether Citric acid Lithium chloride, cryst. Silver nitrate Water Glycerine Castor oil Hanneke.— Pyroxyline Alcohol Ether Citric acid Lithium chloride, cryst. Strontium chloride, cryst. Silver nitrate Water Glycerine Castor oil Hanneke.— Pyroxyline Alcohol Ether Citric acid Calcium chloride, cryst. Silver nitrate Water Glycerine Castor oil Pyroxyline Alcohol 500 ccm 435 ccm 30 g 500 ccm 24¢ 500 ccm 4 ccm This is intended for matt surface paper. Hanneke.— 32s 425 ccm 8 Oz. 7 OZ. 38 gr. 23) or. 185 gr. 270 min. 50 min. 50 min. 230 gr. 8 oz. 7 V4 OZ. 38 gr. 15¥Y er. ian 184 gr. 274 min. 46 min. 46 min. 185 gr. 8 oz. “AL Ovas 38 gr. 31 gr. 197 or: 236 min. 31 min. 31 min. 245 gr. 63% oz. 165 166 PHOTOGRAPHIC FACTS AND FORMULAS Ether Citric acid Calcium chloride, cryst. Silver nitrate Water 575 ccm 6.25 g 6.25 g 30 g 20 ccm Specially suitable for transparencies. Cobenzal.— Pyroxyline Alcohol Ether Citric acid Lithium chloride, cryst. Ammonia Silver nitrate Glycerine Cobenzal.— Pyroxyline Alcohol Ether Citric acid Lithium chloride, cryst. Ammonia Silver nitrate Water 40 g 500 ccm 500 ccm 4.75 2 45 5.5 ccm 27 g 10 ccm 40 g 500 ccm 500 ccm 6.62 g toe 7.5 ccm 20 g 10 ccm This is intended for matt surface paper. Sutton.— Pyroxyline Alcohol Ether Citric acid Lithium chloride, dry Silver nitrate 40 ¢ 500 ccm 500 ccm 13.3 ¢ 43¢ a3/3'2 91% oz. 48 gr. 48 gr. 230 gr. 154 min. 307 gr. 8 oz. 8 oz. 36 gr. 31 gr. 42 min. 207 gr. 77 min. 307 gr. 8 oz. 8 oz. 50 gr. OY, gr. 58 min. 154 gr. 77 min. 307 gr. 8 oz. 8 oz. 102 gr. 33 gr. 255 gr. SILVER PRINTING PROCESSES Water 5 ccm 38 min. Castor oil 1 ccm 8 min. Krippendorff — Pyroxyline Zio. 161 gr. Alcohol 600 ccm OY oz. Ether 400 ccm 634 oz. Citric acid 2) ie 19 gr. Calcium chloride, cryst. 2:52 19 gr. -oilver, nitrate | >’ 2Zlg 161 gr. V alenta.— Pyroxyline 22:52 165 gr. Alcohol | 500 ccm 8 oz. Ether 500 ccm 8 oz. Citric acid 18g 138 gr. Calcium chloride, dry 14¢ 10 gr. Dissolve the above, and add: Silver nitrate 3g 235) or. Ammonia q. Ss. q. Ss. 167 Powder the silver, add just enough ammonia to form a clear solution, and add alcohol 30 ccm (230 min). ‘Then add: Silver nitrate I5¢ US es ws Water 5 ccm 38 min. Glycerine 2.5 ccm 19 min. Alcohol 70 ccm 538 min. Dissolve by heat. This is specially suitable for platinum toning, and gives sepia prints without toning. Liesegang.— Pyroxyline 24¢ 184 gr. Alcohol 500 ccm 8 oz. Ether 500 ccm 8 oz. Lithium chloride, cryst. 3¢ Zo2r: Silver nitrate 24¢ 184 gr. Ashman.— Pyroxyline Alcohol Ether Citric acid Strontium chloride, cryst. Silver nitrate Cronenberg.— Pyroxyline Alcohol Ether Citric acid Lithium chloride, cryst. Strontium chloride, cryst. Silver nitrate Water Lainer.— Pyroxyline Alcohol Ether Citric acid Lithium chloride, cryst. Strontium chloride, cryst. Silver nitrate Water Castor oil Van Norath.— Pyroxyline Alcohol Ether Citric acid Ammonium chloride Silver nitrate 19¢ 500 ccm 500 ccm 2.8¢ 37 19g 2g 600 ccm 400 ccm 20 g 600 ccm 400 ccm 14.5 ¢ 625 ccm 325 ccm 7.22 10g 19¢g 168 PHOTOGRAPHIC FACTS AND FORMULAS 146 gr. 8 Oz. 8 Oz. 224 gr. 284 gr. 146 gr. 192 gr. OY oz. 634 oz. 31 er: ei. 23 gr. 154 gr. 115 min. 154 gr. OY oz. 6%4 oz. 38 gr. 19 gr. 19 gr. 154 gr. 154 min. 31 min. 111 gr. 10 oz. 6 oz. 55 gr. 77 gf. 146 gr. SICVvEk | PRINTING PROCESSES 169 Water 16 ccm 123 min. Glycerine 8 ccm 62 min. Eder.— Pyroxyline 21g SZ ion: Alcohol 600 ccm 9Y4 oz. Ether 400 ccm 6Y, oz. Citric acid 5g 38 gr. Lithium chloride, cryst. Ses eS) ox: Strontium chloride, cryst. ag 23 oY: Silver nitrate l4¢ 107¥Y gr. Water 10 ccm 77 min. Glycerine 4 ccm 31 min. V alenta.— Pyroxyline 2253 VAS) tae: Alcohol 500 ccm 8 0z. Ether 500 ccm 8 oz. Citric acid 18g 138 gr. Calcium chloride, cryst. 14¢ 10.7 er. Silver nitrate 18¢ 138 gr. Water 10 ccm 77 rin. Glycerine 2a eeu 19 min. FLATTENING.—Collodion papers when toned may need to be flattened by immersing them one by one face down in a smooth-bottomed tray containing a very little water. As soon as all are in, drain off the water and let the tray stand in a slanting position for ten minutes before toning. If this is not done, the prints may curl up badly. Subsequent manipu- iavionsvace the sameas for P.O. P.- SILVER PHOSPHATE PAPER.—These are very rapid-printing papers with long scale of gradation. The phosphate emul- sions can be used alone or mixed with citro-chloride emulsions to increase the speed: 170 PHOTOGRAPHIC FACTS: AND FORMULAS Collodion, 4% 2100 ccm 33Y4 oz. Ether 360 ccm 534 oz. Add: Phosphoric acid, sp. gr. 1.725 10ccm 77 min. Then add: Citric acid 80 g 614 min. Alcohol 140 ccm 21% oz. Shake well, and add: Silver nitrate 100 g 770 gr. Hot water 115 ccm 883 min. Alcohol 200 ccm 3% oz. Shake thoroughly, and add: Lithium carbonate 14.5¢ 111 gr. Till there is no longer any effervescence, and add: Glycerine 15 ccm 115 gr. Alcohol 15 ccm 115 gr. Calcium chromate, 10% sol. 0.5 ccm 3.8 gr. This paper may be toned in the ordinary way or, if treated with 2.5 per cent solution of citric acid, till the yellow colour disappears and then washed, it gives rich brown tones on fixation in a hypo plus sulphite bath. Or the following may be used: Collodion, 344% 1960 ccm 31% oz. Phosphoric acid 9 ccm 69 min. Citric acid 772 591 gr. Alcohol 130 ccm 998 min. Shake well, and add: Silver nitrate 100 g 770 gr. Ammonia q.S. q. S. Coarsely powder the silver, add very cautiously enough am- monia to form a clear solution, and add: Alcohol 320 ccm 5 oz. SILVER PRINTING PROCESSES 17s Add this in small quantities to the collodion, shaking thor- oughly after each addition, and add: Ether 320 ccm 5 oz. Glycerine 13 ccm 100 min. Alcohol 13 ccm 100 min. The addition of calcium chromate is not necessary with this emulsion, as it gives sufficiently brilliant prints without. This paper is specially suitable for very brief exposures and devel- opment with a metol-citric acid developer. SILVER BROMIDE PRINTING-OUT PAPER.—This gives a very rapid-printing paper with long scale of gradation: Citric acid 100 g 768 gr. Alcohol 400 ccm 6Y, oz. Dissolve, and add: Collodion, 3% 5000 ccm | 80 oz. Then add: Strontium bromide, anhydrous 16g [23 )en: Glycerine 20 ccm 154 min. Alcohol 30 ccm 230 min. After mixing, add: Silver nitrate 100 g 768 gr. Hot water q. S. q. S. Alcohol 400 ccm 634 oz. Dissolve the silver in as little water as possible, then add the alcohol, and add to the bromised collodion in small quantities, shaking well after each addition. Finally, add: Ether 800 ccm 13 oz. Allow the emulsion to stand a few minutes, and filter through glass wool. This emulsion must be mixed by orange light. It is about three times faster than commercial chloride papers and tones well in the usual baths, but is only suitable for contrasty negatives. The addition of calcium chromate gives more contrast. Even better results are obtained by replacing 172 PHOTOGRAPHIC FACTS AND FORMULAS some of the strontium bromide with anhydrous calcium chloride, thus using in the above: Strontium bromide, anhydrous 10.6 g 81.3 gr. Calcium chloride, anhydrous 3.3¢ 25.4 gr. If a still harder working paper is required, replace the calcium salt by uranyl chloride, 10 g (768 gr.). All these papers tone well in the usual baths, and lose but little in the fixing bath. Manipulation—The phosphate and bromide papers are used in the same way as ordinary printing-out papers. But, in consequence of their high sensitiveness, they should be manipulated in a yellow light, and extreme care should be taken when examining the prints during printing, otherwise a tint will be obtained over that portion of the paper exam- ined. They both tone well either in the separate or combined baths, but are specially suitable for sepia tones by platinum toning. _ Printing-Out Papers GELATINO-CHLORIDE OR PrINTING-OuT Paper. — This paper, also called P. O. P. in England, is coated with an emulsion of silver chloride with an organic salt of silver and excess of silver nitrate in gelatine. The greater the ratio of organic salt, the more vigorous the prints. Many formulas have been suggested, some of which either give poor results or the paper has poor keeping properties, and they are, there- fore, omitted. The following will be found reliable. Abney.— A. Sodium chloride 13.5¢ 104 gr. Citric acid 8.5 g 65 gr. Potassium citrate 11S)35) 119 gr. Water 500 ccm 8 02. Gelatine 54g 415 er. B. Silver nitrate SL SO ar. Water 400 ccm 6Y4 oz. C. Chrome alum 0.6 ¢ 4.5 gr. Water 100 ccm 1¥4 oz. Soak the gelatine in the water for 30 minutes, melt at 50° C. (122° F.), and add B at the same temperature, stirring slowly; finally, add C. This gives a slow printing paper with very long scale of gradation and is most suitable for the combined bath. Barker.— A. Ammonium chloride 29's ZO a ot Rochelle salts 59¢ 45.25 gr. Citric acid 8.1¢g 62 ger. Alum ied 1S) sea Gelatine 136 g 1044 gr. 173 174 PHOTOGRAPHIC FACTS AND FORMULAS . Water 500 ccm 8 oz. B. Silver nitrate 32 g 245 er. Water 500 ccm 8 oz. The gelatine should be equal parts of soft and hard. Mix as above. Vigorous printing, suitable for sulphocyanide and combined baths. , W ade.— A. Ammonium chloride 24¢ 18.5 gr. Rochelle salts 24¢ 18.5 gr. Citric acid 15.6¢ 119.8 gr. Alum 5.2¢ 40 er. Gelatine 32 g 245 er. Water 500 ccm 8 oz. B. Silver nitrate 96 g 737 gr. Water 500 ccm 8 oz. Mix as above. Vigorous but rather slow printing, suitable for both baths. Beadle.— A. Ammonium chloride 3.5 ¢ 26.9 gr. Rochelle salts = as 38 gr. Citric acid 20 g 154 gr. Alum 5g 38 gr. Water 500 ccm 8 oz. B. Silver nitrate 57.5 288 gr. Water 500 ccm 8 oz. Mix as above. Vigorous and fast printing, suitable for both baths. Ashman.— A. Ammonium chloride 42¢ 32.3 gr. Tartaric acid 4¢ 30.7 gr. Sodium carbonate, cryst. q. Ss. q.s. Citric acid 5¢g 38 gr. Ammonium citrate I5¢g 115 gr. PRINTING-OUT PAPERS 175 Gelatine 127 g 975 gr. Water 500 ccm 8 oz. B. Silver nitrate 30.6 g Zao: Water 500 ccm 8 oz. Dissolve the tartaric acid in a little water, and neutralise with sodium carbonate; then mix as above. Very fast and vigor- ous printing, and suitable for both baths. V alenta.— A. Amonium chloride . 2.82 21.5 or Gelatine 96 g 737 gr. Water 750 ccm 12 oz. B. Tartaric acid 2.8¢ 21. S.en: Sodium bicarbonate 14¢ 10.75 gr. Alum 18¢ 13.8 gr. Water 125 ccm 202: C. Silver nitrate 32 g 245 gr. Water 125 ccm 2'0z. Citric acid 8g 61 gr. Dissolve the tartaric acid and the alum in the water, and add mee soda... Fleat ‘A and B to 50° C. (1227 F.), and add €, heated to the same temperature, slowly with constant stirring. Vigorous, rapid printing, suitable for both baths. All the above emulsions can be made much faster printing by allowing them to stand about 1 hour at the mixing tem- perature before coating. These emulsions give glossy sur- faces, when coated on glossy baryta paper. If matt surface papers are required, the quantity of gelatine should be re- duced by about one-sixth, and a matt surface paper used for the raw stock. A very good matt surface can be obtained by the addition of an ammoniacal solution of pale yellow resin, made as follows: Ammonia 20 ccm 153 min. Water 80 ccm 615 min. 176 PHOTOGRAPHIC FACTS AND FORMULAS Add: Yellow resin 4g Jl ee Then heat the mixture until the resin is dissolved, adding more ammonia if necessary. Allow to cool, and add: Gelatine 4g 31 gr. Water 40 ccm 307 min. Neutralise with hydrochloric acid, and add saturated solu- tion of citric acid until the mixture has a distinct acid reac- tion. This should be added to the emulsion, allowance being made for its bulk by reducing the quantity of water used in making up the emulsion. To obtain hard, contrasty printing papers, add to any of the above emulsions from 0.7 to 3.5 per cent of the following solution : Chromic acid 25¢g 192 gr. Water 100 ccm 770 min. When dissolved, add: Calcium carbonate, pure q.s. with constant stirring until the mixture remains turbid, then filter, and wash the filter with: Water to make 250 ccm 4 oz. This forms approximately a 10 per cent solution of calcium chromate. The more of this is added to the emulsion, the harder it works. PRINTING should be carried on until the high lights show a decided tinge; then the prints should be immersed in: Salt 100 g 114 oz. Sodium carbonate, dry 50 g 3% OZ. Water 1000 ccm 16 oz. Bathe for 5 minutes, rinse for 5 minutes, and tone. TONING may be effected either with an alkaline, a sulpho- cyanide, or a combined bath. The first-named does not give PRINTING-OUT) PAPERS Wi, such satisfactory results as the others. The following are typical formulas: Chloride of gold lg LF Se Sodium acetate, or borax 30 g 250) er: or Sodium tungstate or phosphate 10¢ 77 gr. Boiling water | 1000 ccm 16 oz. Or: Borax i 20 g 154 gr. Sodium acetate 20 g 154 gr. Boiling water 1000 ccm 16 oz. Or: | Chloride of gold 0.25 ¢g PO2 ier: Chalk hig) 22 SA soy aso Chloride of lime 0.75 g 5.7 5/21 Water 1000 ccm 16 oz. For this bath the printing must be carried much further than usual, and the prints should be merely washed in water for 5 minutes prior to toning. Or: Chloride of gold 2¢g 15)gn: Sodium bicarbonate 30 g 230 gr. Water 1000 ccm 16 oz. This bath is very rapid in its action and gives blueish to violet-black tones, according to the depth of printing. An- other bath that gives very rich tones is: Chloride of gold 0.5¢ 3.8 gr. Sodium formate 60 g 460 er. Sodium carbonate 0.8¢ 6 gr. Water 1000 ccm 16 oz. The sulphocyanide bath gives better tones, as a rule, than the above. A normal formula is: Chloride of gold 0.25 g Zion: 178 PHOTOGRAPHIC FACTS AND FORMULAS Ammonium or potassium sulphocyanide 3.9 ¢g 30 gr. Boiling water 1000 ccm 16 oz. Dissolve the gold in half the water, add to the sulphocyanide dissolved in the remainder, and use when cold. A very con- venient stock solution can be made as follows: Potassium sulphocyanide 24¢ 184 gr. Water 400 ccm 634 oz. Heat to 98° C. (208° F.), and add slowly with constant stirring: Chloride of gold 8g 61 gr. Strontium chloride 80 g 614 gr. Water 400 ccm 6'4 oz. This should be heated to the same temperature. Allow to cool, filter, and wash the filter with: Water 200 ccm 2 oz. For use mix 1 part with 19 parts of water. The stock solu- tion must be kept in the dark. Sulphocyanide baths are rather apt to give double-toning, that is, blueish high lights with brown shadows. The following bath is free from this defect : Chloride of gold lg 7.7 gr. Salt 20 g 154 gr. Sodium sulphite, dry 0.5 ¢ 3.84 gr. Water 1000 ccm 16 oz. This should be allowed to stand for an hour before use. Red tones can also be obtained by the use of the following: Ammonium sulphocyanide 5g 38.5 gr. Potassium iodide 0.10to0.15¢ O.8to1.15 gr. Gold chloride 0.25 g 1.92 gr. Water 1000 ccm 16 oz. Combined toning and fixing baths have found much favour, as the final tone is easily determined, which is not the case PRINTING-OUT PAPERS 179 with the separate toning and fixing baths. An excellent formula and method of mixing was given by Valenta: Hypo 200 g 314 oz. Ammonium sulphocyanide 25g 192 er. Lead nitrate 10g 77 gr. _ Alum 20 g 154 gr. Water 500 ccm 8 oz. Dissolve the hypo in about three-fourths of the water, and add the sulphocyanide; then add the alum and lead nitrate dissolved in the remainder of the water. Heat the mixture to 50° C. (122° F.) for 10 minutes, allow to cool, and filter. For use, mix: Stock solution 500 ccm 8 oz. Water 500 ccm 8 oz. Gold chloride 08¢ 6.1 gr. The prints must be well washed prior to toning. Fix1nc.—The normal fixing bath, after any separate ton- ing bath, should be a 10 per cent solution of hypo, or an alkaline bath may be used, such as: Hypo 100 g LY oz. Sodium carbonate, dry 6.25 g 48 gr. Salt 12:5) ¢ 96 gr. Water 1000 ccm 16 oz. Or: Hypo 100 g 1Y4 oz. Sodium sulphite, dry WAS) 96 gr. Salt 12.5 ¢ 96 gr. Water 1000 ccm 16 oz. Keep the prints moving in the fixing bath for 10 minutes, and then wash. Occasionally, a second fixing bath is used as conducing to greater permanency. The tone of the prints is to a great extent dependent on the quantity of gold per area, although this, naturally, varies 180 PHOTOGRAPHIC FACTS AND FORMULAS with the character of the print, that is to say, the area of the dark parts of the image. The following will give a rough idea of the quantity of gold to be used for every 645 qcem (100 sq. in.): for red, 0.00324 g¢ (0.05 gr.); for reddish- brown, 0.005 g (0.075 gr.) ; for brown, 0.0065 g (0.10 gr.) ; for warm purple-brown, 0.01 g (0.15 gr.) ; for cold purple- brown, 0.0125 g (0.19 gr.); for cold purple-black, 0.025 g (0.38 gr.). PLATINUM TonING.—The tones obtained with gold range from reds to purples and browns. Colours ranging from sepia to black, without any trace of purple or red, are ob- tained with platinum as the toning agent. A suitable bath is: Potassium chloroplatinite 2g 15.4 gr. Dilute phosphoric acid 30 ccm 230 min. Water 1000 ccm 16 oz. The phosphoric acid may be replaced with dilute lactic acid, or acetic, tartaric, citric, oxalic acid in like quantity; or sulphuric acid, 10 ccm (77 min.), may be used. The above baths keep well and give pure whites. The following acts well when freshly prepared: Platinum perchloride 0.2 ¢ 1.54 gr. Sodium formate 6.3 g 48 er. Formic acid 1.2 ccm 9.2 mm Water 1000 ccm 16 oz. The following is also an excellent bath (Valenta) : Potassium chloroplatinite O.5tolg 3.8to7.6 gr. Metaphenylendiamine O.5tolg 38to7.6 er. Water 1000 ccm 16 oz. For all platinum baths, the prints must be first immersed in a 10 per cent solution of common salt for 5 minutes, then rinsed; after toning, the prints should be immersed in: Salt 100 g 20g: Sodium carbonate, dry 50 g 1 oz. PRINTING-OUT PAPERS 181 Water | 1000 ccm 20 oz. Bathe for 5 minutes, and then fix in 10 per cent solution of hypo. Namias.— Platinum perchloride LU Mes 8.5 gr. Stannous chloride lg FUT as Water 50 ccm 1 oz. Dissolve the platinum in half the water, the tin salt in the remainder, and mix the two solutions; then add: Hydrochloric acid 5 ccm 384 min. Oxalic acid 10g 77 gr. Water to 1000 ccm 16 oz. The prints should be washed in salt and water, and then in plain water before toning. CoMBINED PLATINUM AND GoLp Toninc.—The use of gold and platinum gives pure black or blue-black tones, the blue tinge being dependent on the depth of toning with the gold. Print deeply, and immerse the print in: Salt 252 192 gr. Sodium carbonate, dry 72S) 25 19 gr. Water 1000 ccm 16 oz. Leave for 5 minutes, wash well, and tone in: Borax 10g 77 gr. Sodium acetate, fused 10g 77 gr. Gold chloride 0.5¢ 3.8 gr. Water 1000 ccm 16 oz. Then wash, and tone in: Potassium chloroplatinite 0.7 ¢g 5.4 gr. Citric acid 10g 77 gr. Salt l6g 123 gr. Water 1000 ccm 16 oz. Tone until the prints look purple-black; then wash, and fix. 182 PHOTOGRAPHIC FACTS AND FORMULAS Another process with a mercury salt, which is open to ques- tion as to permanency, is to tone with: Potassium chloroplatinite 3¢g 23 gr. Salt 20 g 154 gr. Water 1000 ccm 16 oz. Tone until a blue-violet colour is obtained; then rinse well, and tone again in: Mercury sulphocyanide 20 g 154 gr. Citric acid 20 g 154 gr. Gold chloride 3g 25 Se. Water 1000 ccm 16 oz. Wash well, and fix as usual. GoLp AND UrANiIuM.—This also gives blackish prints: Gold chloride 0.25 g 1,9 gr. Uranium nitrate 0.25 g 1.9 gr. Salt 4g 31 gr. Sodium acetate 4g 31 gr. Water 1000 ccm 16 oz. Dissolve the gold and uranium, and add sufficient sodium carbonate to neutralise the solution; then add the other in- gredients. Printing must be rather deep; a salt bath should be used prior to toning, and an alkaline bath for fixing. Uranium Toninc.—This gives more or less red tones, the so-called red chalk or Bartolozzi colours. Print rather deeply, immerse in a salt bath, wash well, and tone in: Uranium nitrate 2¢g 15.4 gr. Thiosinamine 10¢g 77 gr. Water 1000 ccm 16 oz. Wash thoroughly, and fix. PALLADIUM ToniInGc.—This gives sepias and warm blacks but is not generally used. Potassium chloropalladite 0.5 g 3.8 gr. Salt 5g 38.5 gr. PRINTING-OUT PAPERS 183 Sodium acetate 5g 38.5 gr. Water 1000 ccm 16 oz. Printing must be deep; the salt bath prior to toning, and the alkaline fixing bath must be used. DEVELOPING PRINTING-oUT Paper.—If a printing-out paper be exposed for a very short time, so that only a very faint image is visible, it is possible to develop it to full inten- sity. The first processes were practically physical intensifica- tion methods, based on the precipitation of the free silver nitrate in the emulsion on the image. As a rule, unpleasant greenish tones were obtained. A typical formula is: Gallic acid 5¢g 38.4 gr. Sodium acetate 10g 77 gr. Glacial acetic acid 10 ccm 7/7 min. Water 1000 ccm 16 oz. This should be diluted with from 5 to 10 parts of water before use. A more satisfactory result is obtained with the following : A. Hydrochinon 10¢g Tf St: Alcohol 100 ccm 770 min. B. Sodium sulphite, dry 10g 77 gr. Citric acid lg 77 Si: Water 100 ccm 770 min. For use mix 5 parts each of A and B, and add 100 parts water. This works slowly, about 15 minutes being required for full development. The prints should be immersed in a 5 per cent solution of salt after development, well washed, and then toned. Pyrocatechin gives more violet tones than the above; pyrogallol works much more quickly: Sodium sulphite, dry 50 g 384 gr. Citric acid 10g 77 gr. Pyrogallol 10g JF 2%: Water 1000 ccm 16 oz. 184 PHOTOGRAPHIC FACTS AND FORMULAS Paramidophenol may also be used (Hanneke) : Paramidophenol hydrochloride 7g 54 gr. Citric acid 8g 61 gr. Sodium sulphite, dry 25¢ 192 gr. Water 1000 ccm 16 oz. Liesegang’s aristogen for the same purpose was said to be: Hydrochinon 10g 77 gr. Sodium acetate 10g 77 gr. Citric acid 10g 77 gr. Sodium sulphite, sat. sol. 500 ccm 8 oz. Water | 500 ccm 8 oz. It was discovered by Wilson that an alkaline developer could be used, if the print were first immersed in potassium bro- mide solution, so as to convert the whole of the silver salts into bromide. After exposure the print should be immersed, without washing, in a 10 per cent solution of potassium bromide for 5 to 10 minutes, then well washed, and treated with the following: A. Hydrochinon 18.2 g 140 ger. Sodium sulphite, dry 45¢ 35 gr. Sulphurous acid 9 ecm 70 min. Potassium bromide 45¢ 35 gr: Water 1000 ccm 16 oz. B. Caustic soda 9g 70 gr. Sodium sulphite, dry 9g 70 gr. Water 1000 ccm 16 oz. C. Ammonium carbonate 36.5 g 280 gr. Ammonium bromide 36.5 g 280 gr. Water 1000 ccm 16 oz. Mix in equal parts before use. The following is simpler: A. Hydrochinon 22.8¢ 175 gr. Sodium sulphite, dry 114¢ 87.5 gr. Sulphurous acid 114¢ 87.5 gr. PRINTING-OUT PAPERS 185 Water 1000 ccm 16 oz. B. Potassium bromide 62.5 ¢g Loz: Ammonia 9 ccm 70 min. or Sodium carbonate, cryst. 45.5¢ ° 350gr. Water 1000 ccm 16 oz. For use mix 1 part of each with 1 part water. Or the follow- ing may be used: A. Hydrochinon 3.65 g 28 gr. Sodium sulphite, dry 3.65 g 28 gr. _ Water 1000 ccm 16 oz. For use, mix 4 parts A, 4 parts B, given above, and 8 parts water. Greater contrasts can be obtained by decreasing A to 3 parts, while flatter prints can be secured by increasing A to 7 parts, the water in each case being increased or reduced, so as to make the total bulk of the solution the same. Another formula (Kodak) is the following: A. Hydrochinon 7.32 56 gr. Sodium sulphite, dry 3.65 g 28 gr. Potassium bromide 14.6 ¢ 112 er. Ammonium bromide 2926 224 er. Water 1000 ccm 16 oz. B. Caustic soda 62.5 ¢ 1 oz. Water 1000 ccm 16 oz. C. Tannin 16.6 g 128 gr. Water 1000 ccm 16 oz. For use mix 150 parts A, 30 parts B, 4 parts C. Whichever developer be used, it is important to observe the greatest care not to expose the paper to white light, as the slightest light action is developed. It is, therefore, advisable to manipulate the paper by yellow light entirely. The image should only be faintly visible after exposure. After the bromide bath, the prints should be washed at least 3 minutes. The developed image is a pale yellow or orange colour; care 186 PHOTOGRAPHIC FACTS AND FORMULAS must be taken not to develop too far, and development should be stopped when the details in the high lights just begin to show. A stop bath of 10 per cent of potassium bromide or 1 per cent glacial acetic acid should be used, the prints thor- oughly washed, and then toned in the ususal way. Disco (DEFENDER) PRINTING-oUT PAPER.—Print two or three shades darker than is desired in the final print. Wash in five or six changes of water before toning, and tone in the following, keeping the prints moving: Gold chloride solution 25 ccm 1 oz. Water 1000 ccm 40 oz. Add enough borax to turn red litmus paper blue. The above gold chloride solution is made by dissolving a 15-grain tube of gold chloride in 15 0z. or 425ccm of water. When the desired tone is attained, transfer prints direct to a 4 per cent solution of hypo. EASTMAN Sotio Parer.—Wash prints in 5 or 6 changes of water before toning. Tone in a plain gold bath, using 044g (lgr.) to 1000ccm (480z.) water. Neutralise by adding a few drops at a time of saturated solution of borax, sodium bicarbonate or sal soda. Test with red litmus paper. When toned, immerse prints in running water, or: Common salt 8g loz, Water 1000 ccm 128 oz. Fix not less than 10 minutes in: Hypo 100 g 13 oz. Water 1000 ccm 128 oz. Solio hardener 4 ccm YZ oz. The Solio hardener is made as follows: Aluminum chloride 250 ccm 3 02. Sodium bisulphite 208 g 214 02. Water 1000 ccm 12.07, Or the following may be used: PRINTING-OUT PAPERS Hypo 75g 6 oz. Alum S258 2Y% 02. Sodium sulphite, dry 2g 80 gr. Water 1000 ccm 70 oz. When dissolved, add: Borax 9.5 ¢ 34 OZ. Hot water 125 ccm 10 oz. This must be made 10 hours before use. CoMBINED BaTH FOR SOLIO.— A. Hypo 90 g 8 OZ. Alum 68 g 6 oz. Sugar 2215 2 2 oz. Water 900 ccm 80 oz. Thoroughly dissolve in cold water, and add: Borax 22.52 2 02. Water 100 ccm 8 02. Allow to stand over night, and decant the clear liquid. B. Gold chloride 0.2 g 7\4 gr. Lead acetate 16g 64 gr. Water 100 ccm 8 oz. 187 This should be shaken up before use and not filtered. For use mix 1 part B with 8 parts A. Place prints in this without washing. Tone to the desired colour, and immerse prints for 5 minutes in a stop bath of common salt, 1:32; then give one change of water, and fix for 10 minutes in: Hypo 50 g 1 oz. Sodium sulphite, dry 3g 30 gr. Borax 12512 4 oz. Water 1000 ccm 20 oz. Wash the prints for 1 hour in running water, or in 16 changes of cold water. The temperature of the combined bath should notexceed 10°C. (507 F.). Mimosa AuROTYPE (SELF-TONING) PAPER.—Print much 188 PHOTOGRAPHIC FACTS AND FORMULAS darker than the finished prints are required to be. Place, without washing, directly in the baths, which should be at 18° C. (65° F.), and keep constantly in motion. For sepia tones: immerse for 10 minutes in a 10 per cent solution of hypo. For brownish-black tones: immerse for 10 minutes in a 10 per cent solution of common salt; then transfer direct to the same strength hypo solution. For dark brown tones: immerse in: Hypo 100 g 2 oz. Salt 100 g 2 oz, Water 1000 ccm 20 oz. Variation in tones from light to dark brown is obtained by decreasing or increasing the quantity of salt in the above bath. As soon as the desired tone is obtained, the prints should be carefully washed by repeated changes of water, or in run- ning water for 30 minutes. The most satisfactory method of drying is to place the prints between clean blotters. GEVAERT Ronix SetF-Tonine PApEer.—This is a collodio- chloride paper. Print a little darker than the finished print is desired to be. For sepia and brown tones, wash prints for three to five minutes in 2 or 3 changes of water, immersing them face down to prevent curling. Fix for 10 to 15 min- utes in: Hypo 100 g 2 oz. Water 1000 ccm 20 oz. Wash for one hour, blot off surplus water, but do not dry between blotters. For dark brown and blue tones, wash as before and then immerse for 5 to 10 minutes in: Salt 100 g 2 oz. Water 1000 ccm 20 oz. Rinse, fix and wash as for sepia tones. Baths should be used only once, Salted Paper PLAIN or SALTED Papers.—In this process the original surface of the paper is practically preserved, the sensitive salts being more or less in the fibers of the paper, in contra- distinction to those processes in which they are suspended in an-emulsion. In all cases, however, a size should be used to prevent too deep penetration into the paper. V arious sizes may be used; starches, such as arrowroot, etc., tend to give brownish tones, while gelatine tends rather to more blueish tones. The size may be applied to the paper first, but it is frequently more convenient to incorporate the salts with it: Arrowroot 20 g 154 gr. Water 750 ccm tZ/oz: Rub the arrowroot into a cream with a little of the water: bring the remainder of the water to the boil, add the arrow- root cream slowly with constant stirring, and continue heat- ing until a translucent liquid is formed. Then add: Ammonium chloride l4g 107 er. Sodium carbonate, cryst. 23 ¢ 177 gr. Citric acid 7g 54 gr. Water 250 ccm 4 oz. As effervescence takes place when mixing this latter solution, it is advisable to make it in a fairly large beaker before add- ing it to the arrowroot. It is as well, though not necessary, to boil this solution for 5 minutes to expel the carbonic acid. The salted arrowroot mixture should be strained through fine muslin while hot. Immerse the paper in the warm solu- tion for 2 minutes, and hang up to dry. When nearly dry, again immerse for the same time, and hang up by the oppo- 189 190 PHOTOGRAPHIC FACTS AND FORMULAS site corners to those previously used. As an alternative to this, the paper may be pinned by two corners to a flat board, and the salting solution freely applied with a broad flat brush. The solution is allowed to dry, and the operation is then re- peated. Increase of the arrowroot by 50 per cent increases brilliancy of the surface. For a gelatine size one of the following may be used: Gelatine 2g 15 gr. Ammonium chloride 18g 138 gr. Sodium citrate 18g 138 gr. Water 1000 ccm 16 oz. Or: Gelatine 4.5¢ 34 gr. Ammonium chloride 18g 138 gr. Sodium citrate, dry 215s 165 gr. Salt 7g 54 gr. Water 1000 ccm 16 oz. Ori: Gelatine 7g 54 gr. Ammonium chloride 14g 108 gr. Water 1000 ccm 16 oz. The more gelatine used, the higher the gloss of the resultant prints. The more citrate used, the more rapid the paper, with less contrast. Soak the gelatine in the water, melt by heat, and add the salts. Matt AND SEMI-MATT Lac Papers.