Volltext Seite (XML)
June 19, 1868.] THE PHOTOGRAPHIC NEWS. 297 It was stated upon the authority of Mr. John Nicol, who presented a detailed account of Professor Smyth’s apparatus and mode of working to the Edinburgh Photographic Society in the year 1 866, that some of these inch-square miniature negatives bore magnifying up to 15 feet very much better than the best pictures of larger size ever before shown to that Society. Two of the miniature pictures shown—those, namely, of the broken corner of the coffer in the king’s chamber of the Great Pyramid—were taken with the magnesium light, with an aperture one-fifth of the focal length of the lens. Nine others of the miniatures were taken with an aperture one tenth of an inch focal length, and five others with an aper ture one-twentieth of the focal length. Professor Smyth has drawn my attention to a curious fact in regard to these negatives. Some of them were intensified with persulphate of uranium, and have been solarized and become quite translucent, but are not at all solarized to chemical rays, as they still give intense pictures, with sharp black-and-white detail. NOTES ON THE CARBON PROCESS. MR. A. J. Drummond, writing to Humphrey's Journal, says: — In the last number of your valuable Journal, a carbon printer asked for information, “ to prevent Swan’s carbon tissue crack ing before and after sensitizing ; also, to prevent bubbles on the tissue when developing ? ” My experience with Swan’s carbon tissue has been the same as that of your correspondent; so much so that on sensitizing in the evening, in the morning I found it curled and cracked so badly that it was almost impossible to use it. I tried various remedies; my first was to sensitize in the morning, and expose when sufficiently dry, without adhering to the negative ; this worked well for a few sheets; but where a number wore to be done, the result would be as above, owing to the length of time required in exposing. Then I resorted to another expedient, steaming, and that I found to be very dangerous, as it was apt to adhere to the negative. At last, almost discouraged by my numerous unsatisfactory experiments, 1 made a trial of rock candy, which resulted in a highly satisfactory manner. Lot your correspondent try this formula, and report the result. To every 12 ounces of bichromate of potash solution I added 4 ounces of rock candy. The weather was very cold; but the mercury in my room stood at 60° F., and the tissue, with the addition of the rock candy, was quite pliable, and answered every purpose. When sensitizing Swan's carbon tissue—No. 3 grade, which as a heavier coating of gelatine—the proportion of rock candy may bo increased to 6 ounces to 12 ounces of solution. The bubbles can only be prevented by a proper con sistency of rubber solution, and being careful to brush the solu tion with an even-flowing coat. Care should bo taken not to got any of the rubber solution on the back of the tissue. I have also found a sample of paper which gives better satis faction in my hands than any I have hitherto used for the first transfer. The paper alluded to is that known among paper dealers as “ Law Point,” weighing 35 pounds to the ream. The desirable qualities of this paper are its absorbent properties, and the heaviness of texture, which makes it invalu able to the carbon printer for transferring the tissue. I immerse the picture to be developed in a water bath about 80° F. After allowing it to soak for a few minutes, raise the temperature to 90 Q F.; the tissue in all probability will be ready to transfer. I am greatly in favour of developing in as low a temperature as possible, as it preserves the half tones ; when the water is too hot it will invariably cause bubbles. Insufficient pressure will cause bubbles ; this no doubt is the cause of your correspondent’s trouble. I recently received from Mr. Swan some fine tissue, prepared of various colours and of different degrees of strength, to suit the several classes of negatives. The principal shades are black, brown, and purple; these are distinguished by the letters A, B, and C, and the strength by numbers. No. 1 is suitable for good negatives, but slightly inclining to hardness in those which yield prints with a little too much contrast oflight and shade. No. 2 is adapted for all good negatives having the following ualities, viz.:—Tho average degree of density, and delicate gradation in the half tones; and also those which are very clear in the deep shades. No. 3 suits negatives which give prints with abundant half tones, but somewhat deficient in vigor. The size of the sheets is 18 by 23. 1 cannot but admire the highly creditable manner in which Mr. Swan has put his tissue in the market; and I would beg leave to suggest to him, when preparing carbon tissue for this climats, that he make it more pliable ; for it is so brittle before sensitizing that it cannot be handled unless slightly steamed in order to soften the gelatine ; and great care must be observed in so doing, or the gelatine may soften, and discharge the pig ment into the bichromate solution. 4 roceedings Of Sucieties. South London Photographic Society. The annual meeting and last meeting of the present session was held on the evening of Thursday, June 11th, at the City of London College, Leadenhall Street, the Rev. F. F. Statham, M.A., F.G.S., in the chair. The minutes of a previous meeting were read and confirmed. Mr. Wharton Simpson exhibited some fine cabinet portraits, consisting of large, brilliant vignette heads by Reutlinger. He also called attention to some paper pulp made from deal, and suggested that it might be worth while to ascertain whether it possessed any value in the manufacture of pyroxiline. The Secretary then read the report as follows : — Annual Report of the South London Photographic Society, 1868. YovR Committee, in submitting their Annual Report of the proceedings of the Society for tho session 1867-68, beg to con gratulate the members on the renewed vitality which the record of the past session so fully evidences. From circumstances which were under discussion towards the close of the last session, it might have been inferred that the interest hitherto felt by members of the S. L. P. Society would possibly become lukewarm, and thereby endanger its success. Actual events have, on the contrary, shown that the same spirit which has always pervaded this Society is still embodied in a “healthy pulsation;” and your Committee, look ing forward to a still higher degree of interest amongst the members, now refer to the proceedings of tho Society during the past year. Your Committee have much pleasure in stating that in the number of papers read there has been an increase compared with the number read last year, and whilst expressing their thanks to those gentlemen who have come forward to read papers, your Committee would still wish to see some fresh recruits to swell the ranks of those members who devote much time and thought to such matters. The following are the names of the gentlemen and the subjects of their papers :— Mr. Meagher, on the Breaking of Negatives. Mr. Blanchard, on the Preservation of Prints by means of Collodion. Mr. E. Cocking, a Suggestion for Raising the Position of Photographers. Mr. F. Howard, on the Introduction of Clouds in Landscape Photography. Mr. J. R. Johnson, on Natural Clouds in Landscape Photo graphy. Mr. J. T. Taylor, on tho Oxyhydrogen Light, and means of Avoiding Explosions. Mr. S. Fry, Omnium Gatherum. Mr. Pearce, a few Thoughts concerning Portrait Photo graphy. Your Committee also have much satisfaction in alluding to a novelty in tho history of the Society, and which has met with great success, viz., the introduction of a “ Question Box,” which, on the occasion of using its contents, proved to be one of the most interesting meetings of the session. The experiment of an exhibition of photographs amongst the members, with conversation thereon, also proved to be a step in the right direction, and your Committee anticipate that on the next similar occasion the result will be still greater in importance. The Committee are indebted to the following gentlemen for interesting specimens, photographs, and other matters; viz Mr. G. Wharton Simpson, Mr. Blanchard, Mr. H. Cooper, Mr.
