Lyon EL Clark^ The LONDON STEREOSCOPIC and PHOTOGRAPHIC Co., Limited, 106 & 108, REGENT STREET, W., AND 54, CHEAPSIDE, E.G. ESTAB. 1-852. PERKEN, SON & RAYMPNT^tr IVEANUPACTUBE iOPTIMUSI MAGIC LANTERNS. Adapted for use -with Limelight. For dissolving Two Lanterns are necessary. Each Magic Lantern is efficient for exhibitions. The Lens gives crisp definition, being a superior Achromatic, Photographic Combination (large diameter black lens), with rack and pinion. It is fitted to a telescopic lengthening tube, so gaining mcreased focal accommodation. The Condenser is composed of two plano-convex lenses of foi5 inches diameter. The refulgent lamp has three wicks (or four wicks 2j. extra), yielding a brilliantly-illuminated picture.— Each is complete in box. Japanned MetaJ. Student's Lantern (to take demonstrating tank), finished I Brass Sliding Tubes. 40/- Mahogany outside iiody, Japanned Metal Stages, and Sliding Tubes. 42/. Russian Iron Body, Brass Sliding-Tub^. 46/- 'OPTIMUS' TRIPLE LANTERN FOR LIMELIGHT. Seasoned Mahogany Body, 4 Panelled Doors, Moulded Foot, picked out with black, Brass Stages and Tubes, Achro- matic Front Lenses, Compound Con- densers £14 10 0 Perforated Russian Iron Body, Brass, Sliding Tubes. 50/^ Mahogany outside Body. 2 Panelled Doors, Brass Stages, and Sliding Tubes. 82/- 'OPTIMUS'BI-UNIAL FOR LIMELIGHT, The Top Lantern may be used separ- ately with Oil Lamp. Seasoned Mahogany Body, 4 Panelled Doors, and Moulded Foot, picked out with black. Japanned Stages & Tubes, Achromatic Photographic Front Lens, Compound Condensers .. £5 12 0 Do., do., all Brass Stages .. £8 8 0 'OPTIMUS' ENLARBING APPARATUS. Patent Quick-Acting Back Adjustment.' This Apparatus comprises superior Mahogany Body Lantern and Lon^ Rpllnwc SSYt^ll"' >S ^^^^ ^'i'"^^' The Lamern ^s fit?S wi?h powerful Refu^^ gent Lamp, with 3 wicks, giving brilliant iUumination. Compound CondenseS. Condenser. s. d. S-in., no front lens 100 6 5- in., with 6- in., no 6- in., with 7- in., no 7- in., with 8- in., „ 9- in>. fi lo-in., „ i2-in., „ If with Russian Iron instead of Mahogany Body. S-in., no lens 75 a 5- jn- and 102 6 6- m., no „ 07 g 6- in., and „ . Il4 ^ 7- in., no ,. .. :. :: {{y g-in-and, 137 9 8- !n., no , 160 0 9- jn 250 0 3-in":::: :: :: :: ifag Q Q ^i!i?i"mm^!?S'^'''i5' f'*'"' '2/-; Coloured, 18/6 per 99, HATTON GARDEN, LONDO 127 0 133 0 151 0 155 0 173 6 256 0 290 0 360 0 580 0 dozen, N, E.C. Established 1852. PERKEN, SON & RAYMENT, Catalogue Free. Discounts for the Trade. CAMERAS, LENSES & PHOTOGRAPHIC APPARATUS. TRADE MARK, OPTIMUS' "OPTIMUS" EURYSCOPE. " Working as it does with such a large aperture (f/6 approx.), it serves as a portrait and group lens, as well as a landscape and copying objective. There is no doubt of its proving a most use- ful lens."— J' Traill Taylor, Brit. Journal of Photography. " We are pleased to find upon trial that the lens ('Optimus' Rapid Rectilinear) sent for re- view is really an EXCELLENT INSTRUMENT." — Photogra- phic News. I should strongly recommend Rayment s Camera. It is Light, Compact, very rigid, and ex- tends to about double the usual focus." — Amateur Photo. 7x5 638. 94s. 6d. Optimns** RapM Enry scope 8x5 9x7 10 x8 UOs. 126s. 220s. Optimus 6 6 7 s 33s. 45s. 49s. 6d. Rapid Rectilinear. 8 9 JO i.2 15 18 ^7 S To TTT 64s. 82s. 6d. 127s. 6d. 142s. 6d. 180s. 225s. ** Optimus'* Wide Angle Symmetrical. 57 9 10 12 15 a t 1 8 ID 39s. 52s. 6d. 82s. 6d. 127s. 6d. 1429. 6d. 180s. ITT 225s. Optimus" Quick- Acting Portrait, Diam.... . ... 2 inches 2| inches. scinches. Price 90s. 120s. 180s. IB 2B 3B Rayment*s Patent Camera {Long Focus\ Price includes 3 Double Dark Slides. 45 X 3? i 5 X 4 I 6| X 4I I 8| X 6^ I 10 X 8 I 12 X lo I 15 X i; 120s. I 126s. I 145s. | 168s. | 212s. | 258s. | 314s. '•Optimus" Camera {Long Focus) ^ Price includes 3 Double Dark Slides. 4i X 3i I 5 X 4 I 6| X 4I I 8^ X 6^ I lo X 8 I 12 X 10 I 130s. I 133s. I 137s. | 175s. | 227s. | 275s. | Portable Camera. Compact, Rigid, and of Excellent Finish. 4^; X 3! I 5x4 I 65 X 4I j 8i X 6^ I ID X 8 I 12 X lo I 15 X 12 102s. 104s. 9d. 118s. 146s. 3d. 174s. 6d. 216s. 274s.6d. IS ^ 33 " Optimus'^ ^^fg Camera ( Price includes 3 Dark Slides. 5 X 4 } 6| X 4I I Si X 6| I 10 X 8 I 146s. 165s. 188s. 235s. Long\ Focus I* '350s. "OPTIMUS" MAGAZINE CAMERA. Twelve dry plates are placed in the upper portion of the grooved travelling reservoir. The bases of these plates rest upon the top of the Camera body. The grooved reservoir recedes gradually from the Ex- posure Chamber when the pinion is revolved— allowing one plate at a time to fall in its groove to the bottom half of the reservoir, and so place its sensitised surface within the Exposure Chamber opposite to the Lens, and exactly in true focussing register. The twelve plates may, if desired, be exposed in as many seconds. There is no possibility of the plates sticking. The Shutter is suitable and convenient. With Rapid Rectilinear Lens, working at F, 8 r» ^ 0 With Rapid Euryscope, working at F. 6 7 7 0 ^9, HATTON GARDEN, LONDON, E.G. / PLATINUM TONING: DIRECTIONS FOR THE PRODUCTION OF THE SENSITIVE PAPER. LYONEL CLARK, C.E., HON. LIBRARIAN CAMERA CLUB. [Amateur Photographer's Library, No. i.] LONDON : HAZELL, WATSON, & VINEY, Limited, I, CREED LANE, LUDGATE HILL. E.G. 1892. 'OPTIMUS' LENSES. Photographic News. " We may call attention to the extensive optical and metal works that Perken, Son and Rayment have established in Hatton Garden, and their photographic cabinet factory in Saffron Hill. At the former we were much interested in the glass-grinding departments — one for photographic lenses, another for spectacles : and we were surprised to find in London such extensive workshops for the metal parts of cameras and optical lanterns ; indeed, we thought outside Birmingham we should not find such workshops in the United Kingdom. The cabinet works in Saffron Hill also interested us much ; the arrangement of the machine tools, and dis- tribution of power on the several floors, being admirable." Photographic News, " We are pleased to find upon trial that the lens (' Optimus * Rapid Rectilinear) sent for review is really an excellent instrument." British Journal of Photography. " The ' Optimus ' Rapid Eury scope manufactured by the firm of Perken, Son and Rayment, Hatton Garden, an example of which is on a camera on our editorial table. With full aperture of If in. (its equivalent focus being 11 in.) it defines with extreme brilliancy, and when used with a stop it easily covers a 10 by 8 plate to the corners, which is larger than that engraved on the mount as its possibility. Working as it does with such a large aperture (// 6 approx.) it serves as a portrait and group lens, as well as a landscape and copying objective. There is no doubt of its proving a most useful lens."— J. Traill Taylor. PERKEN, SON & RAYMENT, S9, Hatton Garden, LONDON. INDEX. PART I. TLATINUM TONING. PAGE Chemistry . 5 History 7 Experiments 17. Printing the proof .23 Toning bath for black tones . . . . .25 Toning bath for warm tones . . . . > 28 Fixing , . - .29 After treatment . 31 Drying the prints 33 Mounting the prints . . . - . • 35 PART II. PEEPAEATION OF SENSITISED PAPER. Choice of paper 40 Sizing the paper 43 Salting the paper . , . . . , - 46 Strength of solution 48 Choice of chloride . . . . . . .50 4 INDEX. PAoa Method and time of applying the salting solution . 55 Sensitising the paper 61 Preparation and preservation of the nitrate bath . 71 Tones obtained by different preparations • ,79 Toning and fixing home-prepared papers . . 80 Treatment of Alpha paper 81 Treatment of Obernetter and Aristotype papers . 82 Albumenised Paper 83 Preparation of silks and stuffs . , , .84 APPENDIX. To make nitrate of silver To prepare chloroplatinite of potassium Stains on fingers, linen, etc. . Platinum residues . Silver residues 85 87 89 91 92 PAET I PLATINUM TONING. I. CHEMISTRY. Platinum — symbol, Pt ; atomic weigM, 197-4 (Watt's " Dictionary/' 1871 Ed.)— belongs to the group of noble metals, like gold, palladium, iridium, etc. ; in appearance it is a white metal, like silver, whence its name (plata, Spanish for silver). Its chief properties, perhaps, are its very great stability under all circumstances, superior in this respect even to gold ; it does not oxidise in the air at any tem- perature ; it is not attacked by any single acid, but aqua regia, a mixture of nitric and hydrochloric acids, will dissolve it slowly ; it is only slightly attacked by sulphur at very high temperatures ; and chlorine is hardly at all absorbed by it. Platinum is now considered to be tetravalent, or tetratomic — that is, its atom requires four atoms of any univalent element to satisfy it Pt Cl^ \ci and form the molecule. In the older chemistry, 6 PLATINUM TONING. however, it was considered to be divalent (CI - Pt - CI) : this will explain how it happens that the salt sometimes sold in the shops mider the name of bichloride of platinum is in reality the tetrachloride, shopkeepers' labels not quite keeping pace with the advances of chemical science. Platinum forms, like mercury and iron, two series of salts, the platinous compounds, in which it acts as if it were diatomic or divalent — viz., PtCl2 and PtO ; the assumption being in these cases that two of the four natural bonds are satisfied by tinic compounds in which it is in its true tetra- valent form — as, PtCl4 and Pt02, etc. The platinous chloride (protochloride of the old chemistry) is a salt of a greenish brown colour, in- soluble in water, but soluble in hydrochloric acid : this menstruum, however, if air be not excluded, will convert it into the higher chloride. Platinous chloride unites, however, with the more basic metallic chlorides, and forms double salts, of which we will take the chloroplatinite of potas- sium as a type : K2PtCl4, or 2(KCl)PtCl2. For the preparation of this salt I refer readers to the appendix at the end of this pamphlet. This salt forms in red four sided prisms, resembling in appearance cayenne pepper, and is moderately secondly, the pla- HISTOEY. soluble in water. It possesses a peculiar interest to all photographers, as it is the salt that is used in Willis's, Pizzighelli's, and other platinum processes. Tetrachloride of platinum : PtCl^. This salt is prepared from metallic platinum, by heating with aqua regia and evaporating ; it forms a reddisli brown mass, which, if pure, is soluble in water. This salt is the common chloride of platinum sold by every photographic dealer in fifteen-grain tubes, and is the salt that has hitherto always been used in platinum toning. According to Pizzighelli, how- ever, this salt is said to be chloroplatinic acid (PtCl42HCl), and undoubtedly it does contain a good deal of free hydrochloric acid, the tendency of which appears to be to render it more soluble in water. Platinum also forms a large and varied series of salts with ammonium, but they are without interest to photographers. HISTORY. The great stability of platmum has naturally led many workers to endeavour to use this salt as the basis of a printing process. In the pre-photo- graphic days, Dobereiner had already experimented with platinum and examined its behaviour under the influence of light, and^ curiously enough, had 8 PLATINUM TONING. nsed the very chloroplatinite of potassium so generally now in use. One of Dobereiner's dis- coveries, and that a very important one, was that a solution containing an oxalate and bichloride (tetrachloride of to-day) of platinum would throw down metallic platinum when exposed to light. Sir John Herschel was also early in the field- and experimented with platinic chloride, neutralised with lime-water in ether ; and noticed^ as did sub- sequently Johannsen, that the action of the violet end of the spectrum precipitated metallic platinum. Robert Hunt appears to have been really the first to try and actually utilise these and his own results as a basis for a paper-printing process. His numerous and interesting experiments will all be found recorded in his remarkable works on Light and Photogeaphy. But the results of his labours were not producible of any working process. As a matter of fact, neither platinous nor platinic salts are practically directly reducible by the action of light in the way that silver chloride or silver oxide is, and so platinum dropped out of the notice of the photographic world. However, the great chemical similarity between platinum and gold caused experiments to be made with this salt as a toning agent, to replace the more commonly used gold — that is to say, an image was first formed of another metal, silver being HISTORY. 9 the one generally used, and this was afterwards converted into platinum by a toning process. A Frenchman — M. de Carranza — appears to have been the first to publish a formula for platinum toning. His formula was published first in La Lumiere^ February 1856, translated into the Journal of Photographic Society ^ 1856, p. 14, and Photographic News^ vol. i., p. 251. He used an acidulated solution : 1 in 2,000 of platinic chloride. This gentleman was shortly followed by Mr. Burnett, who gave several formulae for toning baths, and appears to have experimented with almost all the platinic and indeed platinous salts. One might write a very interesting account of his experi- ments, which are to be found in the pages of the photographic journals for 1858 and 1859. Amongst other experiments mentioned is the use of platinic nitrate or sulphate — that is to say, the free hydrochloric acid in the platinic chloride is neutralised, and nitric and sulphuric acid added. This is undoubtedly the only successful platinum toning bath formula up to the present date. He also in the same paper (British Journal ^ 1859, p. 162) recommends the use of the corresponding platinous salts. And in another article in the same journal he goes so far as to recommend the use of the chloroplatinite of sodium, a salt closely analogous to the potassic one introduced by Willis, 10 PLATINUM TONING. These and other salts of platinum, palladium, and gold he actually recommends as developers of the images formed by his ferric and uranic printing processes, thus very closely foreshadowing the most recent of the platinotype processes. It is interesting to follow out here what is the rationale of a toning process. A somewhat common assumption is that it is a gilding process — that is to say, that the silver image receives a thin layer or coating of gold, like the inside of mugs or spoons are occasionally covered with gold. But such is not the case. To any one who is desirous of closely following out the chemical effect of toning, I should strongly recommend them to peruse the series of articles by MM. Davanne and Girard on this sub- ject, that are to be found in the Photographic News for 1863 and 1864. There can, I think, be no doubt that all kinds of toning (and I consider all platinum processes to be such) resolve themselves into a true substitu- tion process — that is to say, that the silver that is in the image is replaced by gold according to the following equation : Au,Cl3 + 3Ag = 2Au + 3AgCl. Or, when a platinum salt like that in Carranza's formula is used, we have : PtCl^ + 4Ag ~ 2Ag2Cl2 + Pt. This shows that with gold toning three atoms of HISTOKY. 11 the silver that have been produced by the action of light will be converted into a chloride, subse- quently dissolved out in the fixing bath ; and two atoms of metallic gold will be left. Whereas in Carranza's — or, indeed for that, any present platinum toning process — -fom" molecules of the light product will be converted and subsequently dissolved before one platinum molecule will be deposited on the proof. This really means that, supposnig that the colouring powers of silver and gold and platinum were equal, the relative intensities of the resulting image, taking silver itself as 1, would be, gold f, platinum \. However, the colouring power of these salts are not equal, the question of atomic weight also coming into play ; and, what is perhaps still more important, the light product on a silver print is not wholly metallic silver, but is formed pro- bably of a small quantity of metallic silver, some subchloride, and a good deal of sub- or partially deoxydised organate of silver. The precise part that each of these substances plays, or indeed their true composition, is unknown to us ; but from the experiments of MM. Davanne and Girard it would appear that each are more or less equally replaced by gold in the toning. I have noticed, too, that when the purple subchloride of silver is removed by the action of salt, in which it is soluble, toning goes on just the same as usual. 12 PLATINUM TONING. but there is a slight general loss of intensity in the resulting proof. If, however, this salt be dissolved out by means of hyposulphite of soda although the appearance of the print is the same as if salt were used, yet toning takes place very slowly, and recalcitrantly. There is a discrepancy and an anomaly in these two results which I cannot explain ; I may perhaps mention that Davanne noticed some similar anoma- lies in the case of organates of silver toned after fixing (Photographic News^ 1864, p. 29). However, whatever may be the precise chemical changes that take place in toning, we see that theoretically the resulting print should be weaker, slightly so in the case of gold, and very much so in the case of platinum ; and we know from practice that this is really more or less the case in toning. The actual loss is, however, considerably less than we might expect from the equation ; this is no doubt largely due also to the fact that the substitution of the two metals is never very complete. The outside molecules of silver are undoubtedly rapidly con- verted into gold, but this very gold itself tends to protect the inner particles from change, so that some silver invariably remains in the film. Even after so prolonged a toning as thirty hours, during which time the gold was frequently renewed, the resulting deposit was found by Davanne and HISTOKY. 