—With these bleached shellac with gelatine is used as a size. Unfortunately, bleached shellac is quite insoluble in aqueous mediums, and its solubility is very variable, unless freshly bleached: Bleached lac 83 g 637 gr. Borax 42 ¢ 32a 88: Water 750 ccm 12 oz. The lac should be broken up small, added to the borax solu- SALTED) PAPRR Ot tion, and the mixture boiled until it has dissolved, or not less than 2 hours, water being added from time to time to replace that which boils away. Then take: Bleached lac 50 g 384 gr. Sodium phosphate 25g 192 er. Water 750 ccm Zou: Boil in the same way as above, mix the solutions, and add: Gelatine 46 ¢ eS) ie. Water 500 ccm 8 oz. Allow the gelatine to soak in the water for 30 minutes, and melt by heat. Filter the mixture through fine linen. Im- merse the paper for 2 minutes, and hang up to dry. When nearly dry, again immerse, and hang up by the opposite end. To salt this, float the paper on: Ammonium chloride 23 g 177 gr. Magnesium lactate 23 g 177 gr. Water 1000 ccm 16 oz. Then hang up to dry. Either the borax-lac or phosphate-lac may be used alone with half the above quantity of gelatine solution. All plain papers are most satisfactorily sensitised by brush- ing the silver solution on, not floating. Either a plain silver solution may be used, such as: Silver nitrate 62.5 ¢ 1 oz. Water 500 ccm 8 oz. Or an acid one: } Silver nitrate 732 560 gr. Citric acid ay) fe 400 gr. Water 500 ccm 8 oz. Or an alkaline one: Silver nitrate 32 g 245 gr. Ammonia q. S. qs: Water 250 ccm 4 oz. 192 PHOTOGRAPHIC FACTS AND FORMULAS Dissolve the silver, add enough strong ammonia to form a clear solution, and then add: Silver nitrate 32 g 245 ger. Water 250 ccm 4 oz. If necessary add a little more ammonia to clear up any precipitate formed. Papers thus prepared will not keep more than a few hours, but they print very rapidly, and give very vigorous prints. It is better to use the plain silver solu- tions, and fume the paper with ammonia just before use. This can be effected by cutting the paper to size and pinning to the inside of the lid of a plate box, on the bottom of which is a sheet of blotting paper wet with a 10 per cent solution of ammonia. About 10 to 15 minutes will be sufficient. In- stead of the liquid ammonia, coarsely powdered ammonium carbonate may be used, and then the paper should be fumed for 30 minutes. Printing should be carried rather deep and the prints washed with repeated changes of water until no milkiness is seen in the water, or a 5 per cent solution of salt may be used, and the prints then washed for 10 minutes. Toning may be effected with either gold or platinum. Weak baths give the best results, such as: Borax 7g 34 gr. Gold chloride 0.11 g 0.85 gr. Hot water 1000 ccm 16 oz. Sodium phosphate or acetate may be used instead of the borax, and the tones vary from sepia to purple, according to the duration of toning. As the prints always dry a little colder, or bluer, in tone than when wet, allowance should be made for this. A suitable platinum bath is: Potassium chloroplatinite 0.3 ¢g 2.08h Citric acid 8g 61 gr. Salt 2.5 ¢ 19 gr. SALTED VP AE ER 193 Hot water 1000 ccm 16 oz. After toning, the prints should be immersed in a 1 per cent solution of common salt to stop the toning action, fixed in a 5 per cent solution of hypo, and well washed. If resin-sized paper be used, the following will give black and sepia tones direct. For black tones: Sodium phosphate 40¢ S07 ea. Borax 20 g 154 gr. Sodium carbonate ~ l0g 77 gr. Sodium chloride 5g 38.5 gr. Potassium bichromate 0.01 g 0.08 gr. Water 1000 ccm 16 oz. For sepia tones: Sodium phosphate 20 g 154 gr. Borax 40 ¢ 307 gr. Sodium chloride 5g 38.5 gr. Potassium bichromate 0.08 g 0.6 gr. Water 1000 ccm 16 oz. Immerse the paper for 20 to 40 seconds, and dry. Sensitise on: Silver nitrate 50 g 384 gr. Lead nitrate 50 g 384 gr. Water 1000 ccm 16 oz. Neutralise this with sodium carbonate before use. The following method is given by Namias: Gelatine 25g OZ er Zinc chloride, cryst. 6g 46 gr. Citric acid 5g 384 er. Ammonia 6 ccm 46 min. Water 1000 ccm 16 oz. Soak the gelatine in half the water, and dissolve with heat; dissolve the acid in the remainder of the water, add the ammonia and then the zinc, mix the two solutions and filter. 194 PHOTOGRAPHIC FACTS AND FORMULAS Tartaric acid may be used instead of the citric, and darker brown tones are obtained. Immerse the paper in the warm solution and dry. Sensitise by brushing over with either of the following solutions: Silver nitrate 120 g 922 gr. Citric acid 50 g 384 gr. Glycerine 50 ccm 384 min. Water 1000 ccm 16 oz. DS ay Silver nitrate 120g 922 gr. Ammonia q. S. q.S. Water 500 ccm 8 oz. Use enough ammonia to form a clear solution, and then add: Lactic acid, pure syrupy 50 ccm 384 min. Water to 1000 ccm 16 oz. Greater contrasts can be obtained by adding a little 5 per cent solution of potassium bichromate. A more rapid paper is obtained with the following: 768 gr. 384 gr. 384 min. 16 oz. 512 gr. 5 oz. 12.3 gr. 256 gr. Silver nitrate 100 g Uranium nitrate 50 g Lactic acid 50 ccm Water 1000 ccm The following gives sepia tones, but the stock solution will not keep: Ammonio-citrate of iron, green 66.6 g Water 333 ccm Potassium bichromate l6g Dissolve, and add: Silver nitrate 33.32 Water 667 ccm 11 oz. After printing, this paper should be immersed in a 1 per cent solution of oxalic acid, then washed, and fixed in a 2 per cent hypo bath. SALTER DUPARER 195 A casein paper can be made as follows: Ammonium chloride 4g Slee Sodium citrate, neutral 40g 310 gr. Water 400 ccm 6¥4 oz. Dissolve, and add: Casein 40 ¢g 310 gr. Ammonia )S0i 384 min. Water | 350 ccm . SY oz. Warm this until dissolved, then add: Silver nitrate 70g 538 gr. Water to 1000 ccm 16 oz. This paper will not keep well, but can be made more stable by immersion in 3 per cent solution of citric acid. SENSITISING LEATHER, Fasrics, ETc. (Cobenzl).— Ammonium chloride 20 g 154 gr. Gelatine 5¢g 38 gr. Water 800 ccm 13 oz. Soak the gelatine in the water, add the chloride, melt with heat, and add to: Soluble starch 20 g 154 gr. Water 200 ccm 5) Ore, The material should be immersed in this until thoroughly soaked, then hung up to dry; if the fabric is thick and soaks up much of the liquid, more water should be added. When dry, it is silvered on: Silver nitrate 205.8 302 134 on, Citric acid 103 g 791 gr. Water 1000 ccm 16 oz. The fabric should be laid on the bottom of a large dish, a glass rod placed on the top, the liquid poured over, and the rod rolled to and fro; this saturates the cloth without the necessity of touching it with the fingers. Artificial light should be used, and the drying should be as rapid as possible. 196 PHOTOGRAPHIC FACTS AND FORMULAS. After printing, the material should be immersed in salt solution, washed and toned as usual, if desired. Thin veneer wood can be sensitised; maple and plane give the best results; pear is less satisfactory. The wood should be immersed for at least 5 minutes in: Soft gelatine 37. De 288 gr. Water 1000 ccm 16 oz. Soak, melt by heat, and add: Formaldehyde 7.5 ccm 58 min. Dry with moderate heat, and immerse 5 minutes in: Hard gelatine 25¢ 192 gr. Soluble starch 100 g 768 gr. Ammonium chloride 10¢g 77 gr. Water 1000 ccm 16 oz. Again dry, and sensitise in: Silver nitrate 100 g 768 gr. Citric acid 83 g 637 gr. Water 1000 ccm 16 oz. Dry quickly. Print deeply from contrasty negatives, wash and tone as usual. The sensitising of leather, such as split calfskin, is an easy matter, but it will not keep after sensitising. It is advisable to coat it first with plain collodion and then with a collodio- chloride emulsion. Or the following may be used: Hard gelatine 2.5¢g 19 gr. Soluble starch 10g 77 gr. Potassium bromide 8.75 g 67 gr. Cadmium bromide 8.75 g 67 gr. Cadmium iodide 2.9:¢ 19 gr. Ammonium chloride 2.5¢ 19 gr. Water 1000 ccm 16 oz. Saturate the material, dry quickly, and sensitise in: Silver nitrate 40g 307 gr. SA EDP AUPE 197 Citric acid 50 ¢ 384 gr. Water 1000 ccm 16 oz. Clean brilliant negatives and short exposure to a bright light are required; enlargements may also be made. After expo- sure the material should be immersed in a 5 per cent solution of ammonium chloride, and developed with: Pyrogallol 25.2 19 gr. Hydrochinon Taye 58 gr. Citric acid 10g 1/ gt. Sodium sulphite, dry 34 ¢ 260 gr. Water 1000 ccm 16 oz. Temperature 35° C. (95° F.). As soonas the image has well appeared, fix in an acid bath, and tone with gold. For an emulsion for fabrics, either of the following may be used: Hard gelatine 120g 2oz., 47 gr. Water 1300 ccm ZO78 Dissolve, and add: Zinc bromide, cryst. 43 ¢ SoZ on: Cadmium iodide lg Ae os a Cadmium chloride 3¢g 23 gr. Next, add at\70° C. (158° F.): Alcohol 500 ccm 8 oz. Then add in the darkroom: Silver nitrate 50 g 384 gr. Water 100 ccm 770 min. Finally, add: Alcohol 100 ccm 770 min. Digest for 214 hours at 80° C. (176° F.), and then cool down with constant stirring until the temperature is 15° C. (69; F’.), when the emulsion will sink to the bottom of the vessel ; this should be collected, washed, and melted with the addition of: 198 PHOTOGRAPHIC FACTS AND FORMULAS Sodium carbonate 0.2 g 1.5 gr. Ammonium bromide 0.2 g 1.5 ge: Water 2400 ccm 38Y4 oz. Melt at 30° C. (86° F.), and saturate the fabric. This can also be used for paper, and gives from red to black tones, according to exposure and developer. Bromide Paper ExposurE.—The most convenient light-source is an elec- tric incandescent lamp of comparatively low candle-power, not more than 16, otherwise the duration of exposure is so brief that serious errors may arise. It is preferable to have the light-source fitted: with a push button, so that the light is only obtained while the button is pressed. This is handier than the usual form of switch. The light should be located as nearly as possible on a line with the center of the printing frame, and the end of the bulb should be towards the frame. The bench should be marked plainly with a scale of dis- tances, such as a yard measure, exactly parallel to the axial line of the light, and the frame should always be placed squarely at right angles to this scale. The exposures are practically as the squares of the distances between the light and the frame; that is to say, with a given light, negative, and paper, if the exposure at 12 inches is 5 seconds, it will be as 12*: 24? at 24 inches, or as 144:576, or 1:4. The thinner the negative, the greater should be the distance from the light. It is advisable not to select too short a distance, as the expo- sures are inconveniently short. The rule that the exposures are as the square of the distances is not strictly correct, for the light has less penetrative power at greater distances and will not pass through the denser parts of the negative. Slow papers give plucky results from flat negatives, and rapid papers give soft results from hard negatives. DEVELOPMENT.—Practically, the developers for bromide papers may be considered as half the strength of negative developers. Almost any reducing agent may be used, though pyro is the least suitable on account of its liability to stain 199 200 PHOTOGRAPHIC FACTS AND FORMULAS both gelatine and paper and its tendency to give rusty black tones. Amidol and metol-hydrochinon, also called M. Q., are the favourites; the former tends to give blue-black, and the latter pure black tones. Amidol—tThis developer will not keep more than three days, and the most convenient method is to make up a 5 per cent solution of dry sodium sulphite, add 0.1 per cent of potassium bromide (¥4 gr. to the ounce), add 0.8 per cent amidol (4 gr. to the ounce), and dilute with an equal bulk of water just before use: Sodium sulphite, dry 34¢ 260 gr. Potassium bromide 13g 10 gr. Water 1000 ccm 16 oz. When dissolved, add: Amidol 522 40 er. Metol-Hydrochinon.—The mean of the maker’s formulas is: Metol je 27 gr. Hydrochinon 3g 23 gr. Sodium sulphite, dry 21g 160 gr. Sodium carbonate, dry l6g 123 gr. Potassium bromide 13g 10 gr. Water 1000 ccm 16 oz. Eastman Metol-hydrochinon Developer. Elon (metol) 5g YZ oz. Sodium sulphite, dry 75g 7% 02. Hydrochinon 20 g 2 02: Sodium carbonate, dry 105 ¢ 1034 oz. Potassium bromide 2.5 2 120 gr. Wood alcohol 130 ccm 13 oz. Hot water 1000 ccm 100 oz. For use mix 1 part with 6 parts water. Temperature 21° C. (708 Es)! BROMIDE PAPER 201 Eastman Amidol Developer.— Sodium sulphite, dry 120 g LY, oz. Acrol (amidol) 40 ¢ V4 oz. Water 1000 ccm 12 oz. For use mix: Stock solution 157 ccm 1Y4 oz. Potassium bromide, 10% sol. 1.7 ccm 8 drops Water 843 ccm 6 oz. Time of development should be not less than a minute and a quarter. GEVAERT ORTHOBROM AND NOVABROM BROMIDE PAPERS.— Developer for vigorous prints: Metol lg 8 gr. Hydrochinon 3.5 g 28 gr. Sodium sulphite, cryst. 38 g 228 er. Sodium carbonate, cryst. 50 g 384 gr. Potassium bromide lg 3) Bie Water 1000 ccm 16 oz. For soft prints: Metol 5g AO er. Hydrochinon aig area Sodium sulphite, cryst. 62 ¢ Woz: Potassium carbonate 18.5 ¢ 150 gr. Potassium bromide lg 8 gr. Water 1000 ccm lloloz: Dissolve in order given. Prints of any required degree of vigour may be made by mixing the two solutions in suitable proportions. Development time, 3 minutes at 18° C. (65° Be)o eAtter finsing) tix in: Hypo 250 g 4 oz. Potassium metabisulphite 2S 192 gr. Water 1000 ccm 16 oz. 202 PHOTOGRAPHIC FACTS AND FORMULAS Fix 10 minutes, wash 1 to 2 hours, and do not dry between blotters. HAMMER OPAL PLATES.— Metol 5g Y4 oz. Hydrochinon 20 g 1 oz. Sodium sulphite 75g 334 02. Sodium carbonate 125 ¢ 6% oz. Potassium bromide 1:25 to'2.5/ Y% to 1 dr. Water 1000 ccm 50 oz. Add from 120 to 200ccm (6 to 100z.) wood alcohol to prevent precipitation. For use mix 1 part of above with 6 parts water. FACTORIAL DEVELOPMENT FOR BROMIDE PAPER.—Dr. B. J. Glover puts forward a strong case for the application of the Watkin’s factorial system for bromide papers, which, how- ever, is not applicable to development papers on account of the very short time of appearance. The developer he adopts is the Kodak amidol formula at a temperature of 17° C., and he finds a remarkable coincidence between the exposure multi- plied by the time of development, in seconds, for prints showing practically the same result. This forms a constant, which is 1,800. Three cases are cited in which the exposures were 30, 15 and 10 seconds respectively and the factors 10, 15 and 22¥% used. The results were practically indistinguish- able ; and the total times of development were 60, 120 and 180 seconds respectively, which, as will be seen, when multiplied by the exposures, equal 1,800. He formulates his first rule as follows: development must not be for a shorter time than that required to produce the maximum black of the paper. Accepting this, it will be obvious that it will be unnecessary to calculate both exposure and development; one only need be determined and the other is at once deduced therefrom, which practically forms his scond rule. As he puts it: a knowledge BROMIDE PAPER 203 of either the correct exposure or the correct time of develop- ment is a complete guide to both exposure and development, since they are dependent variables in the sense that the pro- duct of one with the other is a constant quantity. The third rule is: the maximum development allowable is that which just stops short of fog or stain or both. Each developer has its own factor, which in the sense of the above rules varies within certain limits, these for the Kodak amidol being from 10 to 30. As a mean 12 is convenient, and it is advisable to adopt this and make trial exposure strips. He lays down the axiom that the correct exposure for a bromide print is that which, when developed with any developer to an appropriate Watkin’s factor, yields a print of the desired depth. This is the only definition in existence, which has any value in practical work. Developing-Out Papers DEVELOPMENT OR GASLIGHT PAPERS.—These are com- paratively slow papers, which can be manipulated in not too bright a white light, though it is safer to use a yellow or bright orange safe-light. ExposuRE.—The exposure is much longer than with bro- mide paper, and it is advisable to use a high candle-power in- candescent lamp, such as a 50-watt Mazda. The distance from the lamp should not be more than 12 inches. Or mag- nesium ribbon may be used, 1 inch at a distance of 12 inches being sufficient for an average negative for cold tones. The longer the exposure, with corresponding increase of bromide in the developer, the warmer the tones. DEVELOPMENT.—Any developer may be used, and, prac- tically, negative developers, with bromide, may be used full strength. Amidol.— Sodium sulphite, dry 32 g V4 oz. Potassium bromide 0.13 g 1 gr. Water 1000 ccm 16 oz. When dissolved, add: Amidol 5.22 40 er. For notes as to the keeping of this, see under Bromide Paper. Metol-Hydrochinon.—The mean of the maker’s formulas 1S: Metol 19¢ 14¥4 gr. Hydrochinon 6.2 g 47 gr. Sodium sulphite, dry 28 g 215 gr. Sodium carbonate, dry 41g 315 gr. Potassium bromide 0.4¢ 3 gr. 204 DEVELOPING-OUT PAPERS 205 Water 1000 ccm 16 oz. All formulas given under Bromide Paper are applicable to development papers. Non-ABRASION DEVELOPERS.—Glossy development papers are likely to show black hair-like lines, due to abrasion of the sensitive surface. The following has been suggested as obviating these: Metol a0 2 27 gr. Hydrochinon 6g 46 er. Sodium sulphite, dry 12¢ O2\er: Sodium carbonate, dry 20 g 154 gr. Potassium bromide 0.4¢ 3 gr. Potassium iodide Tate 15.4 gr. Water 1000 ccm 16 oz. The iodide is the active agent and may be added in about the above ratio to any developer. Or add 0.156 per cent of hypo to the developer, that is, 1.56 g per liter (12 gr. per 16 0z.). Pyro DEVELOPER FOR WARM Brown Tones oN DEVELOP- MENT PAPERS.— A. Potassium metabisulphite 5g 38.5 gr. Pyrogallol 22s 169 gr. Potassium bromide I5¢g Listen: Water 1000 ccm 16 oz. B. Sodium sulphite, dry 87.5 g 672 gr. Sodium carbonate, dry 87.5 672 er Water 1000 ccm 16 oz. For use mix A 10, B 20, water 70 parts. The image appears in from 30 to 40 seconds, and development is complete in 3 or 4 minutes. The prints should be fixed in an acid bath without intermediate washing. Vitava (Kopak) PaPEer.— 1. Elon (metol) 6.5 ¢ 100 gr. Sodium sulphite, dry 100 g 3% oz. 206 PHOTOGRAPHIC FACTS AND FORMULAS Hydrochinon 23g 34 OZ. Sodium carbonate, dry 46 ¢ 1YZ oz. Potassium bromide a25\¢ 50 gr. Wood alcohol 138 ccm 4Y4 oz. Water to 1000 ccm 32 oz. 2. Sodium carbonate, dry 46 ¢ LY oz. Water 1000 ccm" | See In preparing No. 1, dissolve each chemical in three-fourths of the water, heated to about 53° C. (125° F.), before the next is added. Normal development should require from 1% to 2 minutes. 3 For Etching Brown, use: 125 ccm of No. 1, water to make 1000 ccm, and add 7 ccm of 10 per cent solution of potassium bromide (20z. of No. 1, water to 160z., and 60min. of potassium bromide solution). For Athena Old Master and Glossy, use: No. 1, 125 ccm, No. 2, 62.5 ccm, water to 1000 ccm, and add 3.5ccm of 10 per cent solution potassium bromide (No. 1, 20z., No. 2, 1 oz., water to 16 0z., and add 30 min. of potassium bromide solution). Temperature 21° C. (70° F). ARTURA.— 1, Elon (metol) 6.5¢g 100 gr. Sodium sulphite, dry 100 g 3% oz. Hydrochinon 23 ¢ ¥, OZ. Sodium carbonate, dry 782 2% oz. Potassium bromide 3.25 ¢g 50 gr. Water to 1000 ccm 32 oz. Then add: Wood alcohol 138 ccm 41% oz. 2. Elon (metol) 23.5 g V4 OZ. Sodium sulphite, dry 100 g 3% oz. Potassium bromide 9.75 g 150 gr. Water to 1000 ccm 32 oz. DEVELOPING-OUT PAPERS 207 Then add: Wood alcohol 200 ccm 634 oz. 3. Sodium carbonate, dry 94¢ Boe Water } 1000 ccm OZ 02: For normal developer for Artura Iris, use: No. 1, 125 ccm, potassium bromide, 10 per cent solution, 3.5 ccm, water to 1000 cem (No. 1, ate bromide solution, 30 min., water to 16 0z.). For soft developer for Artura Iris, use: No. 1, 62.5 ccm, No. 2, 62.5 ccm, water to 1000 ccm (No. 1, 1 oz., No. 2, 1 0z., water to 16 0z.). For Artura Carbon Black or Carbon Green, use: No. 1, 250 ccm, No. 3, 62.5ccm, potassium bromide, 10 per cent solution, 3.5ccm, water to 1000ccm (No. 1, 40z., No. 3, 1 oz., bromide solution, 30 min., water to 16 0z.). For Non-Curling Film, use: No. 1, 250ccm, water to 1000 ccm (No. 1, 40z., water to 160z.). Temperature of all developers 21° C. (70° F.). Roylon Developer.— Roylon lig 24 gr. Sodium sulphite, dry 23 ¢g 34, OZ. Hydrochinon 45¢ 72 gr. Sodium carbonate, dry 23 g 34 OZ. Potassium bromide, 10% sol. 10.5 ccm 90 min. Water to 1000 ccm 32 oz. Suitable for all grades of Artura, except Carbon Black, for which there should be added 16 ccm of 10 per cent solution of potassium bromide to 1000ccm (¥% oz. to 160z.). Kodelon Developey—F¥or amateur use for Velox, Azo (and other developing papers) and bromide papers. Dis- solve in the order named: Water 1000 ccm 64 oz. Kodelon 0.8¢g 25 gr. 208 PHOTOGRAPHIC FACTS AND FORMULAS Hydrochinon 2.9¢ 90 gr. Sodium sulphite, dry 10.5 ¢ 330 gr. Sodium carbonate, dry 35 g - 2Y oz. Add 2 drops of 10 per cent potassium bromide solution to each 30ccm (loz.) of developer. Use full strength at Ee OO (Coal aia For professional use; soft developer for Artura Iris, Azo and other professional papers. Dissolve in order named: Water 1000 ccm 40 oz. Kodelon - 0.5 ¢ 10 gr. Hydrochinon 2g 40 gr. Sodium sulphite, dry 95¢ 180 gr. Sodium carbonate, dry 95¢g 180 gr. Add 1 drop of saturated solution of potassium bromide to each 60ccm (20z.) of developer. Use full strength at bey CoGare P.) Tozol Developer—Stock solution for developing papers. Dissolve in the order named: Hot water 1000 ccm 30 oz. Tozol 931/32 1 oz: Sodium sulphite, dry 100 g 3 0z. Sodium carbonate, dry 752 2% oz. Potassium bromide 3¢g 45 gr. Wood alcohol 150 g AYA 02. For portraiture on Artura and Azo use 100 ccm of stock solution to 700 ccm water (1 oz. to 7 0z.). For Velox, bromide, and amateur finishing grades of Azo, add 67 ccm (20z.) of dry sodium carbonate to the above quantity of stock solution and for use dilute 1 to 2 for Velox and Azo, and 1 to 6 for bromide papers. Use at 21° C. (70 By): Hator PAPEers.— Metol 0.78 g 15 gr. DEVELOPING-OUT PAPERS 209 Sodium sulphite, dry NZS) (2 Y oz. Hydrochinon 312 ¢ 60 gr. Sodium carbonate, dry Nei VY, oz. Water 1000 ccm 40 oz. Add one drop saturated potassium bromide solution to every 2 oz. of developer (1 ccm to every liter). ‘Times of develop- ment at 18° C. (65° F.): Portraya 1% to 2, Industro 144 to 134, Rito 3% to 1%, Kalo 1 to 1%, Enlarging 1% to 134 minutes. The use of Kalo (slow speed) or Rito (fast speed) with the following developer gives cold, neutral or blue-black tones : Metol 5g Y, oz. Sodium sulphite, dry TI 74 02. Hydrochinon 20 g 2. OZ. Sodium carbonate, dry 125¢ 12 oz. Potassium bromide 2g 100 er. Hot water 1000 ccm 100 oz. For use mix 1 part stock solution with 3 parts water. Hatow Kato & Rito.—For neutral black tones: Metol 0.78 g Son: Sodium sulphite, dry 5) YZ oz. Hydrochinon 3.12); 60 gr. Sodium carbonate, dry 22S 420 er. Water 1000 ccm 40 oz. Add one drop saturated solution potassium bromide to each two ounces of developer (1 ccm to every liter). Awsco Cyxo PAPER.— Metol 0.78 gr. 15 gr. Sodium sulphite, dry 25s 1 oz. Hydrochinon 3.12 ¢g 60 gr. Sodium carbonate, dry 18.75 g 34 02. Potassium bromide 0.26 g 5 gr. 210 PHOTOGRAPHIC FACTS AND FORMULAS Water 1000 ccm 40 oz. Temperature 18° C. (65° F.). Ansco Noxo PaPEer.— Metol 0.78 gr. 15 gr. Hydrochinon 2.8¢ 60 gr. Sodium sulphite, dry 25¢ 1 oz. Sodium carbonate, dry 18.75 g 34 OZ. Potassium bromide 0.376 g 8 ger. Water 1000 ccm 40 oz. Time of development 45 to 60 seconds. ENLARGING CyKo.— Metol 0.78 g 15 gr. Sodium sulphite, dry bZ.5\2 YA oz. Hydrochinon a2 2 60 gr. Sodium carbonate, dry 125.2 YZ oz. Potassium bromide, sat. sol. 1 to3ccm 20 to 60 min. Warm water 1000 ccm 40 oz. Temperature 18° C. (65° F.). KopAK VELVET GREEN AND VELOX PAPERS.— Metol 0.5 g 7 gr. Sodium sulphite, dry 7g 110 gr. Hydrochinon 2¢g 30 gr. Sodium carbonate, dry 13 g 150 gr. Potassium bromide, 10% 40 drops 40 drops Water 300 ccm 10 oz. Mimosa VEROTYPE PApeR.—For pure black tones, use: Sodium sulphite, cryst. 50 g 134 oz. Metol 2g 30 gr. Hydrochinon 6g 92 gr. Sodium carbonate, cryst. 135 ¢g 434 oz. Potassium bromide, 10% sol. 10 ccm 180 min. Water 1000 ccm 35:02. Or the following separate solution developer . DEVELOPING-OUT PAPERS Alt A. Metol l4g Sodium sulphite, cryst. 140 g Water 1000 ccm B. Hydrochinon De Sodium sulphite, cryst. 100 g Water 1000 ccm C. Sodium carbonate, cryst. 150g Flot;water » << 1000 ccm D. Potassium carbonate 150 ¢ Water 1000 ccm — 216 gr. 5 OZ, 35 oz. 270 gr. 3¥Y oz. 35.0Z: 514 oz. By oya: 5% oz. 35 oz. For use mix as follows: for brown-black tones 1 part A, 1 part B, 1 part C, and 3 parts water. By reducing B, a softer developer is obtained; by reducing A, a harder developer is obtained. For blue-black tones: mix 1 part A, 1 part B, 1 part D and 3 parts water. To every 35 oz. of developer, add 1% to 234 drams of 10 per cent solution of potassium bromide. H ydrochinon-Soda.— Sodium sulphite, cryst. 120g Hydrochinon 24¢ Sodium carbonate, cryst. 250 g Potassium bromide, 10% sol. 5ccm Hot water 1000 ccm Time of development 1 minute. EastTMAN Azo PAPER.— Elon (metol) 6.25 g Sodium sulphite, dry 100 g Hydrochinon 25¢g Sodium carbonate, dry 75g Potassium bromide I Z5S Wood alcohol 150 ccm Hot water 1000 ccm 414 oz. 34 OZ. 834 oz. 14 drams 35 oz. 60 gr. 2 02. YZ oz. 1YZ oz. 30 gr. a Ozs 20 oz. For use mix 20z. stock solution, water 140z., and add 212 PHOTOGRAPHIC FACTS AND FORMULAS 4 drops saturated solution potassium bromide. Temperature 21° C. (70° F.). Prints must be exposed so that the time of development will be not less than 45 seconds for No. 1 or 30 seconds for No. 2. For commercial and amateur print- ing, the following is recommended: Elon (metol) 0.73 g 7 gr. Sodium sulphite, dry 13g 110 gr. Hydrochinon 3.6 ¢g 30 gr. Sodium carbonate, dry 18 ¢ 150 gr. Potassium bromide, sat. sol. 0.5 ccm 5 drops Hot water 1000 ccm 20 oz. memperature 21° C).(70"-F2): DEFENDER COMMERCIAL PAPER.— Metol 0.77 g 15 Sr: Sodium sulphite, dry 25° 1 oz. Hydrochinon og 60 gr. Sodium carbonate, dry 18g ¥ Oz. Potassium bromide, sat sol. 8 drops 10 drops Water 1000 ccm 40 oz. d@emperature, 18°C, (65° F.). DEFENDER VELOUR BLACK.— Metol 154¢ 30 gr. Sodium sulphite, dry 12.5¢ Y4 oz. Hydrochinon 4¢ 80 gr. Sodium carbonate, dry | Page YZ oz. Potassium bromide, sat. sol. 512 drops 600 drops Water 1000 ccm 40 oz. For commercial use: Metol lg 20 gr. Sodium sulphite, dry 12-312 Y, oz. Hydrochinon 3g 60 gr. Sodium carbonate, dry 18.75 ¢ 34, OZ. Potassium bromide lg 20 gr. DEVELOPING-OUT PAPERS Zils Water 1000 ccm 40 oz. DEFENDER PROFESSIONAL PAPER.— Metol 0.77 g Sen Sodium sulphite, dry Ws) es VY, oz. Hydrochinon 3¢ 60 gr. Sodium carbonate, dry 12.5¢ V4 oz. Water 1000 ccm 40 oz. Potassium bromide, sat. sol. _ 25to70drops 30 to 80 drops The quantity of bromide determines the tone; with the small- est quantity a comparatively cold tone cone with from 1 to 1% minutes development for correctly exposed prints. Alternative developer for black and white prints : 1. Metol 2¢g 150 gr. Sodium sulphite, dry 33.3 g 3 Oz: Hydrochinon 8.3 ¢ 1% oz. Water 1000 ccm 150 oz. 2. Sodium carbonate, dry 100 g 3 oz. Water 1000 ccm 30 oz. For use mix: Solution No. 1 312.5 ccm 10 oz. Solution No. 2 62.5 ccm Zz Water 625 ccm 20 oz. Potassium bromide 75 (3 $B ace Develop from 1% to 3 minutes. Special stress is laid on the necessity of increasing the quantity of bromide with increase of the temperature of the developer. GEVAERT VITTEX (rapid gas-light paper). —For vigorous prints: A. Metol 0.9¢ 13 gr. Sodium sulphite, cryst. 35 g 1 oz. Hydrochinon 39) 50 gr. Potassium carbonate, cryst. 70g 2 oz. 214 PHOTOGRAPHIC FACTS AND FORMULAS Potassium bromide 0.5¢g 8 gr. Water 600 ccm 20 oz. Dissolve in order indicated. Development, 40 to 60 seconds ab Gs) ao GO) B.)'. For soft prints: B. Metol Nive 25 of. Sodium sulphite, cryst. 28 g 3/4 OZ. Hydrochinon 0.5 ¢ 8 gr. Potassium carbonate, cryst. aoe 1 oz. Potassium bromide 0.5 g 8 ger. Water — 600 ccm 20 oz. Time and temperature as before. Prints of any desired vigour can be obtained by mixing A and B in appropriate proportions. After development, rinse and fix in: Hypo 250 g 5 oz. Water 1000 ccm 20 oz. Potassium metabisulphite 25g Y oz. Fix for 10 minutes, wash one to two hours. Dry flat, but not between blotters. This paper gives warm black tones by simple development, and is not intended for sepia toning in sulphide solutions. GEvAERT Nova-cas (commercial gas-light paper ).— Metol lg 15 gr. Hydrochinon 4¢ 60 gr. Sodium sulphite, cryst. 35 g 1 oz. Sodium carbonate, cryst. 70g 2 oz. Potassium bromide, 10% sol. 30 to 60 drops Water 600 ccm 20 oz. Dissolve in order named. Develop at 18° C. (65° F.). If whites are not clean, add 15 drops 10 per cent solution of potassium bromide to each ounce (30 ccm) developer. After development, rinse thoroughly and fix in: Hypo 150 ¢ 3 oz. DEVELOPING-OUT PAPERS 215 Potassium metabisulphite 25g 4 oz. Water 1000 ccm 20 oz. Fix 10 to 15 minutes and wash 1 to 2 hours. SHorT Stop BatH.—For all developing papers it is advis- able to use a short stop bath. The prints should be rinsed as soon as sufficiently developed, and then immersed in: Acetic acid, 28% 47 ccm LY oz. Water 1000 ccm 32 oz. Use a fresh bath for each batch of prints, as the acid will become neutralized by the alkali from the developer. To reduce glacial acetic acid (9914%) to 28%, add 800 ccm of water to 300 ccm of the glacial acetic acid (8 0z. to 3 0z.). Toning Bromide and Gaslight Prints CoprerR Toninc.—Various shades from red to violet- brown are obtainable by this process, which is based on the deposition of red cuprous ferrocyanide on the image with the simultaneous formation of white silver ferrocyanide. It is actually an intensification process; therefore, the primary image must not be developed too far. Single solution (Ferguson) : Cupric sulphate, 10% sol. 106ccm 1 oz., 5dr: Potassium citrate, 10% sol. 800ccm 13 oz. Potassium ferricyanide, 10% sol. 94ccm loz.,3dr. This solution will keep and does not stain plates or papers; the colours are dependent on the length of immersion. Sed- laczek gives the following formulas for various tones, and, as the baths will not keep well, they should be mixed just before use. In all these formulas, the quantities of the solu- tions should be added to the stated amount of water in the order given: Potassium citrate, 10% sol. 250ccm 334 02. Cupric sulphate, 10% sol. 40 ccm 290 min. Ammonia alum, sat. sol. 100 ccm 14 oz. Potassium ferricyanide, 10% sol. 30 ccm 218 min. Water 750 ccm 12 oz. This gives red or violet-brown tones with clear whites. Ammonium oxalate, sat. sol. 200 ccm 3% Cupric sulphate, 10% sol. 40 ccm 290 min. Ammonium carbonate, 10% sol. 10 ccm 72 min. 216 TONING BROMIDE PRINTS ZN, Potassium ferricyanide, 10% sol. 30 ccm 218 min. Water 800 ccm 12 oz. This gives cherry red tones with a faint tinge in the whites. Potassium oxalate, 10% sol. 100 ccm 14 oz. Cupric sulphate, 10% sol. 40 ccm 288 min. Tartaric acid, 10% sol. 10 ccm 72 min. Potassium ferricyanide, 10% sol. 30 ccm 216 min. Water | 800 ccm 12 oz. This gives red-brown tones. The addition of 100 ccm (1y% oz.) saturated solution of ammonia alum gives browner tones. Ammonium oxalate, sat. sol. 200 ccm 3 0z. Cupric sulphate, 10% sol. 40 ccm 288 min. Oxalic acid, sat. sol. 10 ccm 72 min. Potassium ferricyanide, 10% sol. 30 ccm 216 min. Water 800 ccm 12 oz. This gives a reddish-violet tone. The following bath gives the so-called red chalk or Bartolozzi tones, but the whites are tinged: Ammonium carbonate, sat. sol. 570 ccm 8 oz. Cupric sulphate, 10% sol. 127 ccm 856 min. Potassium ferricyanide, 10% sol. 304 ccm 5 oz. A weak ammonia bath, 1 per cent, will clear the whites. The following gives reddish-brown tones with clear whites (Crab- Eree)): Cupric sulphate i2e2 2st) Potassium citrate 752 576 gr. Ammonium carbonate 6g 46 er. 218 PHOTOGRAPHIC FACTS AND FORMULAS Potassium ferricyanide 12g O2 ar. Water | 1000 ccm 16 oz. With all the above baths much more transparent images may be obtained by immersion for about 5 minutes in a 5 per cent hypo solution. A violet-red tone is obtained (Somerville) by treating a copper-toned image with: Ammonia-iron alum, 10% sol. 100 ccm 14 oz. Hydrochloric acid 10 ccm 72 min. Potassium bromide, 10% sol. 80 ccm 576 min. Water 1000 ccm 16 oz. Bleach the print in: Cupric sulphate 100 g 768 gr. Potassium bromide 100 g 768 gr. Water 1000 ccm 16 oz. Then immerse in a 2 per cent solution of nitric acid for 5 minutes, wash well, and immerse in a 5 per cent solution of sodium sulphite, which gives a brown tone. Bleach the print in: Potassium ferricyanide 13:5\2 104 gr. Potassium bromide 3.5¢ 27 gr. Water 1000 ccm 16 oz. Wash for 10 minutes; then immerse for 1 minute in: Acid potassium oxalate 2/ gs 208 gr. Water . 1000 ccm 16 oz. Then bathe for a few seconds in a 6 per cent solution of ammonia, and immerse in: -Cupric sulphate 10 ¢ 77 gr. Hydrochloric acid 1.5 ccm 12 min. Water 1000 ccm 16 oz. Until the desired colour is obtained ; then wash and fix. Immerse the prints in (Namias) : Rochelle salts 100 g 768 gr. TONING BROMIDE PRINTS P42 Cupric sulphate 10g 77 gr. Water » 1000 ccm 16 oz. Potassium ferricyanide aS 38 gr. Ammonia Gis: q.s Add enough ammonia to form a clear solution. This gives violet tones. Uranium Toninc.