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THE PHOTOGRAPHIC NEWS. Vol. XI. No. 488.—January 10, 1868. CONTENTS. PAGE A Few More Words on India-rubber for Mounting and Transfers 13 The Use of a Second Studio 14 Preservation of Paste, Glue, etc., for Mounting 14 A Novel Hint for Double Printing 14 The Old Toning Bath of Hyposulphite of Soda and Gold 14 Leaf Prints by Photography 15 Critical Notices 16 Another New Dry Process.—Soap in Collodio-Bromide of Silver 17 Against the Use of Distilled Water for Photographic Purposes. By Nelson K. Cherrill 18 Recent Experiments with Collodion 18 PAGE Artistic Pictures Photographically Considered. By E. Dunmore 19 Resuscitation of the Old Toning and Fixing Solution. By Prof. John Towler, 21 Studio Hints. By a Practical Man 22 Proceedings of Societies—North London Photographic Associa tion 23 Correspondence—Carbon Printing—Sugar in the Printing Bath. India-Rubber Mounting—Explanation 23 Talk in the Studio 23 To Correspondents 24 A FEW MORE WORDS ON INDIA-RUBBER FOR MOUNTING AND TRANSFERS. Some further experiments with india-rubber for mounting, and some communications on the subject, suggest a few further hints, of importance. In the first place, on the india-rubber. We find that the solutions formed by various samples of india-rubber differ considerably; some give a solution which always remains semi opaque and turbid looking; others, no matter how dilute, the solution always retains a dark brown colour. The best result we have obtained was from a piece of india- rubber we received from Mr. Woodbury, which had been pur chased, we understood, in Paris. It is apparently prepared expressly for the purpose of solution, being useless for any other purpose in the shape it is kept. It is termed macerated india-rubber, and is, in the rough sheet, almost like a piece of coarse woollen frieze. It dissolves somewhat slowly, and a flocculent insoluble deposit is left. After standing, however, to settle, the solution is very clear and light-coloured, a ten- grain solution being of a straw colour, a twenty-grain solu tion of a deep amber colour. We find that, cut into shreds and just covered with essential oil of rosemary, about a drachm to twenty grains of the india-rubber, a pasty mass is formed, which is readily dissolved on the addition of benzole or highly rectified naphtha. After shaking at intervals for a few hours, the solution should be left to stand to settle, and •in twenty-four hours it is perfectly clear. The mixed odour of the benzole and rosemary is far from unpleasant, and the latter, being the most persistent, overpowers the other, and remains longer than the other. With some samples a twelve-grain of india-rubber solu tion will be found apparently sufficiently adhesive ; but we do not recommend for use a solution containing less than twenty grains to the ounce. Some prints mounted with the twelve-grain solution, in which the surfaces seemed to cohere perfectly, curled tip at the edges after lying a few hours in a warm room, and it was found very easy to separate the print from mould. With a twenty-grain solution the co hesion is more perfect; but the attachment is never so firm as with paste or glue. Io secure the best adhesion with india-rubber both surfaces should possess a very definite film or varnish of the gum. We have seen it stated that the print and mount, after having been coated and dried, present no change in appearance. This is the case when a very dilute solution is evenly applied, and it is possible to secure some degree of cohesion with such a film, but the attachment is very slight, and easily destroyed. We strongly recom mend, therefore, the use of a solution of not less than twenty grains to the ounce; and this should be freely flowed over the surface, not spread as thinly as possible. A thin solu tion has, in some cases, the defect of sinking into absorbent paper, and produces a mottled appearance. It is comparatively useless for any one to attempt mount ing with india-rubber who has not a rolling-press. Although the cohesion of the two surfaces of india-rubber may be secured by rubbing the print well down, the effect is very unsatisfactory and unfinished-looking. When paste or a similar material is used, the paper becomes softened, and by the contraction in drying, a smooth even surface is secured. When india-rubber solution is used no such result is ob tained ; the print is not softened, but retains its harshness, nor is there any contraction; the consequence is that any crease, crack, or slight rumpling which may be in the unmounted print shows very definitely in the mounted print, unless by heavy pressure in rolling it is removed. The rolling is, therefore, imperative to secure even a tolerable appearance as well as perfect cohesion.* The stability of india-rubber as a mounting material must still, however, be considered doubtful. Dr. Diamond recently called our attention to an album in which pho tographic prints had been mounted with india-rubber a good many years ago, and which had recently been examined since the idea was revived of using this material. A la.ge number of the prints had become entirely detached and were loose in the book, the adhesive quality of the india- rubber being entirely gone, a dark brown powdery resinous substance remaining on the mounts. In some cases, where a thin solution had been used and had permeated the print, its surface was mottled with irregular brown stains. The prints mounted with india-rubber appeared in no respect more stable than others produced at the same time and mounted with other materials. A correspondent mentions a recent recommendation, in a contemporary, to use the india-rubber solution as a trans ferring agent for collodion films, and asks if it can bo used with advantage in the simple method of enlargement we recently described as a means of transferring the enlarge ment transparent positive to paper. India-rubber would have, we fear, a serious defect for any transferring process. The fact which we have mentioned, that it darkens under the action of light and eventually changes into a resinous substance without cohesion, would be fatal to its utility. Few samples are, even at the outset, so perfectly colourless as not to degrade the purity of white paper, and the high lights of the transferred enlargement would necessarily suffer. As an aid to lifting the film for temporary purposes, in any case where the qualities to which we have referred would not be important, india-rubber will doubtless bo use ful ; but we cannot recommend it as the permanent support * Since writing the above we notice a letter in a contemporary recom mending, in the absence of a press, rubbing down with the edge of an ivory paper-knife. This is a good suggestion, and is of value with a perfectly smooth unbroken print; but if, from curling in drying, &c,, there is any rumpling of the paper, nothing but rolling will give smoothness and even ness to the mounted print which the softening effect of the paste and the contraction in drying gives to prints mounted in the ordinary way.