13 Girard {Photographic News^ 1863, p. 546) to contain : Silver 0-38 parts. Gold M4 „ With j]iatinnm it is fair to assume the same results will hold, so that we must consider a toned photo- graphic proof to consist of an alloy of silver and gold, or silver and platinum, and probably of defi- nite proportions ; and therefore, although a decided loss in intensity of the image is seen, still it is less than if the whole of the silver were replaced. When platinum is used, the weakening will be more apparent than with gold, on account of its greater valency ; and it is not surprising therefore that, although platinum toning formuljB are to be found in every text-book, still they have never come into any general use. These facts, however, only acted as a further stimulant to active workers, and from time to time experiments were still made in platinum printing processes. Nothing practical, however, was done till Willis entered the field in 1874, and produced the first reliable platinum process, one which with but few modifications survives to the present day in the hot-bath process. Although Willis's process is essentially a toning process, still silver is not used in the production of the provisional image, but he makes use of the 14 PLATINUM TONING. photographic properties of another of the heavy metals — that is, iron. That the action of light reduced the ferric to the ferrous compounds was one of the earliest known facts in photo-chemistry, and the further fact that the ferrous compounds would throw down gold or silver from their soluble salts, whilst the ferric salts would not, was known to Sir John Herschel, who devised therefrom his Chrysotype " process, in which an iron salt is used as a provisional image that is afterwards replaced or toned by gold. If we substitute, however, platinum for gold, we do not get a precipitate, as Willis found in his early experiments. But he either discovered or knew that the addition of a soluble oxalate would cause such a precipitate. Another important modi- fication he introduced was, following on Burnett's lines, the use of a 'pleitinoiis instead of a platin?^? salt, by which means he got twice the amount of metallic platinum for the same quantity of ferrous salt as he would have got if he had used a platinic salt ; and, since the ferrous oxalate has to be formed by light, the importance of this change will be understood. This is the whole rationale of Willis's processes, which are undoubtedly toning processes ; but they have the advantage of replacing the whole of the iron salt by platinum, and not forming an alloy with this metal. Their disadvantages are, the image is HISTORY. 15 only slightly visible during printing, and the paper must be carefully protected from damp. Platinum printing has always had a peculiar fascination for me, and when I met with Mr. Willis's process I gladly took it up and practised it, and hope to do so still. But I could not help feeling that there were some failings in the process, and the advantages that the older silver printing gave us, in its easy preparation, its visibility during the printing, and the wealth of warm tones obtainable by toning, was not alto- gether to be despised. The slimy appearance of albumenised paper, giving the print the appearance of a magnified snails' playground, had always been objectionable to me, although I admired the warm tones obtain- able on it, — tones that I found myself unable to procure on ordinary matt-surface paper by the aid of gold toning. It is not surprising, therefore, that I turned to platinum for aid. Knowing the difficulty of making I an effective platinum toning bath, I tried the addi- tion of oxalate of potash to the ordinary platinic chloride. With this bath I certainly succeeded in toning plain paper prints to a very agreeable colour; but I found the loss of intensity to be very great indeed, and it was necessary to over-print the proofs to an extent that was virtually unpractical. It was 'only natural at this stage, with the knowledge of 16 PLATINUM TONING. Willis's previous labours, that I should turn my attention to the ylsitiiwus salts. I took, however, no practical steps in the matter till the publication of Willis's cold bath platinotype process put the chloroplatinite of potassium — one of the salts used — into my hands. Remembering my previous theories, I proceeded at once to put them to the test of practice, by attempting to tone or convert into platinum the silver image formed by light on the surface of a sheet of plain salted and sensitised paper. Need- less to say, the results were satisfactory — indeed, highly so ; and I at once took the opportunity of a lecture given by Mr. Willis on platinum printing before the Camera Club, on November 29th, 1888, to publish my experiments and exhibit my results. Since this date I have in the few moments of leisure allotted to me worked out the' process more thoroughly, with the result that I am now able to give the working directions for a platinum toning process that will, I believe, be appreciated by many amateurs who, like myself, although disliking the surfac(i gloss and glare of albumenised and gelatin- ised prints, still admire the warm tones that were obtainable on these media. EXPEBIMENTS. 17 EXPERIMENTS. 1 have mentioned in the preceding historical resume that one of the improvements introduced into platinotype printing by Mr. Willis was the addition of a soluble oxalate to the developing or toning bath. I might have said more than an improvement, for it is an absolute necessity ; for without the aid of such a salt the ferrous com- pounds are quite unable to throw down platinum from its salts, as they do in the case of gold or silver. But when we use silver as the basis of our convertable image, this fact no longer holds good, and it is perfectly possible to tone the image with a simple aqueous solution of the platinum salt. I therefore, very early in the course of my experi- ments, discarded all such additions to the toning bath, and confined myself to watching the behaviour of the chloroplatinite of potassium. Naturally one of the first series of experiments was to discover the amount of dilution of the platinum salt that gave the best results. In the ordinary platinotype formula the salt is dissolved in water in the proportions of 1 to 90. Would there be any difference if the strength were in- creased up to, say, 1 in 15 (the strength of their stock P solution), or reduced down to 1 in 1,000 ? 2 18 PLATINUM TONING. I find that within these limits the difference is not appreciable in the results. If the solution be very weak— say, 1 in 3,000 or 4,000 — and espe- cially if the oxalate and phosphate be present, there is a tendency to give the finer details in the half- tones a yellowish colour. Curiously enough, on the other hand, if the solution be very strong, and especially if it be warmed to hasten the toning action, there is the same tendency exhibited. I have frequently observed an analogous eff'ect in silver prints that have been over-toned in some gold baths : for instance, that made up with chloride of lime. The only efi'ect I found in altering the propor- tions of water present was a difference in the time of toning : with concentrated baths the action took place almost instantaneously; with weaker ones it took longer, proportionally too, within limits, to the amount of weakness. There was no alteration, as I had expected there would have been, in the in- tensity curve or gradations of the print — that is to say, a brilliant print always remained a brilliant print, and a soft one a soft one. In this toning diff*ers from development ; for in this process it is an easy matter to considerably alter the character of the negative or print. This unalterability of the intensity curve has its good points. One is not obliged to make up the bath very accurately, and one need not fear that the EXPERIMENTS. 19 last toned prints will vary from the first in their character, through weakening of the toning solution. The washer is therefore able to make his solution up pretty well as may suit the quantity of prints to be toned ; although, as a rule, I prefer it of a strength of about 1 in 250, — a strength which appears to give uniformly good results. I found recorded in the early pages of the British Journal the experiments of a worker who signed himself Gwenthlian," and who stated that he found in platinum toning that, whereas acid solu- tions gave blue-black images, alkaline solutions gave brownish tones. My own experiments do not, however, agree with his. I found no difference in the resulting colour between prints toned in a neutral or acid solution ; and when the solution was made alkaline, toning was very considerably retarded ; indeed, if it were distinctly alkaline in its reaction, toning refused to proceed at all. Even with the strongest solutions no effect was obtained after a lengthy immersion. The effect of the alkali is, however, only to restrain, not to destroy, as is proved by the fact that this same print, on being immersed in water sufficiently acidulated to destroy the free alkali, toned at once to a full black, without the addition of any fresh platinum, there being enough of the salt left in the pores of the paper. As we are never certain of the state of our silver 20 PLATINUM TONING. prints, whicli may be alkaline or acid according to their method of production, the reason of my adding a small amount of acid to the toning bath will at once be understood. I have not hitherto spoken of the manner employed to obtain proofs of different tints or colours. It does not appear possible to precipitate the metallic platinum in any other colour than the black form ; and therefore, if, as in the above experi- ments, the toning be carried on very thoroughly, the resulting print will always be of a constant tone, approaching the black of the ordinary platino- type processes. But, unlike this process, the silver salts of which our preliminary image is formed are always present to some degree, even after the most thorough toning. Undoubtedly the protection afforded to the inner particles themselves by the reduced platinum on their outsides is a partial cause of this ; but I think that a total substitution of platinum for the silver can never be possible, as it probably forms with this metal a true alloy. Platinum is well known to form alloys with silver, which possess the some- what peculiar property of being soluble in nitric acid. We should naturally expect the nitric acid to dissolve out the silver ; but witl: these alloys some of the platinum will also be dissolved ; indeed, when present in certain proportions, the whole will be dissolved. EXPEKIMENTS. 21 The presence of this remaining basis of silver naturally exerts a slight influence over the resulting colour of the print ; and therefore, by using different salting or sensitising mixtures for our prints, we may obtain a series of tones that vary from warm brownish blacks to blacks, and this with a thorough toning. In the working directions in the latter portion of this work, I give the differ euL tints resulting from differently prepared papers. But even with the same brand of paper we can obtain a good variety of tones by pursuing the methods adopted in gold toning — that is to say, we watch the gradual change of colour that takes place whilst the print is immersed in a bath diluted sufficiently to be under control. By this method we get, from any of the ordinary brands of matt- surface sensitised paper, a fair array of tints, vary- ing from brown, through reddish brown, brown black, black and purple black, in accordance as we allow the toning action to continue for longer or for less time. It is evident that our choice of tones is much more circumscribed than if we prepare our own printing papers. This, which is after all an extremely easy and also economical matter, and well within che power of almost any amateur, gives us an almost infinite choice of effects ; for not only do the different salting and sensitising mixtures affect the ultimate results, but the particular kind 22 PLATINUM TONING. of paper used introduces its factor into the equation. Nor, indeed, are we in any way limited to paper ; we can launch out and impress into our service all sorts of stuff's, woven or otherwise. A whole array of silks of different textures are open to us for decorative purposes : the satin jeans with their glossy surfaces, for doyleys and suchlike ; nainsook and fine linens, leather, wood — in fact, almost any substance that is not injured by contact with water can be made subservient to our tastes, and its particular texture brought into play, to aid any particular effect we may have in view. In the latter part of this work I have devoted a certain amount of space to a description of the methods that I have found most suitable for salting and sensitising such materials ; I shall now pro- ceed to give full working details of the methods I have found most suitable for the printing and toning of proofs that have been printed on those commercial brands of matt-surfaced paper that can now be obtained from any of our better dealers. At the end of the directions for preparing sensi- tised paper oneself are also given a few hints of such modifications as may be necessary for toning these papers* II. PBAGTICAL DIBECTIONS. PRINTING THE PROOF. I shall of course assume that my readers have already some slight knowledge of printing albumen- ised paper, and shall give no descriptions of the printing frames, or methods of cutting up the paper/ or placing it in the frames. I shall commence, therefore, by saying that the printing differs in no way from the ordinary method. The paper can be kept and treated in exactly the same way as if it were going to be subjected to gold toning. With regard to the depth of colour to which the proof is to be printed, this follows just the same law — that is to say, it should be slightly over-printed, say, till the highest lights just show signs of degradation. When this point is reached, the dark shadows of the proof, if the negative be a really good one with proper pluck, ought to be just solarised — that is to say, assume a metallic lustre. This is an axiom that is to be found in all books on silver printing, and it is here equivalent 24 PLATINUM TONING. to saying that no special negative is required for my process. If a negative will give a good gold- toned printj it will give a good platinum one. It must, however, also be remembered that matt- surface paper requires stronger negatives than does albumenised paper, and we may state generally that the pluckier the negative the richer and fuller blacks or browns can be obtained. With a thin negative no really vigorous result can ever be obtained on commercial paper, although by sensitis- ing one's own the fault can be somewhat rectified. As a general rule, therefore, a plucky negative will give the best results. On removing the print from the frame, it may either be stored away till a convenient opportunity or at once got ready for toning. The preparation consists in washing the prints in two or three changes of water until all milkiness disappears. I prefer to make this preliminary washing very thorough, as the toning bath, is preferably used in a rather concentrated condition, and the chloride of silver carried over into it, tends to render it cloudy and muddy. I am not also quite certain if it does not tend to react on the platinous chloride and form platinic chloride ; at any rate a bath in which much free chloride is left will after a few days' keeping lose its colour and become inert. The toning bath that I generally use, and the one that is most suitable for a thorough toning, TONING BATH FOB BLACK TONES. 25 witli its resultant dark brown and black colours, is made up as follows : TONING BATH FOR BLACK TONES. -.-^^ ^ Stock Solution A. CUoroplatinite of potassium*... 60 grains. Distilled water up to 2 fluid ounces. This is practically the P solution of the Platino- type Company, and will keep in this condition indefinitely. For the benefit of those who work in decimals or by parts, I might point out that this is equivalent to 1 in 15. Toning Bath. Stock solution A 1 fluid dram. Ordinary water up to 2 fluid ounces. Nitric acid 1 or 2 drops. This represents a strength of 1 in 218, or two grains to the ounce; and those who do not use the platino- type formula can at once make up the sixty-grain tube to thirty ounces of water, and duly acidify the mixture. In winter or in cold weather I prefer to use warm water with the above, so as to bring the temperature up to about 80° or 90° F.; but I must * I must urge on my readers the necessity of obtaining the true chloroplatinite of potassium, and be careful not to be put off with the ordinary chloride or bichloride of platinum (as sold usually in fifteen-grain tubes). 26 PLATINUM TONING. warn workers against overheating, as with such a powerful bath, especially with commercial papers, yellowing of the half-tones would be most liable to occur. With this bath a print should commence to change colour and blacken almost instantly on being placed in contact with the liquid, and toning be complete in two or three minutes. With such a bath, therefore, I recommend toning a single print at a time, and I find the two ounces as given above enough to tone several 12 by 10 prints. My method of working is as follows:— For holding the toning bath I employ one of the plate-glass bottomed dishes as generally used for the develop- ment of bromide papers. I usually turn it upside- down, so as to have the sides as low as possible, and attach three ordinary levelling screws to the upper edge, which now becomes the lower one ; and with these and the aid of an ordinary spirit level I adjust the dish. By this means the toning solution is spread over a large area in a thin but uniform layer, two ounces being, according to my experience, sufficient to cover a dish measuring 18 by 15 in. I then take the wet proof, and, holding it by opposite corners one in each hand, place one corner on to the surface of the liquid with the left hand first, and then, lowering the right hand, allow the print to gradually float on to the liquid, in this TONING BATH FOR BLACK TONES. 