—Treatment of a silver image with a mixture of a soluble uranium salt and ferricyanide of potas- sium results in brown to, red images, the colour being de- pendent on the ratio of the two salts and the duration of toning. Intensification also takes place; therefore, the prints should not be too intense at first. The colour is dependent on the deposition of uranium ferrocyanide, which is soluble in alkalis. Long washing in ordinary water, therefore, will reduce the colour by dissolving the uranous salt. The following baths were recommended by Sedlaczek; all the quantities given represent the amount of 10 per cent solution that should be used, unless otherwise stated: Uranium nitrate 50 ccm 350 min. Ammonium oxalate 100 ccm 700 min. Hydrochloric acid 10 ccm 70 min. Potassium ferricyanide 20 ccm 140 min. Water 1000 ccm 16 oz. This gives brown tones. | Uranium nitrate 50 ccm 350 min. Potassium oxalate 50 ccm 350 min. Hydrochloric acid 10 ccm 70 min. Potassium ferricyanide 20 ccm 140 min. Water 1000 ccm 16 oz. This gives warm brown tones. If a saturated solution of oxalic acid be used instead of the potassium oxalate, redder tones are obtained. Uranium nitrate 50 ccm 350 min. 220 PHOTOGRAPHIC FACTS AND FORMULAS Rochelle salts 70 ccm 490 min. Tartaric acid 100 ccm 700 min. Potassium ferricyanide 20 ccm 140 min. Water 1000 ccm 16 oz. This gives rich brown tones. Uranium nitrate 50 ccm 350 min. Rochelle salts 50 ccm 350 min. Ammonia alum, sat. sol. 100 ccm 700 min. Tartaric acid 50 ccm 350 min. Potassium ferricyanide 20 ccm 140 min. Water 1000 ccm 16 oz. This gives reddish-brown tones. A simpler formula is: A. Uranium nitrate 5g 38 gr. Water 500 ccm 8 oz. B. Potassium ferricyanide 5g 38 gr. Glacial acetic acid 14 ccm 96 min. Water 500 ccm 8 oz. Mix just before use. Or the prints may be immersed in B until bleached, well washed, and then soaked in A until the desired colour is obtained. In this last formula, the salts are dissolved as given; that is, 10 per cent solutions are not used. Olive green tones (Namias). Tone the prints in the usual uranium bath, then wash, and immerse in: Ferric chloride 5g 38:5 BE, Hydrochloric acid 10 ccm 77 min. Water | 1000 ccm 16 oz. Fix in the acid hypo-sodium acetate bath. IRON oR CyANOTYPE Toninc.—In this process the colour is dependent on the deposition of Prussian blue on the image, and this is soluble in alkalis; therefore, long washing in ordinary water is inadvisable. Immerse the prints in a 5 per cent solution of potassium TONING BROMIDE PRINTS Zot ferricyanide with the addition of a little potassium oxalate, wash well, and treat with a 2 per cent solution of iron ammonium oxalate. This salt is the best to use for all iron toning baths, as it is stable and of uniform composition. Sedlaczek’s formulas are as follows, and all the quantities apply to 10 per cent solutions of the salts, unless otherwise stated : Ammonia iron alum 25 ccm 175 min. Potassium citrate 20 ccm 140 min. Ammonia alum, sat. sol. 100 ccm 700 min. Hydrochloric acid 5 ccm 35 min. Potassium ferricyanide 20 ccm 140 min. Water 1000 ccm 16 oz. This gives a deep blue tone. Ammonia iron alum 25 ccm 175 min. Potassium oxalate 60 ccm 440 min. Ammonia alum, sat. sol. 100 ccm 700 min. Hydrochloric acid 5 ccm 35 min. Potassium ferricyanide 20 ccm 240 min. Water 1000 ccm 16 oz. This gives a cold blue. If the hydrochloric acid and alum be omitted, and 10ccm (70 min.) of 10 per cent solution of tartaric acid be used, a grey blue colour is given. Ammonia iron alum 100 ccm 700 min. Potassium bromide 60 ccm 420 min. Hydrochloric acid 10 ccm 70 min. Water 1000 ccm 16 oz. This gives a bright blue. The following was specially recommended by Pfenninger for the blue constituent image in three-colour work. Im- merse the print or transparency in the following solution, made by weight: Potassium ferricyanide 30 g 230 gr. 222 PHOTOGRAPHIC FACTS AND FORMULAS Sodium carbonate, cryst. 10g 77 gr. Ammonium nitrate 10g 77 gr. Salt 10g 77 gr. Water 1000 ccm 16 oz. The image bleaches to a bright greyish brown, and should be then well washed, and immersed in: Potassium bromide 5.5 2 42 gr. Glacial acetic acid 16.5 ccm 127 min. Ammonium iron alum 5.5 ¢ 42 gr. Water 1000 ccm 16 oz. As soon as the prints have assumed a steel blue colour, they should be well washed, fixed in a 5 per cent solution of hypo, again well washed, and immersed for 2 minutes in a 1 per cent solution of sulphuric acid. The prints should be rather darker than usual, as this process reduces the density slightly. VANADIUM ToniInGc.—This gives green tones which vary according to the ratio of iron to the vanadium salt and the duration of the washing. The colour is dependent on the deposition of vanadium ferrocyanide, which is yellow-orange, in combination with Prussian blue; with prolonged washing some of the latter dissolves; therefore, the green becomes brighter. Namias recommended separate baths: Potassium ferricyanide 50 g 384 gr. Water 1000 ccm 16 oz. Ammonia q. Ss. q. S. Add enough ammonia to make the solution smell distinctly after shaking well. Immerse the bleached and well washed prints in a bath compounded of the following stock solutions: A. Vanadium chloride, 2 per cent solution B. Ferric chloride, 2 per cent solution For use take: A solution 125 ccm 2 oz. B solution 125 coma), 34° 2 oz. TONING BROMIDE PRINTS 223 Water | 1000 ccm 16 oz. In the following, direct toning is used, a single bath being employed; the first is by Somerville: A. Ferric chloride 2.32 16 gr. Oxalic acid, sat. sol. 120 ccm 2 OZ. Vanadium chloride 46¢ 32 gr. Nitric acid 10.5 ccm 80 min. Water : 500 ccm 8 oz. B. Potassium ferricyanide 2.32 16 gr. Water 500 ccm 8 oz. Mix just before use. Duration of toning 2 to 4 minutes; wash and fix in: Hypo 200 g Zaz Boric acid 40g 200 gr. Water 1000 ccm 10 oz. Finally, wash for 10 minutes. The disadvantage of the above baths is that some opaque silver chloride is formed, so that the results are somewhat muddy and control of the colour is not easy. By using vanadium oxalate or sulphate, much brighter colours and clearer prints are obtained (Wall). It 1s necessary to make these salts, but this is an easy task: Ammonium metavanadate 100's) 302, 130\er: Oxalic acid, pure 460 gers 1 Ib. Water 500 ccm 17¥ oz. Mix into a cream in a beaker or porcelain dish, and heat gradually with constant stirring. Solution gradually takes place, and the colour turns to orange and greyish-blue, but, as the heat is continued, it becomes a bright blue. Finally, add water until the bulk measures 1477 ccm (520z.). If the sulphate is to be used, although it presents no advantages, use: Ammonium metavanadate 100 9) 3iaz.) 130 ier: 224 PHOTOGRAPHIC FACTS AND FORMULAS Water 500 ccm 17¥4 oz. Mix into a cream and add slowly with constant stirring pure sulphuric acid, sp. gr. 1,845, 70 ccm (1183 min) ; then follow the directions given above. The actual toning bath is: Ammonium oxalate or sulphate solution as above 50 ccm 384 min. Oxalic acid, sat. sol. 50 ccm 384 min. Ammonia alum, sat. sol. 50 ccm 384 min. Ferric oxalate, 20% sol. q. Ss. q. Ss. Glycerine 50 ccm 384 min. Potassium ferricyanide, 10% sol. 10 ccm 77 min. Water 1000 ccm 16 oz. Mix the oxalic acid and vanadium solutions with half the water; then add the alum solution and the ferric oxalate; mix the ferricyanide solution with the glycerine and the remainder of the water, and add to the first solution. The more ferric oxalate used, the bluer the colour; with 10 ccm (77 min.) in the above bath a bright emerald green tone is obtained. Toning takes from 10 to 15 minutes; the prints should be immersed in a 10 per cent solution of sodium sulphate for 5 minutes, and then washed for 10 minutes. Namias suggests the following method of making van- adium chloride: Ammonium vanadate 100 g 768 gr. Hydrochloric acid 250 ccm 4 oz. Water 250 ccm 4 oz. Sodium bisulphite, dry 60 to 80g 460 to 610 gr. Heat until the solution turns blue and dilute to 1000 ccm (16 oz.) with water. For green tones bleach the prints in the usual ferricyanide bath, wash well, and immerse in: Vanadium chloride, as above 25 ccm 192 min. Ferric chloride 2.5'g 19 gr. TONING BROMIDE PRINTS 225 Ammonium chloride 100 g 768 gr. Water 1000 ccm 16 oz. More ferric chloride gives bluer tones. Wash and fix in an acid-hypo sodium acetate bath. Leap Toninc.—Various colours may be obtained by bleaching prints with a lead salt and ferricyanide, and sub- sequent treatment with various reagents. The results are not very satisfactory; there is a very great tendency for the whites to be stained, and great intensification is given. The bleaching bath may be: Lead acetate or nitrate 40g 307 gr. Glacial acetic acid 100 ccm 770 gr. Potassium ferricyanide 60 g 460 gr. Water 1000 ccm 16 oz. When thoroughly bleached, the prints should be washed with three successive baths of 10 per cent nitric acid, then washed for a short time with water, and treated with one of the following baths: ammonium sulphide, 1:3, for black; Schlippe’s salt, 2 per cent solution, for reddish-yellow; potassium chromate, 2 per cent, for yellow; ferric chloride for green; cupric chloride for red; uranium nitrate and ammonium chloride for red-brown; cobalt or nickel chloride for green; mercuric iodide for orange-yellow. Lead-tron for greenish tones (Maquenne).—This is a com- plicated process, which is open to the same objections as above, but the prints must be rather denser than normal, as there is no intensification. Four stock solutions are required, which will keep in the dark: A! Lead acetate 135 ¢ 1036 gr. Glacial acetic acid 100 ccm 768 min. Ferric chloride, dry Los 115 gr. Water 1000 ccm 16 oz. B. Lead acetate 100 g 768 gr. 226 PHOTOGRAPHIC FACTS AND FORMULAS Glacial acetic acid 100 g 768 gr. Water 1000 ccm 16 oz. C. Potassium ferricyanide 100 g 768 gr. Water 1000 ccm 16 oz. D. Ferric chloride V/3\¢ 13.4 gr. Glacial acetic acid 10 ccm 77 min. Water 1000 ccm 16 oz. To make A, dissolve the lead salt in the acid and water, add the iron, shake well, and filter. Blue-green tones are obtained by immersion of the prints for 5 minutes in a 2 per cent solution of glacial acetic acid and then in the following for 6 minutes: A solution 100 ccm 1 oz. C solution 100 ccm 1 oz. Water 1000 ccm 10 oz. Again immerse in the dilute acetic acid bath for a short time, wash well, transfer to a 0.5 per cent solution of citric acid, and wash for an hour. Then rub the surface gently with a pad of absorbent cotton, and immerse in: Potassium chromate 5tol0s. 38 to 77a Water 1000 ccm 16 oz. The colour turns brownish-green; wash the prints, immerse | in the citric acid solution, as above, and wash for a short time. Bright green tones are obtained by preliminary treat- ment with an acetic acid bath and immersion in: A solution 80 ccm 614 min. B solution 20 ccm 154 min. C solution 100 ccm 768 min. Water 1000 ccm 16 oz. Then the prints must be treated with the acetic acid, chromate and citric acid baths. Pure green tones are obtained by treating the prints to a preliminary acid bath, then im- mersing in: TONING BROMIDE PRINTS Zag B solution 50 ccm 384 min. C solution 50 ccm 384 min. Water 1000 ccm 16 oz. Without washing, transfer to the first bath given for blue- green. Rinse well and transfer to solution D. Treat with the dilute acid baths, wash well, and dry. Green tones can also be obtained (Sedlaczek) by bleaching the prints in: Lead nitrate NS 115 gr. Nitric acid 10 ccm 77 min. Potassium ferricyanide lg Te Water 1000 ccm 16 oz. Wash well, and immerse in: Ammonia iron alum 100 g 770 gr. Potassium bichromate, sat. sol. 50 ccm 385 min. Potassium bromide 5g 38 gr. Water 1000 ccm 16 oz. Treat the prints with a 3 per cent solution of hydrochloric acid until the whites are clean. Brighter green tones are obtained by immersion of the lead-bleached image in a 0.5 per cent solution of potassium bichromate, rinsing, and then treating with the above iron alum bath. Or blue-green tones may be obtained by using the following instead of the iron bath: Ammonia iron alum 100 g 7/0 or: Potassium bromide 50 g 385 gr. Water 1000 ccm 16 oz. Uranium AND Iron TonineG (Blake-Smith).—This also gives blueish-green tones: Uranium nitrate 5g 38.5 gr. Ammonio-citrate of iron 5g 38:5 gr: Nitric acid 5g 38.5 gr. Potassium ferricyanide 10g 77 gr. 228 PHOTOGRAPHIC FACTS AND FORMULAS Water 1000 ccm 16 oz. Or the following (Eder) : Uranium nitrate 5¢ 38.5 gr. Ammonio-citrate or iron 5¢ 38.5 gr. Glacial acetic acid 200 ccm 314 oz. Water 1000 ccm 16 oz. CosaLt Toninc (Somerville) —Greenish or green-blue tones are obtained by this process, but they are very unsatis- factory. Bleach the image in: Potassium bichromate 60 g 460 er. Potassium ferricyanide 300 g 544 oz. Water 1000 ccm 16 oz. Then wash until free from any yellow stain, and immerse in: Cobalt chloride 25g 192 gr. Ferrous sulphate 6g 46 gr. Hydrochloric acid 200 ccm 3% oz. Water 1000 ccm 16 oz. Replacement of the hydrochloric by glacial acetic acid gives brighter green tones. The prints should be fixed in: Hypo 250 g 4 oz. Boric acid 45 ¢ 345 gr. Water 1000 ccm 16 oz. Dissolve by heat, and use when cold. Wash the prints well. Or bleach the image in: Potassium ferricyanide 60 g 460 er. Lead nitrate 40 ¢ 307 gr. Water 1000 ccm 16 oz. Wash thoroughly, and immerse in: Cobalt chloride 100 g 768 gr. Hydrochloric acid 30 ccm 230 min. Water 1000 ccm 16 oz. GoLp AND PLatinum ToninG (Somerville )—Gold toning is sometimes resorted to, more to improve the colour of prints TONING BROMIDE PRINTS Zo than to obtain warm tones; and greenish or rusty prints can be improved by placing them face up, as they come from the washing after fixing, on a sheet of glass, dabbing into flatness with a clean pad of linen, and brushing over with: Ammonium sulphocyanide 20 g 154 gr. Gold chloride lg ETN op Hot water 1000 ccm 16 oz. Use when cold. A soft flat brush, without metal binding, should be used. When the desired improvement is reached, that is, when the image becomes black or blue-black, wash well, and dry. Purple blacks can be obtained by bleaching the prints first in: Cupric sulphate TIS) 2s 192 gr. Potassium bromide 25) = 192 er. Water 1000 ccm 16 oz. Rinse, and immerse for 5 minutes in 5 per cent nitric acid, wash, and tone in: Ammonium sulphocyanide 8g 61 gr. Ammonia 3 ccm 23 min. Gold chloride VAS) |e 18 gr. Water 1000 ccm 16 oz. Toning takes from 10 to 20 minutes, and the more ammonia used, the deeper the tone. Platinum toning gives warm sepias, but the results are not permanent. The following may be used (Heatherly) : Potassium oxalate 160 ¢ 1228 gr. Mercuric chloride l3 g 100 gr. Potassium citrate 20 ¢ 154 gr. Citric acid A0 a hihne SOstor: Water 1000 ccm 16 oz. Mix, and add just before use: Potassium chloroplatinite 2s. 2O7 on: Hydrochloric acid 27, ccm 21 min. 230 PHOTOGRAPHIC FACTS AND FORMULAS Water © 1000 ccm 16 oz. When the desired tone is obtained, wash well, and dry; slightly darker tones are obtained if the print is immersed in a 2 per cent solution of sodium carbonate. The following is stated to be suitable for bromide but not development (gaslight) prints: Mercuric chloride 2g 16 gr. Potassium chloroplatinite 4g 32 gr. Citric acid 18¢ 138 gr. Water 1000 ccm 16 oz. This should be made up fresh, and gives warm sepias with slight staining of the high lights. For cold sepia tones, with absence of staining of the whites, add potassium bromide 1g (8gr.) to the above. Wash well after toning. SELENIUM Toninc.—This gives various shades of sepia to purplish-red tones (Mailiani) : Powdered selenium 2tol0g 15.4to/77 gr. Sodium sulphide 100 g 768 gr. Water 1000 ccm 16 oz. Heat the solution till the selenium dissolves, and dilute as required for use. The weaker the bath, the more sepia the colour. On diluting the bath, some selenium is thrown down, and the solution should be filtered, or the prints after toning passed through two or three baths of 1 per cent solution of sodium sulphide. Another (Valenta) : Selenium 16.5¢ 127 gr. Sodium sulphide 200 g 3 1/5 oz. Water 1000 ccm 16 oz. Heat until dissolved, dilute with 5 to 6 times the volume of water, and add pyrocatechin, 1 per cent solution, 20 to 40 ccm to every liter or 154 to 307 min. to 16.0z. If the whites are tinged, pass the prints through weak baths of acid sulphite of soda. | | TONING BROMIDE PRINTS 231 According to Mimosa, if the selenium bath be neutralised with boric acid, there is no precipitation of the selenium; the addition of ammonia reduces the staining of the whites, which may be removed by a 10 per cent solution of potassium metabisulphite. Namias recommends to fuse in a nickel or iron crucible 2 parts of granular selenium with 10 to 15 parts of caustic soda, and, when cold, dissolve in 100 parts of water. The toning bath is: Sodium selenide, thus made 100 ccm 768 min. Sodium sulphide 50 g 384 gr. Water 1000 ccm 16 oz. Bleach the prints in the usual way, and then tone in this solution. A combined toning and fixing bath may be pre- pared by mixing: Hypo 66g 500 gr. Sodium selenide,as above afew drops afew drops Water 1000 ccm 16 oz. Boric acid 40g 307 gr. Dissolve the hypo and the acid in hot water, and add the selenium solution when cold. Better sepia tones are obtained with the following: Powdered selenium 2 parts i Sodium sulphide 50 parts Fuse together and dissolve in 150 parts of water. To make the bath, add a few drops of this stock solution to a 2 per cent solution of sodium sulphide. All selenium salts have an intense garlic odor, which is very lasting. Motyspenum Toninc (Namias)—This gives a deep blue tone: Molybdic acid 100 g 2 02. Ammonia 250 ccm 5 oz. Water 250 ccm 5 oz. 232 PHOTOGRAPHIC FACTS AND FORMULAS When dissolved, pour into: Nitric acid 500 ccm 10 oz. Water | 500 ccm 10 oz. To make the bath use: Molybdate solution above 250 ccm 4 oz. Water 1000 ccm 16 oz. Potassium metabisulphite 50 g 384 gr. This should be used in artificial light, and the prints well washed. ToNnING BY REDEVELOPMENT (Mamnly).—Various tones can be obtained by bleaching prints with the following baths and redeveloping with the given developers: A. Potassium ferricyanide 33 g 250 gr. Ammonium bromide 40 g 31Mier Water 1000 ccm 16 oz. B. Cupric sulphate 50 g 384 gr. Sulphuric acid 6.5 ccm 50 min. Common salt 50 g 384 er. Water 1000 ccm 16 oz. C. Potassium bichromate 20 ¢° Ep Sulphuric acid 50 ccm 384 min. Salt 100 g 768 gr. Water 1000 ccm 16 oz. After bleaching in one of the baths, the prints should be washed for 20 to 30 minutes, and redeveloped in the fol- lowing : I. Metol 10g VA Asa Sodium sulphite, dry 33 g 250 gr. Sodium carbonate, dry 33 g 250 ger. Water 1000 ccm 16 oz. II. Hydrochinon | 30g 250 gr. Potassium metabisulphite 16g 123 ee Water 1000 ccm 16 oz. TONING BROMIDE PRINTS 233 IiJ. Ammonium carbonate 100 g 768 gr. Water 1000 ccm 16 oz. The tones are somewhat dependent on the make of paper, but the following will give a general idea of the tones obtain- able. Bleach in A; develop in equal parts of II and III, diluted with more or less water; rich purplish-brown tones are obtained. Bleach in equal parts A, B, C; develop in I; result, good blacks slightly wanting in depth. Bleach in B; develop in I; splendid velvety blue-blacks in the shadows, like carbon paper. Bleach in C; develop in 4 parts II, 6 parts III and 2 parts water; distinct intense brown with pure whites. Bleach in C; develop in 1 part II, 1 part III, 1 part water; a good sepia, like sulphur toning. Bleach in C; develop in Z parts IJ, 1 part III and 2 parts water; result, a bright brown. Sulphide Toning There are two principal methods of obtaining warm brown or sepia to purplish brown tones: the direct and the indirect. In the former, the image is converted into silver sulphide direct, while in the latter process the silver is first converted into chloride, bromide or iodide, and then into sulphide. Direct Processes.—Alum and hypo (Baekeland).— Hypo 200 g 3 l/Siez, Potash alum 46 ¢ 354 gr. Water 1000 ccm 16 oz. Dissolve the hypo, keeping the temperature of the solution near the boiling point, add the alum gradually with constant stirring, and allow to cool. Heat up to 50° to 60° C. (122° to 140° F.) each day for three days, and then add: Silver nitrate, 10% sol. 5to7Zccm 40to55 min. The bath must not be filtered. Alum-sugar-hypo (Baekeland).— Hypo 25 ¢g 192 gr. White sugar 40g 307 gr. Alum 25g 192 gr. Hot water 1000 ccm 16 oz. Mix as above. It is advisable to wash the prints thoroughly after fixing, and with some papers it is advisable also to immerse for 5 minutes in an alum bath, then briefly wash and tone. The bath should never be above 44° C. (110° F.), the best results being obtained at about 32° C. (90° F.), though toning at this temperature takes 30 minutes. Alum and hypo (Artura).—Specially recommended for development (gaslight) papers, but equally suitable for bromide prints: 234 SULPHIDE TONING 235 A. Hypo 125¢ 2 oz. Potash alum 31g Y, oz. Hot water 1000 ccm 16 oz. B. Silver nitrate, 10% sol. 10 ccm 77 min. Salt, 10% sol. 10 ccm 7/7 min. As soon as A has cooled down, add B with constant stirring. The best temperature is 31° C. (88° F.), and toning takes from 15 to 30 minutes. Alum-gold-hypo (Artura)— Hypo 62.5 g 1 oz. Potash alum 15.5¢ YA oz. Sodium phosphate ibeyesy ces 4 oz. Hot water 1000 ccm 16 oz. Dissolve the salts in the order given. Add, when the solution is cold: Silver nitrate, 10% sol. 10 ccm 77 min. Potassium bromide, 10% sol. 10 ccm 77 min. Finally, add: Gold chloride, 1% sol. 13 ccm 100 min. The working temperature should be 35° to 39° C. (95° to Oe At) When hot toning baths are used, the prints should be allowed to cool before washing; otherwise blisters are very likely to form. Colloidal sulphur (Lumiére).— Hypo 125'¢ 2 2. Hot water 1000 ccm 16 oz. Dissolve, and add: Yellow dextrine, 50% sol. 250ccm 4 oz. And, shortly before use, add: Hydrochloric acid, pure 50 ccm 384 min. The bath will not keep more than about 2 hours. Prints should be immersed in the bath at a temperature of 18° to 236 PHOTOGRAPHIC FACTS AND FORMULAS 20° C. (65° to 68° F.) for 20 to 35 minutes, and apparently no change takes place; but, if washed for 1¥4 hours, the sepia tone makes its appearance. Liver of sulphur or polysulphide process (Woodman) .— Wash the prints free from hypo, harden by immersion in formaldehyde solution, and place at once in a solution of liver of sulphur (sulphurated potash) made by dissolving a piece about the size of a pea in 200 ccm (7 oz.) water. Ammoniacal liver of sulphur (Vero).—The prints must be free from hypo and must not have been dried. Harden by 10 minutes’ immersion in a 10 per cent solution of formalde- hyde, wash, and immerse in: Liver of sulphur 7g 54 gr. Water 1000 ccm 16 oz. Ammonia a few drops Toning is very rapid and purplish-brown tones are obtained. Ammonium sulphide (Kropf )— A. Ammonium sulphide 25 ccm 192 min. Water 1000 ccm 16 oz. B. Ammonium carbonate 3.75 g 29 gr. Water 125 ccm 2 oz. C. Ammonium persulphate 1252 10 gr. Water 125 ccm 2-02; Mix in the above order. The colour of the mixture should be greenish-yellow, and, in about half an hour, turn to golden yellow, when it is ready for use. Prints should be washed for a short time after fixing, and then immersed in the bath at normal temperature; toning takes about 15 min- utes. If heated to 30° C. (86° F.), toning is complete in 10 minutes. Sodium sulphide-ferricyamde (Brown).— Sodium sulphide, 20% sol. 400 ccm 8 oz. SULPHIDE TONING 237 Potassium ferricyanide, 20% sol. 200 ccm 4 oz. The mixture turns milky, but clears up on stirring well. Then add: Potassium bromide, 10% sol. 200 ccm 4 oz. Glacial acetic acid 50 ccm Y oz. Stir until the precipitate dissolves. The prints should be well washed, and, in from 10 to 15 minutes after immersion in the bath, assume a very pleasing brown tone. Sulphide-ferricyanide (Blake-Smith)—Three stock solu- tions are required: A. Sodium sulphide, pure 100 g 4 oz. Water 400 ccm 16 oz. B. Sulphuric acid, pure 25 ccm lioz: Water 250 ccm 10 oz. C. Potassium ferricyanide 50 g 1 oz. Water 500 ccm 10 oz. For use mix: | A solution 60 ccm 460 min. Water 1000 ccm 16 oz. Then add: B solution 180/cem a) Zioz’ Gdn: And, finally, add: C solution 500 ccm 8 02. Toning should be complete in from 2 to 5 minutes. Ammonum sulphide-ferricyanide — A. Potassium bromide llg 85 er. Potassium ferricyanide Si 269 gr. Water 1000 ccm 16 oz. To this, add: B. Ammonium sulphide 25 ccm 192 min. Water 100 ccm 1Y4 oz. This last solution should be mixed just before use. 238 PHOTOGRAPHIC FACTS AND FORMULAS Thiocarbamide-sulphide (Triepel) — Potassium bromide 10g 77 gr. Potassium ferricyanide l5¢g 115 gr. Sodium sulphide 4g 31 gr. Thiocarbamide 2¢g 15.5 gr. Caustic soda 2¢ 15.5 gr. Water 1000 ccm 16 oz. InpirEcT Processes.—The bleaching bath may be made either with a bromide, chloride or iodide. The correct formula for the bromide is: Ammonium bromide lig 85 gr. For the chloride Salt 6.6 g 50 gr. For the iodide: Potassium iodide 18.6 g 143 gr. Each should be added to: Potassium ferricyanide sae 269 gr. . Water 1000 ccm 16 oz. If the halide salts be used in the above quantities, there is no loss in the intensity of the images, which will be the case if they are used stronger. The above may be kept as stock solutions. The following gives a somewhat colder sepia than the above: Potassium ferricyanide 6g 46 er. Ammonia 15 ccm 115 min. Water 1000 ccm 16 oz. Various modifications have been suggested, as: Potassium ferricyanide 23 ¢g 177 gr. Potassium iodide l4¢ 107 gr. Ammonium persulphate l4g 107 gr. Water 1000 ccm 16 oz. Or: Potassium iodide 23 g 177 gr. SULPHIDE TONING Zao Iodine 10¢ 77 gr. Water 1000 ccm 16 oz. In these last two baths the paper turns a deep blue, which may be discharged by immersion in a 2 per cent solution of potassium metabisulphite or sodium sulphite acidulated with a little sulphuric acid. The following was recommended (Greenall) for commer- cial work, as it saves the cost of the halides: Potassium ferricyanide 23 ¢g 177 st: Sodium phosphate PSs 883 gr. Water 1000 ccm 16 oz. Bichromate baths have been recommended, but they require much longer washing to remove the yellow bichromate stain than the other baths. Sedlaczek’s formula is: Potassium bichromate, sat. sol. 100 ccm oz. Hydrochloric acid, 10% sol. 100 ccm faz: Potassium bromide 100 g 1 oz. Water 1000 ccm 10 oz. Blake-Smith recommended : Potassium bichromate 2s: 160 gr. Sulphuric acid 40 ccm 307 min. Salt 100 g 768 gr. Water 1000 ccm 16 oz. Too long washing of the bleached prints causes yellow tones; about 10 minutes in running water is enough. The toning solution is sodium sulphide, and the best results are obtained with the hydrated salt (pure analytical agent). Ordinary technical sulphide should be made into a stock solution and boiled for a short time until a black precipitate forms, or allowed to stand for several days, and then filtered. Old deliquesced salt should not be used, as it consists in great part of hypo and caustic soda, which reduce the strength of the 240 PHOTOGRAPHIC FACTS AND FORMULAS print and cause blisters. A stock solution that will keep (Blake-Smith) can be made as follows: Sodium sulphide 330 g 5 oz. Sodium sulphite, dry 50to65¢gr. %toloz. Water 1000 ccm 15 oz. For use dilute with 9 volumes of water. The bath should not be used too long. Ammonium or barium sulphide may be used instead of the sodium compound: Ammonium sulphide 10to20ccm 77 to 154 min. Water 1000 ccm 16 oz. Or: Barium sulphide 552 25 gr. Water 1000 ccm 16/02; Shake the latter solution for a few minutes and allow to stand for any precipitate to settle, and then filter. The barium salt is more stable than the sodium and therefore preferable in practice. For chlorising or bromising the image, quinone has been recommended (Lumiére & Seyewetz) : Quinone 5g 38%4 gr. Sodium chloride (salt) 6g 46 gr. Sulphuric acid 3.ccm 23 min. Water 1000 ccm 16 oz. Potassium bromide 11 g (85 gr.) may be used instead of the sodium chloride. The bleached images are amenable to exactly the same treatment as all other bleached images. Molybdenum and tin sulphur compounds, called sulpho- or thiomolybdates and stannates have been proposed (Smith) ; the former was introduced commercially as ‘“(Cubrome” and gives excellent results. This solution can be made as fol- lows: Ammonium molybdate 100 g 770 gr. SULPHIDE TONING 241 Hot water 1000 ccm 16 oz. When cold, add in small quantities with constant stirring, ammonium sulphide sufficient to form a deep orange solu- tion. For use mix: Stock solution 100 ccm 7/0 min. Ammonia 10 ccm 7/ min. Water 1000 ccm 16 oz. If the whites of the prints are stained yellow, immerse for a short time in a 3 per cent solution of ammonia, and wash thoroughly. This gives excellent results with the bichromate bleaches. Sodium sulphostannate may be prepared as follows: Sodium sulphide, pure 30 g 230 gr. Water 1000 ccm 16 oz. Stannic sulphide 0g 538 gr. Dissolve the sodium salt in about one-fourth of the water, add the tin salt, and heat gently with constant stirring until dissolved; then dilute to bulk. Stannic sulphide is known | also as tin disulphide, or bisulphide, or mosaic gold. One part of the above solution should be diluted with 9 parts of water for use. Sulphides plus developer—This method gives somewhat darker tones, as some black metallic silver is probably formed with the sulphide. The prints should be bleached as usual (Greenall), and then treated with the following: Metol lg 7/7 gr. Potassium carbonate 1325s 100 gr. Sodium sulphide, 1% sol. 3to5ccm 23 to 40 min. Water | 1000 ccm 16 oz. This gives a warm black, which varies with increase of the sulphide. Valenta’s method requires three stock solutions: A. Pyrocatechin 20g 154 gr. 242 PHOTOGRAPHIC FACTS AND FORMULAS Sodium sulphite, dry 50 g 384 gr. Water 1000 ccm 16 oz. B. Sodium carbonate, cryst. 200 g 3 1/5 oz. Water 1000 ccm 16 oz. C. Schlippe’s salt 10g 77 gr. Water 1000 ccm 16 oz. For use mix 2 parts A with 1 part B, and for sepia tones add 2 per cent C; for warm brown tones add 4 percent C. Toning with mercury sulphides.—In this method the varia- tion of colour depends on the addition of more or less mer- cury salt to the image (Bennett). Two stock solutions are required for the bleaching bath: A. Ammonium bromide Lig 85 gr. Potassium ferricyanide 35 g 269 gr. Water 1000 ccm 16 oz. B. Mercuric chloride 28 ¢ 215 oF) Potassium bromide 28 g 215 on: Hot water 1000 ccm 16 oz. And two stock solutions for the toning bath: I. Sodium sulphide 330 g 5 1/Sag: Sodium sulphite, dry 50 to 65 g 385 to 500 gr. Water 1000 ccm 16 oz. II. Schlippe’s salt 10g (7 /8E: Water 1000 ccm 16 oz. The following table gives the colours obtainable with the various baths: Bleacher Toning bath Black AL iy By I I Brown black AS 2: B, 1 iE Deep brown A, 3;B,1 I Dark brown A Stoi7 > B, 1 I Deep warm brown A I Reddish brown A Lae rere” SULPHIDE TONING 243 Red brown A Lets Th 4 Very warm brown A DV Miy2 Red chalk A Il Schlippe’s salt is also known as sodium sulphantimoniate. The crystals should be rinsed with water before use, and a drop or two of ammonia added to the stock solution. Various tones may also be obtained with mercury salts by the following baths. Bleach the prints in: Mercuric chloride . I2¢ 92 gr. Potassium bromide I2¢ OZ ar: Water 1000 ccm 16 oz. Wash thoroughly, and use the following baths for the various colours : Greyish-black : Hypo 10.5 g 80 gr. Water | 1000 ccm 16 oz. Grey-violet: Hypo 10.5 g 80 ger. Potassium metabisulphite 5.25 g 40 er. Water 1000 ccm 16 oz. Brown to violet-black : Hypo 18.75 g 144 gr. Cupric sulphate 18.75 g 144 gr. Water 1000 ccm 16 oz. The addition of a few grains of sodium carbonate gives darker tones. Brownish-violet : Hypo 12.5 ¢ 96 gr. Silver nitrate 42¢ 32 or: Sodium metabisulphite 6:25 )g 48 er. Water 1000 ccm 16 oz. It should be noted that all mercury toning gives intensifica- tion. 244 PHOTOGRAPHIC FACTS AND FORMULAS Sulphide and Schlippe’s salt Variation of colour may be obtained by combining sodium or ammonium sulphide with Schlippe’s salt (Bishop). Ten per cent solutions of sodium sulphide and Schlippe’s salt should be made, or the com- mercial solution of ammonium sulphide may be used. For red-brown tones mix: Sulphide solution 25 ccm 192 min. Schlippe’s salt solution 75 ccm 576 min. Water 1000 ccm 16 oz. For warm brown: Sulphide solution 50 ccm 384 min. Schlippe’s salt solution 50 ccm 384 min. Water 1000 ccm 16 oz. For brown tones: Sulphide solution 75 ccm 576 min. Schlippe’s salt solution 25 ccm 192 min. Water 1000 ccm 16 oz. Carmine or red chalk tones.