27 manner pushing in front of it any bubbles that may have been formed on the surface. Those who are accustomed to float their own paper, or who work the platinotype processes, will at once understand the above method. Those who do not cannot, however, make any mistake. We have not, as in the cold-bath platinotype, a dry print to handle, but a moist one, which naturally takes to the water again very kindly ; and even if we do not succeed in properly floating the print, but leave portions untouched by the liquid, all is not lost, as in the cold-bath process ; but the print can be lifted and refloated, when the untouched portions, recognised easily by their retaining their reddish colour, will soon commence to tone and catch up the other portions of the print. I feel quite con- vinced that no prints will ever be lost from any errors in the floating. The print may be lifted off the toning bath as often as is thought desirable, and examined by transmitted light — that is, looked through in front of a light ; and, if any redness is still seen in the deep shadows, replace it on the bath. When all redness has disappeared, the toning is complete ; the print should then be lifted slowly by one end off the liquid : this is from motives of economy, and in order to use up as little of the toning solution as possible, for while the print is being slowly raised the liquid on its surface runs back again into the bath. 28 PLATINUM TONING. The print is then thrown into a dish of water that has been rendered alkaline by carbonate of potash or soda. The reason of this is to destroy any acid that the print may carry over from the toning bath, and which if carried into the fixing bath would decompose the hyposulphite, throwing down sulphur, and very probably yellowing the whites of the picture. Of course, if only a limited number of prints are being toned, the hyposulphite itself can be rendered alkaline, and the prints placed in it directly from the toning bath. The toning bath will not keep long after having once been used ; after three or four days some chemical change is set up, and it loses its colour and becomes inert. TONING BATH FOR WARM TONES. I have explained above that the only means of obtaining warm or black tones on the same brand of paper is by stopping the toning at an early stage. The toning bath I have given is, however, so rapid in its action that the prints will not be under control. In cases, therefore, where it is wished to stop the toning at any desired point, I should recommend a bath being made up as follows : Stock solution A 1 fluid dram. Water up to 8 fluid ounces. Nitric acid 2 or 3 drops. FIXING. 29 This is equivalent to a strength of half a grain per ounce, or in metric measures 1 in 875 (it would be quite near enough to take it as 1 in 1,000, or a gramme per litre). In such a bath the prints are treated exactly as in gold toning, and immersed two or three at a time, and turned over from time to time and watched ; and when the colour sought for is obtained they are removed into the bath of weak alkaline water. This bath will have the effect of instantly stopping any further toning action from any platinum salt that is left in the pores of the paper, FIXING. The prints are then immersed in the hypo bath in the ordinary manner. The strength of this bath is somewhat immaterial, but I usually employ a strength of about 1 in 5 of water. A few drops of ammonia should be added to this bath, until it smells fairly strongly of the alkali. We have, I believe, to thank Mr. Burton for this most valuable addition to the fixing bath ; it should never be neglected, for it is almost impossible to obtain good clear proofs if the fixing bath be allowed to get in an acid condition. Proofs that have been toned to the full extent — that is, to a rich black or brown black — should not change colour in the fixing bath, unless the bath be very strong, and they be left in for a very long 30 PLATINUM TONING. time, when a slight general weakening will take place ; in fact, they behave as gold-toned prints will under similar circumstances. But, if the print be only partially toned, there will be a general change in the resulting colour. The cause of this is not far to seek. We know that on removing any print from the frame it will be found to possess a very rich colour, that may vary from a bluish purple, reddish purple, to even red, depending on the preparation of the paper. The purple or bluish portion of this tint is due to the subchloride of silver, that is naturally of a bluish or purple colour. This colour, mixing with the reduced organic salt of silver, which varies from a cheesy yellow colour in gelatine to a foxy red in albumenised prints, gives the resulting rich reddish tones that in many cases are so beautiful. When we come to treat the print with hypo- sulphite of soda, we find that this purple subchloride is destroyed, a small portion being reduced to metallic silver, and the greater portion being dis- solved out. The organic salt of silver is not, however, altered by the hyposulphite ; but, all the purple subchloride having disappeared, the print naturally assumes its true reddish colour. This is the cause of the change of colour when prints are immersed directly in the fixing bath, or indeed in simple salt brine, which is also a solvent of the purple subchloride. AFTER TREATMENT. 31 It is only fair to state that this is not the only theory advanced. MM. Davanne and Girard, who, I believe, would not admit the existence of a sub- chloride, assumed that the reduced silver on the print was able to combine with the albumen or other organate when a saline wash was applied, such a wash having the power of softening the albumen or gelatine. This combination of the metallic silver with the organic size, or lake^ as they termed it, was of the characteristic red colour. Whatever may be the correct explanation, the fact remains that the prints do change colour ; and therefore, if the prints are only partially toned, the resulting colour will also change, proportionally of course to the amount of silver left in them. We cannot of course specify what this change will actually be, as it entirely depends on the kind of paper used ; but experience will soon show the worker what tones he may expect. AFTER TREATMENT. The washed prints should be allowed to remain in the fixing bath for about ten minutes, moving them about frequently, and not allowing them to form a clotted mass, to which the hypo can have no ready access. It must be remembered that the first action of the hyposulphite is to form a double salt with the silver that is insoluble in 32 PLATINUM TONING. water : it is, however, quite soluble in an excess of hyposulphite. It is at once apparent that it is of the highest necessity that plenty of hypo be pre- sented to the print, or this insoluble salt will be left in the paper ; and as this salt is extremely unstable, it rapidly splits up into sulphur and sul- phurous acid, which yellow in their turn all the whites of the prints. If any one is desirous of seeing the effect pro- duced, let them brush a little weak hypo over the surface of an unfixed proof, and let it stand. They will find that the whole paper will rapidly turn of a dirty yellowy brown colour, that cannot be removed by any agents that will not also remove the image. Just as with ordinary gold toning after removal from the hypo, the washing should be thorough, and the prints not merely thrown into a pan in a mass, and then hauled out again and thrown into another ; but each print removed separately from one pan into another. There is no better or more efficacious way of washing prints than by using a squeegee. When the print is removed from the hypo, it is laid face downwards on a sheet of glass, and a squeegee passed over its back once or twice, and the print then placed in clean water ; in this way most of the hypo in the print is removed, and not carried over into the next washing pan to con- taminate it. If the prints be thus squeegeed about DEYING THE PKINTS. 33 ten times, leaving them to soak about five or ten minutes between each, there will be but little danger of any hypo being left in them. When prints on gelatino-chloride are being mani- pulated, it should not be forgotten that they are vastly improved by being passed through a bath of alum and water. A saturated solution of the crystallised alum is best ; this hardens the gelatine, which will otherwise be very liable to suffer in the after treatment. This alum bath should only be used when the print has been nearly completely freed from hypo ; for if this salt be present in the paper in quantity, it will form with the alum a gelatinous deposit, that will dry out of a powdery white, and at the same time be decomposed itself and leave insoluble sulphur precipitates in the film. I take this opportunity of strongly protesting against the use of any hypo eliminators except pure water. Hypo is a salt that is extremely soluble in water, and nothing will be gained by converting it into any other sulphur or soda compound probably less soluble, which after all must eventually some- how or other be removed from the paper, DRYING THE PRINTS. Although we have now passed beyond the domain of any treatment special to my toning 3 34 PLATINUM TONINa. process, still a word or two on the subsequent treat- ment of the prints may not be useless to some beginners. The drying of the prints presents naturally no difficulty, those on the matt paper being conveniently dried between blotting paper, or laid out on this material, or perhaps, what is better, clean linen, to dry. The absence of all glaze on their surface allows them to lie quite flat, and they show no tendency to cockle. Albumenised prints, on the contrary, do roll up occasionally in a very awkward manner. This will be minimised, however, if they are laid out to dry with the albumenised surface downwards. When dry the prints should be trimmed to suit the operator's taste. I do not recommend the trimming of the prints before toning, as some do, on the score of economy of toning solutions, because the dark edges of the print take up a good deal of the platinum. I have always found that prints in the different manipulations are very liable to get torn or spoilt by fingering, especially at the corners. If they have been trimmed, they are then of course useless, and have to be destroyed. The value of one 10 by 8 print will soon compensate for a good deal of toning solution lost on the untrimmed margins. MOUNTING THE PRINTS. 35 MOUNTING THE PRINTS. I have had an opportunity of examining a good many old photographic prints lately, dating from 1855 and earlier, and I have frequently remarked the marvellous difference in stability between those prints that have been mounted in an album and those that have been simply trimmed and kept in portfolios. The action of light appears to have nothing to do with it, as one kind has been no more exposed to light than the other. The cause of the fading, — a real fading I mean, not a yellowing of the high lights (this, by the way, is rarely if ever met with in plain paper prints, being, a special attribute of albumen), but a general loss of intensity, and in some cases almost total disappearance of the image, — the cause of this fading is undoubtedly due to the mountant. An additional and very absolute proof of this fact is given by photographs that have only been mounted round the edges. In such prints the destruction of the image accurately follows- those portions of the prints touched by the mountant. A pretty illustration of this can be seen in Fox Talbot's Pencil of Nature." The larger views have been mounted by the edges only, and the edges only have suffered ; the smaller ones have been pasted or gummed all over, and have faded all over. 36 PLATINUM TONINa. As I am not aware of the composition of the monntants used, it is impossible to say whether all or any particular monntants caused the destruction of the silver. It is more likely caused by a decom- position and consequent acidity of the materials, which react on the silver or oxide of silver of the image. Alum I know will cause a developed print on bromide papers to fade very rapidly ; some enlargements of mine which were mounted by an ordinary map mounter, who uses alum as a pre- servative to prevent his paste becoming mouldy, having now almost entirely disappeared. Alum, as I have satisfied myself by experiment, has a very powerful destroying action both on the developed and printed-out image. Even when strongly toned with gold, a sojourn in alum will very seriously weaken the print ; and proofs toned by my own process also suffer, though in a less degree, from such treatment. Gaining wisdom from these experiences and experiments, I now make it my practice to only mount my prints by the edges, and cover only as little as possible of the print with the mountant. I use for this purpose gelatine or best Scotch glue of a pretty stiff character, nearly as thick as one would use it for gluing wood. My method is as follows : — I lay the print on a board, and, taking a sheet of glass slightly longer than the print in the left hand, I lay it along the edge of the print I am MOUNTING THE PEINTS. 37 mounting, keeping it about one-eighth of an inch from it. I then brush the glue over this portion of the print, the glass protecting all the rest, only a strip one-eighth of an inch broad receiving the glue. The three other sides are manipulated in the same manner, and the print has then a narrow slip of glue all round it. The prints are of course pre- viously damped by putting them in damp blotting paper till they are just flabby but not yet wet, and on being placed in position on the mount are pressed down with a clean sheet of blotting paper, which will absorb any superfluous glue that may exude. The edges of the print naturally dry first, and the glue therefore holds these firmly down, and the centre, afterwards drying, contracts and pulls up the whole print till it is as flat as the proverbial board. The only mistake likely to happen in this method of mounting will be through the print being too wet or the glue too weak, in which case it may not dry and seize hold of the paper before the centre contracts and pulls it off. I think this method of mounting should be more universally employed than it is ; it tends to largely prevent cockling of the mounts ; for the prints, being- mounted almost dry, do not shrink too much. This concludes the first portion of my pamphlet, that describing the manipulatory portions of my process, as applied to the commercial sensitised papers ; but what I look on with special favour is 38 PLATINUM TONING. that these same manipulations can be applied to paper that can be prepared at home, choosing the particular brand that one prefers, and not being tied down to the peculiar tastes of the wholesale dealers. I feel convinced that if amateurs could be brought to appreciate the ease with which paper, linen, silk, wood, or any fabric can be salted and sensitised, more of them would take up this fasci- nating branch of photography. I have therefore devoted the second half of this little pamphlet to a description of those methods which have suc- ceeded best with me of preparing different stuffs and fabrics, hoping thereby that I may induce some amateurs to take the subject up, with the effect, I feel sure, of largely benefiting our exhi- bitions, and generally advancing the status of photography as an art as well as a science. PAET II. PBEPABATION OF SENSITISED PAPEB. In tliis second portion of this pamphlet I propose to deal entirely with the art of preparing paper or other substances for printing on. The preparation of such paper is at the present day almost a lost art ; the prevalence of ready sensitised papers of all kinds and at extremely low prices has entirely driven the home-made article out of the race. But with the advantages that ready-made paper brings it has also its concomitant disadvantages ; we are more or less bound to one quality of paper, slightly thicker or slightly thinner in substance perhaps, or of a more or less hideous tint, but still always the same texture or surface ; and on this ar© indiscriminately printed the bold outlines of large heads or grand landscapes, or the exquisite details of stereoscopic work, or the micrographical fidelity of nature's minutest organisms. Photographic amateurs are, I regret to say, an exceedingly lazy lot, with an increasing and morbid 40 PLATINUM TONING. desire to produce quantity — an appetite largely encouraged by the pack of traders and process- mongers who live on their prey's credulity. With amateurs who care for nothing more than the pro- cess that requires the least trouble I have nothing in common. For them the following pages will be useless. And if this work should meet their eye, — a thing which is highly improbable, for they are the class that do not read, they only ask questions, — let them skip all the rest. Those workers, on the other hand, who are 'familiar with the practice of preparing their own paper will find nothing new. My words are only for those who are willing to cast off the old man of the sea of commercial papers, and are anxious to produce the best results from their negatives, but have not had the opportunity of acquiring the art of silver printing. Such workers will, I hope, find their experimental labours lessened by the following lines, in which I have endeavoured to give a succinct account of the operations that have given me most success. CHOICE OF PAPER. I have experimented with a good many different kinds of paper, and find that any pure and good sort will give good results. The slightly different treatment that different brands require I will touch on when necessary as I go along. CHOICE OF PAPEH. 41 Among the samples that I have found particu- larly useful for obtaming bold effects are a heavy (125 lb.) Whatman's rough drawing paper, and a sort of paper known as imitation Creswick^ also by Whatman, which resembles the last in texture, but has an agreeable soft India tint colour. Bank post papers, such as those produced by King, are very sensitive, and give very vigorous results ; and, being very thin but of hard texture, they are most suitable for mounting. Vellum papers have a hard horny surface, very suitable for some portraits, and are obtainable of pleasant soft tints. Papers that are prepared with a heavy glaze, formed of kaolin or barytes, in which class come cream-laid note papers or lithographic papers, are unsuitable, giving wealj and poor prints. Generally speaking, the purer the paper the better will be the result. The substance employed for sizing the paper has a fairly marked action on the result. It is, I think, chiefly for this reason that the French and German papers are so largely used for printing, these papers being sized either with resin-soap or arrow- root; whereas our English paper-makers use gelatine, and of any but a pure quality, obtained from boiled hides and hoofs, hardened with alum. I think it would be an advantage if our own great paper- makers, such as Whatman, would put on the photographic market an arrowroot sized rough drawing paper. I fancy such a paper, carefully 42 PLATINUM TONING. prepared from pure rags, would prove a [aying speculation.