——These can be easily procured by treatment of a sulphide toned print with gold sulpho- cyanide: Gold chloride 2.3¢ 15 gr. Ammonium sulphocyanide 23g 150 gr. Water 1000 ccm 16 oz. The following (Blake-Smith) acts better: A. Gold chloride lg 1bee Water 225 ccm 7 OZ. B. Thiocarbamide O25¢ 23; OF: Water 1000 ccm 16 oz. C. Sulphuric acid 10 ccm 77 min. Water 1000 ccm 16 oz. For use mix 1 part each of A, B and C with 10 parts water. Allow the action to continue until the deepest shadows are toned. ts as SULPHIDE, TONING 245 Reducing sulphide-toned prints—Sulphide toned prints may be reduced by treatment with most of the usual negative reducers or with chlorine and bromine water, solutions of iodide, permanganate, and sulphuric acid. The most satis- factory are solutions of cupric chloride or bromide, the latter for preference (Smith). The chloride reducer is equal parts of a 5 per cent solution of cupric chloride and a 15 per cent solution of common salt. The bromide reducer is: Cupric bromide . Toe 58 ger. Sodium bromide O25s 480 gr. Water 1000 ccm 16 oz. The cupric bromide in this bath may be replaced by using 8.5¢ (65 gr.) cupric sulphate, and increasing the sodium bromide by 8g (61 gr.). After reduction the prints should be immersed for 2 minutes in a 5 per cent solution of hydro- chloric acid, and washed for about 10 minutes. Partial development and sulphiding—Bleach the prints in the usual ferricyanide and bromide mixture, wash for 90 seconds in running water, and immerse for various times in the following developer ; rinse for 30 seconds, and treat with the usual sulphide bath. Metol 18¢ 14 gr. ' Hydrochinon 46¢ S51et: Sodium sulphite, dry 922 70 gr. Borax 18.4 ¢ 140 gr. Water 1000 ccm 16 oz. The following table shows the various tones obtained : 246 PHOTOGRAPHIC FACTS AND FORMULAS MO]JOA JSed'T MO]JIA 4SOTT LiPee QO] UWseMJ0q o}eIPSUTIDjwUT syIsMIy asueI [NJosN jsOW sy] sulptydjns ou pue pasn aaoieiep ysusl}s [[Ny quid [euro N syIeU10y ayeuogsed WMNIPOS UI ‘das CO] aprydins aprydins W8_ PILL MO]eA JO 9s8uT} JOUT} -SID YIM eidos WIE A, eidas WIe AA vidas eidas JUI}0ZZ97 eidas [007 yoeiq uMOIG O} YORI WIE AA ORG WIV AA ai oad tal qulid poystug JO InoOl[Od Juylnsey “UI ¢ IOF yoeg aprydinsaig “T] oyeuogied WINIpPOS UI ‘DIS CT rq ‘Ol “UIU ¢ IOJ yoeajq = aprydinsaig “6 Wwq puovg Ye S84 “ON FUIIg pos ajed AtoA = Saqnutut 9 pel zeg sojnurm 6 pet JoqystyT = sojynuru 7] pay soynuiwi cy] pet ayejosoyy) = saqnurwt OZ JBJOIA JO asuTy YM pal ayejoooyy) =sojnulMI o¢ “¢ INO N OO peus -yoeq [HUQ “Zz =t dedojaa0q Wor zedo[9a0q ‘ON [8Aouel uO INO[OD Ul OWL, qulig SULPHIDE, TONING 247 GENERAL Notes oN SuLPHUR ToninGc.—R. Bullock of the Kodak Research Laboratory, finds that the character of the emulsion has considerable influence on the resulting colour; the faster the emulsion the more purple the colour, while slow papers tend to give yellowish tones. Also, with a given paper, the degree of development exerts some action, although this may be masked by the character of the emulsion. With a given paper and method of making the black and white print, the hypo-alum and liver of sulphur (potassa sulphurata) toning processes give practically identical results, while the indirect methods, that is, those in which the image is bleached first, tend to give yellowish prints. The effect of a preliminary treatment of the black and white print with sulphide, prior to bleaching, is to give mixed direct and indirect sulphide toning; the results depending on the exact procedure followed, and, therefore, varying in colour. In the indirect process there is no advantage in increasing the ratio of the bromide to more than one-third of the ferri- cyanide. With 10 per cent of ferricyanide, the colour is more yellowish and the bleaching very rapid; with from 3 to 1 per cent, the bleaching is practically no longer and the colours normal: with much less than 1 per cent, bleaching is much slower but the colour just as good. The most advisable strength would thus appear to be 3 per cent, or 30¢ ferri- cyanide per liter (230 gr. to 160z.) with 10g (77 gr.) am- monium bromide respectively. No advantage is to be found by the use of chlorides, while with iodides the tones are more yellowish. For the sulphide bath, a strength of 3 per cent is the best, and the bath should be unsparingly used so as not to exhaust it. Dipping the prints for about 10 seconds into a 1 per cent solution of sodium carbonate, immediately before the sulphide bath, tends to give more purplish tones, particu- larly with development papers, and when a chloride bleach is 248 PHOTOGRAPHIC FACTS AND FORMULAS used. The final conclusions are that: excessive bromide in the bleach leads to loss of image; too long washing after bleaching should be avoided, as well as weakness or too long use of the sulphide bath, and presence of hypo in the latter. The Carbon Process MAKING THE TissuE.—The gelatine mass is prepared with hard and soft gelatine in the ratio of 3:1, or the finest pale carpenter’s glue may be used, with an admixture of sugar candy ; in very hot dry climates a little glycerine. The latter addition is not advisable under ordinary circumstances. A typical formula is: Gelatine 200 g 3Y4 oz. Sugar candy 50 g 384 gr. Water 1000 ccm 16 oz. Colouring pigment Ato lOie | 30/to 77 Sr. Soak the gelatine and candy in the water for about 30 minutes and melt on a water bath. The pigment should be the finest powder colours, as used by artists. It should be worked up with a muller on a sheet of glass with a little of the gelatine solution, and added to the remainder of the solution, well stirred and strained through linen. THE Cotours.—The colours can be mixed in various pro- portions, so that any shade may be obtained, and these should be judged by their appearance when mixed with a little of the gelatine solution and dried. Chocolate brown —lIndian ink 6, English red 4, alizarin 1, dissolved in a little soda solution, purpurine 1 part. Engraving black —Lamp black 19, carmine lake 10, indigo 10 parts. Warm black.—Lamp black 6, carmine lake 6, burnt umber 4, indigo 2 parts. Dark brown.—Indigo 214, Indian red 6, carmine 114, Van- dyke brown 4, lamp black 30 parts. 249 250 PHOTOGRAPHIC FACTS AND FORMULAS Red brown.—Indian ink 6, carmine 8, Vandyke brown 8 parts. Sepia.—Lamp black 4, sepia 35 parts. Pure black —Indian ink 15, Vandyke brown 2, Venetian red 2 parts. Violet black—Indian ink 20, indigo 2, carmine 1 part. Red chalk.—English red 10, Italian red 5, lamp black 0.03 parts. Transparency tissue for enlarged negatives, and positives. —Indian ink 2, Indian red 3, carmine lake 5 parts. To Coat sy Hanp.—Strain the warm mixture into a flat dish standing in warm water, and clear the bubbles off the surface with a strip of paper or thin card. Hold the paper to be coated upright at the further end of the dish, its lower edge just touching the liquid, and gently lower it on to the surface. Float for 2 minutes, and raise with a steady mo- tion; allow to drip and hang up to dry. SENSITISING.—Either ammonium or potassium bichromate may be used: Potassium bichromate 21 to 63g 160 to 480 gr. Water 1000 ccm 16 oz. Ammonia q. S. q. Ss. Enough ammonia should be used to make the solution smell distinctly. For weak negatives use the weakest bath, for normal negatives the mean, and for harsh negatives the strongest bath. Immerse the tissue for 3 minutes, and dry in the dark. The temperature of the solution should be 15° C. C60" EF.) The following gives a tissue that will keep better: Potassium bichromate 20 g 240 gr. Citric acid i 5g 60 gr. Ammonia A NGLd Se qu St He CARBON TROCHSS 251 Water 1000 ccm 2072: Use as above. QUICK-DRYING SENSITISER.—This is convenient, as the tissue will readily dry in from 15 to 30 minutes. Ammonium bichromate 60 g 460 gr. Water 1000 ccm i 1L@oz. Immediately before use mix 2 parts of the above with 3 parts of alcohol or acetone. The tissue may be immersed in this for 3 to 4 minutes, or the solution may be painted on freely. The alcoholic mixture will not keep. SINGLE TRANSFER PapPer.—Brush over plain paper: Soft gelatine 60 ¢ — 460 er. Water 875 ccm 14 oz. Soak the geiatine for 30 minutes, dissolve in a water bath, and raise nearly to the boiling point; add with constant stirring : Chrome alum 1.25 ¢ 10 gr. Water 125 ccm 2 Oz. The mixture must be rapidly used and kept hot, or it will gelatinise. The following may be easily applied with a broad flat brush and dries rapidly: Soft gelatine Pe 54 gr. Glacial acetic acid 35 ccm 270 min. Water 275 ccm 44 oz. Soak the gelatine in the acid and water for 30 minutes, and dissolve by heat; add slowly with constant stirring: Alcohol 680 ccm 11¥Y, oz. Then add in the same way: Chrome alum 16¢ 12% gr. Water 14 ccm 110 min. This solution will keep. FLEXIBLE TEMPORARY SupporT.—Gelatinised paper is coated with a resinous solution. As a rule, a baryta-coated 252 PHOTOGRAPHIC FACTS AND FORMULAS paper is used, either matt or glossy, which may be prepared as follows: Gelatine 100 g 134 oz. Barium sulphate 30 g 230 gr. Glycerine 5 ccm 38 min. Water 940 ccm 14 oz. Soak the gelatine in water, dissolve by heat, and add the baryta rubbed into a cream with the glycerine. Add very carefully, almost drop by drop, with constant stirring: Chrome alum 16g 13 gr, Water 60 ccm 2 oz. Paint the mixture thickly over the paper, or else float it twice, hanging up by opposite ends each time. Obviously, single transfer or commercial baryta paper may be used. WaxiInG SOLuTION,—The temporary support has to be waxed prior to use, and the following may be used: Beeswax 20 g 154 gr. Powdered resin 20 g 154 gr. Turpentine 1000 ccm 16 oz. Melt the wax in a water bath, add the resin, and stir until dissolved; then add the turpentine gradually with constant stirring. This takes from 12 to 24 hours to dry; if ether be substituted for the turpentine, it will dry in a few minutes. Caution.—The water in the bath should boil, and then the gas be turned out, as the vapours of both turpentine and ether are explosive. This should be applied to the paper with a pad, polished off with a dry pad, and then hung up to dry. A.LuM BATH For DISCHARGING BICHROMATE STAIN.— Alum 62:5 2 1 oz. Water 1000 ccm 16 oz. CoLLODION FOR DoUBLE TRANSFER FROM OpaL.—This gives an extremely fine matt surface, without any glaze, if THE CARBON PROCESS 256 matt surface glass be used; if polished opal be used, a high gloss is obtained: Pyroxyline 8.5 ¢g GaleT: Alcohol 500 ccm 8 oz. Ether 500 ccm 8 oz. OpaL Gtass, Ivory or Woop as FINAL SuPPORT.—Coat with the chrome gelatine mixture given above under single transfer paper. For canvas, the surface paint should be removed by scrubbing with hot soda solution, about 10 per cent, until nothing but the priming is left. Paint freely with the chrome-gelatine mixture, dry thoroughly, rub down smooth with fine sandpaper, and repeat the operations about four times. The print should be finally soaked in the gelatine solution, and squeegeed into contact. SUBSTRATUM FOR TRANSPARENCIES.—FEither of the fol- lowing may be used: Gelatine 40 g 307 er. Water 1000 ccm 16 oz. Potassium bichromate 4g 31 gr. Coat the glass thinly, dry, and expose to light for 30 minutes; then wash and dry. Or the glass may be coated with the following, which keeps well: Gelatine 7g 54 er. Glacial acetic acid 34 ccm 260 min. Water 270 ccm ATZ oz. Dissolve by heat, and add slowly: Alcohol 680 ccm ioz: Phenol (carbolic acid) 10 ccm 77 min. Then add, with constant stirring: Chrome alum Cys & 534 gr. Water 14 ccm 107 min. To INTENSIFY CARBON TRANSPARENCIES.—Immerse in: YUANY rea MiNi 254 PHOTOGRAPHIC FACTS AND FOR Potassium permanganate 5g 38 gr. ge Water 1000ccm 16 0z. Rinse and dry. Weak solutions of acid aniline dyes may also i! be used, about 0.5 per cent. By the use of the latter it is possible to alter the colour in any desired manner. The Gum-Bichromate Process PIGMENTS FOR GuM-BicHROMATE (Kosel).—Powder or tempera colours should be used. Warm brown: Bone black, 5 parts; Vandyke brown, 3 parts; ivory black, 2 parts; Indian red, 1 part. Purple brown: Ivory black, 5 parts; Vandyke brown, 4 parts; dark alizarin lake, 2 parts; Indian red, 1 part. Yellowish brown: Ivory black, 5 parts; bone black, 5 parts; burnt sienna, 1 part. Dark brown: Bone or ivory black alone. Brown (for sunset effects): Bistre. Brown, medium shade: Bone black, 5 parts; Vandyke © brown, 4 parts; burnt sienna, 1 part; Indian red, 1 part. Bright brown: Bone black, 5 parts; Vandyke brown, 4 parts; sienna, 4 parts. Deep brown: Ivory black, 5 parts; Vandyke brown, 3 parts; Indian red, 1 part. Bide.) Ivory or peach black, 5)\\patts ;) mdigo) 5) parts: fats blue; 1) part. Dark green; Bone) black; 5 parts; Paris blue, 2 parts: Or) Bone) black; 5 parts; indigo,):5) parts; blue ‘black, (5 parts; Paris blue, 1 part; cadmium yellow, 1 part. Bright green: Vandyke brown, 3 parts, Paris blue, 1 part. Olive green: Sienna, 2 parts; indigo, 2 parts; bone black, 5 parts. Red: Ivory black, 5 parts; burnt sienna, 2 parts; Indian red, 2 parts. Warm red: Bone black, 5 parts; red chalk, 3 parts; Indian red, 1 part. 255 256 PHOTOGRAPHIC FACTS AND FORMULAS Dark red: Peach black, 2 parts; alizarin lake, 1 part; Indian red, 1 part. Black, for pencil drawings: Graphite. Black: Peach or blue black. Warm black: Ivory black. ARABIN GuM-BICHROMATE Process.—The best Soudan gum arabic should be sifted through a 40 mesh sieve. Take: Hydrochloric acid 7.5 ccm 127 min. Water 150 ccm 5Y4 oz. Heat to 50° C. (122° F.), sift in 100 g (3% oz.) of the gum, and stir until dissolved; then add methyl alcohol, 600 ccm (21o0z.), and stir until the arabin is precipitated. Filter through linen, and squeeze out as much alcohol as possible. Then break up the lump, put in jar, and cover with fresh alcohol; leave for some hours with constant stirring until all the water has been absorbed by the alcohol. Squeeze dry, spread out to thoroughly dry, and powder. To make the coating mixture, take: Arabin 20 g 300 ger. Magnesium carbonate 20 g 300 gr. Water 40 to75ccem 1% to2% oz. The quantity of water depends on the thickness of the solu- tion desired. Mix the pigment of the desired colour with the above until a thick cream is formed, add an equal volume of 15 per cent solution of ammonium bichromate, and spread on paper. Development is effected in the usual way with mater at about 30° Cii(957 dae FORMULA FOR PurE WHITES.—Frequently pure whites are difficult to obtain with this process, and the following is said to obviate this trouble: Potassium bichromate 722 550: 2: Water 450 ccm 7 02. Dissolve by heat, add enough ammonia to make the solution THE GUM-BICHROMATE PROCESS Za7, smell distinctly, and then heat to drive off excess of ammonia. Beat the whites of several eggs to a froth, and allow to stand for 24 hours to liquefy. The pigmenting solution is: Bichromate sol., above 450 ccm 74 02. Cupric sulphate 90 g 720 gr. Gum arabic, powdered 800 ¢ 13% oz. Pigment 600 g 10 oz. Albumen 200 ccm S/S); 0z: Glycerine 100 ccm 768 min. Mix well, and apply as usual to the paper. The Iron Processes FERROPRUSSIATE OR CYANOTYPE Process.—This process is much used for the preparation of engineering and draughtsman’s plans, giving white lines on a blue ground, that is to say, a blue image is formed by the action of light. The sensitive solutions can be made as follows: A. Ferric ammonium citrate (red) 250 ¢ 4 oz. Water — 1000 ccm 16 oz. Filter. B. Potassium ferricyanide 200 g 3 1/35.02: Water 1000 ccm 16 oz. Filter. The ferricyanide must be in perfectly clear ruby-red crystals, free from any adherent yellow powder; it is advis- able to allow a little more in weighing out, and place the crystals in a flask; pour in some distilled water, shake, pour off the water, and repeat this operation; then add the water for the solution, and heat until dissolved. Mix the two solu- tions in equal volumes and filter. Either float the paper on the solution for 3 minutes, or paint the solution on freely with a broad flat brush, and dry as quickly as possible, prefer- ably by heat. A much more sensitive paper is obtained by using the green ammonio-citrate of iron; then the solutions should be: A. Ferric ammonium citrate (green) 125 g 2 oz. Water 500 ccm 8 oz. Filter, and add: B. Potassium ferricyanide 45¢ 346 gr. Water 500 ccm 8 oz. 258 Ty THE IRON PROCESSES 259 Filter. The method of using is as above. Brighter prints are obtained by the addition of 0.5 per cent of oxalic acid to the above; the paper keeps better if 0.05 per cent of potas- sium bichromate is added. The use of sodium or ammonium ferric oxalate gives greater speed than the above, but the paper does not keep so well. The sensitiser should then be: Potassium ferricyanide 133 ¢ 1021 gr. Ferricammonium citrate (red) 166 ¢ L277 se: Sodium or ammonium ferric oxalate 33 g 25920, Water 1000 ccm 16 oz. All these solutions are sensitive to light. Other iron salts may also be used, for instance: A. Sodium or ammonium ferric oxalate 250 g 4 oz. Water 1000 ccm 16 oz. B. Potassium ferricyanide 250 g 4 oz. Water - 1000 ccm 16 oz. Filter both solutions, mix, and again filter. Or the follow- ing may be used: A. Tartaric acid 180 g 1382 gr. Ferric chloride, anhydrous 68 g 220%: Ammonia q. S. q. S. Water 1000 ccm 16 oz. Dissolve the acid in three-fourths of the water, then add the iron, and, when dissolved, add sufficient ammonia to neu- tralise the acid, about 175ccm (2%40z.) being required; excess of ammonia must be avoided. Filter, and add to: B. Potassium ferricyanide PANT a 1666 gr. Water 1000 ccm 16 oz. Mix the two solutions. This gives greater sensitiveness, but the prepared papers to not keep so well as the others. 260 PHOTOGRAPHIC FACTS AND FORMULAS It is important that the paper base should be free from wood pulp, preferably sized with starch, and with a hard surface. It has been suggested to add white dextrine to the sensitiser, but this lowers the keeping quality. The paper should be exposed preferably to sunlight until the ground, corresponding to the whites of the negative or plan, appears a dark olive-green; it should then be thoroughly washed with running water, and the lines should appear white on a deep blue background. With stale paper or with excess of or impure ferricyanide, the lines will appear more or less tinted. With underprinting the colour is more or less pale. Fre- quently, by somewhat prolonging the washing, the lines will clear up; or this can be much curtailed by using a 0.01 per cent solution of ammonia or sodium carbonate. This gives a violet tinge to the blue, and this can be corrected by subse- quent treatment with an acid, 5 per cent of hydrochloric, oxalic or sulphuric acid, or alum solution of the same strength. A much more stable and contrasty image is ob- tained if the print is developed with a 0.2 per cent solution of potassium ferricyanide, and well washed for four or five minutes. Numerous methods have been suggested for toning blue prints, but, as a rule, the results are extremely unsatisfactory. Immerse the dry print in: Ammonia (sp. gr. 897) 12.5 ccm 96 mia. Water 1000 ccm 16 oz. As soon as the blue color disappears, wash for a few minutes, and then immerse in a 2 per cent solution of tannin; this gives a blackish colour, but the outlines may become blurred from spreading of the colour into the whites. Or the print may be well washed in distilled water, and bleached in yellow light in: Silver nitrate 20 g 154 gr. THE IRON PROCESSES 261 Water 1000 ccm 16 oz. Wash with distilled water, and fume with ammonia, expose to light, and develop with ferrous oxalate; then wash thor- oughly. The cyanotype process may be used for making lantern slides or transparencies, though, naturally, the colour is suit- able for but few subjects. The sensitising solution is rather weaker than used for paper: A. Ferric ammonium citrate (green) 250 g 4 oz. Water 1000 ccm 16 oz. B. Potassium ferricyanide 100 g 768 gr. Water 1000 ccm 16 oz. Mix in equal volumes and filter. Gelatinised glass (fixed out dry plates may be used) should be immersed for 5 minutes, and rapidly dried. The sensitiser will not keep when mixed. The plates should be exposed like the paper, and washed in the same way. PELLET’s oR Gum-IRon Process.—This process gives blue lines on a white ground, thus the reverse of the cyanotype process, from a drawing or plan. The paper has very poor keeping qualities. Originally patented by Pellet. Three stock solutions should be prepared (Pizzighelli) : A. Gum arabic 200 g 5/5) oz Water 1000 ccm 16 oz. B. Ammonio-citrate of iron (red) 500g 8 oz. Water 1000 ccm 16 oz. C. Ferric chloride 500 ¢ 8 oz. Water 1000 ccm 16 oz. These solutions will keep indefinitely in the dark, with the exception of A, which becomes acid in about a week. For use mix in the following order: _A solution 200 parts 262 PHOTOGRAPHIC FACTS AND FORMULAS B solution 80 parts C solution 50 parts It is important to adhere to this order, for, if A be added to C, the mixture becomes lumpy and useless. The mixture is at first thin and fluid, but soon becomes more viscous, and in a few hours cloudy and of the consistence of soft butter. It should be used in this condition and will keep in the dark for several days. Haugk recommended: Gum arabic solution, 1:5 300 to 350 parts Ammonium ferric oxalate solution, 6:10 100 parts Ferric chloride solution, 1:2 20 to 30 parts Float the paper on this mixture. Another excellent formula (Waterhouse) is: A. Gum arabic 170g 6 oz. Water 650 ccm 22 oz. B. Tartaric acid 40 ¢ 617 gr. Water 150 ccm 5 oz. C. Ferric chloride solution, sp. gr. 1.453 100 to 120 g 1543 to 1851 gr. Filter the gum solution through a sponge or pad of cotton, and mix with the acid; then add the iron solution, which should be weighed, not measured, with constant stirring. Allow the mixture to stand in the dark for 24 hours, and add water to make the specific gravity 1.100. Well-sized paper, preferably gelatine-sized, should be fastened by pins to a flat board, and the mixture applied not too thickly with a flat brush. As soon as the brush begins to drag, the coating should be evened out with a round brush with circular strokes. This operation should be performed by artificial light, and the paper rapidly dried in the dark. The paper should be kept under pressure. The exposure will be from 15 to 40 seconds in the sun, or proportionately longer in diffused WHE) TRON PROCESSES 263 light under a drawing; the image is seen in a bright yellow colour on a darker ground. Development is effected with a 20 per cent solution of potassium ferrocyanide; the paper may be pinned to a board, and a very soft brush, charged with the solution, passed over the surface, care being taken not to rub up the image. Or the edges of the paper may be turned back to the height of about an inch and the print floated, face down, on the solution. The edges are turned up to prevent any solu- tion touching the back of the print, which would cause blue stains. In about half an hour, if the print is floated, a corner may be turned back and the image examined; if it is fully visible, the print should be washed with a spray or in run- ning water for a short time, immersed in a 1 per cent solu- tion of hydrochloric or sulphuric acid, the surface gently rubbed with a soft brush to remove the slight blue deposit, then again washed in water, again brushed, and hung up to dry. Corrections can be made with solution of potassium oxalate, about 15 per cent, thickened if necessary with gum arabic. FERROGALLIC OR INK Process.—This is also sometimes known as Colas’s process. It gives black lines on a white ground. The sensitiser is a mixture of ferric chloride or sulphate, and tartaric acid, thickened with gum, or gelatine: Ferric chloride 50 g 1 oz. Ferric sulphate, basic 25)¢ 4 oz. Tartaric acid 45 ¢ 432 gr. Water 500 ccm 10 oz. Dissolve, and add: Gelatine 25g Y, oz. Water 250 ccm 5 oz. Soak the gelatine in the water for 30 minutes and melt with 264 PHOTOGRAPHIC FACTS AND FORMULAS heat. Filter the mixture through fine linen. Or the follow- ing may be used: Gum arabic 100 g 768 gr. Ferric chloride 328 g 2519 gr. Tartaric acid 220 g 1690 gr. Ferric sulphate, basic 220 ¢ 1690 gr. Water 1000 ccm 16 oz. Dissolve in the above order and filter. The following (Fisch) is only suitable for heavily sized or gelatinised papers: Ferric chloride 100 g 768 gr. Water 500 ccm 8 oz. Dissolve, and add: Tartaric acid 30 g 230 gr. Water 500 ccm 8 oz. Or the following (Shawcross) may be used for any paper: Gelatine 137 ¢ 1052 gr. Ferric sulphate, basic 55 ¢ 422 gr. Sodium chloride 87 g 668 gr. Tartaric acid I7¢g 130 gr. Ferric chloride 137 g 1052 er. Water 1000 ccm 16 oz. The solutions should be applied with a broad flat brush or pad by artificial light, and rapidly dried. The paper will keep for 2 or 3 weeks. Exposure should be made under a drawing for about 10 minutes in sunlight, or until the lines appear yellow on a white ground. Development is effected on: Gallic acid 6g 46 gr. Oxalic acid lg 77 gr. Water 1000 ccm 16 oz. Or: Gallic acid 1252 96 gr. Alum 125g 96 gr. Water 1000 ccm 16 oz. THE TRON PROCESSES 265 The image should become black in from 3 to 5 minutes. The print may be completely immersed in the developer or floated on its surface. As soon as the image is intense enough, wash with repeated changes of water, gently blot off the surface water, and hang up to dry in a warm place. It should be noted that the ferric sulphate used in this process is the basic variety, also known as subsulphate, or Monsell’s salt. GREASY OR PRINTER’S INK Process.—In this process the solubilisation of a colloid by the action of light on the iron salts, and the capacity of the insoluble colloids for taking greasy ink is employed; it was suggested by Fisch: Gum arabic 320 g 2451 gr. Water 1000 ccm 16 oz. Dissolve, and add: Martanicracid 70g 540 er. Water : 250 ccm 4 oz. And add, with constant stirring: Ferric chloride solution, 45° Be. 225g 302z., 288 gr. Then add: Manganese sulphate 10g 77 or, Water 25 ccm 192 min. Allow to stand in the dark for several hours, and then filter through fine muslin. Coat the paper in the usual way, and dry at 35° to 45° C. (95° to 113° F.). Or the following may be used: Gum arabic 325 g 2496 er. Water 1000 ccm 16 oz. Dissolve, and add: Tartaric acid TNS 576 gr. or Citric acid 300 g 44/5 oz. Then add, with constant stirring: Ferric sulphate 26g 200 gr. 266 PHOTOGRAPHIC FACTS AND FORMULAS or Ferric nitrate 400 g 634 oz. And add in the same way: Uranium nitrate 6g 46 gr. or Uranium chloride 200 g 3% oz. Finally, add: Ferric chloride solution, sp. gr. 1.453 210 ccm 3Y oz. Filter through muslin and coat well-sized paper therewith. The exposure will be from 3 to 6 minutes in sunlight. Place the print face up on a sheet of zinc or glass, and with a roller lightly charged with printer’s ink roll up the surface until uniformly grey. Immerse the inked print in cold water, transfer to a metal or glass plate supported at an angle, and allow a spray or stream of water to play over the surface; with a pad of absorbent cotton gently rub the print. The exposed parts will be gradually dissolved, leaving only the inked parts. TRUE-TO-SCALE Process.—A cheap and ready process for obtaining a few, about 25, pulls in printer’s ink from line drawings, etc. A good black original is the best. Ferro- prussiate or cyanotype paper should be exposed under the plan or drawing, and without development laid down on a “graph” or jelly, gently rubbed into contact, and immediately stripped. The jelly is now rolled over with a good letter- press ink with a composition roller and it only takes on the lines. A piece of paper is now laid on the jelly and rolled over lightly with a light roller, and, on lifting, the impression will be found on the paper. Inking must be done before each pull. The jelly can be made as follows: Glue 500 g 8 oz. Water to make 1000 ccm 16 oz. Allow to soak for some hours, melt with heat, and add: Gelatine 62.5 g 1 og. THE: TRON PROCESSES 267 Water to 125 ccm 2 oz. Soak, melt by heat, and add: Ferrous sulphate 33.3 g YZ oz. Glycerine 33.3 ccm YZ oz. Strain, and cast into flat tins. Or the following may be used: Gelatine 450 ¢ 1 Ib. Water 2550 ccm 90 oz. Size powder _ 450 ¢ 1 Ib. Iron alum 42¢ LY, oz. Water . 570 ccm 20 oz. Dissolve the gelatine in the water ; then add the size powder. Dissolve the alum in the water, and add to the gelatine-glue solution gradually, stirring all the time. Pour into tins or on a slab. After use it can be remelted and used again, but a little fresh jelly should always be added. Or the following (Albert) : Gelatine | 160 g 1228 gr. Glycerine 15 ccm 115 min. Ox-gall 25¢g 192 gr. Ferrous sulphate 2g 15.4 gr. Water to 1000 ccm 16 oz. Soak the gelatine in water, melt, add the other ingredients, and, finally, the iron salt dissolved in a little water. Cast on zinc which has been roughened with emery to cause it to adhere well. The coating should be 2mm (1/25 in.) thick. PLAYERTYPE.—This is a method of copying printed matter invented by J. H. Player, in which a sheet of sensitive paper, bromide or development (gaslight), is placed face down on the printed matter, pressed into contact and exposed through the back. On development a negative copy is obtained. The slower papers are more suitable; the paper should be pressed into contact by a sheet of plate glass, and the latter covered with a yellow filter which can be made by immersing fixed out 268 PHOTOGRAPHIC FACTS AND FORMULAS dry plates in a 2 per cent solution of tartrazin. The exposure varies from 30 seconds to 2 minutes, according to the sensi- tiveness of the paper and the strength of the light. The developer should be preferably hydrochinon well restrained with bromide, as generally used for line work. Printing-out paper may be used in the same way. And also the following (Albert) : Albumen 60 ccm 460 min. Fish glue, Le Page’s 40 ccm 307 min. Ammonium bichromate 45 ¢g 346 gr. Water 1000 ccm 16 oz. Or: Fish glue 37.5 ccm 288 min. Ammonium bichromate 3g 23 gr. Grape sugar 3.25 g 25 gr. Water 1000 ccm 16 oz. Dissolve the sugar in about one-fourth of the water before adding the other ingredients. Glass should be coated with a whirler and exposure is best effected with a half-watt lamp at a constant distance, the glass being placed with the coated side down on the drawing. Development is effected with hot water, and the print can then be stained up with a solution of a dye, such as chrysoidin, water soluble nigrosin, or by immersion in a 4 per cent solution of potassium permangan- ate, which gives a deep brown image of manganese dioxide. CopaLt-IrRoN Printinc (Burian)—This process seems more suitable for line drawings than prints from ordinary photographic negatives. Oxalic acid 8¢g 61.5 gr. Water 30 ccm 230 min. Heat until dissolved, and add: Ammonium oxalate, neutral 24¢ 184 gr. When dissolved, add: THE, TRON) PROCESSES 269 Cobalt carbonate 8g 61.5 gr. Effervescence takes place, and the mixture should be digested until it turns red. The cobalt carbonate can be made by adding 39 g (299.5 gr.) crystallised sodium carbonate to 16 g (123 gr.) of crystallised cobalt chloride, and washing and drying the precipitate. To the above red liquid, cooled down taro: (95°F .), add: Lead peroxide ~ 5¢g 38.5 gr. Glacial acetic acid. 3 ccm 23 min. On shaking, the solution turns a deep green. From this point all further operations must be conducted by yellow light. Add: Lead peroxide 5g 38.5 gr. Glacial acetic acid 3 ccm 23 min. Pour the solution out into a flat dish, and allow to evaporate until crystals form and it is dry. Add 10ccm (77 min.) of water, filter, and make the bulk up to 1000ccm (160z.). The iron salt is obtained by mixing 20g (154 er.) of ferric sulphate with ammonia, washing the precipitate, and adding 36 g (276.5 gr.) of acid ammonium oxalate. This can be made by adding 30ccm (230min.) of ammonia to 100g (768 gr.) of oxalic acid, gently heating, adding more am- monia until the solution smells distinctly of ammonia, then heating to drive off excess of ammonia, adding 100¢ (768 gr.) of oxalic acid, heating until dissolved, and allowing to crystallise. The actual sensitising solution is made by mixing 2 parts of the cobalt solution with 1 part of the iron. Paint on the paper with a brush and dry rapidly; the paper should be a green colour. Exposure may be to daylight or an arc, and the image should show a bright yellow on the green ground. Development is effected in a 1 per cent solu- tion of potassium ferricyanide until the whites appear white; then briefly wash and immerse in 1 per cent hydrochloric 270 PHOTOGRAPHIC FACTS AND FORMULAS acid; again wash and immerse in a 1: 400 solution of sodium sulphide until the paper turns grey; then wash until white. The sensitised paper will only keep about 6 hours. If the ordinary ferric oxalate be used, the process is said to be suitable for ordinary negatives. KALLITYPE.—This is a silver-iron printing process, based on the light-sensitiveness of ferric salts, which are reduced to the ferrous state. The ferrous salts dissolve in the devel- oper, and reduce silver nitrate to the metallic state at the points where the ferric salt has been reduced by light. Hall’s Formulas.— A. Ferric oxalate 200 g 1 oz. Gum arabic 20 g 48 er. Water 1000 ccm 5 oz. B. Ferric potassium oxalate 62.5 g 4 02. Water 1000 ccm 8 oz. C. Oxalic acid 125 ¢ 4 oz. Ammonia 52 ccm 100 min. ~ Water 1000 ccm 4 oz. D. Potassium bichromate 62.5 ¢ 120 er. Water 1000 ccm 4 oz. For use mix 480 parts A, 240 parts B, 30 parts C, and 4 parts D. Then add silver nitrate, dry, 37.5 parts. For thin and. soft negatives, increase the proportion of D from 30 to 50 per cent, and reduce the proportion of C by one-half or more. Developer : Sodium acetate 125 ¢ 1 oz. Tartaric acid 3/123i¢ 12 or. Solution D, above 5to50ccm 10to 100 min. Water 1000 ccm 8 oz. Clearing bath: Sodium citrate 31.25 ¢g ¥4 oz. Citric acid 5g 20 gr. THE IRON PROCESSES 271 | Water 1000 ccm 8 oz. Wash the prints well and fix in: Hypo 50 g 1 oz. Ammonia 12.5.cem 120 min. Water 1000 ccm 20 oz. Thomson's formulas.— Ferric oxalate 150 ¢ 75 gr. Ferric ammonio-citrate, brown 20g 10 gr. @upric chloride’ |. 18¢ 9 gr. Gum arabic 20 g 10 gr. Water 1000 ccm 1 oz. Dissolve the ferric oxalate in warm water and allow to stand all night; then add the other ingredients, and filter. The solution will not be clear. Print until the deepest shadows are well visible. The developer is composed of equal parts of a 5.2 per cent solution of Rochelle salts and a 9.4 per cent solution of borax with the addition of 0.02 to 0.8 per cent potassium bichromate, which keeps the whites pure and acts as a restrainer. The prints should be left in the developer for 30 minutes, well rinsed, then fixed in: Hypo $1.25 ¢ 240 gr. Ammonia 7.8ccm 60 min. Water 1000 ccm 16 oz. Wash for 30 minutes. Thomson's later formulas.— 1. Ferric ammonio-citrate, brown 20¢ 10 gr. Ferric oxalate 66 ¢ Saar, Potassium oxalate 74 ¢ O7 er. Cupric chloride fie 6 gr. Gum arabic 20g 10 gr. Potassium bichromate sol., 1:48 2tol0ccm 1to5 drops Water 1000 ccm 1 oz. 272 PHOTOGRAPHIC FACTS AND FORMULAS 2. Ferric ammonio-citrate, brown 12g 6 gr. Ferric oxalate 60 g . 36 er Potassium oxalate 60 g 30 gr. Cupric chloride 12¢g 6 gr. Gum arabic 20 g 10 gr. Water 1000 ccm 1 oz. 3. Ferric ammonio-citrate, brown 50g 25 Sm, Ferric oxalate 30 g iSiem Potassium oxalate 70g 35.e1 Cupric chloride l6g 8 er. Oxalic acid 30 g 15 en. Silver nitrate 30 g 15 gr. Gum arabic 20 g 10 gr. Water 1000 ccm 1 oz. Add potassium bichromate solution, 1:48, as desired. In preparing these solutions, mix in the above order, leave for 24 hours in the dark, and filter through cotton. Print faintly, and develop in: Silver nitrate 80 g 40 gr. Citric acid 20 g 10 gr. Oxalic acid l6g 8 gr. Water 1000 ccm 1 oz. Add sodium phosphate 3g (1% gr.) for blue-black tones. For use mix 1| part with 7 parts water. Fix in: Hypo 3to4g 24to 32 oz. Water 1000 ccm 16 oz. For brown, blue-green, and other colours: A. Ferric ammonio-citrate, green /0¢ 35 gr. Ferric oxalate l6g 8 gr. Potassium oxalate I2¢ 6 gr. Oxalic acid 44¢ 22 gr. Uranium nitrate 40 ¢ 20 er. Gum arabic 20g 10 gr. PHP IRON PROCESSES 278 Water 1000 ccm LOZ: Potassium bichromate solution, 1:48 6tol2ccm ‘'3to6drops Allow to stand 24 hours in the dark; then filter. B. Silver nitrate 100 g 50 ger. Citric acid 60 g 30 gr. Tartaric acid 20 g 10 er. Water 1000 ccm 1 oz. First coat the paper with A, and allow to dry; then coat with B. Print in the sun until the half tones are slightly tinted. For sepia tones wash and fix in: Salt 4g ior Hypo 4g 12 gr. Water 1000 cem 6 oz. For green tones immerse the print in: Potassium ferricyanide 3g 4 gr. Nitric acid 3 ccm 4 drops Water 1000 cem 4 oz. Remove from this solution just before the green tone is reached, and fix in weak hypo. Platinotype This process is based on the light-sensitiveness of ferric oxalate, which is reduced by the action of light to ferrous oxalate, which dissolves in the alkaline oxalate used as a developer, thus reducing the platinum salt, used in the sensi- tiser, in situ; the iron salts form no part of the image. It is important that the ferric oxalate should be free from ferrous salt, and the most satisfactory way to ensure this is to prepare it. The following method should be adopted: Ammonia iron alum 520 ¢ . 90z4 S0iee Water 500 ccm 8 oz. Heat until dissolved, allow to cool slightly, and add: Ammonia 200 ccm 31% oz. Stir well for about 5 minutes. Then filter the solution, and wash the filter with repeated lots of water until the filtrate is no longer alkaline to litmus paper. Then dissolve in: Oxalic acid, pure 215¢ 1651 gr. Hot water 800 ccm 12 oz. Pour this solution over the filter repeatedly until all the ferric hydroxide is dissolved; wash the filter with sufficient water to make the volume of the solution 1000 ccm (16 0z.). An alternative method, which obviates the necessity of filter- ing, but takes longer, is to powder some iron alum, and weigh out the above quantities. Place the powder in a tall graduate; the tall metric cylindrical graduates are the most convenient. Pour on the powder the above quantity of am- monia mixed with an equal volume of water. Stir for a few minutes, and allow to stand for 10 minutes. Fill up the graduate with water, shake or stir well, allow to stand until the precipitate has somewhat subsided, and syphon off the 274 ARG = = eS ee —. > PEATINGEY Ey 275 supernatant liquid. Repeat these operations until the liquid no longer turns red litmus paper blue. Finally, allow the precipitate to settle, and syphon off the water until the total bulk measures no more than 850ccm (1314 0z.). Add the oxalic acid dry, stir well for a few minutes until the solution clears up, then filter, and wash the filter with enough water to make the total bulk 1000 ccm (160z.). The result will be a 20 per cent solution of ferric oxalate with an excess of 1.2 per cent of oxalic acid. The addition of the oxalic acid and the subsequent filtration must be effected by artificial light, not daylight, and the solution must be kept in the dark. Dry ferric oxalate, as obtainable commercially, is rarely suitable. Another stock solution required is a mixture of lead-iron oxalate. This is made as follows: Lead acetate, pure 10g 154 gr. Water 100ccm 30z., 183 min. Dissolve by the aid of heat, and add: Oxalic acid, pure 4¢ OZ. or. Water 50 cem)) oz) 330) min A white precipitate of lead oxalate is formed, which should be collected on a filter, well washed with water, and dried. Add 1 part of the dry precipitate to 100 parts of the normal ferric oxalate solution, as given above. A stock solution of sodium ferric oxalate will also be required: Sodium ferric oxalate 500 g 3840 er. Water ~ 1000 ccm 16 oz. Shake until dissolved and filter. A stock solution of oxalic- gelatine will be required, but this will not keep more than 3 or 4 days: Gelatine 10¢ 96 gr. Water 100 ccm 2 OZ. 276 PHOTOGRAPHIC FACTS AND FORMULAS Allow to soak for 15 minutes, dissolve by heat, and add: Oxalic acid, pure 2.0 2 24 gr. There will be further required a 10 per cent solution of sodium platinum chloride (NaC1),.PtC1,.6H,O, and a 1 in 6 solution of potassium chloroplatinite. All stock solutions must be kept in the dark. The best results are obtained with pure linen papers; cheap wood-pulp papers will not give good results. While it is not absolutely essential with good papers, a preliminary sizing is desirable, and for this purpose gelatine, arrowroot, or tragacanth may be used. The disadvantage of gelatine is that it is very prone to form air bubbles, and arrowroot is preferable. To prepare the gelatine size, make a 2 per cent solution of gelatine in water, and add 1 per cent of alum. To make the arrowroot rub 20 g (154 gr.) into a thin cream with water, add to 1000 ccm (16 0z.) boiling water with constant stirring, and continue boiling for 5 minutes. Allow to cool, and remove the skin which forms on top. The gelatine size must be used warm. To apply the size, the paper should be pinned to a drawing board, or other flat surface at the corners and the size applied with a broad flat brush in straight strokes, first across and then up and down the paper, until the surface is uniformly wet. Then a round soft brush, a perfectly clean shaving brush being excellent, should be worked all over the surface until it appears even and begins to lose its gloss. It may then be hung up to dry. For rough drawing papers the sheets should be immersed in the size for from 5 to 30 minutes, according to the thickness of the paper, and the roughness of the surface. The paper should be drawn over the edge of the dish, so as to wipe off as much solution as possible, and then hung up to dry with the end that leaves the dish last at the top. — on Pie RN © myer 2/7 Tue Corp Bats Process.—To sensitise the paper it should be fastened by glass-headed push pins to a flat surface. with a sheet of blotting paper underneath. As it is important that the sensitising solution should not come into contact with the pins, it is advisable to provide the latter with guards, which can easily be prepared by cutting small squares of cardboard, turning up the edges, and passing the pins through the middle. As the paper expands and crinkles on application of the liquid, the pins may be removed, and the paper restretched and again pinned down. The sensitiser is: A. Potassium chloroplatinite sol. 3 ccm 50 min. Lead-iron sol. 4.5 ccm 75 min. Sodium chloroplatinate 7.5 drops 7.5 drops Water 3to8ccm 50 to 130 min. Or: B. Potassium chloroplatinite sol. 3 ccm 50 min. Lead-iron sol. 4.5 ccm 75 min. Oxalic-gelatine sol. 1 ccm 17 min. Sodium chloroplatinate 7.5 drops 7.5 drops Water 3to8ccm 50 to 130 min. Or: C. Potassium chloroplatinite sol. 3 ccm 50 min. Lead-iron sol. | 3 ccm 50 min. Sodium ferric oxalate sol. 2ccm 33 min. Sodium chloroplatinate 7.5 drops 7.5 drops Water 3to8eccm 50 to 130 min. The quantity of water in each formula is dependent on the surface of the paper; smooth surfaces require less, rough ones the greater quantity. Increase of the water to 2 to 14 times that given above gives grey prints. The above quantity of sensitiser is sufficient for 3750 qcm (580 sq. in.) of paper. Increase of the sodium chloroplatinate gives increased con- trasts, or an equal volume of a 10 per cent solution of 278 PHOTOGRAPHIC FACTS AND FORMULAS potassium bichromate may be used instead. Omission of these naturally gives softer effects. Sensitiser A with arrow- root sizing tends to brownish-black tones, but with plain, not arrowroot-sized, drawing papers, black tones; with gelatine- sized papers blue-blacks are given. A and B give too hard prints with contrasty negatives; then C should be used, as this gives softer results. After printing until the image is faintly visible in greyish- violet against the pure yellow unprinted parts, the print should be rapidly and evenly immersed in either of the following developers: Neutral potassium oxalate 250 g 4 oz. Water 1000 ccm 16 oz. Or: Neutral potassium oxalate 100 g 770 gr. Potassium phosphate 50 g 384 gr. Water 1000 ccm 16 oz. It is preferable to take hold of both ends of the paper, im- merse one end in the developer, face down, draw right through the solution and then turn face up. Development is comparatively slow and takes from 1 to 2 minutes; the dish should be gently rocked. As soon as sufficient depth is attained, immerse the print, without washing, in: Hydrochloric acid 20 ccm 154 min. Water 1000 ccm 16 oz. face downwards. The dish should be rocked. After 5 min- utes, remove the print to a second dish of water acidulated as above, and, after 15 minutes, remove to a third dish of half the above strength of acid. At the end of 15 minutes, place the print in running water for 30 minutes, then blot off between blotting papers, and dry. Dilution of the developer gives more brilliant prints; or the same result may be ob- tained by adding 2 to 5 per cent of a 1 per cent solution of PLATINGT VEE Zi potassium bichromate; but, in this case, printing must be carried further than usual. In place of the bichromate, 0.5 to 1 per cent of ammonium persulphate may be used, which shortens the scale of gradation, and this is particularly useful in the case of over-printing or when thin flat negatives are used. SeprA Paper, CoLtp BatH.—Brown or sepia tones are readily obtained by the addition of a mercury salt to the sensitiser, and the best is mercuric citrate, prepared as fol- lows: Yellow mercuric oxide 5g 96 gr. Citric acid 255 480 gr. Water 100 ccm 4 oz. Heat until dissolved, and filter. The actual sensitiser 1s: Ferric oxalate sol. 8 ccm 130 min. Potassium chloroplatinite sol. 4 ccm 65 min. Mercuric citrate sol. 1to4ccm 16 to 65 min. Sodium chloroplatinate sol. 2to5drops 2to5 drops This should be applied as described above and to the same area of paper. The best developer is one of the following: Neutral potassium oxalate 100 to 300g 154 to 462 gr. Water 1000 ccm 16 oz. Or: Potassium oxalate 70 to 300g 538 to 2304 gr. Potassium phosphate 30 g 230 er. Oxalic acid 10g 77 gr. Water 1000 ccm 16 oz. The stronger the developer, the more rapid its action and the softer the print; the more mercury salt used, the weaker should be the developer; with contrasty negatives and with less mercury, the stronger should be the developer. Prints 280 PHOTOGRAPHIC FACTS AND FORMULAS should be developed for not less than 5 minutes. The acid baths should not be stronger than from 0.5 to 1 per cent; the acid treatment with the three baths should not last longer than 30 minutes in all. The smaller quantities of the mercury solution give the best colours. For this process the best results are obtained with paper sized with agar-agar, which may be prepared as follows: Agar-agar 10g 77 gr. Water 1000 ccm 16 oz. Soak for 24 hours with an occasional stir, then pour off the water, and add enough fresh water to make the total bulk to the above quantities. Heat until boiling, and allow to boil for 10 minutes; filter through a piece of well-washed linen, and allow to cool until a firm jelly is obtained. This jelly should be squeezed twice through coarse canvas, so as to divide it up into little nodules. A small quantity should be placed on the paper, worked all over with a fairly stiff brush, then equalised with circular strokes with a softer brush, and dried. The quantity used depends on the surface of the paper, but this should not be strongly glazed when dry. Tue Hor Batu Processes.—In this process a hot devel- oper is used and the sensitiser should be: Ferric oxalate sol. 6 ccm 42 min. Potassium chloroplatinite sol. 4ccm 28 min. Gelatine-oxalic sol. 1 ccm 7 min. Greater contrasts in the prints may be obtained by the addi- tion of 5 to 10 drops of sodium chloroplatinate solution or a 1 per cent solution of potassium bichromate. The same. developers as used for the cold bath papers may be used at a temperature of 50° to 75° C. (122° to 167° F.). For sepia tones the sensitiser should be: Ferric oxalate sol. 6 ccm 100 min. Potassium chloroplatinite sol. 4ccm 67 min. PEATINOTYEE 281 Mercuric chloride, 5% sol. O:2'to l'cem) 3. to’ l/min. Sodium chloroplatinate 2to10drops 2to 10 drops Water 2to4ccm 33 to 67 min. The quantity of water is as before regulated by the surface of the paper. The solution should be applied in the manner already described. The best developer for this paper is: Potassium oxalate 100 ¢ 770 gr. Potassium phosphate 50 g 380 gr. Citric acid 20 g 154 gr. Potassium chloride 10g 77 SE: Water 1000 ccm 16 oz. Weeeea temperature of 70° EG: (158... CoLtp BatH PAPER (Lainer).— A. Ammonium ferric oxalate 50 ¢ 134 oz. Water 58 ccm 2 oz. Oxalic acid, 10% sol. 8 ccm 150 min. B. Potassium chloroplatinite 2¢g 30 gr. Water 10 ccm 150 min. The sensitiser for 3352 qcm (520 sq. in.) should be: A solution 4 ccm 68 min. B solution 8 ccm 136 min. Potassium bichromate, 4% sol. 8 ccm 136 min. Immerse the exposed print for from 1 to 3 minutes in the developer, special salts being supplied for this, until fully developed ; then clear in four acid baths of hydrochloric acid, 1:60, and wash for a short time in running water. For sepia prints the developer should be heated to 66° to 88° C. (150° to 190° F.), and the prints cleared in three acid baths of half the above strength. Development should be effected in a feeble white light. The addition of 2 to 4 drops of a 10 per cent solution of potassium bichromate to the developer increases the brilliancy of the prints. 282 PHOTOGRAPHIC FACTS AND FORMULAS PALLADIOTYPE PAPER.—This paper gives a very visible printing image, and exposure should be carried on until all details are visible. Immerse the prints face up in: Sodium citrate 232.5'e 10 oz. Citric acid 23.25 ¢ 1 oz. Water 1000 ccm 43 oz. For black prints the temperature should be kept between 7° and 16° C. (45° to 60° F.). For sepia paper use: Sodium citrate 50 g 6 oz. Citric acid 2.62 150 gr. Water 1000 ccm 120 oz. Heating the developer to 38° C. (100° F.), not beyond, gives warmer tones. Clearing bath for both papers: Sodium citrate 2325 ¢ 10 oz. Citric acid 93 g 4 oz. Water 1000 ccm 43 oz. For use mix 1 part with 7 parts water. Three baths should be used, with 10, 15, and 20 minutes in the first, second, and third baths respectively. For brilliant prints add from 4 to 6 drops of a 10 per cent solution of potassium bichromate to the developer. Wash the prints in running water for 10 or 15 minutes or in several changes of 10 minutes each. SATISTA PAPER.—Print until a faint image appears, and develop in: Potassium oxalate 200 g 8 oz. Oxalic acid 522 100 gr. Water 1000 ccm 40 oz. Temperature about 21° C. (70° F.); for warmer tones heat to 38° C. (100° F.). Clear the prints in: Sodium citrate 4g 1Y4 oz. Water 1000 ccm 75 02. Three baths are advisable of 5, 10, and 15 minutes respec- tively, followed by a short washing for 10 minutes, not PEATINOTY EE 283 longer, in running water or several changes of water. Then fix in: Hypo 125 ¢ 6 oz. Water 1000 ccm 48 oz. for 15 minutes. Finally, wash in running water for 45 minutes or in about 12 changes of water. The water used for the clearing bath must be free from lime. To free water from lime, dissolve oxalic acid 0.5 g (15 gr.) in 75 oz. (1000 ccm). Allow to stand for some hours, and decant from the precipitate. THE PLATINUM-IN-DEVELOPER PRoceEss.—A variation of the platinotype process consists in using either no, or very little, platinum in the sensitiser, and adding it to the devel- oper. For this arrowroot size gives the best results, and the paper should not be highly sized. The sensitising solution may be one‘of the following: A. Lead-iron sol. 5 ccm 80 min. Mercuric chloride, 5% sol. 0.2 ccm 3 min. Water 3to6ccm 48 to 92 min. B. Lead-iron sol. 5 ccm 80 min. Potassium chloroplatinite sol. 0.5 ccm 8 min. Water 3to6ccm 48 to 92 min. C. Lead-iron sol. 5 ccm 80 min. Potassium chloroplatinite sol. 0.3 ccm 5 min. Sodium chloroplatinate sol. 0.4 ccm 6.5 min. Water 3to6ccm 48 to 92 min. D. Lead-iron sol. 5 ccm 80 min. Sodium chloroplatinate sol. 0.8ccm 13 min. Water 3to6ccm 48 to 92 min. A and B are suitable for normal negatives; C gives greater contrast ; and D should be used for very soft negatives. The area of paper is as previously stated. It is preferable to 284 PHOTOGRAPHIC FACTS AND FORMULAS allow the paper to dry at normal temperatures. The devel- oper should be: Potassium oxalate lg 16 gr. Potassium chloroplatinite lg 16 gr. Potassium phosphate 0.5 ¢ 8 gr. Water 12 ccm 192 min. Glycerine 6 ccm 96 min. Place the print face up on a sheet of glass, and paint with the above, using a broad flat brush, and working as quickly as possible. For the above area of paper about 20ccm (154 min.) of developer will be required. For line work or black and white work, this process 1s very suitable, and the following sensitiser should be used: Lead-iron sol. 7 ocem 120 min. Potassium chloroplatinite sol. 0.375 ccm 6 min. Neutral potassium chromate, 1% sol. 0.375 ccm 6 min. Water 7.5 ccm 120 min. The above quantity is sufficient for 5940 qcm (870 sq. in.). The best developer for this work is: Potassium chloroplatinite 12 ccm 84 min. Glycerine 50 ccm 350 min. Water 450 ccm 8 oz. Thirty ccm (1 0z.) should be used for the above area. Actu- ally, this process is as cheap as or cheaper than any silver printing process. The acid baths must be used with all papers as already described. PLATINUM PRINT-oUT PapER.—It is possible to prepare platinum paper that will print out in the printing frame, but it does not keep well, and the results are greatly dependent on the humidity of the paper at the time of printing. If too dry, only the shadows will appear; while if too damp, flat PLATINOTYPE 285 foggy results are obtained. The stock solutions are: A, the normal potassium chloroplatinite solution; B, sodium ferric oxalate 50g (40z.), water 100 ccm (80z.); C, gum arabic 50g (40z.), water 100ccm (80z.). The sensitiser is: Potassium chloroplatinite sol. 4 ccm 65 min. Sodium oxalate sol. 6 ccm 98 min. Gum sol. 4 ccm 65 min. Increased contrast may be obtained by the addition of sodium chloroplatinate or potassium bichromate solution as in the other processes. The paper must be dried quickly. Expos- ing the paper to steam after printing, if the image appears of sufficient depth only in the shadows, is of some assistance, but, at the best, it is not a satisfactory process. Sepia TONES BY DEVELOPMENT.—Ordinary hot bath paper may be developed to sepia by the use of the following devel- oper (Hubl): Potassium oxalate 100 g 768 gr. Potassium phosphate 50 g 384 gr. Citric acid 20 g 154 gr. Potassium chloride 10g 77 gr. Mercuric chloride 10¢g TG, ae Water 1000 ccm 16 oz. Use at a temperature of 80° C. (176° F.). Or the following may be used: Potassium oxalate 65g 500 gr. Potassium citrate LL 85 er. Citric acid l6g 123) or Mercuric chloride 6.75 g 52\iet: Water 1000 ccm 16 oz. Heat to 35° C. (95° F.). Or the following (Jacoby) may be used: Potassium oxalate 250 g 4 oz. Zinc oxalate 100 to 125g 800to 1000 gr. 286 PHOTOGRAPHIC FACTS AND FORMULAS Water 1000 ccm 16 oz. Heat to 21° to 28° C. (69° to 83° F.). The larger the quantity of zinc oxide the warmer the tone. Or: Potassium oxalate 200 g 3% oz. Acid ammonium phosphate 25g 200 gr. Cupric sulphate lg 8 er. Water 1000 ccm 16 oz. The following complicated developer has also been recom- mended: A. Potassium oxalate 250 g 4 oz. Water 1000 ccm 16 oz. B. Cupric chloride 32 ¢ 125 er. Water 1000 ccm 8 oz. C. Mercuric chloride 62.5 ¢ 1 oz. Water 1000 ccm 16 oz. D. Lead acetate l6g 32 gr. Water 1000 ccm 4 oz. Add 12 parts of A to 4 parts B, then 4 parts C to 1 part D, and heat until the precipitate first formed is redissolved. Use at a temperature of 80° C. (176° F.). LocaL DEVELOPMENT.—By thickening the developer with glycerine, it is possible to develop cold-bath prints locally, so as to obtain various effects. Paint a sheet of glass larger than the print with glycerine, thinly and evenly. Use four teacups or saucers; fill A with pure glycerine; B, with glycerine 10 parts, saturated solution of potassium oxalate 1 part; C, with glycerine 10 parts, saturated solution of potassium oxalate 5 parts; D, with saturated solution of potassium oxalate. Lay the print face up on the glycerined glass, and dab into contact with a pad of clean linen. Paint the whole of the print with the pure glycerine, using a long- handled soft brush, and allow to soak for 3 minutes. Sat- urate the brush with the B mixture and paint over the whole PLATING? VEE 287 print. Then charge the brush with C solution, and paint those parts which it is desired to bring out more than the rest. Finally, treat any desired part with D solution. The glycerine merely prevents any lines of demarcation showing. The subsequent acid bath treatment is as usual. _ INTENSIFYING PLATINOTYPES.—Weak platinotype prints can be intensified, and, unless much under-printed, good re- sults are obtained. Silver intensification ( Clarke) —This is extremely liable to give a coarse granular deposit, which makes it unsatisfac- tory on the whole: Glacial acetic acid 150to 160 drops 50 to 60 drops Pyrogallol 2g 13.5:er. Water 1000 ccm 16 oz. Dissolve, and add: Silver nitrate, 12% sol. 20 drops 8 drops It is advisable to flood the print, which must be quite free from iron salts and acid, with the pyro solution, then to pour off the solution; add the silver to it, again flood the print, and repeat until sufficient intensity is attained. Hydrochinon or metol may be used instead of the pyrogallol. The print should be well washed, and, finally, fixed in weak hypo. Intensification with platinum (V ogel) — Potassium oxalate developer 5ccm 80 min. Water 50 ccm 800 min. Potassium chloroplatinite sol. 3to5drops 3to5drops This also tends to give coarse grain, and the whites are very apt to be stained. Far better results are obtained by the following (Hubl) : A. Sodium formate, 10% sol. B. Platinum perchloride, 2% sol. For use add 5 parts A to 200 parts water, and then add 5 288 PHOTOGRAPHIC FACTS AND FORMULAS parts B. Intensification will be complete in about 15 minutes. Intensifying with gold (Dollond)—The print should be placed face up on a sheet of glass, and, if previously dried, must be soaked in water first. Dab into flat contact with a clean linen pad, and paint the surface with glycerine, using a soft brush. Then pour on the surface a few drops of a 1.5 per cent solution of gold chloride and paint rapidly over with the brush. As soon as the desired intensity is reached, rinse under the tap, and sponge back and front with a normal metol developer diluted with an equal volume of water. There 1s some danger of the white assuming a pink or blueish tint with this process. ToniInG PLATINOTYPES.—Platinum prints can be toned with uranium, iron, and catechu. The first gives brownish- red tones, the second blue, and the third browns. For the uranium toning the following stock solutions are required: A. Uranium nitrate 100 g 768 gr. Glacial acetic acid 100 ccm 768 min. Water 1000 ccm 16 oz. B. Potassium ferricyanide 100 ccm 768 gr. Water : 1000 ccm 16 oz. C. Ammonium sulphocyanide 500 g 3840 er. Water 1000 ccm 16 oz. For use add 10 ccm A to 1000 ccm water (77 min. to 16 oz.) ; then add 10 ccm (77 min.) C and, finally, 10 ccm (77 min.) B. Instead of the sulphocyanide, 5ccm (35 min.) of a 10 per cent solution of sodium sulphite may be used. The well- washed print should be placed in a dish, well flooded with plenty of the solution, and the dish rocked until the desired tone is obtained. On the slightest sign of the solution becom- ing cloudy, pour off and apply fresh; otherwise the whites will be stained. The iron toning requires: PEAT INO TY Es 289 C. Ammonia iron alum 100 g 768 gr. Hydrochloric acid 100 ccm 768 min. Water 1000 ccm 16 oz. For use add 5ccm (35 min.) A to 1000 ccm (16 0z.) water, fren 2 cam) (14 min.) B, and; finally, 5 ccm (35 min.) €. Both these baths, particularly the uranium, intensify the prints. The catechu toning process (Packham) gives warm brown tones, but it is difficult to keep the whites pure; on the other hand, this is rather effective than otherwise, as the print ap- pears as if prepared on toned paper. A stock solution is prepared of: Catechu 78¢ 600 gr. Water.” 1000 ccm 16 oz. Boil for 5 minutes in a glass or porcelain vessel, and add: Alcohol 200 ccm 3 1/5:0z For use mix: | Stock solution Pe) CSO 20 min. Water , 1000 ccm 16 oz. When used cold, this takes some hours to tone, but, by rais- ing the temperature to 55° to 64° C. (130° to 147° F.), only about 15 minutes is necessary. Should the whites be stained, and it is desired to remove this, soak in: Castile soap 9g 69 gr. Sodium carbonate, cryst. 18g 138 er. Water 1000 ccm 16 oz. When the stain is reduced, wash and dry. Copper Toninc (Menke)—Four stock solutions are re- quired : A. Cupric sulphate A4lg 38.5 gr. Water 1000 ccm 16 oz. B. Potassium ferricyanide Ses 274 er. Water 1000 ccm 16 oz. 290 PHOTOGRAPHIC FACTS AND FORMULAS C. Potassium citrate, sat. sol. D. Potassium sulphocyanide 100 g 768 gr. Water 1000 ccm 16 oz. For use mix in the following order: A 140 parts, B 140 parts, C 24 parts, D 50 parts. As this is nothing more than a modification of the copper toning process for bromides, pre- sumably the same class of tones will be obtained. Biur Prints spy DEVELOPMENT (Waverley) .— Potassium oxalate, 1:3 sol. 22 ccm 170 min. Potassium ferricyanide, 10% sol. 9 ccm 70 min. Glycerine 55 ccm 42 min. Water 1000 ccm 16 oz. Printing must be carried deeper than usual. The prints as- sume a green tone in the developer and only turn blue in the acid baths. PRINT-OUT SEPIA PapER.—Another method of obtaining pure brown tones is by the admixture of some palladium salt with the sensitiser, potassium chloropalladite in 10 per cent solution being used. The paper should preferably be sized with arrowroot, and the sensitiser is: Potassium chloropalladite sol. 4ccm 65 min. Sodium ferric oxalate 6 ccm 97 min. Lead-iron sol. 2 ccm 32 min. Water 3to6ccm 45 to 96 min. The image is so slightly visible that an actinometer should be used. Development should be effected with steam or by pressing the prints between damp blotting papers. Another method is by the use of mercury (Pizzighelli) : A. Potassium chloroplatinite 10 ¢ 70 gr. Water 60 ccm 420 min. B. Sodium ferric oxalate 40 g 280 gr. Gum arabic 40 g 280 gr. PEA ING a Vie oon Sodium oxalate, 3% sol. 100 ccm 700 min. Glycerine 3.ccm 21 min. Potassium chlorate 0.5 g oo 20: Heat the sodium oxalate solution to 40° to 50° C. (104° to 122° F.), add the iron salt, the chlorate, and the glycerine; pour on to the gum, rub until dissolved, and strain through linen. The chlorate can with advantage be replaced by about 10 to 20 drops of 1 per cent solution of potassium chromate. C. Mercuric chloride, 5% sol. 20ccm 140 min. Sodium oxalate, 3% sol. 40 ccm 280 min. Gum arabic 20 ccm 140 min. Glycerine 1.8 ccm 12.5 min. This is prepared in the same way as B. For sensitising 2000 qcm (310 sq. in.) use: Solution A 5 ccm 35 min. Solution B 4 ccm 28 min. Solution C 4 ccm 28 min. The following may also be used ( Watzek) : Sodium ferric oxalate 10 ccm 160 min. Potassium chloroplatinite 6 ccm 92 min. Mercuric chloride 5 drops 5 drops Add a few drops of 1 per cent solution of potassium bichro- mate to obtain contrasts. The other salts should be saturated solutions at 18° C. (64° F.). The paper should be sized with starch or arrowroot, two to three coats being used. Printing is continued until the desired depth is reached. RESTORING PLATINOTYPES.—Sometimes through insuff- cient washing the paper of platinotypes yellows with age, due to the action of the air on the residue of iron salts. This stain can be removed by treatment with a weak solution of chloride of lime or eau de Javelle. Make a saturated solu- tion of chloride of lime in water, filter, and add 1 part of the clear solution to 100 parts of water, then add dilute hydro- 292 PHOTOGRAPHIC FACTS AND FORMULAS chloric acid until there is a faint smell of chlorine. Or mix 1 part of chloride of lime with 1 part of sodium carbonate and 10 parts water, stir well, filter or decant the clear solu- tion, add 90 parts water, and faintly acidulate as above. Im- merse the stained print in either of these solutions until bleached; then wash and dry. This treatment cannot affect the image. VARNISHING PLATINUM PRINTS.—Frequently platino- types appear rather dull and sunken-in compared to their appearance when wet. Application of print varnishes will then brighten them up; but the surface should not appear glossy. Artist’s size, diluted with warm water, may be used; or megilp may be used in the same way; or the print may be sprayed or lightly painted with 1 part of mastic varnish diluted with 8 parts alcohol. For stronger effects ordinary negative varnish may be applied locally or generally with a brush. Or a solution of gelatine, about 4 per cent, may be made, the print bodily immersed in this while warm, and hung up to dry. Or the print may be rubbed with en- caustic paste. PLATINUM ReEsipuES.