* Another defect frequently found in English papers is the prevalence of small particles of brass or metal, probably torn off the machinery or the drying webbs, embedded right in the texture of the paper. On the application of the silver solution, this speck sets up a centre of decomposition of the latter, and a moss-like marking of blackened silver is formed on the paper. Fortunately these markings become apparent as soon as the silver is applied, and the paper can be at once rejected. Another point which is rather trying is to have to throw away a large portion of an expensive sheet of paper, because the manufacturer chooses to expand himself, or at least his name, over a good quarter of the sheet in the form of a water-mark. In thick paj)er this is not seen if the right side be sensitised ; but in some papers it is terribly apparent. It is astonishing that artists have so long allowed them- selves to be victimised by the makers ; photo- graphers have years ago left them and taken their custom to France and Germany, where the manu- facturer is content with a modest and gratuitous advertisement just along one edge of the paper. In addition to the ordinary run of papers, any * Since the above was written I learn that Eeeves &; Sons are selling a specially pure nnbleached paper, known as Arnold's, which appears particularly suitable for silver printing ; it is obtainable only in the hot-pressed form. SIZING THE PAPER. 43 unflyed fabric that is not injured by water will serve most excellently for a basis for positive proofs. The surface of leather or wood is also admirably adapted for this purpose ; indeed, with a little care almost any material can be made subservient to the artist's wants. SIZING THE PAPER. In any ordinary silver-printing process we have three main elements that influence the reduction of the silver salts ; these are, first, the paper, or more properly speaking the sizing or organic matter introduced into the paper, for pure cellulose is almost if not entirely without action on silver salts ; secondly, the saline wash, that is used to form eventually by double interchange the silver chlo- ride, that is the basis of all silver printing ; and, lastly, the soluble silver salt itself. The sizing of the paper has a twofold action in all printing processes. First, it acts like a glaze to hold the silver salt in suspension, and keep it more or less on the surface of the paper, therefore the quantity of size to be used must largely depend on the amount of surface effect we wish to obtain. If we were to take blotting paper, and form chloride of silver on it without any size, the chloride would be held in the pores in the interior of the paper, and an image would appear dull and sunk in. On 44 PLATINUM TONING. the other hand, if the quantity of sizing used be very large, such as is found in albumenised or gela- tinised papers, the whole image will be right on the very surface, and the details be very sharp and brilliant. It is therefore evident that the amount of size given in any formula must depend on the amount of gloss we wish to obtain ; but, at the same time, a naturally absorbent paper, such as plate paper, will require a larger quantity than a hard horny paper like bank post or cartridge papers. The quantity I give in the following formula is what I have found about sufficient, when applied to rough drawing papers, to keep the image well on the surface, but yet offer no appearance of gloss on the finished print. It will be for operators themselves to modify the results according to the particular vehicle they use, and the particular results they wish to obtain. The amounts I use are almost the maximum possible without causing gloss; for I prefer to use as much size as I can, as there is every advantage in so doing, for it renders the paper tougher and the print more brilliant. But the sizing has another important action in silver printing — that is, it chemically combines with the silver nitrate, and forms a fresh silver salt, termed generally an organate^ which possesses many properties that strongly influence the result- ing print. We cannot do better than here make a few SIZING THE PAPER. 45 elementary experiments as to the action of light on silver compounds ; they will give us an insight into silver printing that will serve us on many a future occasion. In plain paper printing, and indeed for the matter of that in albumenised paper, the silver salt that is found to be best suited to the action of light is the chloride. Now this salt is produced by double decomposition by adding a soluble silver salt such as the nitrate to a soluble choride such as sodium chloride ; silver chloride, an insoluble white salt, is then formed, and sodium nitrate remains in solution. If we take some of this chloride that has been so formed on a strip of glass, and expose it to light, it will be found to darken, and turn of a lilac blue colour, more or less dark according to the length of exposure. If we take another portion of this chloride, and mix with it some organic size such as gelatine or albumen, and expose this to the same light, it will change colour also, but will become of a more or less reddish colour. When we treat the two samples with hyposulphite of soda, we perceive a great difference in the result; the blue sample is almost totally dissolved away, whereas the reddish sample changes but slightly, becoming if anything more red. It is clearly evident, therefore, that the sizing used enters into chemical combination with the printing salt, and forms a fresh chemical compound, 46 PLATINUM TONING. acted on by ligM^ and that such compound resists the action of hyposulphite. Therefore, since hypo must be subsequently used as a fixing agent, it follows that the positive image must be formed of a substance that will resist its action : in other words, our printing salt must be more than silver chloride ; it must be a silver organate. We here have another reason why size should be employed in printing. As a matter of fact, every kind of paper, except perhaps the purer kinds of filter paper, contains originally enough size in its manufacture to fulfil these conditions ; so that the extra quantity of size added to the salting formula is not requisite for this purpose. But the important bearing that size has on the resulting print should not be forgotten for this reason. As the size is usually applied to the surface of the paper at the same time as the salting solu- tion—except in cases of very porous paper, in which case it may be advisable in order to prevent a too great sinking in of the image to apply a prelimi- nary sizing to the paper before salting — we will at once proceed to settle the best amount of alkaline chloride that should also be applied to the paper. SALTING THE PAPER. We can either apply a soluble chloride to the paper, and then by the addition of the soluble silver SALTING THE PAPER, 47 salt form the chloride ; or we can apply the silver first, and then the soluble chloride, and it makes a very great difference in the result which salt we apply first. Let us return to our experiments again, but use paper this time. If we soak a slip of paper in an aqueous solution of sodium chloride and let it dry, we shall have nothing but sodium chloride in the paper ; if we apply a nitrate of silver solution in excess to this, the chloride of sodium. will be all converted into chloride of silver, but there will still be some nitrate of silver un- altered, which will dry on the surface of the paper ; and we shall have therefore a film of chloride of silver with nitrate of silver in excess. If, on the other hand, we apply the nitrate of silver first and let it dry, and then treat it with a solution of sodium chloride, we shall have now a film of silver chloride ; but sodium chloride, instead of silver nitrate, will be in excess. Now expose these two strips to light. We shall see that not only will the first strip darken more quickly, but it will grow much blacker, eventually assuming an almost metallic appearance ; whilst the second will never progress beyond a weak bluish tint. It is therefore evident that it is essential that silver nitrate should be in excess ; and therefore the salting solution should always be applied to the paper first, and then this be subse- quently floated on the silver bath* 48 PLATINUM TONING. STRENGTH OF SOLUTION. Any one consulting the different formulae of different workers must feel rather staggered by the very great varieties in the strength of the salting solutions each writer proposes. It is evident at first sight, since we form a chloride of silver by a chemical substitution, that this must take place in definite quantities; and therefore some connection will be found between the strength of the salting and sensitising solutions that will ex- plain some of these differences. But still there is a decided difference in results obtained from weakly salted or strongly salted papers, — a difference that no alteration in the strength of the silver bath will compensate for. It vrill here be interesting to the student if he prepares a few strips of paper, and salts them on baths of different strengths. After sensitising them on the same silver bath, and exposing them and noticing their different behaviour, he will learn far more in a few minutes than he possibly can by pages of reading. The first difference he will notice is that the rapidity increases with the amount of salt present, as does also the degree of blackening the paper assumes. However long he may print, a paper only slightly salted will never give a vigorous deposit of coloured silver; and a paper prepared with a bath of STRENGTH OF SOLUTION. 49 medium strengtli will take a long time or require very brilliant light before it attains a maximum darkening. On the other hand, paper that is richly- salted darkens very quickly and attains great in- tensity under the influence of a feeble winter's light, and in a strong light assumes a true metallic lustre. The advantage that can be taken of this fact will have been already noticed by the thinking reader. A hard negative is one where the contrast between the high lights and the shadows is very great — that is to say, the shadows have to be exposed a very long time before the light can penetrate the high lights. We should therefore in such a case decrease the quantity of salt on the paper; for in this case it will require a long exposure to darken the shadows, and the detail in the high lights will have had time to make its appearance. In the case of a thin negative the opposite obtains. The high lights are formed by such a feeble deposit that all the detail in these is impressed on the paper before the shadows have had time to attain even a moderate amount of blackness. In such a case it is therefore evident that our procedure will be to increase the amount of salt, and make the paper capable of darkening to the maximum degree with a feeble light. It is one of the great advan- tages of preparing one's own paper that it gives one a still further chance of correcting errors in the negatives, whether from exposure or development. 4 PLATINUM TONING. CHOICE OF CHLORIDE. It is clear that, since all we require from salt added to the paper is its chlorine, it does not very much matter what chloride we use, providing only in changing from one to the other we remember to make the change in chemical proportions, so as to have the same amount of chlorine present in each case. The chlorides that are most commonly used for salting pa]3er are those of barium, sodium, or ammonium, and their proportions are 22, 11, and 10 — that is to say, that if a formula gave ten grains of ammonium chloride, and you wished to use barium chloride instead, you would require twenty-two grains of the latter, or eleven grains of sodium chloride, to form the same amount of chloride of silver. It is generally stated that the different chlorides produce prints varying slightly in colour. This is undoubtedly true to a small extent ; for at the same time that chloride of silver is formed on the joaper a nitrate of the base of which the chloride consisted is also formed, and remains and dries more or less on the surface of the paper. But when prints are being made with the in- tention of being toned, the alteration is really not very apparent, especially if they be sensitised with ammonio-nitrate, — a way I shall presently advise. Therefore I consider it absolutely a matter of in- diflference what chloride is used. I generally prefer CHOICE OF CHLORIDE. 51 myself the ammonium salt, my reason being tliat the product of this is ammonium nitrate ; and my favourite sensitising bath is formed of oxide of silver dissolved in ammonium nitrate. I therefore introduce no fresh complications by this salting mixture. The salting bath I prefer is made up as follows : * Arrowroot 180 grains. Chloride of ammonium 160 Water 20 fluid ounces (1 pint). The arrowroot should first be worked up to a paste with cold water, avoiding lumps ; then nearly the full amount of hot water is added — the liquid has then a milky appearance ; it should then be brought up nearly to the boil, avoiding boiling if possible, as this fills the solution with small bubbles, that are apt to leave insensitive spots on the print when floated. The point aimed at in heating the solution is to get the arrowroot into a gelatinous stage ; this is easily observed by the liquid losing its milky appearance and becoming clear, or nearly so. A little help from the culinary department will be of aid to any one in doubt at this stage of the process. When the solution has somewhat cooled, the ammonium chloride that has been previously dissolved in a little water is added, and the solu- * This bath should be tested with litmus ; if acid, add a little ammonia till alkaline reaction sets 52 PLATINUM TONING. tion well stirred, when it is ready for use. The ammonium chloride should not be added when the liquor is very hot, or it will be decomposed and ammonia given off, as will be recognised by the smell. This salting bath will give prints of a red colour, that after toning will become of a brownish black, especially when sensitised on plain nitrate. I generally prefer to make a further addition to the sensitising bath, and that is citrate of soda. The effect of adding this organic salt appears to be to give a more vigorous image of a purplish colour, that seems to consist of more silver, the citrate acting in the same way as an organic size ; and prints prepared on this bath are more suitable where a complete and thorough toning is wished for. The fact of their containing more silver admits of more platinum being deposited, and a degree of black- ness in the shadows can be obtained only com- parable to a cold-bath platinotype. This bath is made up as follows : Grains, or Grammes. Chloride of ammonium* 120 „ 14 Carbonate of soda re-crystallised 240 „ 28 Citric acid crystals 60 „ 7 Arrowroot 180 „ 21 Water 1 pint or 1,000 c.c. (1 litre). * The crystaUised chloride is meant, — not sal-ammoniac, which is very impure and very deliquescent. No correct quantities can be weighed ; it also contains free HCl. CHOICE OF CHLOEIDE. 53 The chloride of ammonium, carbonate of soda, and citric acid are all dissolved together. As they are in crystals, their dissolution will not be very rapid, and no very great effervescence will be set up ; otherwise, if they were made in separate solutions and mixed, they would probably throw themselves out of the beaker from the excessive effervescence The above quantities should leave the solution alkaline. It is well, however, as the strength of these chemicals varies, to make sure of this fact, which is best done by adding a drop or two of a carbonate of soda solution to the above ; if an effer- vescence results, it shows that there is an excess ot citric acid, and more carbonate should be added until all ebullition ceases.* It is important that the solution be not distinctly acid, as it will then have an action on the sizing of the paper, and the salt will sink into the texture, and the resulting prints will be fiat and weak. The method of preparing the arrowroot and adding the salt will be exactly the same as already described. If it be preferred, gelatine can be used, although the arrowroot sizing appears most suitable for platinum toning. In such a case the above formula should contain 240 grains (28 grammes) of gelatine. The ordinary esculent variety sold by Nelson in six- * Old ammonium chloride is apt to become acid from giving off ammonia. 54 PLATINUM TONING. penny packets is what I generally use.* The method of preparing the gelatine is slightly different. The shreds are first to be put into cold water, in which they should be left to soak till they have absorbed all the water they can. This can easily be ascer- tained by their appearance, as they lose their horny opaque character, becoming lighter and trans- lucid. The cold water is then poured off and hot added, when the gelatine will all dissolve. If neces- sary the heat must be increased till this takes place. The subsequent proceedings are the same as when arrowroot is used. The above strength of gelatine will, on cooling, solidify more or less into a fairly strong jelly, and will require reheating each time it is used. The arrowroot will, however, not do so, or at least should not do so. If it be of sufficient strength to set, the danger may be incurred of its forming in greasy streaks on the surface of the paper, especially if the solution has been applied with a brush. Other colloids, such as starch, Iceland moss, or even best glue, may be used for sizing papers ; but, on the whole, I prefer arrowroot, which is moreover excessively easy to procure. It should, however, be made up fresh each time, as otherwise the gela- tinous portion is apt to separate out by subsidence, leaving a merely aqueous solution. * 240 grains is a maximum quantity for rough papers; hot pressed or not wiU require less. METHOD. 