—The high cost of platinum makes it well worth while to save all platinum residues. Scraps of paper, if unexposed, should be exposed to daylight and developed in the usual way. Print trimmings should be burnt, the scraps of the paper previously dealt with being mixed with them. The developer should be mixed with one- fourth its volume of saturated solution of ferrous sulphate, boiled, and the platinum precipitate allowed to settle or be filtered out. The first and second acid baths should also be saved, boiled down until of convenient bulk, at least one- fourth their original volume, and scrap zinc added. Black platinum is precipitated, and may be collected on a filter. It is not worth while to make the residues into platinum salts, en ma 5 _—" PLATINOTYPE 295 but the residues should be sent to a refiner, who will allow cash for them, with the deduction of a small fee for refin- ing. An alternative plan is to mix the developing and acid baths, and immerse sheets of clean copper therein, when the platinum will be deposited on the copper as a precipitate. The platinum deposited on the copper can be scraped off, and mixed with the precipitated metal. PLATINO-URANOTYPE.—A little-used process (Reynolds). Two stock solutions are required: A. Uranium chloride, sat. sol. B. Potassium chloroplatinite 4g 60 gr. Water 48 ccm LY4 oz. Mix in equal volumes, paint over well-sized paper, and rapidly dry. Potassium chlorate may be added to increase contrast. Print until only a faint trace of an image is visible, and develop on a ferrous oxalate developer. Wash the prints in three successive baths of hydrochloric acid, about 1% per cent, wash, and dry. MERCURO-URANOTYPE.—Very little used (Reynolds). Two stock solutions are required: A. Saturated solution of uranium chloride B. Saturated solution of mercuric chloride For use mix 8 parts A with 1 part B and apply to paper. Expose until the image is seen in full strength, then float on a dilute solution of chloride of gold or potassium chloro- platinite. Wash in water acidified with hydrochloric acid, wash and dry. The toning may be omitted when warmer tones are obtained. PALLADIOTYPE.—Coat paper with uranium chloride, ferric oxalate, or sodium ferric oxalate, or a mixture of all three. Expose until the image is faintly visible; then float the print on: 294 PHOTOGRAPHIC FACTS AND FORMULAS Potassium chloropalladite lg 1 gr. Water 500 ccm 1 oz. Or paint this over the print, wash in acidulated water, then in water, and dry. The image is somewhat similar to platino- type, but of a warmer colour. To DIsTINGUISH A BROMIDE FROM A PLATINUM PRINT.— Touch a small corner of the print with a saturated solution of mercuric chloride, or a 10 per cent solution of potassium cyanide. In the first case, the bromide image is bleached, and, in the second, the bromide image is dissolved; platinum images are unaffected. a y if ¥ ‘ PS ee Ozotype and Allied Processes OzotTyPEe Process.—This process is based on the transfer of the hardening effect of a chromate salt formed by exposure to light in the presence of a colloid, to another film containing a pigment. A well-sized paper should be chosen, or be sized with a 2 per cent solution of gelatine. With rough or absorbent papers it may be necessary to give two or three coats, allow- ing to dry after each. Or the following may be used: Soluble starch 100 g 768 gr. Water 200 ccm 4 oz. Rub into a cream, and add to: Boiling water 800 ccm 1Z\oz: Allow to boil for 5 minutes, then filter through thick linen, and add: Formaldehyde 50 ccm 25 min. Alum 0.5¢ 3.8 gr. An almost clear solution that keeps well should result. Pin the paper to a board, and with a pad or flat brush paint the surface until it appears uniformly wet. Papers with very smooth surfaces may be floated on the above, diluted with an equal volume of water, or a 10 per cent solution of fish glue may be used in the same way. The paper must be thoroughly dried. The sensitising solution may be (Manly) : Potassium bichromate 50 g 384 er. Manganese sulphate 50 g 384 gr. Water 1000 ccm 16 oz. Or (Hubl): Potassium bichromate 60 g 460 er. Manganese sulphate 30 g 230 gr. 205 296 PHOTOGRAPHIC FACTS AND FORMULAS Alum 20 g 154 er. Boric acid 30 g 230 gr. Water 1000 ccm 16 oz. It is as well to add to this a few drops of fish glue. A piece of linen or Canton flannel should be wrapped round a reason- ably large pad of absorbent cotton, some of the above solu- tion poured on to the middle of the paper, evenly distributed with the pad, and then the paper hung up to dry in the dark. The exposure will be from 3 to 5 minutes in summer, and from 15 to 25 minutes in winter. The paper should then be washed in water, but too long washing must be avoided. A piece of pigment tissue, the same size as the paper, should be immersed in the following: Hydrochloric acid 2 ccm 15 min. Ferrous sulphate BS 27 St. Water 1000 ccm 16 oz. This is suitable for normal pictures; for contrasty prints reduce the iron salt to 2.5g (19gr.); and for soft prints increase to 4.5¢ (35 gr.). When the tissue is quite limp, immerse the print in the bath, bring the two surfaces into contact, lift out together, squeegee into close contact, and leave for from 30 to 60 minutes, the longer time giving greater detail in the prints. Development may be effected at once, or delayed for some hours if more convenient. A later procedure required the following stock solutions: A. Hydrochloric acid 28 ccm 1 oz. Cupric sulphate 31 ccm 480 er. Water 560 ccm 20 oz. The working solution was composed of : Hydrochinon 0.6 ¢ 9 gr. Water 1130 ccm 40 oz. Solution A 14 to 28 ccm Y4 to 1 oz. For soft pictures of small size from hard negatives, use the OZOUV EE AND AMIE D PROCESSES 7 (297 lesser quantity of A; for normal negatives use 21 ccm (34 oz.) ; and for large prints from soft negatives use the full quantity of A. The pigment tissue should be immersed in the above for 30 seconds, the print also immersed therein and brought into contact face to face, lifted out, thoroughly squeegeed, and left in contact as advised for the first bath. If the two are left in contact for more than 14 hours, they should be afterwards immersed in cold water for from 30 to 45 minutes. Development may be effected as in the carbon process with water from 43° to 46° C. (109° to 115° F.). As soon as development is complete, the print should be im- mersed in a 5 per cent solution of alum or: Alum 28 g 1 oz. Hydrochloric acid 1.7 ccm 30 min. Hydrochinon 0.6 ¢ 10 gr. Water 560 ccm 20 oz. for the same time, and then washed. OzosproME.—In this process, pigmented tissue impregnated with a bichromate and ferricyanide is brought into contact with a bromide print. The metallic silver reduces these com- pounds, and the gelatine is hardened in contact with the silver, so that it becomes insoluble in hot water, just as though it had been exposed to light. Practically, it is a carbon process, in which chemical action does the work of light; it is, therefore, possible to carry out the process at night, and many carbon prints may be obtained from one bromide, if thought desirable. Any good bromide print may be used; but the best results are obtained with those not on baryta-coated paper. The print should be first hardened by immersion for 5 to 10 minutes in a 5 per cent solution of alum, or formaldehyde, or a 4 per cent chrome alum solution, washed, and dried. The ozobrome or sensitising solution is as follows (Manly) : 298 PHOTOGRAPHIC FACTS AND FORMULAS Potassium bichromate 6g 46 gr. - Potassium ferricyanide 6g 46 gr. Potassium bromide 6g 46 gr. Alum 32g 23'Btp Citric acid lg 7 gr. Water 1000 ccm 16 oz. Or (Schmidt) : Potassium bichromate 8g 61 gr. Potassium ferricyanide 10g 7/7 gr. Potassium bromide 72g 54 gr. Alum lg 7.7 gf. Citric acid 0.5¢ 3.8 oF: Water 1000 ccm 16 oz. Or (Faworski) : Potassium bichromate 8.3 g 64 gr. Potassium ferricyanide 6.6 g 51 gr. Potassium bromide 6.6 g 51 oe Chrome alum 3g 23 gr. Citric acid lg 7.7 gr. Water 1000 ccm 16 oz. In hot weather the addition of 1 per cent of magnesium sulphate to the above baths is advantageous; or of (Namias) : Chromic acid 5¢g 38.5 gr. Potassium bromide 20 g 154 gr. Water 1000 ccm 16 oz. The bromide print should be immersed in cold water for 10 minutes, and placed face up on a sheet of glass. The pig- ment tissue should be soaked in 1 part of the ozobrome solu- tion diluted with from 4 to 5 parts of water for 2 to 3 min- utes, and then transferred to an acid bath. This is preferably kept as a stock solution: Chrome alum 100 g 768 gr. OZOUY EE. AND ALLIED PROCESSES ') (299 Oxalic acid 20 g 154 gr. Water 1000 ccm 16 oz. For use mix 150 parts with 850 parts of water, and add 1.2 parts citric acid. This last addition is not essential, but it keeps the whites cleaner. In this acid bath the tissue should be allowed to remain not longer than 7 to 15 seconds, then drawn once or twice over the surface of clean water, and squeegeed into contact with the wet bromide print. The two should be left under light pressure for about 15 minutes, and can then be developed like an ordinary carbon print with water at 407 to 45 CG. (104° to 113° F.). Then the print should be fixed in hypo and ferricyanide to remove the silver, washed, and dried. In this case, the bromide print forms the basis of the carbon print. In the alternative or transfer process, the bromide print is stripped from the pigment tissue, the latter squeegeed into contact with transfer paper, and developed as usual. The procedure is precisely the same up to the point of development. At this point, the print and the adherent tissue are immersed in water for 1 minute, the print pulled off, and immersed in a dish of water. The carbon tissue is squeegeed into contact with transfer paper, which has been soaked in water for about 15 minutes, and then treated as in the carbon process. The bromide print should be well washed for 30 minutes, then immersed in daylight in an ordinary developer until fully developed, then washed, and dried. It can be repeatedly used in this way. It is obvious that en- largements may be treated in this way. CarBro Process.—This is practically the ozobrome pro- cess. Iwo stock solutions are required: A. Potassium bichromate 50 ¢ ] oz. Potassium ferricyanide 50 g 1 oz. Potassium bromide 50 g oz: Water 1000 ccm 20 oz. 300 PHOTOGRAPHIC FACTS AND FORMULAS B. Glacial acetic acid 50 ccm 1 oz: Hydrochloric acid, pure 50 ccm 1 oz. Formaldehyde 1100 ccm 22 oz. The working solutions are: First bath. ~n boSs Scale of reduction for which exposure is known. 2238 OT can n 1 $ $ 2 + : (elias $ en eT at 30 Mar RE PE 18 | 22) 2) SMS Ness se By 3 A UE LE AS 2 ee ea Biss 3 Pua Sole Te PS eee 2a 2 ee ig Ee On tae eS Ey Ce Te eM Ee 4 2 | 3 | ey} £11 14} 14] 14] 14 | 1 1} See ee nO sa es Pree 2 2 Ly LET IN | ei Bay Bd ea | 1 | 1} | 1} | 14 eee te Noe 1g eyo Ee To ee ee eae ie ir an eC ea) tl tbat oie Pema ale ee ee To use ma table find in the top horizontal line the scale of reduction for which exposure is known. Under this scale the relative time of exposure for different degrees of reduction will be found opposite the new scales of reduc- tion marked in first vertical column. 336 PHOTOGRAPHIC FACTS AND FORMULAS SoLaR PRINTING.—Frequently used for making enlarge- ments with plain surfaces for working-up with crayon, water colour and oils: Potassium iodide fobs 125 gr. Ammonium bromide Jae 50 gr. Ammonium chloride 2g 16 gr. Gelatine 12.5 2 96 gr. Albumen 110 ccm 134 oz. Water 1000 ccm 16 oz. Soak the gelatine in three-fourths of the water for 30 min- utes, melt in a water bath, add the salts, cool down to about 38° C. (100° F.), add the albumen, which should have been previously whipped to a froth and allowed to liquefy, and add enough water to make up to bulk. Apply to the paper with a sponge or Blanchard brush, and dry. Sensitise with: Silver nitrate 100 g 1Y4 oz. Glacial acetic acid 50 g 34 OZ. Water 1000 ccm 16 oz. Apply with sponge or brush, and dry. The exposure with a good light will be about 60 seconds. The developer is: Gallic acid 12.5 ¢ 96 gr. Lead acetate 22g 16 er. Water | 1000 ccm 16 oz. Add just before use a little of the silver nitrate solution. Apply with brush or sponge. Or: Milk 1000 ccm 16 oz. Glacial acetic acid 38 ccm 288 min. Stir well, filter, and add to the filtrate: Potassium iodide 14.5 g 112 gr. Potassium bromide Se 27 gr. Paint over the paper, and dry quickly. To sensitise, float on or paint with: Silver nitrate 84 ¢ 642 gr. ENLARGING oar, Glacial acetic acid 126 ccm 2 oz. Water 1000 ccm 16 oz. Develop with: Pyrogallol 6.25 g A8 er. Glacial acetic acid 83 ccm 640 min. Citric acid 0.13 ¢g ons Water 1000 ccm 16 oz. Or coat with: | Arrowroot 20 g 154 gr. Potassium iodide 10 ¢ 7/ gr. Salt 30 g 230 gr. Citric acid lg 8 er. Water 1000 ccm 1G/oz: Heat the mixture until a clear liquid is formed, and float the paper, or paint the solution on with brush or sponge. Dry. Float the paper for 5 minutes on: Silver nitrate Ths) 576 gr. Citric acid ae 38 ger. Water 1000 ccm 16 oz. Expose until the outlines appear, and float on: Gallic acid 2¢g 15 er. Glacial acetic acid 10g 77 gr. Water 1000 ccm 16 oz. When the image is dense enough, float the print on repeated changes of water, and fix in a 20 per cent solution of hypo. CASEIN Paper.—Dissolve as much fresh casein as possible in 100 ccm of strong ammonia, precipitate with dilute hydro- chloric acid, press the mass through linen, allow to dry, and powder it: Casein, as above 300 to 400g 5to6% oz. Water 1000 ccm 16 oz. Boil until dissolved, and add: Boric acid ll.5g 88 gr. 338 PHOTOGRAPHIC FACTS AND FORMULAS Hydrochloric acid 11.5 ccm 88 gr. Citric acid 7g 54 gr. Water 800 ccm 1234 oz. Allow the mixture to cool, remove the skin, press through a fine cloth, coat the paper, and dry. This will keep any length of time. The paper is salted by floating on: Ammonium bromide 20g 154 gr. Magnesium iodide 48 ¢ 370 gr. Magnesium chloride 8g 61 gr. Water 1000 ccm 16 oz. This should be sensitised on: Silver nitrate 100 g 768 gr. Glacial acetic acid 40 ccm 307 min. Water 1000 ccm 16 oz. Small sheets may be floated, and large ones can be painted with the solution. Expose while damp until the details are visible, and develop with: Gallic acid 20 g 154 ger. Lead acetate 10¢ ie Glacial acetic acid 75 ccm 576 min. Water 1000 ccm 16 oz. After development immerse the print in weak soda solution, and fix. ee ee Flashlights Metuops oF Usre.—Flashlights may be divided into two classes: A, pure magnesium powder blown through a flame; and B, magnesium mixed with some substance, rich in oxy- gen, which can be fired with a cap, electric or pyrophoric spark, etc. The first named are less used at the present time than the second class, and they require no comment, as special lamps to burn alcohol, benzolene gas, etc., can be obtained commercially. Gunpowder was one of the first compounds used for firing the second class of flashlights ; but it soon gave place to gun- cotton or pyroxyline, the usual proportions being pyroxyline 1 part, magnesium 2 parts. The cotton should be pulled out to a loose long tuft and the magnesium sprinkled over it. Strips of thin celluloid may be used in the same way, firing being effected by a long taper or match tied to the end of a stick. The manufacture of flashlights is exceptionally dan- gerous, and should not be undertaken by any but experienced chemists. Mixtures oF MAGNESIUM WITH NITRATES.—In all cases, the weight given should be mixed with 1 part of magnesium powder. Thorium nitrate, 0.5; this must be dried at 100° C. (212° F.) before mixing. Strontium nitrate, 1.5; must also be dried. Potassium nitrate, 1.5. Ammonium nitrate, 2; not advisable as the salt is hygroscopic, and the mixed powder will not keep well. Sodium nitrate, 3. Cadmium nitrate, 1; basic cadmium nitrate must be used, which can be made as follows: dissolve 100 g (3% oz.) cadmium nitrate in 100 ccm (3%4 oz.) hot water in a porcelain dish, add a few drops of 10 per cent solution of caustic soda, until a precipitate is 339 340 PHOTOGRAPHIC FACTS AND FORMULAS formed. Evaporate until dry, dry for some time at 105° C. (220° F.), and reduce to powder. Lithium carbonate, 1; alone with magnesium or mixed with one of the above, gives a red light. Potassium permanganate, 1.3; does not explode when struck ; gives brown smoke and more sparks than others. Manganese dioxide, 1; should be very finely powdered. Per- fectly safe, burns fairly rapidly with little smoke. CHLORATES, PERCHLORATES, ETC.—Potassium chlorate, 2 or 1; must be powdered. Potassium perchlorate, 2; also in powder. Sometimes a mixture of the two is used, as chlorate, 34, perchlorate, 34. Both the salts must be in fine powder before mixing, and should preferably be mixed with a feather on a sheet of paper, as strong friction is apt to cause an explosion. These compounds cannot be sent through the post. Potassium or ammonium persulphate, 2. Potassium or ammonium bichromate, 2; burns rather slowly. Chrome alum, anhydrous, 1; a perfectly safe mixture. FLasH SHEETS.—Flash sheets may be prepared by sus- pending magnesium powder in celluloid or pyroxyline solu- tion, casting on glass and stripping before quite dry. The following mixture has also been proposed: Magnesium 1 part Potassium chlorate 2 parts Celluloid varnish 3 parts To be used in the same way. Another method proposed is to coat paper with starch paste, rub magnesium powder into it, and dry. Thin blotting paper, soaked in solution of potas- sium bichromate and dried, is thus pasted and dried. FLasH CanbDLEs.—Slow-burning mixtures can easily be made, and the so-called time-light candles are small tubes of paper, impregnated either with pyroxyline solution or potas- sium nitrate, and filled with a magnesium compound. Or the containers may be made of thin aluminium foil, 0.1 to FLASHLIGHTS 341 0.3mm thick (1/25 to % inch). Typical mixtures are as follows (Novak) : Magnesium 2.5, cerium nitrate 1.75, strontium carbonate 0.75; burns in 5% seconds. Magnesium 2.5, cerium nitrate 1.5, strontium carbonate 1; burns in 4.5 seconds. Magnesium 2.5, cerium nitrate 1.25, strontium nitrate 1; burns in 1.3 seconds. Magnesium 2.5, strontium nitrate 1, strontium carbonate 1; burns in 1.3 seconds. Magnesium 2.5, strontium nitrate 1, strontium carbonate 1.5; burns in 4.3 seconds. Magnesium 2.5, magnesium carbonate 2.5; burns in 11.2 seconds. Anhydrous salts must be used in all cases. So-called orthochromatic candles can be prepared by in- corporating certain salts, which give coloured lights. For red, lithium carbonate 1, with the strontium mixture given above. For yellow, sodium nitrate 5. For green, cupric sulphate 2, barium nitrate 2. SLOW-BURNING PowbDErs.—Slow combustion of flash pow- ders is also obtained by an admixture of shellac; for instance, 1 part of shellac is melted by heat with 9 parts of strontium nitrate stirred in, allowed to cool, and powdered. Or mag- nesium 6, potassium chlorate 12, antimony sulphide 2; or magnesium 2.5, strontium nitrate 5, strontium carbonate 2.5, amorphous phosphorus 0.25, have also been recommended ; but the fumes are poisonous. Bethge patented the following mixtures, of which 2 to 3g burn in 30 seconds: magnesium 2.5, cerium oxalate 1.5; magnesium 2.5; cerium oxalate 1.5, vanadic acid 0.08; magnesium 2.5, cerium oxalate 1; mag- nesium 2.5, calcium oxalate 0.75; magnesium 2.5, cerium oxalate 0.5, calcium oxalate 0.5; magnesium 2.5, manganese 342 PHOTOGRAPHIC FACTS AND FORMULAS oxide 5; magnesium 2.5, cerium oxalate 0.5, manganese oxide 0.25. The chromates or tungstates of thorium may also be used, and the mixtures keep well and give little smoke, such as magnesium 1, thorium chromate 2. Lumiére patented the use of the chromates of iron, manganese, chromium, nickel, cobalt, aluminium, cerium, lead, copper and antimony, as giving little smoke. Boric and silicic acid have also been patented when added in equal quantity to the magnesium, and these mixtures are non-explosive, give little smoke and almost as much light as the permanganate mixtures. Aluminium may be used in place of magnesium, but it does not give quite so actinic a light. It may also be mixed with magnesium. A slow-burning aluminium mixture is alu- minium 6, potassium nitrate 6, barium nitrate 6, dextrine 2, sulphur 1. The aluminium powder is sometimes greasy and clumps together ; in this case, it should be mixed with benzole, petroleum ether, gasoline, or as these are dangerous, carbon tetrachloride may be used. The mixture should be well shaken, the powder allowed to settle, the liquid poured off, and the powder allowed to dry. AMOUNT OF FLASHLIGHT PowpER NEEDED.—Orostini gives the following table of the quantity of magnesium and stop to be used: Distance of object Quantity of magnesium in grams from light Rey, 7:90 filo false 1 meter 0.07 0.01 0.2 0.4 0.8 2 meters 0.28 0.04 0.8 1.6 a2 3 meters 0.63 0.09 1.8 3.6 72 4 meters (Pvt 1.06 32 64 128 MAGNESIUM FOR UNDERGROUND Worxk.—Martel divides the subjects into two classes: (1) short distances from 15 to 20 meters, and (2) long distances from 15 to 60 meters. For the shorter distances he recommends three or four strips FLASHLIGHTS 343 of magnesium ribbon, 3mm broad and 0.5 meters long, wound into a spiral torch which gives an exposure of from 1%4 to 3 minutes; from three to six of these spirals will give exposures from 15 to 20 minutes; up to 10 meters one spiral is enough; up to 15 meters three or six should be used. Placing magnesium powder in 5 g lots and firing with a tuft of pyroxyline, one charge will be enough up to 10 meters; for greater distances successive charges should be fired. Flash powders are not satisfactory; they are dangerous and give more smoke. For longer distances blow-through lamps should be used, using about 8g up to 60 meters; up to 40 meters 5 g. DuRATION OF FLaAsH.—Londe states that the duration of a flash is dependent on various factors; but, calling the unknown ingredients of a powder X, the following table gives the duration: 1. X 100, magnesium 150, duration of flash, 0.07 seconds; 2. X 100, magnesium 175, duration of flash, 0.10 seconds; 3. X 100, magnesium 225, duration of flash, 0.11 seconds; 4. X 100, magnesium 250, duration of flash, 0.12 seconds. Old powder fires more slowly than freshly mixed. The weight of the charge plays a part in the duration: 1 g burns for 0.03 seconds, 2g for 0.05 seconds, and 3¢ for 0.07 seconds. The particular manner in which the powder is laid also affects the flash: 1 g in a heap burns for 0.2 seconds, while 1 g spread out burns for 0.4 seconds. The method of firing also affects the duration: Electric, duration 0.14 seconds; percussion cap, 0.144 seconds; match, 0.188 seconds; touch paper, 0.280 seconds. : Any flash longer than 0.12 seconds will show movement of the eyes. Colour Photography THREE-CoLouR FiLtTers.—The quantity of dyes is given in grams per square meter and grains per 1000 square inches. An 8 per cent solution of gelatine should be prepared (see Orthochromatics ). Red filter: Rose Bengal L25e 12.53 er. Tartrazine 20¢ 19.9 gr. Green filter: Naphthol green 04g 3.98 gr. Patent blue 0.2 ¢g 1.99 gr. Tartrazine 10¢ 9.95 gr. Blue-violet filter : Acid rhodamine 0.6 g 5.97 gr. Toluidine blue 18¢ 17.91 gr. The usual quantity of dyed gelatine is 700 ccm per qm (15 oz., 435 min., per 1000 sq. in.). ADDITIVE FILTERS.—These are used for additive projection or with the photochromoscope. The gelatine should be pre- pared as previously described. Blue-violet filter : Crystal violet 1.38 g 2.63 gr. Methylene blue 0.46 g 0.876 gr. A few drops of glacial acetic acid should be used to dissolve the above. Allow the same quantity of dyed gelatine to the same area. Green filter: Tartrazine 0.533 5.3 ote Patent blue 0.089 g 0.883 gr. Naphthol green 0.178 g 1.76 gr. 344 COLOUR PHOTOGRAPHY 345 The green filter is always difficult to adjust, and it is advis- able to make four or five of different depths, increasing the quantity of dye by one-fifth each time. Red filter : Tartrazine 2.03 g 20.17 gr. Rose Bengal 772; 7 NSZ ot, In order to prevent the double reflection from the back of the plain mirrors in the chromoscope, under the red filter should be placed a plain glass coated on the back with: Patent blue 0.0285 g 0.284 gr. Under the blue filter, should be placed a plain mirror coated with: ) @artrazine 0.0142 g 0.142 er. Naphthol green 0.023 ¢ O227 ier Patent blue 0.0345 g 0.340 er. AUTOCHROME PLATES.—Primary developer: A. Pyrogallol 30 g 230 gr. Potassium bromide 30g 230 gr. Sodium bisulphite lye 2 drops 1 drop Water to 1000 ccm 16 oz. B. Sodium sulphite, dry 100 g Th hs Ammonia, sp. gr. 0.92 150 ccm 2 oz., 252 min. Water to 1000 ccm 16 oz. For use this stock solution should be diluted with 3 times its volume of water. The actual developer is: Solution A 100 parts Solution B, diluted 100 parts Water to 1000 parts To compensate for errors in exposure and variations in temperature, the following system was devised: Have ready in a small measure 45 ccm (345 min.) of dilute B solution to be added wholly or partly to the bath during development. if necessary. As soon as the plate is in the developer, count 346 PHOTOGRAPHIC FACTS AND FORMULAS the number of seconds from the moment of entering until the appearance of the first outlines of the image, exclusive of the sky in landscapes. The number of seconds elapsing before the appearance of the image is the guide to the further development of the plate, which should be carried out accord- ing to the following table: Quantity of ammonia solution B diluted to %4 Total time of Time of first appear- strength to be added development including ance of image after image appears time of appearance Seconds ccm Minutes Seconds 22 to 24 None 2 25 to 27 2 2 15 28 to 30 8 2 30 31 to 35 15 2 30 36 to 41 20 Z 30 42 to 48 25 ha 30 49 to 55 30 is 45 56 to 64 | 35 3 0 65 to 75 40 4 0 over 75 45 5 0 The additional quantity of B solution must be added when the outlines begin to appear. Almost every developing agent has been suggested, but the following are satisfactory: Sodium sulphite, dry 50 g 384 gr. Ammonia, sp. gr. 0.92 33 ccm 253 min. Potassium bromide 6g 46 gr. Metol 4¢g 31 gr. Hydrochinon IZ 92 gr. Water to 1000 ccm 16 oz. Or: Metol 6.5 g 50 ger. Hydrochinon 2.10 ¢g 16 gr. Sodium sulphite, dry 40 ¢ 307 gr. Potassium bromide Diss 19 gr. COLOUR PHOTOGRAPHY 347 Sodium hyposulphite 0.10 g 0.77 gr. -Ammonia, sp. gr. 0.88 20 ccm 154 min. Water to 1000 ccm 16 oz. For use dilute with an equal volume of water. The small quantity of hypo causes the image to reverse in this solution, and development should be carried on until the highlights or flesh tones just begin to show reversal, when viewed against the light. Instead of using hypo, an excellent developer is obtained by using potassium ferrocyanide, 4g (31 gr.). The following is stated to commence the development from the bottom of the film: Amidol 6.6 g 51 gr. Sodium sulphite, dry 19¢ 145 gr. Sodium bisulphite lye 19 ccm 145 min. Potassium bromide 19to3.3¢ 14.6to25 gr. Water 1000 ccm 16 oz. Reversing solution: A. Potassium permanganate 2¢g 15 gr. Water 500 ccm 8 oz. B. Sulphuric acid, c. p. 10 ccm 77 min. Water 500 ccm 8 oz. Mix in equal volumes just before use. The A solution must be kept in the dark. The following is preferable, being free from some disadvantages of the permanganate: Potassium bichromate 5g 38 gr. Sulphuric acid, c. p. 10 ccm 77 min. Water 1000 ccm 16 oz. SECOND DEVELOPMENT.—Any developer may be used for the second development after reversal; the makers recom- mend: Sodium sulphite, dry I5¢ 115 gr. Amidol 2 38 gr. Water | 1000 ccm 16 oz. 348 PHOTOGRAPHIC FACTS AND FORMULAS INTENSIFICATION.—The following silver intensifier was recommended by the makers: A. Pyrogallol 3g 23 gr. Citric acid 32g 23 gr. Water 1000 ccm 16 oz. B. Silver nitrate 5g 84 er. Water 100 ccm 3Y4 oz. For use add 10 parts B to 100 parts A, and immediately apply to the plate. The mixed solutions rapidly turn cloudy; then the solution should be poured away, and fresh applied. This should not take more than about 30 seconds, as a rule; then the plate should be well washed, immersed in a 2 per cent solution of the clearing bath, well washed, and fixed. The following intensifier may also be used: Cupric sulphate 20 g 154 gr. Potassium bromide 20 g 154 er. Hydrochloric acid 5 ccm 38 min. Water 1000 ccm 16 oz. As soon as the plate is bleached, rinse rapidly, and treat with a 5 per cent solution of silver nitrate; then clear in a neutral permanganate bath, and redevelop with amidol or treat with a 5 per cent solution of sodium bisulphite. _ VARNISHING.—The makers recommend: Gum dammar 200 g 3¥ oz. Benzole 1000 ccm 16 oz. The following is preferable as being less dangerous as regards fire risks: Gum dammar 20 g 154 gr. Manilla copal, powdered 50 g 384 gr. Carbon tetrachloride 1000 ccm 16 oz. As soon as the resins are dissolved, the mixture should be heated to the boiling point, and then filtered while hot. Tue Pacet PLate.—With this a separate panchromatic COLOUR |PHOTOGRAPEY 349 plate is exposed in close contact with the taking screen, developed in the usual way and fixed, washed and dried. From this negative a positive is printed by contact and bound up with a viewing screen. As a rough guide the exposure with f:8 in good light with sunshine for an open landscape is about % second. For portraiture, head and shoulders, outdoors in diffused light, f:8, about 3 seconds. Snap shots should not be attempted except in the brightest light at f:6.5 and not less than 1/10 second.. The speed of the plate is approximately 11 Watkins, F24 Wynne with filter and taking screen. A special devel- oper is issued by the makers, but any one may be used if diluted with an equal volume of water. Green light or total darkness must be used, unless desensitising is adopted. The transparency must be of a black tone, free from fog, brilliant and full of detail. Special plates and developers are made for this work. Tue AGFA PLATE.—This plate is of the combined type, like the Autochrome, and must be placed in the plateholder glass side to the lens. A special compensating filter is obtain- able, which may be placed in front of or behind the lens, and in the latter position it lengthens the focus about 1.5 mm. The exposure is about 60 to 80 times that required for a rapid plate and for a sunny landscape about midday with f:6.8 one second exposure should be correct. The developer recommended is: Metol 1Z25)2 96 gr. Hydrochinon 5g 384 gr. Sodium sulphite, dry 80 g 614 gr. Potassium bromide 48¢ 37 er. Ammonia, sp. gr. 0.91 25.9 ccm 196 min. Water 1000 ccm 16 oz. Dissolve the metol and hydrochinon in warm water and add 350 PHOTOGRAPHIC FACTS AND FORMULAS the sulphite and bromide. When the solution is cold add the © ammonia. For use mix 1 volume with 3 of water and use at 18° C. (65° F.). Development time, 3 minutes. Then rinse slightly and immerse in the following reversing bath: Potassium bichromate 5¢ 38 gr. Sulphuric acid 10 ccm 77 min. Water 1000 ccm 16 oz. The plate may now be handled in daylight and after about 3 minutes in this bath it should be washed for 30 seconds and reimmersed in the developer for about 2 minutes. Then wash in running water for 3 minutes. Drying should be effected in a warm place, but not by heat. The plate may be varnished by gently heating first and then coating with 3 per cent solution of gum dammar in benzole. a _ Photomechanical Processes The wet collodion process, collodion emulsion, lead, copper, and acid silver intensifiers, and reducers are dealt with in other sections. See index. } CLEANING ZINC AND CoppEer.—For line work very fine pumice powder should be applied with a felt pad or soft scrubbing brush and water and applied in the same direction as the original lines of the polish. For half-tone work on zinc or copper well washed whiting made into a paste with water and a little ammonia should be used with a swab of absorbent cotton. Or, for copper, American polishing char- coal, with rounded end, may be used in straight lines with plenty of water. PASSING OR GRAINING BATH FoR ZINC.— Powdered alum 31.25 ¢ Y, oz. Nitric acid 3.125 ccm 24 min. Water 1000 ccm 16 oz. GRAINING BATH FOR COPPER.— Chromic acid 23 g 175 gr. Water 1000 ccm 16 oz. ALBUMEN SENSITISER FOR LINE WorK ON ZINC.— Albumen (white of egg) 23 ccm 175 min. (Or dried albumen) 6.5 ¢ 50 gr. Potassium bichromate Se 40 er. Water 1000 ccm 16 oz. FisH-GLuE SENSITISER.— Fish glue 47.5 ccm 365 min. Ammonium bichromate 0.132 ¢ 1.04 gr. Water 1000 ccm 16 oz. Add enough ammonia to give a bright yellow colour. This 351 352 PHOTOGRAPHIC FACTS AND FORMULAS film must be burnt in after development. INKING-UP LINE PRINTs oN Zinc.