55 METHOD AND TIME OF APPLYING THE SALTING SOLUTION TO THE PAPER. If it be required to use the above salting solutions at once, it will be probably necessary to filter them. Flannel or fine muslin is perhaps the best for this : in fact, information may again be sought from the cook, and the household jelly bag impounded into service. If the solution be allowed to stand over night it will filter itself, or at least a clear liquid can be obtained from the top by decantation. As a matter of fact, I prefer not to filter the arrowroot. If a sufficient depth be used in the salting dish, all impurities will sink to the bottom and do no harm, and it is always better to use it fresh. If a large quantity of paper is to be treated (and since simply salted paper will keep indefinitely this will probably be the case), the best method of applying the solution will be by floating the paper on a thin layer of the solution spread over any ordinary dish, the paper being lowered down on to it so as to avoid bubbles, and left in contact for about a couple of minutes or so, the time naturally depending on the paper used. I need hardly point out that the right side of the paper should be chosen for floating. This can be generally ascertained by inspection ; there is a rougher look about this surface, the other side 56 PLATINUM TONING. which has rested on the strainers having a more moulded appearance. The water-mark will always settle this question if any difficulty is found. When this is read correctly — that is, right way up — the side that then faces the eye is the correct side to salt. When once ascertained, a mark should always be made — preferably on the reverse side — to obviate the chance of sensitising the side that has not been salted. Care should always be taken that none of the liquid get on the back or wrong side of the paper, as dark patches will be left on the finished print at those places wetted by the liquid. The time that the paper is left on the bath is somewhat dependent on the nature of the salting mixture. If this contains a good deal of size, the floating need be but short, for the colloid will come off on the paper in a thickish film, containing a sufficiency of the chloride ; but if the size be in a minimum amount, and the paper somewhat hard, longer time must be allowed for the liquid to penetrate through the surface of the paper. If, on the contrary, the paper be naturally porous, a very short contact with the bath will suffice. But at the same time it is never advisable to too much curtail the time of floating, or the resultant prints will appear of a weak reddish colour, printing but slowly even in strong light ; so that, except in the case of very thin papers, I generally float from METHOD. 57 two to three minutes, and with thick drawing paper five minutes, or even longer. When a rough surface drawing paper is to be salted, it will often be found that the surface is most repellent ; and when a corner is lifted off the bathj it will be seen that the liquid has only touched here and there. It is surprising in this case what patience will do ; and if the sheet be left in contact with the bath sufficiently long, it will gradually become entirely impregnated. But if the paper be found very horny, it will save time if it be brushed over with a very weak 1 in 100 solution of hydrochloric acid (commercial), or with a solu- tion of ox-gall such as is used by water painters, or even a little of the salting mixture can be rubbed on. Should it only be required to salt a single sheet of paper, the solution can be very well brushed 58 PLATINUM TONING. over tlie paj^er, that has been previously pinned down on a board. The best form of brush that I have found for this purpose is a modification of the Blanchard brush. A piece of swansdown cahco is taken, and a sheet of the new celluloid now used for film photography. The swansdown is laid fluffy side outwards on the celluloid sheet, and the two are doubled, swansdown outward, without making a sharp bend, and the two ends brought together and retained by an indiarubber band between wooden clips. The down of the calico is sufiiciently absorbent to take up the liquid, and the celluloid sufficiently elastic to keep it firm without scraping ; the film being doubled insures the edge being in a perfectly straight line. This brush can of course be made of any length, and is a most useful adjunct in nearly all photo- gra23hic manipulation. Care must be exercised in coating a sheet of paper, in order that the film, especially if it con- tains much of the size, may be of equal thickness ; otherwise, on hanging the sheet up to dry, the size may run into streaks, which, although not apparent on the dried sheet, will after exciting and printing come out very much deeper in tone, owing to the presence of more chloride. In all cases, when paper is salted by brushing on, it is necessary to allow the paper to lie flat for a minute or two, so as to imbibe sufficient of the liquid. METHOD. 59 It is sometimes recommended to soak the paper in the salting bath. For negative work this is all very well, as it is quite immaterial whether the image be formed in or on the paper — in fact, the more deposit attainable the better ; but in the posi- tive process the only useful image is that formed on the surface of the paper. The presence of a chloride right in the pores of the paper requires a great deal of silver nitrate to convert it, and until it is all converted we can never have nitrate in excess, and we know that this is a necessity. We shall thus fill the pores of the paper with silver chloride, that will never be touched by light — for a thin surface layer of darkened chloride effectually protects the salt that is beneath it — but will be simply fixed out in the hypo bath and wasted. On the whole, I consider floating to be far the most satisfactory method and most conducive to good results. In the case of a single sheet specially salted for some specific purpose brushing on may be re- sorted to, but for general use the floating is the best. The salting and drying of the paper may of course be conducted in any light, the paper being still entirely insensitive. My own practice is to hang them up by one corner to laths of wood in a closed passage, that can be warmed by a gas jet, thus constituting an impromptu drying cupboard. It is certainly advisable to dry the paper as quickly as possible, as this tends to prevent the salting liquid 60 PLATINUM TONING. sinking too mncli into the pores of the paper; keeping it, so to speak, more on the surface, especially if the amount of size present be rather high. When dry the sheets can be stored away in a port- folio or cupboard till required, as in this condition they keep indefinitely. The professional who prepares silver paper naturally salts and sensitises the sheets of paper as large as he can obtain them, the usual size being 22 J'^ X 17|'' ; but I think most amateurs will find it convenient to deal with much smaller sizes, as -these do not necessitate the purchase of large dishes. The size I usually adopt is about 12" x 10", because this is the size of negative I work, and my ordinary dishes come in handy, and the whole manipulations are much simplified, it being an easy matter to deal with such a small size. Drawing paper (Whatman's) is usually made in the size known as double elephant ; this measures 40' X 26|". By folding it twice in the width and four times in the length, we obtain eight sheets 10'' X 13", very suitable for 12" x 10" work. If we fold it four times in the length and three times in the breadth, we get twelve sheets 10" x 9". Or, again, for whole plate size, twenty pieces 8'' x 6|" will be obtained. The paper would of course be pre- ferably prepared in pieces 8" x 13", as some little waste will always take place at the ends where the paper is pinned down to sensitise or hung up to dry. SENSITISING OB EXCITING THE TAPER. 61 Other papers are made of different sizes, and I append here a list of the ordinary sizes and the generic names of drawing papers. Inches. Inches. Emperor 72 x 48 tAntiqnaiw 52| x 30|- tDouble Elephant 40 x 26| Atlas 34 X 26 Colombier 34| x 23^ timperial 30 x 22 Elephant 28 x 23 Super Royal 27 x 19 tRoyal 24 x 19^ fMedium* 22 x 17^ Large Post 20J x 16| Copy 20 X 16 tDemy 20 x 15J Post 19 X 151 Foolscap 17 X 13^ Pott 15 X 121 SENSITISING OR EXCITING THE PAPER. The operation of sensitising, although not requir- ing a dark-room, is preferably carried out by gas light, or in a room with the blinds drawn down. A moderate amount even of daylight is not very injurious. For instance, the window of the dark- * This is about the size that is used in foreign printing papers, and is the size of the ordinary sheet of albumenised paper, t Those marked f are the sizes most commonly met with. 62 PLATINUM TONING, room may be left open during the operation, but the drying of the paper should be strictly conducted only in artificial or yellow light. I have spoken of the diversity of opinion as to the strength of the salting bath ; but the variations that have been given from time to time in the strength of the silver bath are much greater. In the early stage of the collodion process, it was the fashion to use baths of the strength of 125 grains to the ounce. (It has always been customary to speak of the strength of the silver bath as so many grains of silver nitrate per ounce of bath solution, and I therefore retain the term.) After these strong baths a reaction set in, and they fell as low as 20 grains to the ounce ; but nowadays the general tendency seems to be in favour of baths of 60 grains to the ounce — that is, about 14 per cent. It is pretty evident that the strength of the bath can have no very great effect on the print ; there is a certain quantity of chloride in the paper, and when this is presented to the silver nitrate silver chloride will be formed. If the silver nitrate is very strong, the formation will be very rapid ; if weak, it will take longer ; but the result will be that all the chloride will eventually become silver chloride. Theoretically, therefore, the result should be the same, if a weak bath and a lengthy floating is used, as if the bath were strong and the floating short. SENSITISING OB EXCITING THE PAPER. 63 There are, however, certain differences in the results obtained by weak and strong batlls. These will perhaps not be noticed nntil the strength is reduced, say, to below 30 grains ; but after this the prints will become weak and reddish, having no density. The cause is probably of a twofold nature. It is well known that a strong nitrate bath coagulates albumen, whilst a weak one dissolves it. The action is pro- bably somewhat the same when other organic colloids are used, and therefore a weak bath by dissolving off some of the sizing also destroys some of the salting mixture. Secondly, we have ascertained that it is necessary that free silver nitrate be in excess if we wish vigorous prints. Now only a certain amount of mixture can be retained on the surface of the print ; and if this moisture only contains a minimum amount of nitrate, but little will be left on the print ; whereas if it be a concen- trated solution that is employed, a fair amount of free nitrate will remain. For this reason I prefer, therefore, to use a mode- rately strong bath — that is, 60 grains to the ounce — and never allow the strength to fall below 40 grains. In metric measures the bath will be equivalent to 14 grammes in 100 c.c. of bath solution. Such a bath as the above constitutes the ordinary sensitising or exciting bath of the photographer, and is used for albumenised paper ; it has the drawback, however, that paper floated on it will not 64 PLATINUM TONING. keep long — a few days at most. Furthermore, when used in conjunction with plain paper, it does not give images of the greatest vigour ; and, having the idea of subsequent toning in view, it is very desirous that our image should be formed of as great a deposit as possible. Plain paper does not carry with it the same quantity of organic matter as does an albumenised print, in which the albuminate of silver forms the largest part of the image. It is therefore advisable to add an organic salt of silver to our sensitising bath, and the one I have found most suitable is the citrate. The citrate of soda added to this salting bath is already present in its maximum quantity. It is a very deliquescent salt, and if the proportion given above were increased the paper would always be damp. Another way of forming citrate of silver would of course be to add citric acid to the salting solution ; but this would have this effect of destroy- ing the size, and giving the picture a sunken-in appearance. It therefore only remains for us to add it to the sensitising bath. This can be done perfectly well, as no precipitate will be formed on adding a solu- tion of citric acid to the nitrate of silver solution. The addition of the citric acid plays another and not unimportant part. If salted paper be floated on simple nitrate of silver, it will not keep beyond a few days — sometimes not even that. Now the cause SENSITISING OR EXCITING THE PAPER. 65 of this is iindoubtedly the free nitrate of silver that is left on the surface of the paper. This can be easily proved, because, if the free nitrate be removed by washing, the paper will be found to keep fairly well ; but the drawback of this is that such washed paper becomes very insensitive, and requires fuming with ammonia before vigorous prints can be pro- duced. But if, instead of floating the paper on silver nitrate, we float it on silver citrate, no free nitrate will be left, only free citrate, which has no tendency to spontaneously decompose when protected from light. Now there are two ways of preparing such paper. We can sensitise on the ordinary nitrate bath, and when the paper is dry float again on a solution of citric acid, by which means all the free nitrate will be converted into a citrate. Such paper will keep good and pure for a very long tim^e, and it is most probably the way in which the ordniary albumenised sensitised paper of commerce is prepared, although the precise manipulations are kept secret. Or we can add the citric acid at once to the nitrate of silver, and then float the paper on the mixed solutions. On the whole, I prefer this system, as it involves less time and less trouble; and although the paper does not keej) perhaps quite so well as commercial paper, still it keeps reasonably ; and as my custom is only to sensitise about as much as I require, I have experienced no great loss from the paper going bad. 5 66 PLATINUM TONING. The following is then the bath that I recommend for exciting papers salted according to the formulae given above : Dissolve 25 grains crystallised citric acid in | ounce water. Dissolve 60 grains silver nitrate (re-crystallised) in ^ ounce water. When both salts are dissolved mix the two solutions^ and they are ready for use at once. IN METBIO MEASUEES. Citric acid 5^ grammes. Silver nitrate 14 „ Water 100 c.c. The above proportions are given in Captain Abney's work on silver printing, and as I find from experiment that they are most suitable I there- fore give them unchanged. The acidity of the above bath^ although prejudicial when the alkaline gold toning bath is to be used, comes in very usefully when the acid platinum bath is employed; and it is, of all the different sensitising mixtures I have experi- mented with, the one that has given the best results.^ There is, however, another method of sensitising which I sometimes employ when the weather is dull or the negatives are weak, as it is extremely rapid in its action, and tends to produce extremely vigorous images. This is the modification of the ammonio-nitrate bath, introduced by Dr. Hardwich, SENSITISING OR EXCITING THE PAPEB. G7 and is virtually oxide of silver dissolved in nitrate of ammonia. If strong ammonia be added to. silver nitrate, a brown precipitate is instantly thrown down : this is oxide of silver. If the ammonia, however, be added in excess, it will be redissolved, oxide of silver being soluble in this menstruum. This solution constitutes the ammonio-nitrate of silver, and is undoubtedly the most rapid printing-out process known ; it has, however, the grave drawback that neither the solution nor the paj)er coated with it will keep, as it spontaneously discolours in a short k time, however carefully kept. It is this solution, in fact, which is the common marking ink of the housekeeper, the presence of which a hot iron is sufficient to disclose. In hot weather paper pre- pared with this salt will not keep over night, but will be found to have turned yellow and destroyed the purity of the high lights. Dr. Hardwich's improvement enables one to keep the mixture when in the dark for some considerable time, providing, however, it be not used ; and the paper itself will keep a day or two, the time depending largely on atmospheric conditions. The solution is prepared as follows : Sixty grains of nitrate of silver are dissolved in half an ounce of distilled water ; to this strong ammonia (880^^) is added ; a brown precipitate is formed ; the ammonia is still added until the Uqnid 68 PLATINUM TONING. shows signs of clearing. During the operation the liquid should be constantly agitated with a glass rod. The last drops of ammonia should be added cautiously, so as to only just redissolve the j)recipi- tate, leaving no excess of the ammonia. Half of the above liquid is taken, and nitric acid is added to it till litmus paper shows a slight acidity ; the two liquids are then mixed together, and if neces- sary the bulk made up to one ounce with water. The liquid will probably require to be filtered, as a brownish precipitate sometimes results. After this it is at once ready for use. When I first observed the above precipitate, I was very mu^h . afraid that I had formed some fulminate of silver, a particularly explosive salt, which is formed by adding very strong ammonia to oxide of silver, precipitated by potash ; but I find that Dr. Hardwich has noted this same precipitate, and docs not find it to be fulminating silver. Owing to the fact that this solution raj)idly deteriorates when in contact with organic matter, prints cannot well be floated on it in the same manner that the paper was floated on the salting- bath. Organic matter of the size would be rapidly carried into the bath, and set up centres of destruc- tive action. It is therefoi^e customary to apply this solution with a brush, or with a glass rod. The brush I cannot recommend, unless a new one be U5(.ai f()r every batch of paper sensitised. The hairs SENSITISING OB EXCITING THE PAPER. 