—Use photo-transfer ink, thinned down with very little turpentine, and apply with compo or fine nap leather roller. DeEvELOPING LINE Prints.—Immerse the plate in water, to which a few drops of ammonia have been added, and rub with swab of absorbent cotton. Harp ENAMEL FOR ZINC.— Fish glue 650 ccm Fresh white of egg 130 ccm (Or dried albumen) 92¢ Ammonium bichromate I5¢ Ammonia 15 drops Water 1000 ccm 10% oz. 2 OZ. 70 gr. 115 gr. 10 drops 16 oz. Beat the albumen to a froth and mix in the glue and again beat up, allow to stand eight hours, then dissolve the bichro- mate, then add the ammonia and filter through absorbent cotton. The following gives a much tougher film: i: Fish glue 187.5 ccm Belting cement, Le Page’s 93.75 ccm Ammonium bichromate 15.6¢ Albumen 187.5 ccm Ammonia 7.8ccm Water 1000 ccm . Le Page’s belting cement 312.5 ccm Chromic acid 2.85 g Ammonia 11 ccm Water 1000 ccm Pure rock candy 68 g Ammonium bichromate 34 g 3 02. 1Y4 oz. 120 gr. 3 az: 60 min. 16 oz. 507% 21.75 on, 87 gr. 16 oz. 524 er. 262 gr. Add the acid to the water, then the ammonia and finally B with constant stirring. PHOTOMECHANICAL PROCESSES 353 HARDENING BATH FoR ENAMEL PRINTS ON ZINC.— Ammonium bichromate a I51e 27.5 ote Chromic acid 0.3 ¢g 2.2%. Methyl alcohol 143 ccm 2 1/3\0z: Water 1000 ccm 16 oz. Immerse the developed plate for from three to five minutes. Dye SOLUTIONS FoR FisH-GLUE Prints.—0.5 per cent solution of methyl violet or eosine. Hatr-Tone ENAMEL FOR COPPER.— Le Page’s fish-glue 200 ccm S/S Oz: Albumen 131.25 g 2 0z., 44 min. . Ammonium bichromate 2.7/5 2 213 gr. Ammonia 33 drops 25 drops Water 1000 ccm 16 oz. Beat the albumen to a froth. Allow to stand 8 hours and add the glue and then the salts dissolved in some water, make up to bulk, and filter. BITuMEN ProOcEss.— Syrian asphalt, fine powder 42.5¢ 320 gr. Chloroform 400 ccm (6372/5) (0745 Benzole, anhydrous 600 ccm 9 3/5 oz. Venice turpentine WAV) 96 gr. Oil of lavender 40 drops 32 drops The coated film should be a transparent golden colour. The exposure is very long even in sunlight. Develop with recti- fied turpentine. Etcuinc BatTus For Z1nc.—Weak bath for first bite for line or half-tone, 1 per cent nitric acid. Deep etching for half-tones, 2.5 per cent nitric acid, 1.875 per cent for fine etching half-tones on zinc. For cold enamel: Nitric acid 15.6 ccm 4 oz. Alcohol, 40% 1000 ccm 16 oz. 354 PHOTOGRAPHIC FACTS AND FORMULAS The exposed image is not burnt in, only heated to dry and harden. Scum REMOVER FOR COPPER.— Acetic acid 100 ccm 698 min. Common salt 187.5 ¢ 3 0z. Water 1000 ccm 16 oz. The same quantity of hydrochloric acid may be used instead Or the acetic. MacHINE EtcH1ING.—Levy machine, first etch, 10 per cent acid for 30 to 40 seconds; second etch, 15 per cent for 1 to 114 minutes; third etch, 20 per cent for 4 to 5 minutes. Air pressure for first etch, 44 to 34 lb.; second and third etches, 1 1b. A single etch with 10 per cent acid for 30 to 40 seconds is generally enough except for extra deep work. For Holt machine and line work on zinc, 7.5 per cent with three bites and rolling up between. Total time for full depth, about 18 minutes. For half-tone on zinc, use the same solution as for line work, for 114 minutes; then roll up and powder, and etch for 2 minutes. For half-tone on copper use perchloride of iron solution 35° Bé. or a 35 per cent solution of anhydrous ferric chloride. Air pressure 14 to % |b., time for first bite 30 seconds and total time 314 to 4 minutes after stopping out. If the iron solution is very acid, add a little ammonia until a slight pre- cipitate is formed, then boil and filter. CoLLotyPE.—Grinding New Plates. Sift over the surface finely sifted emery powder, wet well with water and grind with another plate with circular motion. Wash well after grinding. Cleaning Old Plates. Soak in 5 per cent caustic potash solution for 4 days or place in hot 10 per cent solution of sodium carbonate. Scrape off old film with hard brush. Re- grind before use. : PHOTOMECTANICAL | PROCESSES SoD Substratum. Whites of fresh eggs 312 ccm 5 oz. Sodium silicate 125 ¢ 202) Water 1000 ccm 16 oz. Beat the whites to froth and allow to settle, filter and add the other ingredients. Pour a little on the plate, drain slightly and place on leveled stand to dry. Or: A. Gelatine I5¢ bison: Water | 500 ccm 8 oz. B. Alum 10¢ 80 gr. Water 500 ccm 8 oz. Dissolve the gelatine by heat, add the alum solution warmed up, and add Sodium silicate sol. 46g 34 OZ. The plates should be warmed and the solution applied with a broad camel-hair brush and dry. A stock of plates may be thus prepared, but they should be rinsed in water and again dried. Sensitive Solution. Hard gelatine 46¢ 350 gr. Water 1000 ccm 16 oz. Allow to soak for 30 minutes and melt and add: Potassium bichromate 16.5 ¢ 126 gr. and filter. Allow 44 min. to every 100 sq. in. (682 ccm per square meter). Place the plates in the drying box and warm up to 48° C. (120° F.), carefully level and coat. The tem- perature of drying must not exceed 54° C. (130° F.). After exposure wash in water at 15° C. (60° F.) until all trace of yellowness has disappeared, then dry. Etching the Plate. Actually a moistening solution, there being no etching action. The plate should be rinsed in water, blotted off and covered with a mixture of 3 parts glycerine and 2 parts water for about half an hour. Or equal parts of 356 PHOTOGRAPHIC FACTS AND FORMULAS glycerine and water plus 2 per cent of ordinary salt may be used. PHOTOGRAVURE.—Negatives should be full of detail and without hardness and preferably carbon transparencies should be made, showing all details in the high lights, with- out great density. The thinner these are kept, providing details in the high lights are visible, the better. Special transparency tissue is issued by the makers, or standard brown may be used. Cleaning the Copper Plate. Rub over with 5 per cent solu- tion of potassium carbonate with cotton swab, rinse well and treat in the same way with 5 per cent solution of sulphuric acid. Wash well and polish with whiting made into paste with 3 per cent solution of ammonia. Rinse plate with hot water and dry with clean cloth. Graining the Plate. The usual dusting boxes should be used and the longer the time between setting the powdered asphalt in motion and the insertion of the plate the finer the grain. For a coarse grain wait for 20 seconds. Allow the plate to remain for from 2 to 5 minutes. For very fine grain it may be necessary to shake box and grain two or three times. Resin may be used but does not give such good results in unskilled hands. Setting the Grain. Grip the edge of the plate with a hand vice, using card to protect the copper, and heat over a gas flame, with continual movement so as to even the heat, until a steel blue colour shows. Mounting Resist. Place the grained plate in water at 21° C. (70° F.), slip in the tissue and brush the face with a soft brush to remove air bubbles. Bring the two into contact and lift from the water, squeegee well, and place between blotters for 10 minutes. Develop with water at 38° C. (100° F.) or if underexposed raise temperature to 49° C. (120° F.). PHOTOMECHANICAL PROCESSES 337 Rinse in cold water and dry. If etching is to be done at once, flow over with equal parts of methyl alcohol and water and dry on whirler. Varnishing. The back and edges of plate should be painted with a 20 per cent solution of bitumen in benzole or Mogul varnish thinned down. Etching Solutions. Anhydrous ferric chloride is used. It is advisable to add to this 6 per cent of freshly precipitated ferric hydroxide, just cover with distilled water, and make solutions up to 43, 40, 38, 36 and 33 degrees Beaume with distilled water. The following strength solutions correspond to the above: 43° = 46 per cent; 40° = 41 per cent; 38° = 39 per cent; 36° = 36 per cent; 33° — 33 per cent. To each of these the ferric hydroxide may be added, well shaken and allowed to settle for use, or the whole solution made up very strong, heated with the hydroxide and then diluted to the above strengths. The weaker the solution the stronger the etching. As soon as etching is complete, rinse the plate, immerse in 10 per cent solution of caustic potash and rub with swab of cotton. Then rinse, dry, remove grain with benzole, clean plate with 1 per cent nitric acid and finally with washed whiting and ammonia. PHOTOLITHOGRAPHY.—Transfer paper should be sensitised with a 4.5 per cent solution of potassium bichromate, rendered alkaline with ammonia in winter and with the following in summer : Potassium bichromate 22.5.2 175 gr. Manganese sulphate Sls) & 24 gr. Water 1000 ccm 16 oz. Temperature of bath 15° C. (60° F.), time of immersion 5 minutes. It is as well to squeegee the paper to plate glass so that it may dry with a polished surface. After printing place on rolling up board and apply the ink in a very thin 358 PHOTOGRAPHIC FACTS AND FORMULAS film with a velvet roller. Place in water for about 3 minutes and then roll up again with the roller; this removes the ink and any slight veil can be removed with a wet swab of cotton. Free from water drops by lightly touching with blotting paper and pin to board to dry. Direct PRINTING ON ZINC AND ALUMINIUM.—Sensitise with: White of egg 62.5 ccm — 1 oz. Fish-glue 15.6 ccm V4 oz. Ammonia bichromate 7.82 60 gr. Ammonia q.S. q.S. Water 1000 ccm 16 oz. Enough ammonia should be added to make the solution a clear lemon yellow. For large plates the volume of the solu- tion may be increased by one-fourth with water. VANDYKE OR REVERSE Process.—Zinc plates should be grained with the graining bath given for line work and coated with the following: Fish-glue lllg 853 min. Ammonium bichromate zie 170 gr. Chromic acid 0.13 g 1 gr. Water 1000 ccm 16 oz. After exposure, under a line copy, develop with plain water and dye up with aniline dye. The plate should then be passed into a bath of: Ferric chloride, 31% sol. 2ccm 16 min. Water 1000 ccm 16 oz. Leave the plate until the colour disappears, then rinse and dry. Treat the plate with asphaltum washout tincture, and ink up with the following: Bitumen, powdered 4 parts Litho chalk printing ink 1 part Litho writing ink 1 part 2 ——— PHOTOMECHANICAL PROCESSES 359 Burgundy pitch 1 part Mix with heat and thin with the minimum of turpentine. There must be but a very thin film of ink on the plate. Allow the plate to dry and develop with water, plain or very slightly acidulated with hydrochloric acid. Weights and Measures RULES FOR THE CONVERSION OF WEIGHTS AND MEASURES. W eights. — Grains to grams: Take 6 per cent, and add 8 per cent. Grams to grains: Multiply by 15, then increase result by 3 per cent. Ounces to grams: Multiply by 28, then increase result by 1% per cent. Grams to ounces: Take 3 per cent, and increase it by 1/6 + (5 per cent of 1/6). Pounds to kilos: Take 40 per cent, and increase it by 10 per cent + (1/3 of 10 per cent). ‘Kilos to pounds: Multiply by 2, then increase result by 10 per cent + (2 per cent of 10 per cent). Lengths. — Inches to centimeters: Multiply by 2, then increase result by 25 per cent + (8 per cent of 25 per cent). Centimeters to inches: Take 40 per cent, and diminish it by 1% per cent. Yards to meters: Take 70 per cent, and increase it by 30 per cent + (2 per cent of 30 per cent). Meters to yards: Add 9 per cent and 4 per cent of 9 per cent. Fluid Measures.— Pints to liters: Take 40 per cent, and increase it by 40 per cent + (5 per cent of 40 per cent). Liters to pints: Multiply by 2, and diminish result by 12 per cent. Example: Required the number of grams equal to 15.432 grains: 360 oh WEIGHTS AND MEASURES 361 6 per cent of 15.432 =0.92592 8 per cent of 0.92592 = 0.0740736 0.9999936 The result should be 1 g, and the error is less than one in one hundred thousand. In all the above rules, in no case is the error greater than one-thousandth. Table to convert grams per liter to grains per 16 ounces.— G per liter Gr. per 16 oz. G per liter Gr. per 16 oz. 1 7.68 10.5 80.64 15 11G5Z 11 84.48 2 15:30 1S 88.32 ys) 19.2 12 92.16 3 23.04 V2.5) 96.0 J 26.88 13 99.84 4 S072 165) 103.68 4.5 34.56 14 107/52 5 38.4 14.5 111.36 Beye 4224 15 1ulG).2 6 46.08 1525 119.04 6.5 49.92 16 122.88 7 SAE 16.5 126.72 7.9 57.6 Wi 130.56 8 61.44 WAS 134.4 8.5 65.28 18 138.24 9 69.12 18.5 142.08 9.5 72.96 19 145.92 10 76.8 19% 149.76 20 153.6 To find the number of grams per liter, divide the number of grains per ounce by the following factors: O27) G per liter Oz.) G periliter ] 0.48 10.5 5.04 362 PHOTOGRAPHIC FACTS AND FORMULAS 1.5 0.72 11 ‘il Since 2 0.96 115 Bie yale LZ iz 5.76 3 1.44 Leo 6.0 Me 1.68 13 6.24 4 1,02 13.9 6.48 4.5 2.16 14 6.72 5 2.4 14.5 6.96 op 2.64 nny. 72 6 2.88 15.5 7 44 6.5 3.12 16 7.68 i 3.36 16.5 7.92 75 3.6 17 8.16 8 3.84 175 8.4 8.5 4.08 18 8.64 ? 4.32 18.5 8.88 9.5 4.56 19 9.12 10 48 19.5 9.36 20 9.6 Approximate rule to convert English weights and measures into metric: 1. Call the new volume of solvent 1000 ccm. 2. If any of the ingredients run to ounces, take their ratio to the solvent, and write down the same ratio to 1000 in grams. 3. Divide each grain item by half the number of ounces, and write the result down in grams. PERCENTAGE SOLUTIONS.—Some dispute has prevailed as to the exact meaning of “x per cent solution,” but in photo- graphic practice it means x parts in 100 parts of the total bulk of solution. As most chemicals are sold by the avoirdupois ounce of 437.5 grains, and liquids are measured by the ounce of 480 minims, some confusion has arisen. The following WEIGHTS AND MEASURES 363 tables show: (a) the accurate quantities of solids to be dis- solved in sufficient liquid to make a total bulk of 100 parts for the various percentages; (b) the number of grains to be dis- solved in sufficient solvent to make 1 ounce of any given percentage. | 1 per cent 4.375 gr. Zs Ne Sai: Biles GER ote, SER AY UZ SOs Son onan ZV .SHo Opa dee 26:25. Aes civ 30.625 “ Stain S5.0N ic, SO ns 39379) 10 esee tae AS 7D. The number of grains of a solid which must be dissolved in sufficient liquid to make 1 fluid ounce for the various per- centages : 1 per cent 4.8 gr. Dene ae oon, Sig sti 14.4 “ BT olan SIA SN eae we 24.0 “ ar ay 2S Sia Fn S20 SHG 38.4 “ ais 43.2 “ Oe aang 48.0 “ These tables are sufficient to calculate any percentage or volume, by merely multiplying or adding. Example: Re- quired to make a 15 per cent solution, how many grains are required : 364 PHOTOGRAPHIC FACTS AND FORMULAS 10 per cent = 43.75 5 per cent = 21.875 65.625 gr. Required 16 oz. of 10 per cent solution, how many grains — | required: 4 48 X 16 = 568 gr. / The following tables are sufficient to enable anyone to read- } ily convert the metric into the customary units, and are based on those published by the U. S. Bureau of Standards. Lengths. — Inches Centimeters Inches Centimeters 0.3937 =] 1 = 2.5400 0.7874 —=2 2 = 5.0800 1.1811 = 3 3 = 7.6200 1.5748 = 4 4 = 10.1600 1.9685 = 5 5 = 12.7000 2.3622 = 6 6 == 15.2400 2.7559 = 7 rf = 17.7800 3.1496 = § 8 = 20.3200 3.5433 —=9 9 = 22.8600 Areas.— Square Square Square Square Inches Centimeters Inches Centimeters 0.1550 = |] 1 = 6.452 0.3100 —2 2 = 12.903 0.4650 = 3 3 == 19.355 0.6200 —=4 . 4 = 25.807 0.7750 = 5 5 == 32.258 0.9300 = 6 6 = 38.710 1.0850 =7 7 = 45.161 1.2400 = 8 8 = 51.613 1.3950 = 9 9 = 58.065 = Ona Se Sse ee WEIGHTS AND MEASURES 365 Masses.— Grains Grams Grains Grams 1 = 0.0648 15.4324 =] Z = 0.1296 30.8647 = 3 = 0.1944 46.2971 = 4 == 0.2592 61.7294 = 4 5 = 0.3240 77.1618 —5 6 = 0.3888 92.5941 = 7 == 0.4536 108.0265 == 8 = 0.5184 123.4589 — 8 9 = 0.5832 138.8912 = Liquids. — Cubic Cubic Fluid Centimeters Minims Centimeters Ounces 1 = 16.230 29.574 = | y = 32.460 59.147 = 2 3 = 48.690 88.721 = 3 4 = 64.920 118.295 == 4 5 = 81.150 147.869 = 5 6 = 97,380 177.442 = 6 7 = 113.610 207.016 —=/ 8 = 129.840 236.590 =— 8&8 9 = 146.070 266.163 —9 hei. 5. eallon — 3785.43 ccm: one liter — 33 fd oz, SOA niin. The above tables apply to the English weights and mea- sures, with the exception of the liquid measures; the English gallon measures 160 fld. oz. = 4545.96 ccm. The following, therefore, must be used for conversion of the same: Cubic Cubic Fluid Centimeters Minims Centimeters Ounces 1 = 16.894 28.4123 — 1] 2 = 33.788 96.8245 =2 366 PHOTOGRAPHIC FACTS AND FORMULAS a == $0.682 85.2368 = 4 = 67.576 113.6490 == 5 = 84.470 142.0613 = 5 6 = 101.364 170.4735 = 7 = 118.258 198.8858 — 8 = 135.152 227.2980 = 9 = 153.046 255,7103 = COMPARISON OF THERMOMETER SCALES.—Equivalence of Centigrade (Celsius) and Fahrenheit Thermometers. Oenti- Fahren- Centi- Fahren- Centi- Fahren- grade heit grade heit grade heit 0 32.0 35 95.0 70 158.0 1 33.8 36 96.8 71 159.8 2 35.6 37 98.6 72 161.6 3 37.4 38 100.4 73 163.4 4 39.2 39 102.2 74 165.2 5 41.0 40 104.0 75 167.0 6 42.8 41 105.8 76 168.8 7 44.6 42 107.6 77 170.6 8 46.4 43 109.4 78 172.4 9 48.2 44 111.2 79 174.2 10 50.0 45 113.0 80 176.0 11 51.8 46 114.8 81 177.8 12 53.6 47 116.6 82 179.6 13 55.4 48 118.4 83 181.4 14 5/2 49 120.2 84 183.2 15 59.0 50 122.0 85 185.0 16 60.8 51 123.8 86 186.8 17 62.6 Be 125.6 87 188.6 18 64.4 aS 127.4 88 190.4 19 66.2 54 129.2 89 192.2 20 68.0 55 131.0 90 194.0 21 69.8 56 132.8 91 195.8 22 71.6 57 134.6 92 197.6 23 73.4 58 136.4 93 199.4 24 75.2 59 138.2 94 201.2 20 77.0 60 140.0 95 203.0 26 78.8 61 141.8 96 204.8 27 80.6 62 143.6 97 206.6 28 82.4 63 145.4 98 208.4 WEIGHTS AND MEASURES 367 212.0 221.0 230.0 239.0 248.0 Chemical Tables TABLE OF SYMBOLS AND MOLECULAR WEIGHTS OF THE MORE IMPORTANT COMPOUNDS USED IN PHOTOGRAPHY Name Symbol Weight 24 clo) (81 AD OG ADS AI OLS eS RE Cs He Ooo. 2 58 — sulphite aden is) halle’ atin oe C,H, OH SOs Na‘roicieeee 162 PNET ACETAC olga oa ws eleimtendr mania Hy Oe oo. os one 60 Se MNERT SOTO! UN bcc eis blo vale piers ee C. Hs COOH. 442s 122 SORES Wales ON NE RGL Oa etic eres Hs BOs (cies kee 62 aE Deh 2 0,6) 9 ae Un ag i pa C. Hs OW ail ere eee 94 — chlorochromic ........... Gl Ce O; OR its. Cee 136:5 35 — chromic (anhydride) ..... Cr Os L202 a eee 100 ee MC LEMNG RMU a Yala ie gan a Ce Hs 0; 0) 0. eee 210 ee LAAT OTRAS NEI a gale oiaeie a ep Hay Sa OF soos eee 162 eA 5) 9 0 91M UR LMP Uy a A HCO. 60 46 SES Toa hol AAAI a AR A nt (OH): COOH, H:.0 . 188 — hydrobromic .........000. Bf Br. ie 81 ae MMV GROCAIOTIC | '.'o)e'ss gue ols aig H Cl sla'Sihiv cee sea en 36.5 ey MVOLOUNMOTIC | sass o's sw scc's ees FE ae Oe 34 rota 4) oY 515 (tnd MNO LINES Bele ale en CH, CH (OH): COOH: 90 AAA CELD [eA UN Nady ae ESA AREER AD AA HNOs") 300 oe 63 asco) (| SRM AR OM RSA RR CRM Ne dee Be He Ce On ee eee 126 mae | UEC EMIOMAC (5.0 Ciwiclee bones Fis Sis Oa) ctecis sass Cee 258 nee | ORC MRORIIE 12. 5 aL ie a. H Cr Oss Lisa 117 Se! MOMOSMMONEC | (0/c sion sia ase aie Hs) POs |. i cdi dete 98 Pa MUGEN i ied Wialuleic tal Ria egnm iete Bah C. Hs (NO:): OH . 2a 139 ar MOU OSB leh wee as needle Hs: (OH )33)..0. eee ‘2 126 mar IGEN ITE 114!) cit cia wate mite ale a ie C. Hy (OB) COOR ae 138 eoaai STAID NIIAC) 4.2 said ioia @ elavilevess Bis SOa seals s Bae 98 pn) SUL DAUITOUS) | bc lave Wiesel die eld oie Hy SOs 430) See 82 SNA MEUTATING ul tai Sic luyh te valet ab eag aah iene Ca He OS Sf eee 322 seh RERTOAT AES hu ha. see node webs ne letieae iets C. H: (OH): (COOH): ... 150 eta paIGnge: 0. Susu ld Ha Sy Oe So. 2 a 225 calli £16116): € oa AD ae ERD Ie Hy Ss Qe veces even 194 Alcohol (methyl) \.5/.65 0 5 waieweats CH OF vou oi ee 32 —_ (ethyl) Sialelals vate verion stebeverete C,H; OF 22 ee 46 Alama amnimonda ol) Kk ee Al; (NH.):2 (SO.)4 24H:20O . 906 Tae DM LLe 2165) =k NS MRE AD RT Cra Ks (SQ) a 2450 eae 998 — iton ammonia ........5.: Fe. (NHz)2 (SOs) 24H:O . 964 Re MN MOERUSED (sinc ucla ase ee ah eM uine Al, K; (SO«)« 24H20O ..... . 948 368 CHEMICAL TABLES Name Aluminium chloride ............ — Stilplaate ees see _ sulphocyanide ....... PAMEIROTLIC isis ees leveieials Sisieie Bee ele ee Ammonia ..... Pee iapaaveesece wyacah evabe Ammonium bichromate ......... — bromide ot .).) eet as — Carbonate) Ve waciekies — chloride W358 ceo es — Chromateund. sie Lae —_— ClimAaber es oi ae — VOUIG Gare 50 Aha iene siete — molybdate ws. owe — AMET ATC icloicee hse eines — ORDALONG Mae cr cmuierent, Moe — PELSUIpNAate: |). senses — PHOS phate. siaseoes — Sitlplaten cos satan cere — Sulphide eo aves ee —_ sulphocyanide ...... — Vanadates. 65 eudicie wets PEMA ACCEALEN yes g oia/ oie 1d «vl oleate MRA ONTO Gero) sicie!c's Scots eealeruratele PATAMIAIVE Np Yo ict sn 's shes 6 msi e erate Antimony, sulphide ............ JS UN PEN DIETS s SIA ene Rp ENTE. CAE eee ee pe aievtntade DEOMIGE 5s o:40::0w oe ie s,s Se ACN OT IGE) aha love evel eles dw 0 oem Me ie OGLE) oe 5 dere sieie'e o Rede a UATE ATC His cious e'sie cela ole calve eM PCTORIGE (5 os bine oe hes SEO) caf a ere Benzole (benzene) i. ).6 5 waa isje sss Borax (see Sodium Borate) JES POLE TUITE shel Se a A a EAU CGadmiunic bromide ob ses — Chloride soy ecg hae _ TLOVSUR GTS OUR aR ne th Galo ccanbide Me) ack eka — CALDONALG en s5 chains S — chloride (cryst.) ...... — chloride (fused) ...... — hypochloritey <.. cis — Sulphate peas earn ciee a sce hydroxide (slaked lime) Symbol Weight UA la ta @y eres els ciate eieh= 267 Als ae LOMALO MY Fs, cielelarste 634 AIL CEN Sel loses sine sae elsiee 402 we H. OH (NH:)2 2HC!I . ele (NI), Cray Orn ei te Bishi oes 252 Nay Bree Siieiscnine sian 32) « 98 NHag COE NEL, COOH INDETA peer ei Bistelaeiamiershel ae — INGE Ge ea aie tavatetas sbetet siete 53:5 (NHaz)s Er Oia eae ieia yas 152 eee Cae Or cies. 226 Ne reenter el chai stevsl enue 2 145 Ea MO; Ou 4H:0 ....1236 OA ae ER NEN AEA 80 (NH,): COME Oe ee 142 CNET iz Sa Os) tomsiysoeierieiele 228 CNG) ay EPO a eines ee og 132 CNET aa SOg ieee sae iiwse 132 NIELS ye saraicie cinta ieuere vere 51 NE CNS itis cccls nineteen 76 NH, a Lid lela g ote eae koteba Aly, Cr llira! Oana elses Nevers nae oneie ee 130 CaN Eley Rb, ae as ee 93 Sia Sar ea hae se ceaigite reas mens ans 336 (CeH2(NOz)3)2 N NH .... 456 C (GH OH) as Ee On 290 Ba Bri ZO ee eras 333 Bala: ZHCOnee iene 244 Flas EIA ATA NN AUER SRN a MEI ch) 391 Ba (NOs): asl clelaneli el ete) slisieteltalelle 261 Alo) VOILA VHS iaipert ce nes OEE 201 Ba iSO ie Sa he 233 ONG & (FU ee oo ee aN ARH NRG. Ld 78 Bees ale Seas shes eno Ege 80 Cd Brg Ate ee yaaa 344 COG es OB) NT ON RS UN ea React 183 CTE eho ay Rees SER clan 366 Cay Caveat Si ean een 64 LONG OC GRC a ae peepee tc 100 (OF) Cl. 6H:O s40000 60000 CO56 219 CaniGle eee ete es Re an aie vane CaO AG Uae ant Ske ey rate 153 Car SORE Ome. fps es as 172 Cac (OH) sent ona cca 74 Mol. Name Symbol Weight Carbon, bisulphide ............. C Sa dic see ee eee an 76 CONG ee Gilad Sint Wle ela ale Ciz Hie Os (NOs). cece cccee 504 Ceric, Salma os peas twas Ce (SO.)s) 4HO (aca eee 404 Ciarat tiyawate 2b sie Geis eis C.Ch. CH. (OM )s 02 3geee 165.5 | CRSA ONTARIANS 0! 2h 0) e\elithal ere Bln CH Ch fo.46 eee 119.5 Chrysoidine erecccccscccce eeivew Co Ee Na Ca Bis sail: eapiag' | Comalt, Wohlorade i)0 c's die ia le Co\ Cl. 6H:O 5 nee 238 Capper, MEARE bole Utome eelee Cu Bre sce dense ee 223.5 ae chloride eecveevecee eeeece Cu Cl. 2H.0 eeoeceeecece see eens 170.5 Ec) 32 (0 oe eM Aad) Cu (NOs)s 6HO joke 357.5 Botte Vy) MERE MIAEES 1 2. Ae alias mle atadenie Cu) $0, 5H0: |. cosh oe 249.5 Cyanine i i i Cx Has Na LEC E AS 0 544 Ta 7 1 AUST ARR DR BIRR A (Ce Hi Os) >. See aired Diemigophenol ios as eee as C,H, OH |(N2)s\5. 27030 124 Bae od Aa hae ike Lice ela nee Na or Ki Salt. of ioc Ua ae C.H.i(CO)2-0(CsH OH X*)2 — BUG ASINE: fi sidan sales aheac egietele els C.H.(CO)2.0(C.HOHX:*)2 — ST ge PORE NEN A BE agg Ys Ce Hy (Oo oc 74 Ferrous and ferric salts (see Iron) PGT MANE HL wlee vi6t caine oie anole 40% sol. of CH2O .......... — EV cot a0 SN Lg MD a ee ADEA C. Hs (OH) s). 63 Sega 92 RASTER ei NN Us eS Le C. Ha OH NHCH;: COOH . 167 Gold, chloride yellow .......... H ‘Aw Cl. 480. ue 412 _— i Y OWM fee bie sic aol e's FE, Aw) Cleo. nhl ee 340 — — potassium ....... K Au Chi 2HsO) . 0 ae 414 — et) SNRAEAD | L22y la ye Na Au Cl. 2HsO }. cusaenaee 398 Hydrogen, peroxide ............ BOs de Se eee 34 EI ArOdiiMOne 0. 4e Widisleiey & sigan Ce Ha (OH) a iin ee 110 Fo Ce AES LE DRS IASG A ge eee ee ie a Ui ahaa 127 fodiogs chloride hour ek Tr Che nee eee 299.5 — tetrachloride ........... Tp Chis yc 2 ee 335 — potassium tetrachloride . Ka Ir Cle ............eeeees 484 ++ sodium ‘tetrachloride ./..)\Nas Ir Cleo. 00 0c. eee 452 Tron. Ferric chloride (dry) ........ Fes hei. 325 —) chloride (( hunip)) 4.4) 2'.. Fe; Cl. :1ZH,0 | 30) 20a 541 — ammonia citrate, brown 4 Fe Co Hs O;, 3(NH4)s Ce HO; 3Fe (OH )s) 2270 2030 as — — green 5FeC.H;0.2(NH:.):CsH:;O;N HCHO; 20 ne 1956 rel | MADER RRR NS CI Oa DG a Fes (Ca Oa) aie eee 376 * The X in these formula may be bromine, iodine, or chlorine, which elements in other proportions constitute the various commercial dyes. ¢ Glycin is vy oxyphenyl-glycin or y-oxyphenyl-amido-acetic acid. CHEMICAL TABLES Name Tron. Ferric Ammonium oxalate .. — potassium oxalate ...... aoe SOM OXALALE: .\/4 5,01 om «!e 2 chloride (dry) ...... —_ — (cryst.) . — GRANTS) Gea lelelew olersote — potassium oxalate ... — Sulphate. 2eihvie/ees s — ammonia sulphate ... Wa ACCLALE We ic tdi siete s(aiele ae sieve SEMMIRILIEL ATE |). Jia ie s\e olu's\oleiavaia sie. e's NOTRE NM CATISEIC 0/0 ss. vie s/ajaiele lates « alam: bromide) |.) 2.0.6 a. — EATMOWMALE oie /e!evaila/e) slave) ols — Chlonidey Gey Wasi natels ele — OEE HE NOe sa Si nstetaua id ietovats Magnesium, chloride ........... — St MACE) ic eel acicleveteiee Manganese, peroxide .......-.0. — Sal phate ij \sreie sonics Rts TIERV AVIV daiel io g)ss'e! ssa iis ieidie sia.slers _ BiGMlonidel) oe siecle atete — MOGI N tee teie) siers ic letel slatenans, — potass. iodide (soluble) IN MeEta Teele a) gn oie ore aint Srey ovale adicye’e Paliadious) chloride...4'.... 32s — potassium chloride .. Pant aAmidopnenol ss... 6s osc Phenol (see Acid, carbolic) Platinum per (or bi)chloride ... Potassium, ammonium chromate . bicarbonate bichromate boro-tartrate bromide carbonate (dry) .... chlorate chloride chloro-platinite chromate citrate cyanide ferricyanide ferrocyanide hydrate eooeeeee ea@oeoeosveese lee else el=ial4 371 Mol. Symbol Weight (NHs)s Fe (Ca Ox): 3H:20 . ae K; Fe (C2 Ox): SEO siiiats Nao Fe (SOos 11H20 . "O76 Fee ee Relay eial ake sareliats islietake (sis 127 Fe! Gls 4aO) cic es oa) e)n/eto\ sini 199 Fe C; 0, 2H:0 ........--.' 180 K. Fe (C2 vat 2H2O0 oehewceae 328 Fe SOs FN ES GSE RE ae 278 Fe (NHa,):2 ASOD: 6H20 . aue Pb eee His ©2) 2) SEO oop. 379 Pb CN Gs) ae oiea sya einieieieie hele 331 Dit) Cai alaa/aue ta) eleheye lata) 24 DTA 25 GU ie aya ne r AR 87 Liz EY © EME UV EARN AU SAIN fet at 74 Ave (Case has 2H2O) . 42.5 PEL Tiel e Ai cta tvalais ete lalaateyattae . 134 IY ak ©) DA RO Ea es 95 Me SOM 7H yee ea 246 Miri Oa) oe ales aia staple 87 Mn SOs cel a Ws Oi UE HHS AU 225 EU eee ner aie! de tavel eretetsters 200 FS Cae er aictaharetalerebe altel 271 1 CU RST AE an Sl ie 454 PR ZR te cnaladensyaraita 786 (CceH:OHNHCHsp):2H2SO. 344 PNG ey arsaalanelia 177 Kea Pele eave ietivetalelaatatelela 326 Ga ENTE OED) tiene ayete whalers 109 He) Pe Cl yOHeO) erase 516.4 Ko NE Ce Oe sane 173 is es a Rina Red Reed te 100 ORS te Nee nag 294 C i (OH), (CO2)2 BOK . 214 BE eae came saleinebenagals 119 Bee CO ae yea siaiuiatate anaes 138 CIO aio eerie atalah ai alent 122.5 LON) MA IA eM ASTRA 74.5 LENS a 8 PU ARN A Pea 413.4 1 EET Oe ail @ TRIACS PLA UES 194 Le ON o EG Fale 6 NAR eG es 342 Fe CN eis aici ayalsvalea 65 K; Fe (CN )e er ea 329 Kg e CENDe 11 Oy © aN) BE tee * Metol is the sulphate of mono-methyl-para-amido-phenol. 372 PHOTOGRAPHIC FACTS AND FORMULAS Mol. Name Symbol Weight Potassium JOGide 5% ,)./6 0/5 Sew eines KOT. A 166 — metabisulphite ...... Ka 'S3 Ose Se ee 222, — AEG ALE ot) ects aioe tie'ats K. NOs 55 onde ee 101 — RIMEEAP Seine See stele glare K'NQs ...0002 5 85 — eee eh) aa an Ks Cy Oc HO)... eee 184 — percarbonate ........ Ky Cy: O63. eee 198 — perchlorate '.\.30%. 2 5) KO CL On.ki0).0. 0. Dee 138.5 — permanganate ....... Ks Mn. Os: 0. 2 a ee 316 — perstlphate sce yen. Kee: Se Og inins cee ae 270 — SIP MALE Cece meee KeSOe eos eae 174 SMPMOCVAMIGe |e... casas w a eee K CON Shichi ee 97 Pe VROCATEC HI”... a1 shares ache eicre ns Co Hy (OH) 2 45. See 110 BROCHENIS SALE icine Siaial wales wines K Na C. Hi Os 45-0 eee 282 Schlippe’s salt (sodium sulphanti- moniate ) iks| si(asvexeyle)e\ia/leila tarjeye\niinllela’ «jie Nas Sb S, 9H: *. one 479 Seer HECEALE ic Ce Mis eked ces Ag C, Ha On). tee eee 167 — ammonium nitrate ...... Ag NO:t+2Ng).) 2.550 204 EATEN TAS GG) 61.605 | SAPO a Ag Br soo ocdiee ee see ee 188 ER es 3612) aE Ma Sen Ags COs ssc oc' deck 276 Sees eT AE eS ceed e Giheea'g toh 8 ie Ag Gl) acc2) 2 143.5 NINE 5 «2 oh Ne eG Ages Ce Hs, O73. 4. 513 See AMAT LLE Niele te Maralle aia. al biaieveiacs Ag F 4H,0 *: 2... :200 eee 199 ETM |6< Sc (UNA UAUT ROE UR GU aD ee Teh bob leet er 235 SN NIRS TREN To islet ici Lien! wie Gian As NOs Joyo 170 Sool AMIEEILE Sc ail ico cas Sislcls wae ok Ag’ NOs iho 6.0. (ee eee 154 == Wxalabe tesa cies paieee Ags Ca Ou o.oo ee eee 304 eay YORAM! Valo Walon Bite rate Se eB Ags Ooi ei 224 rat MOOS PALE |. Ue) ucle be gd ees a's Ags POs). 00505. Ssh 419 ==) te SpHAte, C2 UNE U ef Ags SQe i225 weet eee 312 eh SUM DMIGE:, 46 Sc uinls'y aieiaie bee Aga 8 vis ode ish oe 248 ity Geb EBACE Y tins uh Cala eee eee Ags Cy Hy O6..5..3 ee 363.4 SGU ECOEAEE V8 io diet kis alee ee NaC. H: QO. 3H:0). 332eee 136 — ao NSE) eee eid Na) C2. Hs ‘O22... ae iee eee 182 —— (| bicarbonate ........60 6s Na! H COs i455 84 SW ICH OMIALE: M5) Sesaip aria Gis Na:z.Cr2'Q, 220: . kee 298 Ce DASTERPHNIEE ical Selene Mielaie Na! H SOs)... See eee 104 Ey vt BORAGE) Sicuckeroitnalah ae whe Ais Nas Bs O; 10H2O) . 2.0088 382 ol) PORAIAE) hah hor ete lie LUN Na. Br 2830 2 eae 139 — carbonate (dry)* ...... Naz COs ise oie oe oe 106 — carbonate (cryst.) ..... Naz CO;'.10H.0 se.) 286 oo WIM Onde iN. tay Na. Cl soil ce oe 58.5 — chloro-platinite ........ Na: Pt: Cle 6GHsO 'o,..5 oe 560.4 Peet TRE WCU) oN RU he Oe Nas Cy Hs O; 514H:0 (ieee 357 Sl OTIS re se Ge oa ea INO sc. oe art 42 * In formule 10 parts anhydrous (= dry) soda carbonate can be used in iti ws 27 parts cryst. soda carbonate. 10 parts of cryst. equal 3% parts of the dry. CHEMIGAL TABLES 373 Mol. Name Symbol Weight Stwdian: hyG@tate (Caustic) ai...) Day OL ie tele erajalois/ain ov s/e\a/ ole.» 40 — hydrosulphitef ......... Na Eis Oupe ities 42s eeisist 88 — hyposulphitef .......... Nagi 2) Oa Sa eens eit abels 248 aE AOGIC EN ig Stine vincaes whale obese Nai rine tinea aa etsdehurs oS lere 150 SAM TINGLE EN ie set sheryl sin aisha sole Nae NiOsaueceinutiaualy anaits 85 — nitro-prusside .......... Na, Fe, CCN (NO), 4H:.0 600 <= Oxalate sen a ee Naz C; O, Nosonoonodcoddes 134 == PMOSPMALE) ee. We cin 6 Naz EUR @.AZTIC@ vay cia iiaiel. 358 — tribasic phosphate ...... Nas POZE Oy Belm yi 380 — sulphate (cryst. Hers Naa SOe OEE Ot md ntsc 322 SMM S TI TATCEG)/, «sinus aes alata abel ees Nasi Si Die @y nck cee stars 240 —— sulphite (dry)§ :.....:. Naa Sa Ae eee ee ra a eR cua 126 — See A CCLY Ss penalise ee Naz SOs 7HE@ ase e aes 252 CIM StAater ay meats lee Nain) War '@a 28H) iy sn 3598 Stromtium, bromide’. .....5.2. « Se Brainerd Oy tan nen vane ae ociall 247.5 — chloride) (dry) 24655 SSN Oe regu ete tears 158.5 — Ser WNC ELY SE. oe ke |) oie lac bda Oras es csmreeratets 194.5 — TOCHIGI Ss ia Waele peor Rr URI NU Lone Nn 341.5 — TMILcrALeL NE aus yew eth alk Sr CNOR aie eee eae ee 211.5 MiMoOGAEHAMIGe (255.5 ccc ak lad ss CS CN are ieee uae 76 BIN NOOSIMI AINA) esis osc Sele eas see ek 8 @Sv (NE?) NUE Corie wae: 116 Thymol 90060000 OOO dG OlUIb OGG 0510/5 CHa Cs Hs ORG Ga oye 150 Wm (Stannous) chloride :.:..:. Sn; C oa sO hea aera: 225 Wicanitm acetate osc. os vee ss UO:z (C2 Hs O2)2 2H20 .... 426 — Chloride j.'s cps samivaornts Wi ORCI oS at erste ele a ene tia 343 SP AMIGGATE es 5.45 sisi leases WOs NOD a OEOE ena 504 AEE MALE. 6 hee uivsce tease ee ZY SOL /EGO) eae han ee 287 mAb OF ATOMIC WEIGHTS OF THE CHEMICAL ELEMENTS Atomic Weight Accurate in Round Atomic Name Symbol Numbers Weight A AIASTAATITUAERT 55, 3 e655) dialer sces Se 8 Al Bi. 27 EMINIMIO TV vay Hsin Sia ears Sieicie's Sb 120 120.2 PN TSVSIC A Re es NR tA ee RC en A 40 39.9 PSNI tere SiS, Pela acs bk As 7s) 75.0 MATA renee Rs a cals Ba SZ 137.43 Betyllatnahonicua ak sts atsles Be = Gl 9.1 9.1 J ESISTAAUOILS gis aC Sle MR age Bi 208 208.0 ) BAG E OS 0 hoainP Meee alee cst ae A B 11 11.00 OMIM a PE on ofc eicie a Br 80 79.96 {7 Called ‘‘hyposulphite’’ by chemists. £ Called ‘‘thiosulphate’’ by chemists. § In formule, 1-part of anhydrous (= dry) soda sulphite can be used in place of 2 parts cryst. soda sulphite and vice versa. 