69 of the brush are rapidly destroyed by the silver solution, unless they are kept impossibly clean; and if the brush be mounted in metal, this will be rapidly attacked, and metallic silver formed, which will make black and dirty streaks on the next sheet of paper. The glass rod I find does not act well with rough paper. This method consists of pouring the required amount of solution along a glass rod placed at the one end of the paper ; this is then rolled forward, and pushes the liquid before it, leaving only a thin film on the surface. This acts very well with smooth surface paper, but with the rough varieties leaves the surface most unequally covered. I have found — and I have tried, I think, all known methods — that the best way of coating the paper is by using the modified Blanchard brush I have recommended for applying the salting solution. This is covered with a clean double thickness of swansdown calico, and sufficient of the liquid poured in a small pool into one end of the paper, and with the brush smoothed over the whole surface, wetting everywhere equally. The amount of liquid must of course depend on the preparation and quality of the paper. For 13 by 10 sheets of rough drawing paper, I find a pool about the size of a crown piece the correct quantity. This is a more expeditious and nearly as accurate a method of measuring the quantity required as a pipette or graduated measure ; 70 PLATINUM TONING. the eye soon gets educated, and appreciates at once whether more or less is required. The quantity should not be stinted, as otherwise the prints will be weak. It is well worth while as an experiment to apply the silver very unequally, and then expose the whole sheet to light. The different degrees of darkening are very instructive, and may prove use- ful in determining the cause of subsequent failures. The paper should be allowed to lie flat for at least a minute after the solution has been apjplied, so that it may be properly imbibed ; the sheet can then be hung up by one corner and dried in the ordinary way. Moderate heat may be applied : for instance, the print may be held in front of a fire, or hung up over a paraffin lamp or stove. It is most important that an excess of silver nitrate be left on the surface of the print. With the strong salting baths I have given, unless plenty of nitrate be applied, it will all be converted into chloride, and instead of getting a vigorous print of a red brown to black colour we shall only get a faint image of a slaty blue colour. When the paper has been covered with the nitrate, it should be looked at by reflected light ; and if all the surface glistens with moisture, there will probably be enough nitrate present. It is always advisable to add so much nitrate that, when hung up to dry, drops collect at the lower end of the paper. Undoubtedly a drying cupboard is a great luxury. THE NITI?ATE BATH. 71 Snch a one can be easily constructed out of a pacldng-case. 1 do not find that the products from a paraffin or gas lamp are in any way injurious to the paper, and therefore if a hole be cut in the bottom of a pacldng-case, and the chimney of a lamp inserted in it, a piece of zinc being placed directly over the funnel, and holes being cut in the top, the hot air will rapidly circulate through the box and quickly dry the paper, which can be sus- pended from pins in the top. Such a box, although entirely useless for dry plates, will do very well for silver paper, and will be found very useful, although it is by no means absolutely necessary. PREPARATION AND PRESERVATION OF THE NITRATE BATH. As a rule, however, amateurs require rarely such a stock of paper as to require any special drying arrangements ; a sheet or two at a time is generally sufficient for their requirements. Considering this fact, I should hardly recommend them to go to the somewhat large initial expense o^ making up a silver bath of sufficient quantity to float their prints on it. To make up twenty ounces of bath — by no means a large one — we should require nearly three ounces of silver ; whereas if the silver be invariably applied like the ammonio-nitrate with a Blanchard brush, only just the quantity required need be made up. Besides, even if a stock solution 72 PLATINUM TONING. be prepared, only just what is required is used, and there is practically no waste, and the stock solution is left uncontaminated. AVhen we come to see the special precautions required in keeping the bath up to strength and free from discoloration, we shall see that this is an important point. I therefore most strongly recommend all amateurs to use the brushing-on process, and simply prepare their paper, whether it be by the citrate or ammonio-nitrate process, just as they require it. It is perfectly possible to have a sheet of paper in the printing frame fifteen minutes after it has been excited, and it is my invariable custom to prepare the paper just as I want it. For those, however, who have enough work to make it worth their while to use the floating process, I append a few instructions, culled from different sources, on the keeping of the silver bath. If it is intended to use a bath and float the prints, some considerable amount of solution will be required. Not only is a certain quantity required to fill the dish in which the paper is to be floated, but a considerable bulk must be left in the bottom of the bottle, containing the sediment and other im- purities, unless the troublesome expedient of filtering be resorted to each time. Generally speaking, about two pints or forty ounces is the quantity made up. The quality of water used for the silver bath is not of any absolute importance. A good working THE NITRATE BATH. 73 bath could be made up with the commonest and dirtiest water, but it is more economical to use dis- tilled water. If chlorides be present in the water, chloride of silver will be formed and thrown down, and can be filtered out ; and if any other animal substance is present, if the bath be sunned, it will also be thrown down. Nitrate of silver, indeed, is one of the most delicate tests for the presence of organic matter in water, as it combines with this latter, and under the influence of light is reduced and blackened and falls to the bottom. But all this is an expense, the silver being rendered useless ; and therefore it is always advisable to use good rain or distilled water. However pure a bath may be on first making up, it soon gets contaminated — first by the double decomposition, when nitrate of ammonium, or what- ever be the base of the chloride used, is formed at the same time as chloride of silver. This is a soluble salt, and has no deleterious effect ; indeed, its addition to the bath is sometimes recommended in dry climates. If a bath be used over and over again, it may at last get saturated with this salt ; but this is not likely to soon happen, as the greater part of the nitrate formed is retained on the print. But another and greater cause of impurity is the organic size that is little by little carried into the bath; this will cause the bath eventually to turn almost black, or at least dark brown. 74 PLATINUM TONING. Many ways have been proposed to correct this, and it is rather difficult to select any particular one. The following method is due to Captain Abnej^, and may therefore be presumed to be the best. This consists in adding about five grains of sodium carbonate to each pint of the discoloured solution ; shake well, and expose to sun- light. The organic discoloration is oxi- dised, and gradually falls to the bottom. If a little freshly precipitated silver be added, the reduction will take place more speedily. The clear solution is then decanted off or filtered ; or if the supply of bath be sufficient, it can be left in the bottom of the bottle. A convenient bottle for this sort of work can be made as follows : — Any wide-mouthed bottle is taken, and its cork is per- forated with two holes. In these holes glass tubes are inserted : one projects into the interior of the bottle to within an inch or two of the bottom ; its outside end is bent round, pointing downwards : the THE NITRATE BATH. 75 other only jnst passes through the cork. One applies one's month to this and blows air into the bottle. The liquid is then forced out of the other tube into the dish or tray, leaving the sediment undisturbed. To return the liquid the cork with both tubes is of course removed and the solution poured in. When a piece of salted paper is floated on a silver bath, it takes up some of the liquid ; but in converting the nitrate into a chloride it takes more of the silver than is contained in the actual amount of liquid it absorbs ; therefore the bath becomes impoverished in silver, as each successive piece of paper is floated on it. And instead of our paper being excited on a bath of sixty grains, it will eventually be excited on one of forty grains or even less. It is therefore necessary, in order to keep the bath up to working strength, to continually add fresh nitrate of silver to it. But it is necessary to know how much a bath has been impoverished, or one cannot tell how much silver to add. An argentometer is the instrument usually recommended for this purpose ; but it cannot be much relied on, owing to the fact of the formation of ammonium nitrate and the organic matter in the bath. The addition of the citric acid would also falsify the readings, the argen- tometer merely determining by displacement the specific gravity of the liquid. If only nitrate of PLATINUM TONING. silver is present, the results would be all right ; but with the addition of fresh substances it would be impossible to know what effect was due to them. A very good method of estimating the actual amount of silver, independent of other chemicals, is due to Mr. Burton, and is as follows : For this volumetric estimation are required a burette to hold one thousand grains and a pipette to hold one dram. A burette is simply a tube with a tap at its lower end, and is graduated wrong way up, so to speak — that is, the zero is at the top; and therefore the quantity that has been run off* is read directly without any subtrac- tion sum. Such a burette is of course supported in a frame or universal holder, so that it stands vertically. A pipette is a glass tube with an en- largement blown on it, the other end being drawn out to a fine point. The tube is graduated, and therefore any small amount of liquid can be drawn up into the tube, and thus a very accurate measure- ment of small amounts can be made. The upper end of the pipette is of course closed with the finger when full ; by this means the liquid is retained in the tube during conveyance into any other vessel. The following solutions are prepared : r Distilled water 22| ounces. ^ /* \ Bromide of potassium ... 87-| grains, r Water 1 ounce. 5 grains. THE NITRATE BATH. 77 To estimate the amount of silver in any un- known bath sohitiouj one dram of it is taken in the pipette and placed in any white vessel, — a tea-cup or an ordinary beaker with a sheet of white paper behind it will do. An ounce of water is then added and one drop of solution (6). This drop will turn the solution bright red, — at least, if it does not, more should be added till it does become clearly red; but no more than is absolutely necessary to produce such redness should be added. The burette is next filled up to the zero line with solution (a), and the tap being opened the liquid is allowed to pour into the cup containing the coloured solution, with constant stirring. As the liquid from the burette touches the other liquid the colour will be discharged ; but when stirred the colour returns. At a certain point, however, the return of the colour becomes slower and slower. At this point the burette solution must be carefully added drop by drop, until the red colour refuses to return even after considerable shaking. The burette tap is then closed, and the quantity of solution used up read off. Each ten figures read off indicate a strength of one grain to each ounce of bath solution, and each unit one-tenth of a grain ; therefore if 475 grains are read ofi' on the burette the strength of the bath is 47| grains per ounce. It is a matter of the simplest calculation, therefore, to find out how much fresh 78 PLATINUM TONING. silver nitrate must be added to bring the bath up to the desired strength. When a silver bath is past all repair, and refuses to clear or become workable, the best way is to precipitate the whole of the silver from it and make it up afresh. If a practice is made of keeping residues, it is perhaps the simplest to at once add the bath to the liquid residues and precipitate them in the ordinary way. But if residues are not kept, the bath can be treated directly in the following manner : — Acidify the bath slightly with nitric acid (10 drops to the pint), and throw in some granulated zinc ; silver will be thrown down fairly rapidly, and the zinc be dissolved. If all the zinc disappear more should be added, until a little is left unchanged. If after three or four hours some is still left, it may be inferred that the silver has been all thrown down. The bulk of the fluid should then be decanted off, and the remainder filtered. From this filtrate any lumps of zinc should at once be picked out, and a little dilute hydrochloric acid added to dissolve any other zinc that may remain. When the effervescence, if any, is over, the zinc will have been all dissolved. The precipitate should be then washed and dried, and heated in a crucible over a Bunsen to a red heat, to carbonise all organic matter. Next cover it with nitric acid (1 in 4), and gently warm it ; the silver will be gradually dis- solved, with production of red fumes of nitrous TONES OBTAINED BY DIFFEKENT PREPABATIONS. 79 oxide. (This operation should be performed out of the way of any tools, as nitrous oxide is a terrible rusting agent.) When a further addition of nitric acid causes no more fumes, the dissolution of the silver is complete. It has then simply to be evaporated to dryness. (This evaporation is preferably twice performed.) Water is then added in such q^uantity that the solution is over strength. The argentometer is then brought into use, and the solution diluted to the required strength. After being filtered to get rid of the carbonaceous matter, sodium carbonate can be added till a slight precipitate of carbonate of silver is formed ; this insures the neutrality of the bath. If citric acid is to be added, this is of course not necessary. TONES OBTAINED BY DIFFERENT PEE- PARATIONS OF THE SENSITIVE PAPER. I have pointed out elsewhere that our only means of obtaining different colours or tints in our result- ing prints is by leaving a portion of the silver image untoned. Now we have a certain power of modifying the inherent colour of the silver image, by choosing certain mixtures for our salting and toning formula. We have really two somewhat wide courses to follow — namely, whether the paper be in an acid or 80 PLATINUM TONING. an alkaline condition — the first state tending to give the image of a very red colour^ v^hich remains after fixing ; the second producing prints of a deep purple colour, fixing out of a deep sepia brown colour. The red tone, mixing with the black of the platinum, tends to give a reddish brown or reddish purple tones ; whilst the brown tones give pure sepia browns, or, if pushed far, most solid blacks. An intermediate bath — that is, a neutral or nearly neutral one — will give also brownish tones ; or if hard toned, prints resembling Indian ink drawings. The acid bath is of coarse the one salted with ammonium chloride, and sensitised on silver citrate; or the mixed chloride and citrate salting bath may be used, but is hardly necessary if the citric acid be added to the silver. A neutral bath would be the chloride and citrate salting bath, and the plain nitrate of silver exciting bath. The alkaline bath will of course be either salting formula, but sensitised on the ammonio-nitrate of silver. HINTS ON TONING AND FIXING HOME- PREPARED PAPERS. As a rule all home-prepared papers tone with much more difiiculty than the ready-prepared papers bought in the shops. Papers sensitised on TREATMENT OF ALPHA PAPER. 81 the ammonio-nitrate bath are excessively slow in toning ; the reason for this is not far to seek, for we know that the toning bath should be acidj whereas of course the ammonio-nitrate paper is sufficiently alkaline to neutralise the free acid in the toning bath. Therefore in toning thick drawing papers, so prepared, it is advisable to give them a preliminary bath of citric or acetic acid, and to use the toning bath warm, and with an extra amount of nitric acid in it. Owing also to the much greater quantity of silver in home-prepared papers, the preliminary washing before toning should be very thorough, or the toning bath will soon become contaminated with chloride of silver, and get very muddy and dirty. TREATMENT OF ALPHA PAPER. The Alpha paper as sold by the Ilford Company is as successfully toned by the chloroplatinite bath as it is by gold. It is of course advisable in exposing and developing the prints to obtain them of as warm a tone as possible. The reason of this is that, if the prints developed up black, it would be very difficult to know how toning progressed. I find that perhaps the most satisfactory bath for these papers is the ordinary developing solution as recommended by the Platinotype Company, 6 82 TLATINUM TONING, This is made up as follows : D. Oxalate of potash 5 ounces. Monopotassic orthophosphate ... 3 „ Water 50 „ P. Potassium chloroplatinite ... 60 grains. Water 2 ounces. Take three parts of one part of P, and two parts of water. Those workers who do not use the Platinotype process can substitute oxalate for the phosphate oi potash, and the formula would stand : D. Oxalate of potash 8 ounces. Water ... 50 „ The reason why I prefer this formula is that platinum, especially when acid, has a tendency to coagulate and stain gelatine, and by using this bath we do away with the acid toning bath. OBEENETTER AND ARISTOTYPE PAPERS. The same remarks and formula apply to these papers also. I notice that Mr. Stieglitz — an early worker with platinum — also prefers the above bath for these prints. ALBUMENISED PAPEH. 83 ALBUMENISED PAPER. If albumenised prints are to be treated, some slight modifications in the working directions may have to be made, depending very largely on the state of the albumen. As a rule, albumenised prints will always tone much more slowly than plain paper prints : this fact was noticed from the very first by Haackmann {Photographic NewSj vol. i., p. 251). It would appear, therefore, that the reduced albuminate of silver that is formed by light has a mechanically retarding action, tending to prevent the free interchange of the two metals. Theoretically, therefore, we should try to soften the coagulated albumen by treating it with some chemical reagent that has a tendency to dissolve the albumen. Such agents are tartaric, acetic, and tribasic phosphoric acid. Practically, I have found that they do act so ; and therefore in cases where the albumenised prints tone very slowly it is advisable to pass them through a pre- liminary bath of ordinary acetic acid one part, water fifty parts, leaving them in for two or three minutes. Such a bath will scarcely be needed with freshly prepared albumenised paper ; but when the paper has been kept for a long time, especially if in a dry place, the albumen gets exceedingly hard or horny, and tones with great difficulty. 84 PLATINUM TONING. PREPARATION OF SILKS AND STUFFS. It is impossible to give any precise directions for the preparations of fabrics generally. It must naturally depend on the nature of the material. As a rule, the surface being somewhat glossy, the amount of size to be added must be considerably lessened, and in the case of thin silk, such as sarsenet, or nansook cotton, it may be done away with altogether. In such a case, however, it will be advisable to add some organic matter to the salting solutions, such as gallic acid, say, three grains to the ounce. The advantage of doing away with sizes in the thin silks is, that they have no tendency to lose their natural gloss. However, if dextrine be used instead of gelatine, the same effect will be pro- duced, as this substance will wash out in the after treatment. Thin silks are preferably salted and excited by being attached to a wooden framing, otherwise it will be found very difficult to apply the exciting solution equally, and white insensitive wavy lines will be formed. Thick materials, such as satin jeans, on the con- trary, want well sizing, or otherwise the silver will be formed in their interior, and blotches and stains may be caused. The gloss of sizing can always be subsequently destroyed by acids or strong alkalies, such as carbonate of soda or potash. APPENDIX. TO MAKE NITRATE OF SILVER. Take any standard coin, or scraps of silver obtained from any jeweller — the purer the better ; the pro- bable adulterations will be tin or copper. Dis- solve the silver in nitric acid one part, water two parts. The tin will be then thrown down as stannic oxide. Filter out and evaporate the solu- tion to dryness ; redissolve it in water (pure), filter, and again evaporate to dryness. If copper is present, the crystals will have a bluish appearance ; if only present in small amounts, no harm will arrive from this ; but the copper can be eliminated by treating the dissolved crystals with silver oxide, when the copper will be thrown down as an oxide in the form of black powder. The silver oxide should be gradually added until the blue colour has disappeared. The chemical action here is that the silver oxide will interchange with the copper nitrate to form copper oxide (insoluble) and nitric 86 APPENDIX. acid, whicli will then dissolve any silver oxide that may be left. As a test to see whether any copper is left, a drop or two of the solution is taken, and diluted ammonia added till the precipitate first formed is redissolved. If no blue colour is apparent, the substitution of the silver for the copper has been complete. The solution should again be evaporated to dry- ness, and the bath can then be made up as desired. If an argentometer be used, water can at once be added to the solution without evaporation, as the actual strength of the solution can be measured and water added till it becomes of the desired strength. Oxide of silver is formed by adding carbonate of potash solution to silver nitrate solution till all precipitate ceases ; the liquid will then consist of insoluble silver oxide and soluble nitrate of potas- sium. If for use in the positive bath, the oxide can be added directly, as the potassium nitrate does no harm to this ; but if the bath is required quite pure, the oxide should be washed to get rid of the soluble nitrate. APPENDIX. 87 TO PREPARE CHLOROPLATINITE OF POTASSIUM. (From Pizzighelli and Hiibl on Platinotype.) A proper laboratory is required for these operations. Take 50 grammes of platimim cliloride (chloro- platinic acid), dissolve in 100 c.c. of pure water, and filter if necessary. Then lieat to 100° C. in a water bath, and pass through it a strong stream of washed sulphurous acid gas. After a while the yellow liquid will begin to assume the characteristic red colour of the platinous chloride. The liquid has then to be tested from time to time to watch its progress. A little is taken on the end of a glass rod, and mixed with a little ammonium chloride on a watch-glass ; the presence of any unreduced or platinic chloride is shown by the formation of an insoluble yellow precipitate of chloroplatinate of ammonia. The quantity of this precipitate that is formed should be noted, as one can judge from this of the amount of reduction that is going on. When the precipitate begins to form but slightly, the stream of gas should be checked, so as to have the operation well under control ; and as soon as the liquid ceases to give a precipitate, the gas stopped completely. The reason for this is that, if allowed to continue, the gas would commence to attack the platinous chloride formed, and further convert it to a plati- 88 APPENDIX. nous sulphide, a salt not reducible by ferrous salts. On the other hand, if the action be stopped too soon, platinic chloride will be left, and in the further operations would be thrown down as an insoluble salt. Hence care is necessary in the above operations. The solution that is obtained consists of a mixture of platinous chloride, sulphuric, and hydrochloric acids. To convert this into the double salt, it should after cooling be poured into a porcelain basin, and a hot solution containing 25 grammes of chloride of potassium in 50 c.c. of water well mixed with it by stirring. The chloroplatinite then separates in the form of a crystalline powder. It is allowed to settle twenty-four hours ; the crystal- line deposit is collected on a filter, the mother liquor being drained off ; it is then washed with a little water and then a little alcohol, until the last washing gives no acid reaction. The powder is now spread out on filtering paper and left to dry in a dark-room, as the salt when moistened with alcohol is reduced by the action of light. Salt thus prepared is perfectly pure and can be used at once. 74 or 75 grammes of the double salt should be obtained from each 100 grammes of platinic chloride, this being about 93 per cent, of the theoretical quantity. No effort need be made to obtain from the mother liquor a still further quantity of potassium chloroplatinite. APPENDIX. 89 STAINS ON FINGERS, LINEN, ETC. Prevention is certainly better than cure, and there is no reason why with care any of the silver solution should find its way on to the operator's fingers, especially if he take the common precau- tion of using a bone or ivory forceps for lifting the prints oj0f the exciting bath. But accidents will happen, and the probability is that unsightly brownish stains will make their appearance sooner or later on the operator's hands and linen. In their incipient form nitrate or even ammonio- nitrate of silver stains are extremely easily got rid of— that is to say, if they are treated before the action of light has had time to darken them. In this unreduced stage, although insoluble in water, they are of course easily soluble in any of the ordinary fixing agents, such as hypo. But one does not care, except at the end of a day's work, to contaminate one's fingers with hypo, which is very liable to make its presence visible on the* next print handled ; but fortunately chloride of sodium or common salt does equally well. The best way is to keep an open-mouthed jar half filled with a strong solution of salt — brine, in fact — and if any silver get on the fingers, they are simply inserted in this brine, and rubbed together a little ; a dash of pure water is then sufiicient to cleanse them. 90 APPENDIX. Should, however, the presence of stams be dis- covered only from inspection — that is to say, when the light has done its work — and the silver is re- duced, it is still perfectly possible to remove them. Cyanide of potassium is often recommended for this. I do not like it because of its very poisonous qualities, although it is very efficacious ; for the same reason another excellent device, iodide of potassium followed by hypo, is barred. The plan I, however, adopt is an equally simple one, and quite free from any poisonous character. It is, in fact, Howard Farmer's reducing solution. To a saturated solution of hypo a few drops of a saturated solution of ferrid cyanide of potassium (red prussiate of potash) are added ; a rag is dipped into this, and the spots well rubbed with it, when it will be found that they speedily disappear. The stains from ammonio-nitrate are more stubborn ; but even they will soon become so faint as not to signify. The only point to be ob- served is that the operation must not be carried on by daylight. The above mixture is very sensible to the blue rays, and is rapidly converted from a rich orange colour to a transparent or faintly bluish liquid, in which state it is inert in action. Practi- cally speaking, any of the perchlorides — iron, copper, etc. — can be used, followed with hypo ; but the above has always proved the most satisfactory in my hands, with the exception, perhaps, of the potassio- ferric oxalate, which, while it oxidises reduced APPENDIX. 91 silver very rapidly, is not destroyed by hypo. I mention this salt, as it is the one used in the preparation of the platinotype papers, and it may therefore be found in the operator's laboratory. PLATINUM RESIDUES. Platinum is a sufficiently valuable metal to make it worth everybody's while to save what he can of it. The old toning baths and the washing water (the prints are passed through after toning) are especially rich in the metal, and these liquids should be poured into any bottle, and an ounce or so of the ordinary ferrous oxalate developing solu- tion added. The bottle should be stood aside, and the platinum will be found to be rapidly thrown down in the metallic state. The major portion of the liquid is decanted off, and the residue filtered and dried, and can be sent to the refiner's at once ; or it can be converted into the platinum chloride, for subsequent conversion into chloroplatinite of potassium. In case any iron should be present, it is best to treat the filtrate with a fairly strong solution of sulphuric acid ; this will dissolve out any iron in the form of the sulphate without in- juring the platinum ; the residue should be washed and dried and dissolved in aqua regia — nitric acid 1 part, hydrochloric 4 parts — with gentle warming. As little aqua regia as possible should be used, only 92 APPENDIX. just sufficient to dissolve the platinum, as it lias subsequently all to be evaporated off. The dis- solution of the platinum should be conducted out of doors, or in a well-ventilated room, as the fumes of nitrous oxide given off are most unpleasant, and rapidly rust iron or steel objects. The residue left after evaporation is chloroplatinic acid, and can be weighed and at once used for the production of the chloroplatinite of potassium. SILVER RESIDUES. I think that many photographers will be sur- prised to learn that for every hundred ounces of silver they use for sensitising paper ninety-seven of them go down the sink, and are utterly wasted. In other words, that if a sheet of sensitised paper before exposure contain a hundred parts of silver, after printing and fixing it will contain at most only three or four parts, ninety-seven or ninety-six parts being completely lost. It is not surprising, therefore, that I advise all photographers, however humble their output, to save their residues, — not that they can expect to recover the whole 97 per cent., but they should certainly get a return of something like 80 per cent. From the following table, the result of careful analysis, made by MM. Davanne and Girard, we APPENDIX. 93 can see exactly place : where the different losses take Draining papers First and second washing waters be- fore toning Hypo bath Washing water of fixed proofs Cuttings and clippings Remaining on proofs Loss t*. ••• e*» ••• Silver per cent. 1-028 52-860 32-100 4-110 4-570 3-100 2-232 100-000 It will be at once seen that the majority of the silver is found in the preliminary washing waters and the hypo bath, being about 85 per cent, of the whole ; so that if we only manage to save a fair proportion of this we shall effect a notable economy in our nitrate of silver bill. A sheet of paper measuring 17|" x 22|" will take up about 37 grains of silver — say, 36 ; and we should easily be able to recover of this about 27 grains; or, in intrinsic value, for every ten shillings' worth of silver we should get back seven-and-six- pence from our residues, — on the whole, not a bad return. Residues should be divided into three classes. The clippings, cuttings, and spoilt papers form one 94 APPENDIX. class; the washings before fixing a second; and the old hypo baths themselves the third. The first class can be neglected, as it is always very small, precaution of course being taken to fix out any unreduced silver from spoilt prints. In the second class — the first washing waters — the silver is in the form of a chloride, and forms the milky cloudiness so very observable in washing the prints. The first two washings at least should be saved, and poured into a tub or some utensil, a little hydrochloric acid or common salt added, and the liquid allowed to settle. When the top liquid has cleared, it should be decanted off*. When sufficient of the white chloride is left at the bottom of the tub, it can be collected on a filter, and be sent at once to the refiner's; or if preferred it can be treated with zinc in the manner described for treat- ing an old and spent silver bath (p. 78) ; it is then in a state to be at once made up into a new exciting bath, as it is not likely to contain any impurities. The old hypo baths cannot of course be treated in the same way, since chloride of silver is soluble in this menstruum ; neither can zinc very well be used to precipitate silver, as sulphide of zinc appears to be formed in the operation. The usually adopted plan is to add liver of sulphur, and throw down the silver in the form of the sulphide, which is then roasted to free it from the sulphur, and then fused. There are two drawbacks to this method: the stench APrENDIX. 95 produced thereby is beastly and even injurious, and the roasting of the residue is nearly as in- odorous, and if not properly carried out — that is to say, if any free sulphur is left — explosions may occur when the mass is fused. If this system of treat- ment be resorted to, the precipitated sulphide should be sent direct to the refiner's. But the simplest and perhaps best way is Da- vanne's method. This simply consists in immers- ing a plate of copper in the hypo bath, and letting it stand for about four days. Silver is gradually deposited on the cojjper, whilst the copper is dis- solved in the liquid. From time to time, therefore, the copper plates, which are simply stood up against the side of the tub, should be brushed ; the metallic silver will then gradually settle to the bottom, and when sufficient has been collected it can be filtered and washed. The dried filtrate consists of metallic silver mixed with a little copper, and can of course be at once converted into silver nitrate, contami- nated with a little copper, giving it a bluish colour. This colour will cause no harm to the print, as it is soluble ; but if it is very strongly present, it can be got rid of by adding gently silver oxide in the manner described in the preparation of silver nitrate. Another method of getting rid of the copper is by precipitating the silver nitrate in the form of chloride by the addition of common salt. Sufficient 96 APPENDIX. brine has been added when an addition of salt to a small amount of the liquid gives no further cloudi- ness. The copper chloride will remain in solution, and the heavy silver chloride can be easily freed from it by washing. The pure chloride of silver should be added to that obtained from the washing waters^ and the whole treated in the manner there described. 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SWIFT & SON, Manufacturing Opticians TO HER 31 A JE STY S SCIENTIFIC GO VERNMENT DEPARTMENTS. SEVEN GOLD MEDALS AWARDED. LIST OF PHOTOGRAPHIC LENSES. PORTRAIT PARAGON. PORTABLE PARAGON LENSES, This is the only series of Lenses made, ranging from 5^ in. to 30 in. focus, with both combinations cemented. Each combination in this series is made with the new Abbe- Schott glass. Intensity F.4. Price No. Size of Plate. Dia. of Lenses. Equiv. 'InRigid Settings Focus. withWaterhouse Diaphragms. 1 Stereo 5J £4 10 0 2 X 3i If 5 8 0 3 6 „ 4 6 „ 5 2 7i 6 6 0 4 2i 81 7 7 0 6 8 „ 6 2| 10 10 10 0 6 10 „ 8 3i 12i 16 0 0 7 12 „10 15 „12 3f 15 21 10 0 8 4J 18 28 0 0 9 20 „ 16 51 24 51 0 0 10 23 „18 6i 30 77 0 0 UNIVERSAL PARAGON LENSES, PORTRAITS, GROUPS, STUDIES IN STUDIO, & PANEL PICTURES. No. View Size. Group Size. Dia. of Leases. Back Focus. Prices in Rigid Mounts 1 8^x 6^ 7ix 4| 2 ins. 8^ ins. £6 15 2 10 „ 8 8i„ 6i )> lOf „ 8 2 3 12 „10 10 „ 8 it 131 „ 11 5 4 15 „12 12 „10 p a 16i „ 14 17 5 18 „16 15 „12 i» 20 „ 22 10 6 22 „18 18 „16 5 a 24 „ 40 10 7 25 „21 22 „18 6 n »» 30 „ 53 10 8 28 „24 25 „20 7 36 „ 72 0 WIDE-ANGLE LANDSCAPE LENSES. Working Aperture, U.S., No. 4, F.8. No. Size of Plate. Dia. of Lenses. Equiv. Focus. Price. 1 5 X 4 1§ ins. 6^ ins. £2 19 0 2 7i, 4i If » 7 „ 3 5 0 3 8i, 8^ „ 4 1 0 4 10 „ 8 10 „ 4 19 0 5 12 ,, 10 ^ » 12 » 6 6 0 6 16 „ 12 n u 15 7 19 0 7 18 „ 16 3 ,, 18 9 9 0 8 22 „ 20 3f „ 22 „ 12 12 0 9 25 , 21 4i „ 25 „ 17 2 0 LANDSCAPES, ARCHITECTURE, AND COPYING. Large Medium Small Equiv. Focus, No. Stop Stop Stop Price. covering. covering. covering. 1 3x3 4 X 3 5x4 3 in. £2 14 0 2 4 „ 3 5 „ 4 7i., 4^ 4 „ 2 18 6 3 5 4 7i„ 4i 7i„ 8 „ 5 5 „ 3 3 0 4 8 ,, 5 81 „ 6^ 6 „ 3 12 0 5 8 „ 5 8L, 6i 9 „ 7 7 „ 4 10 0 6 fi„ 61 9 „ 7 10 „ 8 8 ,r 5 8 0 7 9 „ 7 10 „ 8 i2 „10 9 » 6 6 0 8 10 „ 8 12 „ 10 13 „11 10 „ 7 4 0 9 12 „10 13 „ 11 15 „12 12 „ 8 2 0 10 13 „11 15 „ 12 18 „16 15 „ 9 0 0 11 15 „12 18 „ 16 22 „18 18 „ 10 16 0 12 18 ,,16 22 „ 20 25 „21 21 „ 13 10 0 RAPID PARAGON LENSES, FOR GROUPS, VIEWS, INTERIORS, AND COPYING. Size of Size of Dia. of Equiv. Price in Rigid Setimg. View, Group. Lenses. Focus, 4x3 Stereo. 