374. PHOTOGRAPHIC FACTS AND. FORMULAS Atomic Weight Accurate in Round Atomic Name Symbol Numbers Weight REET 16 PUR ELAN eR pa Cd 112 112.4 Cem APTERR Ae ure cate Guana inten te Cs 133 132.9 Meera Cia deine aie atu a Ca 40 40.1 BET gue cs UNMANNED A C 12 12.0 StI OL ioe te laes we Ce 140 140.25 CACHE TNGN ND ahs aig wh eee Gly Cl 55.9 35.451 Cesena Tata Pei oe Solas! ainsi te Cr 52 52:48 AAAS EAN AD Nols EU Co 59 59.00 TOE MeN alsa g el ele alms Cu 63.5 63.60 ot is Oe Re RSI ER ERE Er 166 166.0 PANOLIIE Oe ie Oa tlats e F 19 19.0 (Gadolinitiin’) | ici iecias Lee des Gd 156 156.01 ACIS MOBI BST SRE DIE Ga 70 70.0 CeCe TATIITED oe fas cies wei esle s Ge 724 72.5 BLS RUM ITE BO Au 197 197.2 eS OEMS MOP NY A AUT He 4 4.0 PAO PEN. re ss ahaa (eas iaie H 1 1.008 Teac GRIN sei Sere iene ene alee & In 115 115.0 GAS OU ee Wi puntata Ace ig I 127 126.97 LCS e ec A ee Rg Ir 193 193.0 Toc UT AT SOUS BDL ON RUNES git Fe 56 55.9 Dart hiruenyian (Oates ue us La 139 138.9 eT URI RU Ee Dteeai cain a Pb 207 206.92 LS TET ec ALES RAN AAR Li 7 7.03 Masriesiitent yo oie ibe s sie clas cole Mg 24 24.36 DA MEATIESE lial Ow aM ase Mn 55 55.0 DCCC VO eles eig tetany) Hg 200 200.0 Motybdertam io). oe ec sieaes Mo 96 96.0 INGOG YIN elutes oo Nd 144 143.6 Lop Pel< ©) UPON Ge APU ARRAS ERS Ni 59 58.70 Lig Ya/oh 105 5s WONG UV SEAS Nb = Cb 94 94.0 CEE OCE SD CM Cie a Ain N 14 14.04 CPST COU oe MC Ruh igs Os 191 191.0 Oxygen (Standard) ....... O 16 16.0 TTT MC AM ig Pd 106 106.5 POS EIGT AIBN Hae aie koi alae 's P 31 31.0 Pst aie eis sada neat Pt 193.4 194.8 PORASSMTME INE Ni) Solin K 39 39.15 Prascodyminn oo Aika Pr 141 140.5 CHEMICAL TABLES 3/7) Atomic Weight Accurate in Round Atomic Name Symbol Numbers Weight LACT ST pe ERIN DLP A Ra PMOMTUITIN Se chs ale aiaekel cs Wa aud Rh 103 103.0 JES UL OSGLNG Fag Ay aU AN Rb 85 85.5 REPEIMETISUIETT a) s)ohs00. ee evel'e alc lb ole Ru 102 101.7 SATII ieee eee Sm 150 150.3 SSC UNI CILRTA SN area ee ones lel Grand Sc 44 44.1 SSI ERITEIENI a Aiehslsie a ohutey sles aleve Se 79 79.2 Sl) TETSN VRE ei A a Si 28 28.4 SUN Sree NE a UAL Ag. 108 107.93 SOUGHT OT LEV NR aN CAO Na 25 23.05 ShESTCTERAT EE 00 IN A aL TRA A Sr 87.5 87.6 SSC OLALE De DIRS SO La I a S 32 32.06 TPS VAITEI UD Fea (CRAIC NU mee LD Ta 183 183.0 Me MATTE iPicic sb kiehs deca eb Te 128 127.6 AP Cesel ou Eh ga AeA Og EE Te A Tb 160 160.0 Siberia ya os aicse ue Ti 204 204.1 MULT TeARITTAT ese i) a0 ols raha anh 233 232.5 Spee OETA 8 cele o oie aka be ele Tu 171 171.0 TSR hh NO ARI aR a aC Sn 118 119.0 MBG se Ses es hb date Ti 48 48.1 PENI OS EET fos 3). w vic oO dee ale W 184 184.0 MO ectNdENETI 5 2s) 'ssoic's ol oe cateie a U 240 238.5 RAINY) ah ae vin delalaeclein'S g V 51 51.4 WHECEDIUIGNN ) \e:c'c ee cee ae ceca Yb 173 173.0 BYPECT ACEI aie We a ion Yt 89 89.0 LEA CANON MN aS Zn 65 65.4 Appendix EastMAN Priates.—After June 30, 1924, the distribution of Seed, Standard and Stanley Plates will be discontinued by the Eastman Kodak Company. The new Eastman Plates listed in the left hand column can be used for the same purposes as those formerly supplied, which plates are listed opposite in the centre column. The approximate relative © speeds are given at the right. Eastman 40 Seed 30 Eastman 36 Seed 26X Eastman Speedway _— Seed Graflex Eastman Process Seed Process Eastman 33 Seed 23 Standard Extra Imperial Stanley Regular Eastman Polychrome Standard Polychrome Eastman Commercial Stanley Commercial Seed Non-Halation L Ortho oe Standard Orthonon Eastman S C Ortho Seed L Ortho Eastman Post Card Standard Post Card Eastman Lantern Standard Lantern Slide Eastman Universal Slide (Regular, Slow) (Regular, Slow) Seed Lantern Slide Eastman X-Ray Seed X-Ray W. W. Panchromatic Seed Panchromatic 376 100% 80% 150% 5% 26% 80% 90% 30% 80% 80% 32% 3% 27% Index Acid Bath for Platinotype, 278. Acid Fixing Bath, 124. Acrol, 91. Activol, 109. Additive Filters, 344. Adurol, 91. ; Agfa Colour Plate, 349. Albumen Sensitiser, 351. Alcohol, 21. Alcohol, Denatured, 21. Alcohol, Methyl, 21. Alkaline Amidol, 93. Alkaline Fixing Bath, 123. Alkaline Toning Bath, 176. Altitude Exposures, 72. Alum Bath, 252. Alum-Gold-Hypo Toning, 235. Alum-Hypo Toning, 234. Alum-Sugar-Hypo Toning, 234. Aluminium, Blackening, 6. Aluminium Flashlights, 342. Alums as Hardeners, 129. Amidol, 91. Amidol, Alkaline, 93. Amidol-Pyro, 93. American Photography Expo- sure Tables, 51. American Photography Plate Speeds, 55. Ammonia Fixing Bath, 125. Ammonium Persulphate ducer, 146. ie Sulphide Toning, 36. Rimes of Flashlight Powder, 42. Angle of View Tables, 45. Aniline Process, 318. Aniline Black Process, 320. Anthracotype Process, 317. Aquarelle Printing, 306. Arabin Gum-Bichromate, 256. Asphalt Backing, 32. Re- Atomic Weights, 373. Autochrome Plates, 345. Autochrome Developers, 345. Autochrome Intensification, 348. Autochrome Reverser, 347. er Ceca Second Developer, 347. Autochrome, Varnishing, 348. Azol, 109. Backgrounds, 1. Backing, Asphalt, 32. Backing, Black, 33. Backing, Caramel, 31. Backing, Chrevetot’s, 33. Backing, Collodion, 32. Backing, Cornu’s, 32. Backing, Oxgall, 34. Backing Plates, 31. Backing Sheets, 34. Backing, Soap, 34. Bartolozzi Tones, 182. Beach’s Developer, 113. Beck Meter, 75. Belitzski’s Reducer, 141. Bichromate Reducer, 142. Binding Lantern Slides, 330. Bitumen Process, 353. Black Backing, 33. Black for Cameras, 6. Black Varnish, 154. Blackening Aluminium, 6. Blackening Brass, 4. Blackening Wood, 4. Bleach, Bromoil, 303. Blocking-out Medium, 157. Blue-green & Green Sensitisers, Blue Prints, Toning, 260. Blue Process, 258. Bottles, Ink for, 6. Brass, Blackening, 4. Brasses, Memorial, 3. 377 378 PHOTOGRAPHIC FACTS AND FORMULAS Bromide Paper, 199. wale y Paper Development, 99. Bromide Paper Developers, 200- 202. Bromide Paper Exposure, 199. Bromide Paper Factorial De- velopment, 202. Bromide Paper Speeds, 67. Bromide Print for Bromoil, 311. Bromide v. Platinotype, 294. Bromoil Bleach, 303. Bromoil Bromide Print, 311. Bromoil Presses, 310. Bromoil Process, 302. Bromoil, Rubbing, 307. Bromoil Transfers, 306, 312. Burroughs - Wellcome Plate Speeds, 55. Cameras, Blackening, 6. Caramel Backing, 32. Carbon Tissue, Making, 250. Carbon Process, 249. Carbro Process, 299. Carmine Toning, 244. Casein Paper, 195, 337. Celluloid Varnish, 155. Cements, 8. Ceric Sulphate Reducer, 143. Certinal, 109. Chemical Tables, 368. Chlorate - Magnesium Flash- lights, 340. Chrevetot’s Backing, 33. Chrome Alum Fixing Bath, 124. Chromium Intensifier, 134. Citol, 109. Cleaning Glass, 8. ue Photogravure Plate, Cleaning Zinc & Copper, 351. Clearing Baths, 128. Coating Carbon Tissue, 250. Cobalt Toning, 228. Cobalt-Iron Process, 268. Coefficient, Temperature, 78. Coins, Photographing, 3. Cold Bath Platinotype, 281. Cold Bath Sepia Platinotype, 279 Cold Bath Process, 277. Cold Varnishes, 150, 154. Collodio - Chloride Emulsion, 160 Collodio-Chloride Prints, Flat- tening, 169. Collodion Backing, 32. Collodion Transfer, 252. Colloidal Sulphur Toning, 235. Collotype, 354. Colour Photography, 344. Pic ete Methanol or Spirit, i _ Combined Developing & Fix- ing, 85. wish Toning & Fixing, 178. Combining Lenses, 43. . Comparison of Plate Speeds, 69. Conjugate Foci, 49. Continental Plate Speeds, 61. Contrast Developer, Cramer, 101. Conversion of Weights & Meas- ures, 360. Copper Bromo-Iodide Intensi- fier, 139 Copper Ferrocyanide Intensi- fier, 137. Copper Half-Tone Enamel, 353. Copper, Scum Remover, 354. Copper-Silver Intensifier, 135. Copper-Tin Intensifier, 136. Copper Toning, 216. Cornu’s Backing, 32. Correction for Spectacle Lenses, Crystal Varnish, 156. Crayon Fixative, 157. Cupric Chloride Reducer, 144. Cyanotype Process, 258. Cyanotype Transparencies, 261. Damp-proof Glue, 9. Debenham’s Reducer, 141. Denatured Alcohol, 21. Depth of Focus, 42. INDEX Depth of Focus Scale, 41. Desensitising Plates, 28. Devarnishing Negatives, 154. A ta Sepia Platinotype, 85. Developer, Acrol, 91. Developer, Activol, 109. Developer, Alkaline Amidol, 93. Developer, Amidol, 91. Developer, Amidol-Pyro, 93. Developer, Azol, 109. Developer, Beach’s, 113. Developer, Certinal, 109. Developer, Citol, 109. Developer, Contrast, 101. Developer, Diogen, 94. Developer, Eastman Film, 100, 103, 119. Developer, Edinol, 94. Developer, Eikonogen, 95. Developer, Elon, 95, 101. -Developer, Ferrous Oxalate, 95. Developer, Glycin, 98. Developer, Hydrochinon, 99. Developer, Kachin, 109. Developer, Kalogen, 109. Developer, Kodelon, 101. Developer, Lantern Plate, 331. mee Metol-Hydrochinon, Developer, M. P., 100. Developer, Motol, 101. Developer, Neol, 107. Developer, Ortol, 107. Developer, Paramidophenol, 108. Developer, Paramol, 109. Developer, Paranol, 109. ane ia Paraphenylendiamin, 9. Developer, Pyrocatechin, 109. Developer, Pyro, “B. J.,” 112. Developer, Pyrogallol, 111. Developer, Pyro-Caustic, 112. Developer, Pyro-Acetone, 113. Developer, Pyro-Metol, 119. Developer, Rodinal, 108. Developer, Standard H. & D., 112. Developer, Tank, 113. of Developer, Tozol, 122. Developers, 91. Developers, Tank, 91. mien at Autochromes, 345, 347. Developing & Fixing Combined, 85 Developing Line Prints, 264. Developing P. O. P., 183. Developing-out Papers, 204. Development, 76. Development Factors, 76. Development, Factorial, 76. Development Papers, 204. Development Papers, Artura, 206. Development Papers, Athena Old Master, 206. Development Papers, Azo, 211. Development Papers, Cyko, 209. Development Papers, Develop- ers, 204. Development Papers, Develop- ers, Non-Abrasion, 205. Development Papers, Defender, 2125 213: Development Papers, Enlarging Cyko, 210. Development Papers, Etching Brown, 206 Development Papers, Gevaert, 213: Development Papers, Gevaert Nova-Gas, 214. Development Papers, Haloid, 208. Development Papers, Kodelon Developer, 207. Development Papers, Mimosa Verotype, 210 Development Papers, Noko, 210. Development Papers, Pyro De- veloper, 205. Development Papers, Roylon Developer, 207. Development Papers, Short Stop Bath, 215. Development Papers, Tozol Bath, 207. 380 PHOTOGRAPHIC FACTS AND FORMULAS Development Papers, Velox, 208. Development Papers, Velvet Green, 210 Development Papers, Vitava, 205. Development Papers, Vittex, 213 Development, Stand, 80. . ee eee Toning, 45. Development, Thermo, 77. Dextrine Mountant, 325. Dextrine-Gum Mountant, 325. Diagonals of Plates, 46. Diagram Lantern Slides, 330. Diamond Cement, 9. Diaphragm Apertures, 44. Diaphragm Systems, 74. Diazotype Process, 320. Dichroic or Green Fog, 129. Diogen, 94. Direct Negatives, 15. Direct Prints on Zinc, 358. Direct Sulphide Toning, 234. Distribution of Spectrum Col- ours, 23 Dry Mounting, 327. Duodecimal & Metric Systems, 364. Duration of Flash, 343. Dusting-On, Pepper, 316. Dye Intensification, 140. Dyeing Fish-Glue Prints, 353. Eastman Film Developers, 100, 103) 119. Eastman Plates, 376. Eder’s Reducer, 144. Edinol, 94. Effect of Stop Aperture, 71. Eikonogen, 95. Elconal, 109. Eliminators, Hypo, 126. Elon, 95. oa C. C. Printing-out, Emulsion, Printing-out, 173. Enamel for Zinc, 352. Endemann’s Process, 320. Enlarging, Exposures-in, 335. Enlarging Exposures Variation, Enlarging & Reducing Table, 334 Etching Bath, Zinc, 353. Etching, Machine, 354. Pe Photogravure Plate, 357; . Exposure, 51, 60. oe Effect of Altitude, 2 Exposure in Enlarging, 335. Exposure Meters, 75 Exposure Meter Paper, 75. Exposures for Interiors, 73. Exposures, Pinholes, 48. Exposures in Reducing, 335. Exposure ‘Tables, American Photography, 51. F Values, Variation of, 71. Fabrics, Fireproofing, 5 Fabrics, Sensitising, 195. Factorial Development, 76. Factorial Development of Bro- mide Papers, 202. Factors, Development, 76. Farmer’s Reducer, 145. Feertype Process, 320. Ferric Oxalate Making, 274. Ferric Reducers, 145. Ferrogallic Process, 263. Ferroprussiate Process, 258. Ferrous Oxalate, 95. Film Developers, 100. Films, Stripping, 157. Filters, Additive, 344. Filters, Orthochromatic, 29. Filters, Three-Colour, 344. Final Support, 253. Fireproofing Fabrics, 5. Fish-Glue Prints, Dyeing, 353. Fish-Glue Sensitiser, 351. Fixative for Prints, 157. Mixing, 123: Fixing, Plain Bath, 123. Fixing, Alkaline Bath, 123. INDEX Fixing, Acid Bath, 124. Fixing, Acid-Alum Bath, 124. Fixing, Acid-Chrome Alum Bath, 124. oaeee Rapid Ammonia Bath, 12 Fixing P. O. P., 179. Fixing and Clearing, 123. Flash Candles, 340. Flashlights, 339. Flashlights, Aluminium, 342. Flashlight Candles, 340. Flashlight, Chlorate, 340. Flashlight, Duration of, 343. Flashlight, Magnesium-Nitrate, 339. Flashlights, Orthochromatic, 341. Flashlights, Perchlorate, 340. Flashlight Sheets, 340. Flashlight, Slow-Burning, 341. Flashlights, Using, 339. Flashlights, Weight Needed, 342. Flash Sheets, 340. Flattening C. C. Prints, 169. Focal Length of Lens, 35. Foci, Conjugate, 49. Focus & Optics, 35. Focus, Depth of, 42. Focus Scale, Depth of, 41. Focusing Rules, 43. Fog, Dichroic, Red or Green, 129 Fourtier’s Reducer, 144. Fraunhofer Lines, lengths, 22. Wave- Gaslight Papers, 204. Gelatine Mountant, 326. Gelatine Mountant, Liquid, 326. Gelatine P. O. P., 173. Glass, Cleaning, 8. Glass, Matting, 7. Glass, Photographing Objects Under, 4. Glass Safelights, 17. Glass, Silvering, 9. Glassware, Photographing, 3. 381 Glue, 9. Glycin, 98. Gold & Platinum Toning, 228. Gold & Uranium Toning P. O. PAV TeZ) Gold Residues, 126. Graining Copper, 351. Ce Photogravure Plate, 356. Greasy Ink Process, 265. Green Safelights, 19. Green Tones, 227. Green & Yellow Sensitisers, 24. Green & Yellow-Orange Sensi- tisers, 25. Ground Glass Substitutes, 7. Gum-Bichromate Pigments, 255. Gum-Bichromate Process, 255. Gum-Iron Process, 261. H. & D. Standard Developer, 2 Half-Tone Enamel, 353. Hard Enamel for Zinc, 352. Hardening Agents, Alum, 129. Hardening Baths, 127. makes Harsh Negatives, 147, Harsh Negatives, Harmonising, 1 Harvey Plate Speeds, 55. Hot Bath Platinotype, 280. Hot Varnishes, 150. Hydrochinon, 99. Hypersensitising Plates, 26. Hypo Eliminators, 126. mee Ferricyanide Reducer, Hypochlorite Reducer, 141. Indirect Sulphide Toning, 238. Ink for Bottles, 6 Ink Process, 263. Inking-Up Line Work, 352. Intensification, 130. Intensifier, Agfa, 133. Intensifier, Chromium, 134. Intensifier, Copper Bromo- iodide, 139. 382 PHOTOGRAPHIC FACTS AND FORMULAS Intensifier, Copper Ferrocyan- ide, 137 Intensifier, Copper-Silver, 135. Intensifier, Copper-Tin, 136 Intensifier, Dye, 140. Intensifier, Eder’s, 132. Intensifier, Formalin, 132. - Intensifier, Lead, 138. Intensifier, Mercuric Iodide, 133. Intensifier, Mercuric Sulpho- cyanide, 133. Intensifier, Mercury, 130. Intensifier, Monckhoven’s, 131. Intensifier, Quinone, 138. Intensifier, Schlippe’s Salt, 132. Intensifier, Silver-Cyanide, 131. Intensifier, Stannous Tartrate, 132. Intensifier, Uranium, 137. Intensifying Autochromes, 348. Intensifying Carbon Transpar- encies, 253. Intensifying Platinotypes, 287. Interior Exposures, 73. Iodide-Hypo Reducer, 143. Iodo-Cyanide Reducer, 143. Iron or Cyanotype Toning, 220. Iron Processes, 258. Itterheim’s Process, 316. Ivory Final Support, 253. Kachin, 109. Kallitype Process, 270. Kalogen, 109. Kodelon, 101. Lainer’s Reducer, 143. Lantern Plate Speeds, 68. Lantern Screen, Flexible, 6. Lantern Slides, 330. Lantern Slides, Binding, 330. Lantern Slide Developers, 331. Lantern Slide Diagrams, 330. Lantern Slide Sizes, 330. Lantern Slide Spotting, 330. Latitude Light Tables, 52. Lead Intensifier, 138. Lead-Iron Toning, 225. Lead Toning, 225. Leather, Sensitising, 195. Lens Focus, 35. i Sit ca Stereoscopic, Lenses, Care of, 50 Lenses, Combining, 43. Light Tables for Latitudes, 52. Line Drawings from Prints, 14. Line Prints, Developing, 352. Line Prints, Inking-Up, 352. Line Sensitiser, 351. Liquid Glue, 9. Liquid Safelights, 16. Liver of Sulphur Toning, 236. Local Development, Platino- type, 286. Lumiére’s Reducer, 143, 147. Machine Etching, 354. Machinery, Photographing, 3. Magnesium - Chlorate Flash- lights, 340. Magnesium-Nitrate 339. Magnesium, Underground, 342. Making Carbon Tissue, 249. Making Ferric Oxalate, 274. Marine Glue, 9. Matt Lac Plain Papers, 190. Matt Varnishes, 150. Matting Glass, 7. Mechanical Reduction, 148. Medium, Blocking-out, 157. Medium, Retouching, 156, 157. Memorial Stones & Brasses, 3 Mixtures, Mercury Intensifiers, 130. Mercury-Cyanide Reducer, 144. Mercury Sulphide Toning, 242. Mercuric Iodide Intensifier, 133. Mercuric Sulphocyanide Inten- sifier, 133. Mercuro-Uranotype, 293. Meter, Beck, 75. Meter, Imperial, 75. Meter, Watkins, 75. Meter Wynne, 75. Meters, Exposure, 75. INDEX Metol, 101. Metol Poisoning, 102. Metol-Hydro Developer, 103. Methanol, Eagle, 21. Methyl Alcohol, 21. Metric & Duodecimal Equiva- lents, 364. — - Mimosa Aurotype P. O. P., 187. Molybdenum Toning, 231. . Monckhoven’s Intensifier, 131. M. P. Developers, 100. Motol, 101. Mountants, 325. Mountants, Dextrine, 325. ee Dextrine & Gum, 325. Mountants, Gelatine, 326. Mountants, Liquid Gelatine, 326. Mountants, Starch-Gelatine,326. Mountants, Starch Paste, 327. Mounting, Dry, 327. Mounting, Photogravure Re- sist, 356. Mounting Stereo Prints, 328. Moving Objects, Shutter Speeds, 72. Namias’ Reducer, 142. Negatives, Devarnishing, 154. Negatives, Direct, 15. Negrographic Process, 316. Neol, 107. Night Photography, 73. eee Flashlights, Non-actinic Paper, 20. Non-Achromatic Lens Correc- tion, 47. Objects Under Glass, Photo- graphing, 4. Oxgall Backing, 34. Oilograph Process, 306. Oil Printing, 305. Oil & Bromoil Process, 302. Opal Glass Final Support, 253. Orthochromatic Filters, 29. Ae amare Flashlights, 383 Pent Photography, Orthochromatising Plates, 24. Ortol, 107. Ozobrome Process, 297. Ozotype Process, 295. Paget Colour Plate, 348. Palladiotype, 282, 293. Palladium Toning, 182. Panchromatic & Red Sensitis- ers, 25. Panchromatising Plates, 27. Paper for Exposure Meters, 75. Paper, Non-actinic, 20. Papers, Developing-out, 204. Paramidophenol, 108. Paramol, 109. Paranol, 109. Paraphenylendiamine, 109. Pellet’s Process, 261. Pepper Dusting-on Process, 316. Percentage Solutions, 362. Permanganate Reducer, 142. Phosphate of Silver Paper, 169. Photography at Night, 73. Photogravure, 356. A potgeraure Cleaning Plate, 356. Photogravure tions, 357 BO ery ate Graining Plate, Etching Solu- Photogravure, Setting Grain, Photogravure Mounting Resist, Photogravure Varnishing, 357. Photolithography, 357. Photomechanical Processes,351. yea for Gum-Bichromate, Pinhole Exposures, 48. Plain Fixing Bath, 123. Plain Papers, 189. Plain Papers Casein, 195. Plain Papers, Printing, 192. Plain Papers, Resin-sized, 193. Plain Papers, Sensitising, 191. 384 PHOTOGRAPHIC FACTS AND FORMULAS Plain Papers, Sepia-iron, 194. Plain Papers, Sizing, 189. Plain Papers, Toning, 192. Plate Backing, 31. Plates, Desensitising, 28. Plate Diagonals, 46. Plates, Hypersensitising, 26. Plates, Orthochromatising, 24. Plates, Panchromatising, 27. Plate speeds, 55. Plate Speeds, American Photo- graphy, 55. Plate Speeds, Burroughs-Well- come, Plate Speeds, Comparison, 69 Plate Speeds, Continental, 61. Plate Speeds, Harvey, 55. Plate Speeds, Watkins, 55. Plate Speeds, Wynne, 55. Platinotype, Cold Bath, 281. Platinotype, Developers, 278. Platinotype, Hot Bath, 280. Platinotype, Local Develop- ment, 286. Pee Print-Out Sepia, 90. Platinotype Process, 274. Platinotype v. Bromide, 294. Platinotypes, Intensifying, 287. Platinotypes, Restoring, 291. Platinotypes, Toning, 288. Platinotypes, Varnishing, 292. Platino-Uranotype, 293. Platinum Acid Bath, 278. Platinum Paper, Sizing, 274. Sauer Sma ue Process, a Platinum Print-Out Paper, 284. ee Process, Cold Bath, Platinum Residues, 126, 292. Platinum Toning, 229. Platinum Toning P. O. P., 180. Platinum & Gold Toning P. O. Portes: Playertype Process, 267. Poisoning, Metol, 102. Powder Process, 314. Presses for Bromoil, 310. Primuline Process, 320. Printer’s Ink Process, 265. Print Varnish, 154. Print-Out Platinum Paper, 284. tate ee Bromide Paper, Printing-Out Papers, 173. Printing-Out Papers, Develop- ing, 183 ee Papers, Disco, Printing-Out Papers, Eastman Solio, 186. Sapte Papers, Printing, Printing-Out Papers, Toning, 176. Prints, Line Drawings from, 14. Prints on Zinc, Direct, 358. . Process Pyro Developer, 111. Pyro; ti. Pyro-Acetone, 113. Pyro-Amidol, 93. Pyro-Caustic, 112. Pyro-Glycerine, 111. Pyro-Metol, 121. Pyro-Potash, 113. Pyro-Soda, 112. Pyro-Soda, “B: J," ite Pyro Tank Developers, 113. Pyrocatechin, 109, Pyrogallol, 111. Quick-Drying Sensitiser, 251. Quinone Intensifier, 138. Quinone Toning, 240. Ratio Aperture, 44. Red Chalk Tones, 182, 244. Red Tones, 178. Reducers, 141. Reducer, Ammonium Persul- phate, 146. Reducer, Belitzski’s, 141. Reducer, Bichromate, 142. Reducer, Ceric Sulphate, 143. Reducer, Cupric Chloride, 144. Reducer, Debenham’s, 141. Reducer, Eder’s, 144. INDEX Reducer, Farmer’s, 145. Reducer, Ferric Oxalate, 141. Reducer, Fourtier’s, 144. Reducer, Hypochlorite, 141. ae Hypo - Ferricyanide, 45. Reducer, Iodide-Hypo, 143. Reducer, Iodo-Cyanide, 143. Reducer, Mercury-Cyanide, 144. Reducer, Permanganate, 142. Reducer, Quinone, 147. Reducer, Spiller’s, 144. Reducing, Exposures in, 335. Reducing Sulphided Prints, 245. Reduction, Mechanical, 148. ‘Residues, 125. Residues, Gold, 126. Residues, Platinum, 126, 292. Restoring Platinotypes, 291. Retouching Varnish,’ 156. Reverse Process, 358. Reversing Autochromes, 347. Rodinal, 109. Rules for Focusing Hand Cam- eras, 43. Safelights, Glass, 17. Safelights, Green, 19. Safelights, Liquid, 16. Satista Paper, 282. Salted Paper, 189. Screen Plates, 345, 348, 349. Scum Remover, 354 Selenium Toning, 230. Peete Paper Aurotype, Self-Toning Gevaert, 188. Self-Toning Ronix, 188. Sensitiser, Albumen, 351. Sensitiser, Fish-Glue, 351. Sensitisers, Blue - Green & Green, 24. Sensitisers, Green & Yellow, 24. Sensitisers, Green, Yellow, Orange, 25. Sensitisers, Panchromatic & Red, 25. Sensitiser, Quick-Drying, 251. Sensitising Carbon Tissue, 251. 385 ahi ea Leather, Fabrics, 195. Sensitising Wood, 196. he Platinotype, Cold Bath, 279 Sepia Platinotype, Developed, 285. Sepia, Print-Out Platinotype, 290. Setting Photogravure Grain, 356 Sheets, Backing, 34. Short Stop Bath, 215. Shutter Speeds for Moving Ob- jects, 72. Shutter Speeds, Timing, 51. Silver Bromide P. O. P., 171. Silver Phosphate Paper, 169. Silver Printing Processes, 160. Silver-Potassio-Cyanide Inten- sifiers, 131. Silvering Glass, 9. Silverware, Photographing, 3. Single Transfer Paper, 251. Sizing Platinum Paper, 274. Slides, Lantern, 330. Slow-Burning Flashlights, 341. Sobacchi’s Process, 317. Solar Printing, 336. Soap Backing, 34. Solutions, Percentage, 362. Solution, Waxing, 252. Spectacle Lenses, 47. Spectrum Colours, Distribution of, 23: Speeds, Bromide Paper, 67. Speeds, Lantern Plate, 68. Speeds, Thermo Development, Spiller’s Reducer, 144. Spirit, Columbian, 21. Spotting Lantern Slides, 330. Stand Development, 80. Starch-Gelatine Mountant, 326. Starch Paste, 327. Stereoscopic Work, 328. Stop Aperture Effect, 71. Stop Aperture Systems, 74. Stripping Films, 157 Studio & Workroon, 1. 386 PHOTOGRAPHIC FACTS AND FORMULAS Sulphide - Developer Toning, 241 Sulphide-Ferricyanide Toning, 236 Sulphide-Schlippe’s Salt Ton- ing, 244. Sulphide Toning, 234. Sulphocyanide Toning Bath, T77: Sulphur Toning, 247. Support, Flexible Temporary, 251 Symbols, Molecular Weights, 368. Table, Enlarging & Reducing, 334 Tank Developers, 88. Telephoto Formulas, 47. Temperature Co-Efficient, 78. Temporary Support, 251. Thermo Development, 77. cee Development Speeds, Thermometer Scales, 366. Thiocarbamide-Sulphide Ton- ing, 238. Thiomolybdate Toning, 240. Thiostannate Toning, 240. Three-Colour Filters, 344. Timing Shutter Speeds, 51. Toning Blue Prints, 260. Toning Bromide & Gaslight Prints, 216. Toning by Redevelopment, 232. Toning Platinotypes, 288. Toning (PO. Pease: Toning Bath, Alkaline, 176. ee Bath, Sulphocyanide, Toning & Fixing Bath, Com- bined, 178. Tezol, 122: Transfer Paper, Single, 251. Transfers, Bromoil, 306. Transfer with Collodion, 252. Transparencies, Blue, 261. Transparencies, Carbon, 253. Transparencies, Cyanotype, 261. True-to-Scale Process, 265. Undersrnend Magnesium Work, 342. Uranium & Iron Toning, 227. Uranium Toning, 219. Uranium Toning P. O. PB.) 962: Uranium Intensifier, 137. Using Flashlights, 339. Vanadium Toning, 222. Vandyke Process, 358. Variation of F Values, 71. Variation of Enlarging Expo- sures, 72. Varnishes, 150. Varnish, Black, 154. Varnish, Celluloid, 155. Varnish, Crystal, 156. Varnish, Cold, 150, 154. Varnish, Hot, 150. Varnish, Matt, 153. Varnish, Print, 154. Varnish, Retouching, 156. Varnish, Zapon, 155. Varnishing Autochromes, 348. ee Photogravure Plate, 357. Varnishing Platinotypes, 292. View Angles, 45. Watkins Plate Speeds, 55. Watkins-Powers Numbers, 49. Wave - Lengths Fraunhofer Lines, 22. Waxing Solution, 252. Weights & Measures, 1, 360. Weights & Measures Conver- sion, 360. bie ey & Measures Tables, 361. Willis’s Process, 318. W. P. Numbers, 49. Wood, Blackening, 4, Wood Final Support, 253. Wood Sensitising, 196. hadcirs Panchro Developers, 8. Wynne Plate Speeds, 55. Zapon Varnish, 155. Zinc & Copper, Cleaning, 351. Zinc, Etching Baths, 353. Ansco Photoproducts, nc. BINGHAMTON, N. Y. Manufacturers of: Ansco Speedex Film—for all roll-film cameras. The film in the red box with the yellow band. Extra speed, extra latitude, more good negatives under a wider range of light conditions. Ansco Cameras—priced from $1 to $75, with many models making a strong appeal to the expert and discriminating photographer. Catalog at your dealer’s or by mail. Noko Paper—for amateur finishing and commer- cial work. Built to meet the requirements of photo- finishing plants. A quality product at attractive prices. Commercial Cyko—a fast contact paper for com- mercial photographers and amateurs. Enlarging Cyko—the finest projection paper made. For enlargements of true professional quality, with full scale of tones from rich luminous blacks to pearly highlights. Very easy to work. Professional Cyko—The standard of uniformity and quality for the best grade of studio work. Ansco Portrait Film—a cut film of high speed and quality to meet the most exacting studio requirements. Film and camera dealers everywhere. Paper stock houses at convenient points. Price lists and complete information on request. ANSCO PHOTOPRODUCTS, INC. Binghamton, N. Y. Off Quality for } ert speed and clearness, Means Good Roll Films orthocromatic, anti-halo, non- Film Packs curling Plates a plate for every purpose Color Plates for pictures in natural colors Process and Intaglio for Reproduction and Engraving Plates and Films Plants Portrait Films an ideal Agfa-emulsion for por- traiture on a heavy celluloid base Developers Rodinal, Metol, Glycin, Amidol, etc. Blitzlicht (Flashlight) producing the most intense light, but hardly any smoke, noise- less combustion Agfa Flashlight Lamps Amateur and professional sizes AGFA PHOTO HANDBOOK by Dr. M. ANpDRESEN 300 p. text, fully illustrated, with useful information. Ask for illustrated catalog and price list, and special information leaflets on Color Plates, Light Filters and Negative Material for process work. ofc Prodesctsd , tne. 114-116 East 13th Street, New York City, N. Y. A Bausch & Lomb Lens For Every Purpose TESSAR Ic, f£: 4.5—Master of speed and light. Un- excelled for ultra rapid work, portraits, groups, land- scapes, etc. The most universal of the unsymmetrical anastigmat lenses. TESSAR IIb, £: 6.3—For general use on hand-cameras, for groups, landscapes, commercial photography, en- largements, etc. Similar to TESSAR Ic, but more compact and with less speed. PROTAR Vlla, f: 6.3—A rapid, convertible anastig- mat lens, adapted for landscapes, architecture, por- traits, groups, etc. For purposes requiring long focus, medium speed and narrow angle. PROTAR IV and V, f: 12.5 and f: 18—Rapid ana- stigmat wide angle lenses of short focus, for archi- tectural and interior work, and groups. PLASTIGMAT, f: 5.6—For artistic and blended photographs, including portraits, landscapes and architectural subjects. Produces the desired soft effect at full aperture. There is a Bausch & Lomb Photographic Lens for every purpose. Send for your copy of our illustrated cata- log, “What Lens Shall I Buy?” which outlines the requirements of different branches of photography and recommends the proper lenses. Bausch €4 lomb Optical ©. 238 FREEMAN STREET, ROCHESTER, N. Y. New York Chicago Boston San Francisco Washington London GOERZ PHOTOGRAPHIC LENSES of high grade: the old reliable Dagor, f: 6.8, for hand cameras and commercial work; wide angle Dagor, f: 9, with plenty of light for ~ focusing (new) ; Dogmar, f: 4.5-£: 5.5, the ideal speed lens, the single lenses give large size images; Syntor, f: 6.8 and Tenastigmat, f: 6.3, moderate speed, inex- pensive hand camera anastigmats; Portrait Hypar, f£: 4.5, the portrait lens without harsh wire edge sharp- ness; Kino-Hypar, f: 3 and f: 3.5, for movie cameras; Kino-Telegor, f: 6.3, for telephoto movie effects; Telegor, f: 6.3, a fast working telephoto lens for re- flecting cameras, for sports and naturalist photography; Artar and Gotar Lenses for the photo-engraver; Compound Shutters, etc. OUR CAMERA LINE comprises Roll Film Tenax; Pocket Tenax for plates and film packs; Taro and Manufoc Tenax, with double extension for plates and film packs; Ango Focal Plane Cameras; Stere- oscopic Cameras; Hahn-Goerz Motion Picture Cameras and Projectors. Complete “line of accessories, plate-holders, film pack adapters, kits, etc.—carried in stock. Other products are Binoculars, Telescopes, Polar- iscopes, Barometers and Scientific Instruments of varied types. Information and Printed Matter on Request C. P, GOERZ AMERICAN OPTICAL GOMPARY 317AF East 34th Street, New York City GEVAERT PAPERS and PLATES PAPERS RONIX—Daylight Printing, Self Toning NOVAGAS—Contact, Prints, Any Artificial Light VITTEX—Contact or Enlarging, Artificial Light NOVABROM—Enlarging, a Bromide for All Work ORTHOBROM—Bromide for Pictorial Work BROMOIIL—Special for This Process PROOF PAPER PLATES Sensima 500HD Portraiture Sensima Ortho s5ooHD Portrait, Press, Landscape Sensima Ortho Anti Halo 500HD All Around, Ortho Sensima Mat (Matte Emulsion) 500HD Portraiture Special Sensitive zooHD Al! Around Work Orthochromatic 40o0oHD Used With a Filter Ortho Anti Hale 250HD Used With a Filter Filtered Ortho 250HD No Filter Needed With This Plate Ordinary Process Ortho Process Lantern Slides, Black Lantern Slides, Warm Tone Fast plates should be developed 50% longer than slow plates. The Sensima Mat Plate saves time on account of its matte surface. Filtered Ortho Plates have incorporated with the emul- sion a filtering medium which holds back the ultra violet rays but admits the yellows and greens. AOHHQHMMAHW HO RHOCUONKH QHHNPHQOHORN UHNHHHawmHn THE GEVAERT COMPANY OF AMERICA, Inc. 423 To 439 WEST 55TH STREET NEW YORK Chicago Branch—Geo. W. Mackness Co., 180 N. Wabash Ave. THE LARGEST and Most Comprehensive CATALOGUE Ever Offered to CAMERA ENTHUSIASTS Your copy, 228 pages, is ready. Send in your name and address, right now, while you have this notice before you. CAMERAS, KODAKS, LENSES & SUPPLIES of every description, Domestic and Foreign, are listed in this Catalogue, at the very lowest possible prices. EVERY ITEM GUARANTEED Besides, you have the privilege of testing what you purchase, 10 days. After which time, if unsatisfactory, you can return and we will refund in full, or, we will exchange for something else you may wish instead. REMEMBER TOO:— We deal in used equipments. If you wish a used Camera, Kodak or Lens, send for our special bargain book, free on request. WE HAVE HUNDREDS OF unsolicited testimonials from customers who are pleased with our service as well as merchandise. We can do likewise for you. WE BUY OR TRADE OUTFITS Perhaps you have one you wish to trade or sell. Send in a complete description of it, and we will make you the very best offer in cash or trade. CENTRAL CAMERA CO. 112 South Wabash Ave., Dept. P.F. Chicago, Illinois NASON? )> gu 7a Thien HON es 1 RON x Sas eset ere Sete Betitesiete eee