1 in. 4i in. £3 12 0 5 „ 4 X ^\ 1 „ 6 »» 3 16 0 6 „ 5 5 4 1| i» 4 14 6 8 „ 5 n „ 4i If It 9 )i 5 3 6 8^„ 6i 8 „ 5" li „ 11 »» }> 5 17 6 9 „ 7 8i „ 61 If „ 12 6 15 0 10 „ 8 8i „ 6^ If „ 14 it 7 12 0 12 „ 10 10 » 8 » 9 2 „ 16 it 9 9 0 13 „ 11 11 n M 18 it 10 7 0 15 „ 12 13 » 11 2^ „ 10 ft it 13 0 0 18 „ 16 15 M 12 3 „ 24 16 13 0 22 „ 18 18 „ 16 3i „ 30 it It 22 10 0 25 „ 22 22 „ 18 4 „ 34 27 0 0 28 „ 24 25 „ 20 38 36 0 0 WIDE-ANGLE PARAGON LENSES. Giving 100° of angle for Photographing Cramped Positions. No. Largest Dimension of Plate. Dia, of Front Combin, Back Focus. Equiv, Focus, Price, 1 7i X U iin. 3i in. 4 in. £4 1 2 81 „ 61 4^ „ 5i „ 4 19 3 12 „10 6i „ 7 „ 6 19 4 15 „12 n „ 8^ „ 9 9 5 18 „10 2h it 11 it 13, „ 12 12 6 22 „20 14 „ 15^ „ 18 0 7 25 „21 3| „ 17 „ 19 „ 27 0 Iris Diaphragm fitted to above Lenses. For Price, etc., send for List. The above 2>rices are subject to lOjJer cent, for cash with order, DNIYERSITY OPTICAL WORKS, 81, Tottenham Court Road. W.C, C.P.S. Special Yentilated Dark Tent. Has a working spaee of 33 inches from right to left, when extended on a table (the rigid part is 18 inches long by 12 inches broad and 12 inches high, the remainder flexible). Admits half the body, covering 48 inches from back to front. It has a special and efficient Ventilator. May be used on a Tripod Stand for outdoor work ; when so required we attack Special Mocks for the purpose. {Vide Woodcut.) Price, with Skeleton Roof, 23/6 ; without, 21/- ; per post, 24/6 or 22/- With Tripod Stand, 15/- extra. Extra large size, 31/6. Inlet Tube, 3/6 extra; Outlet Tube, Support, and Funnel, 3/6 extra. This is meeting with most favourable appreciation all over the world. C. W. writes:— "I have now, for the first time, an opportuTiity of giving my testimony to the usefulness and convenience of your Changing and Developing Tent. I took it with me on a tour in IfcHy, where, without it, I would have been oblio"ed to develop my trial Plates at night in the hotels, but with it I have been able°to do so in the afternoons when not otherwise engaged. I have just returned from a tour through Naples, and though I have made several hundred exposures, they have been almost all correct, as I was able to discover how I was going on, by developing a Plate or two every day. I shall certainly recommend your Tent." THE C.P.S. "Cliameleon" Dark-Room Lamp. THE PERFECT NON-FOGGING LAMP. It is a Three-cornered Lamp ; the hack has a sliding ventilating door, fitting over the outside arm of the wick regulator. The side A has a double flashed Ruby and Yellow glass removable ; inside this, a piece of Fine Obscueed Glass, B- The other side has a removable deep Ruby glass, C outside, and inside this an Orange glass, D. The size of the separate sides of light is, 6J X 5 ; 6J x 5. Price, for PARAFFINS, 10/6; per post in box, 11/6. „ „ GAS .. .. 15/-; „ „ 16/-. Larger sizes, with hivged frames and 8x5 glasses, 26/- ; per post in box, 27/3. A NEW & IMPROVED INDIAN CHAMELEON liAMP, with loose Interchangeable Glass, now ready, 35/- each. Small size, clasping at front, 30/-; per post, 1/6 extra. T. H. M. (M.D.) writes I have tested the glass, and find it more non-actinic than ordinary ruby glass. In the lamp it transmits a better working lights and after development there is no trace of fog. SOLE MAKER: PRESTON, 4, HIGH STREET, SHEFFIELD (Late CuBLEY & Preston). CATALOGUES ON APPLICATION. 1 WILKINSON & CO. ESTABLISHED 1859. WHOLESALE, EXPORT, AND RETAIL NEW PATENT PORTABLE " SATURATOR." Gives purely white light ; steady ; 500 candle power (6J lbs. weight) ; uses less oxygen than any other form of limelight. Circular for penny stamp. OPTICAL LANTERNS. Single, Double, and Tri-unial. Most modern and approved design : high-class finish. All are tested before leaving us. Jets, dissolvers, and fittings. LECTURES ILLUSTRATED to order on any Subject. Slides made from Negatives, Prints, Engravings, Plans, etc., etc. Colouring XLxmepavcncics of cvcv^ kiuD* TERMS MODERATE. WILKINSON & Co.'s Slides were used 200 Consecutive nights at the late Royal Polytechnic, London. There are no Slides to equal our Best Productions. HOLMESIDE, SUNDERLAND. 1 1 MUCKLOW'S ALBUMENIZED, SENSITIZED AND MATT SURFACE PAPERS. ^-*>^ ^^jg^ PREPARED with the greatest care to ensure Rapid Printing, Good Toning, and Freedom from Blisters. They have been used for the past nine years, and numerous unsolicited testimonials speak for their unsurpassable good qualities. They are well suited for shipping, as these papers have been kept TWO YEARS, and then produced brilliant pictures. EXTRA BRILLIANT SENSITIZED PAPER. 13/6 per Quire ; 7/- ^-Quire ; 4/- i-Quire. MATT and SINGLE.— 12/6 per Quire ; 6/6 i-Quire ; 3/6 i-Quire. BRILLIANT PAPER READY CUT FOR MOUNTING. THE NEW PLATINUM TONING PAPER is now ready, and also A NEW ALBUMEN PAPER, free from every disagreeable SMELL and BLISTERS. This Paper prints Quicker and Deeper than the ordinary Albumen Papers, and will render Printing a pleasure instead of a trouble. First-class Lenses at extremely Low Prices; Cameras and DryPlateSi Photographic Apparatus, and Pure Chemicals. PURE MOUNTS of every description Manufactured on the Premises, Blocked and Printed in every style. Most Liberal Terms to Dealers and Shippers. MANUFACTORY: 2, TURLE ROAD, TOLLINGTON PARK, LONDON, N. "AUTOCRAT" (Regcl.) MAGNESIUM MAGAZINE. )i Delivers Fifty successive 5-grain f^^-...^^^ Charges of Powder. Any one can use it, and successful ^ FLASH PHOTOGRAPHY is made possible. Post Free . . . .1/3 Charged with Best Powder . 2/6 yL^Bo. sTIvTaIrtin, M^M ' Optician, BREAMS' BUOJNGS, LONDON, E.C. ^^^^^^Hm^ Price List of Photo. Apparatus, Developing, v^^^ Retouching and Printing, Free. BURR'S PHOTOGRAPHIC LENSES can be had on trial. The First Prize, £25, of the Edwards's Isochromatic Dry Plate Competition, and the First Silver Medal of the Royal Cornwall Exhibition, Falmouth, was awarded to F. W. Edwards, Esq., for Photograph 23 x 18, taken with these lenses. BURR'S NEW DETECTIVE DOUBLET, £2. C. BURR, WAKEFIELD STREET, EAST HAM, LONDON. H. HUGHES & SON, The New London Photographic Stores. AMATEURS' COMPLETE SETS, h^U 35/-; i-PL, 70/-; i-Pi., lOO/-. New Special ^-Plate Camera, best make, with one Back, 60/-. Best value ever offered. New Illustrated Catalogue post free. 59, FENCHURCH STREET, LONDON, E.G. PLATINOTYPE PRINTING Carefully Executed Prom PHOTOGRAPHERS' OWN NEGATIVES By RICHARD KEENE, DERBY. LIESEGANG'S AEISTOTYPE PAPER (fSn^^k). Is certainly the finest Silver Paper in the Market."— E. J. Wall. MAKES GOOD PRINTS FROM WEAK NEGATIVES. THE PAPER OF THE FVTIIRE. To be Imdfrom most Dealers, or from ED. LIESEGANG, DUSSELDORF, GERMANY. JOHN WHITFIELD, F.C.S., Apparatus ON HIRE. SCARBRO'. Free " D ark-Room." These LENSES are Designed on the most approved Scientific Principles, and every detail of their Construction is of the highest order of excellence. MR* TElEqraphic Address Vs Pn-i- frpp Lenses LeicesterV cP vr-°5r Tree Our Catalogue contains abundant and definite Scientific data concerning all Instruments, and is mailed free on application. IRIS DIAPHRAGMS, STANDARD LENS SCREWS, SPECIAL DETECTIVE LENSES, LENSES FOR GROUPS, VIEW FINDERS AND METERS, SPIRIT LEVELS ^OR^ CAMERAS. Sole Importers for Europe of BLAIR HIGH-GLASS AMERICAN TOURIST CAMERAS ENGLISH FINISH, AMERICAN INGENUITY. CATALOGUE POST FREE. TAYLOR^ TAYLOR, T hOBSON, HEAD OFFICE & FACTORY, LEICESTER. OPFICE X STOCK ROOlViS, 6, SOUTHAIVIPTON ST.. HIGH HOLBORN. LONDON, WO, THE CAMERA OF THE FClTURE. SHEWS ECLIPSE HAND CAMERA (Patent). HIGHEST AWARD PARIS EXHIBITION, 1889. Now made in all Sizes up to 8^ x 6i Equally suitable for Time Exposures. Largely used by Artists at Hon e and Abroad, perfect i)ictures being obtained with this little instrument which, wi.h the ordinary apparatus, it would be impossible to obtain. SHEWS Patent BAMBOO WALKING CANE TRIPOD, WITH UNIVERSAL TOP, as/- Eclii)se Pocket Apparatvis closed for the pocket. For Plates 4J x 3^, £4 9/- View Finder . . . 7/6 for FilmS, OtC Plates and Solutions 7/6 The ECLIPSE, fitted with Roll Holder for 48 P'ilm Negatives, with Show's Pa- tent Automatic Changing Back for Plates, with Double Backs See the Ecli2')se PampJilet, free on application to — J. P. SHEW & CO.5 87 <& 88, NEWMAN STREET, 4 Poors off Oxford Street, I^ONDON, W. MAGIC LA NTERNS AND SLIDES. Has now completed his immense Stock of Lanterns and Slides, which is now, without doubt, the Largest Collection in the "World, and is in the position to supply the Trade, Shippers, and Exhibitors at such very Moderate Prices, that none of the Stores, or so-called Manufacturei-s, are able to compete. It is on account of the large number of Lanterns sold that Walter Tvler can sell a full-sized practical Lantern, with 4-inch Compound Condensers, Por- trait Combination Lenses, and 3-wick Paraffin Lamp, for 29/6. This is a Lantern usually sold by other houses for £3 3s. But the perfection of all Lanterns is Walter Tyler's "HELIOSCOPIC," with Patented Lamp, which gives a light nearly equal to Limelight. The Lenses fitted to this Lantern are equal in quality to those supplied to a Lari- tern value £30; Limelight can be used without any alteration. This Instrument possesses all the quali- ties desired, thoroughly good Opti- cal parts, best Illuminating power, extreme Portability, best Workmanship, price complete, £4 4s. Very large numbers are selling every week, and hundreds of Testimonials can be seen, if desired. Hundreds of Lanterns and Slides, purchased or exchanged in summer time, can now be had ; great bargains. Telephone No. 4848. All requiringVery Best Value should not fail to send for the largest and most complete Catalogue, containing Instructions for Working Lanterns, which will be sent Post Free. WALTER TYLER5 48, Waterloo Road, LONDON, S.I£. A NOVEL LIST OF NOVELTIES. Contains 9 Photographs of Prize-Winninsr Pictures in 1889 Competition, 1 Photo Etching, £30 in Prizes, Spasmodic Mutterings,Cuttings, Culhngs, Practical Hints, ^-•-'^-rO \J*^ ^-."^^ aiqa and List of Old and New ^--^'T^'fCVv , c.t, T, Novelties in ^,.^^^^'cJ^ i^ct- ^^'-^Tylar's Iliad,' Apparatus. _„.i**DIT10N-A.L MAHOBANY DARK SLIDES. BEST QUALITY. FITTED TO ANY CAMERA. Book pattern, with Hinged Shutters, J -plate, 4/6; J-plate, 8/6; J-plate, 12/- A reduction for three. All sizes made. Over 3,000 of Talbot's Improved Dark Slides have been sold in 07ie year. Several hundred testimonials have been received. List and Press Opinions FnEB SLIDES TO FIT LANCASTER'S CAMERAS IN STOCK. THE "DIAMOND" DETECTIVE or HAND CAMERA. The Smallest, LigUtest, and Cheapest cflicicut Hand Camera yet introdueed. PRICE 30s. COMPLETE, IN CASE. TAKES 12 PICTURES WITHOUT RECHARGING. This instrument is well made and finished, and fitted with a Rapid Rectilinear Lens, always in focus ; the size of the Camera is only 5 J X 3 X 3 J, yet it takes 12 negatives on ordinary dry plates 2| x 3i without recharging. There is also a Finder and a Shutter for time or instantaneous exposures. Price includes one dozen plates ; extra plates 10^?. dozen. Send for Particulars and Testimonials. SPECIMENS OP WORK, TWO STAMPS. NEARLY BEADY. NEW l-PLATE HAND CAMERA. TATTERSALL'S PATENT. One-half the weight and one-half the size of any other J-plate Hand Camera. The only Camera holding a magazine of plates that can be used on a stand with a focussing screen. Send for full particulars. TALBOT & EAMER, Blackburn. Mention this FuhUcation, LONDON, E.G. The London agent foe LANCASTER & SON, W. TYLAR, and C. BURR. Full stock kept, and 5 % discount allowed. Burr 15 %. We advertise our latest novelties and inventions weekly in Photography," the popular Id. Journal. NEVER BE WITHOUT 1^ ABRAHAM'S ANNUAL^ Contains Special Original and Instructive Articles by Messrs. Lyonel Clark, Georgb Davison, A. R. Dresser, E. A. Golledge, W. Jerome Harrison, Chapman Jones, J. Fortune Nott, Andrew Bring le, E. J. Wall, and W. Willis, and a perfect Storehouse of Useful Information ; also a Full and Comprehensive Catalogue of all the Leading Photographic Requisites in the World. Price 6<^., 2J0st free. ABRAHAM'S FAMOUS HAND CAMERAS, "IDEAL" £ "VICTOR." Each takes 12 Plates 4^ x 3^ . Only one movement. PERFECT TRIUMPHS OF GENIUS!!! Price 3^. each, nett. Or covered in Leather, with two Patent Finders and best Rectilinear Lens, d£5 15^.; less 10 % cash. THE CHEAPEST HOUSE FOR EVERYTHING CONNECTED WITH PHOTOGRAPHY. SPECIAL ATTENTION TO ORDERS BY POST. Come and inspect our stock, the most varied in London. THOMAS'S PALL MALL PLATES AND FILMS ARE THE QUICKEST, RICHEST, AND BEST. It is not yet universally realised that our Extra Eapid Plates are not sold at 1/3 per doz. Js, but at 1/- which, with their rich film, combined with ultra sensitiveness, places them far beyond comparison with the plates for which even 1/6 is demanded. If 1/6 is not objected to, see that you get sterling value for your money by asking for our THICKLY-COATED PLATES, which are the Acme of Perfection. Entirely free from Halation in all ordinary work, Interior or Exterior. COMPLETE PRICE LISTS OH" APPLICATION. AGENTS, ALL DEALERS. R. W. THOMAS &L Co., Ltd., 10, PALL MALL, S.W. FACTORY-THORNTON HEATH. Telegraphic Address— " RUTH RA," LONDON. 10 p 1 1 ( t a n , 25, NEWMAN STREET, OXFORD STREET, W. DALLMEYER'S Photographic Lenses Are used by all the Leading Photographic Artists throughout the world, and have obtained the HIGHEST AWARDS wherever exhibited. DALLMEYER " On the Choice and Use of Photographic Lenses." Eighth Thousand. Is. This Pamphlet contains concise information for Selecting Lenses for any particular purpose whether in Portraiture, Landscape, or Archi- tectural Subjects, etc.; the proper use of Diaphragms; Tables of Comparative Exposures ; the use of the Swing Back to the Camera ; a simple Explanation of the law of Conjugate Foci, and Tables for Reduction and Enlargements. DALLMEYER'S New Descriptive Catalogue (Post free on application) Contains full particulars of all Lenses and the purposes for which they are designed ; also of the latest inventions in Photographic Lenses, MORGAN & KIDD, Inventors of the )5lt6E]\[JFIC 6EIi??¥ip-B^0MIDE P^BCE^g. The Standard Method of Producing Permanent Enlargements and Contact Prints. PRICE LIST OF BROMIDE PAPERS, For Enlarging, and for Contact Printing direct from the Negative by Artificial Ligbt. Size. 1 doz. Size. 1 doz. \ doz. Size. 1 doz. 1 doz. 8x5 81 X 01 (2 doz.) 1/3 1/3 1/9 2/3 10 x' 8 12^ X 10| 15.^ X 121 18 X 15 3/. 4/6 7/" 9/6 3/- 4/- 5/3 23 X 17 25 X 21 30 X 23 30 X 25 12/6 18/6 24/6 26/6 6/9 10/. 12/6 14/. In Rolls of 20 ft., 17 in. wide, 12/- ; 25 in. wide, 17/6 \ and 30 in. wide, 21/. Smooth or Kough Surface same price. Smooth is always supplied unless rough is specially ordered. Note. — Any quantity of Bromide Paper is sent post free. Sample Sheet, 23 x 17^, 1/6. ENLARGEMENTS Mounted on best quality Plate Paper Mounts, with India Tint and Plate Mark Spotted and Evened. Permanent Enlargements by the process from good small Negatives of Landscape, Portrait, or Architectural Subjects, compare favourably with the finest examples of Steel Engraving. PRICES. Size of Print (approximate). Single Copy. FROM SAME NEGATIVE. Size of Print (approximate). Single Copy. FROM SAME NEGATIVE. 3 Copies, each. 6 Copies, each. 12 Copies, each. 3 Copies, each. 6 Copies, each. 12 Copies, each. X 4| 8| X 6| 12 X ^ (Small Panel) 12 X 10 15 X 12 21- 3/6 4/6 4/6 5/6 1/9 3/2 4/- 4/- 5/. 1/8 3/- 3/9 3/9 4/9 1/6 2/10 3/6 3/6 4/6 17 X 10^ (Large Panel) 18 X 15 23 X 17 24 X 20 30 X 25 6/- 7/- 9/6 12/6 19/6 5/6 6/3 8/8 11/3 17/6 5/3 5/10 8 - 10/8 16/6 5/- 5/6 7/9 10/- 15/6 For Prices of Finishing, in Black an^ White, or Painting in Water Colours or Oils, see Catalogue, post free on application. Framing.— Prices of Framing and Patterns of Moulding free on application. MORGAN & KIDD, ARGENTIC GELATINO-BROMIDE WORKS, F0©T lOilB, lieHMOMl, LOMION, S.W. PARIS ; 29, Boulevards des Itauens. Telegrams ; "Argentic," Richmond, Surrej. W. WATSON & SONS, Manufacturers op High-Class Photographic Instruments, 313, HIGH HOLBOBN, LONDON, AND AT 251, SWANSTON STREET, MEIBOXIRNE, AUSTRALIA. Steam Factories--^, 10, 11, 16, & 17, FULWOOD'S BENTS, W.C. Sole Manufacturers and Patentees of WATSON'S 'ACME' CAMERA. Introduced 1889. The lightest to carry and the most convenient to use of all first-class Tourists' Cameras. WATSON'S PREMIER CAMERAS, Made with interchangeable parts, and in very highest quality workmanship. DETECTIVE CAMERAS, CYCLISTS^ TRIPODS, ENLARGING LANTERNS, &c., &c. SENSITIVE PAPERS, Albumenised or Matt Surface. ), 6/6 ; i quire, 3/6. Sample sheet, lOd.^ post free. the "Watson" Instruments has repeatedly ^ J 3US INTERNATIONAL EXHIBITIONS, TWENTY ^: 2 ^' \ ^L^^ Led by them, including TWO GOLD MEDALS jther occasions a SINGLE AWARD HIGHER ANY OTHER COMPETITOR. everything required in Photography sent part of the world on application. SONS, 313, Higli Holbom, London. ISTABLISHED 1837. MORGAN & KIDD, Inventors of the ^It6E]^TIC 6EIi?l¥ip-B^0jaiDE P^0CEg^. The Standard Method of Producing Permanent Enlargements and Contact Prints. PRICK LIST OF BROMIDE PAPERS, For Enlarging, and for Contact Printing direct from the Negative by Artificial Light. Size. 1 doz. Size. 1 doz. I doz. Size. 1 doz. 1 doz. 4i X Z\ (2 doz.) 1/3 10 x" 8 3/. 23 X 17 12/6 6/9 X 4| 1/3 12i X 10| 4/6 3/. 25 X 21 18/6 10/- 8x5 1/9 15.1 X 12i 7/- 4/- 30 X 23 24/6 12/6 81 x 01 2/3 18 X 15" 9/6 5/3 30 X 25 26/6 14/. In Rolls 0/20 ft., 17 in. wide, 12/- ; 25 in. wide, 17/6 ; and 30 in. wide, 21/. Smooth or Kough Surface same price. Stnooth is always supplied unless 7'ough is specially ordered. Note, — Any quantity of Bromide Paper is sent post free. Sample Sheet, 23 x 17^, 1/6. ENLARGEMENTS Mounted on best quality Plate Paper Mounts, with India Tint and Plate Mark Spotted and Evened. Permanent Enlargements by the process from good small Negatives of Landscape, Portrait, or Architectural Subjects, compare favourably with the finest examples of Steel Engraving. PRICES. Size of Print (approximate). Single Copy. FROM SAME NEGATIVE. Size of Print (approximate). Single Copy. TR'HOM SAME NEGATIVE. 3 Copies, each. 6 Copies, each. 12 Copies, each. 3 X 4| 2/- 3/6 1/9 3/2 1/8 1/6 17 X lOJ 6/- 8i X 6| 3/- 2/10 (Large Panel) 12 X 7i 4/6 4/- 3/9 3/6 18 X 15 7/- (Small Panel) 23 X 17 9/6 12 X 10 4/6 !/■ 3/9 3/6 24 X 20 12/6 15 X 12 6/6 6/. 4/9 4/6 30 X 25 19/6 For Prices of Finishing, in piack an^ White, or Paintii Oils, see Catalogue, post free on application. Framing.— Prices of Framing and Patterns of Moulding free MORGAN & KIDD ARGENTIC GELATINO-BROMin^ KEW FOOT lOilB, IICMMOM, W PARIS : 29, BouLEVAKCS CES IiAUENS. Telegrams ; "Arg< W. WATSON & SONS, Manufacturers of Hlgb-Class Photographic Instruments, 313, HIGH EOLBORN, LONDON, AND AT 251, SWANSTON STREET, MEIBOURNE, AUSTRALIA. Steam Factories--^, 10, 11, 16, & 17, FULWOOD'S RENTS, W.C. Sole Manufacturers and Patentees of WATSON'S 'ACME' CAMERA. Introduced 1889. The lightest to carry and the most convenient to use of all first-class Tourists' Cameras. WATSON'S PREMIER CAMERAS, Made with interchangeable parts, and in very highest quality workmanship. DETECTIVE CAMERAS, CYCLISTS^ TRIPODS, ENLARGING LANTERNS, &c., &c. SENSITIVE PAPERS, Albumenised or Matt Surface. Per quire, 13/- ; J quire, 6/6 ; J quire, 3/6. Sample sheet, 10^., post free. The Excellent Quality of the •* Watson" Instruments has repeatedly received recognition at various INTERNATIONAL EXHIBITIONS, TWENTY AWARDS having been gained by them, including TWO GOLD MEDALS PARIS 1889, and on FIVE other occasions a SINGLE AWARD HIGHER THAN THAT OBTAINED BY ANY OTHER COMPETITOR. of Canreras, Lenses, and everything required in Photography sent post free to any part of the world on application. W. WATSON & SONS, 313, High Hota, London. Established 1837.