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THE PHOTOGRAPHIC NEWS. Vol. XXIX. No. 1400.—July 3, 1885. CONTENTS. PAGE Recent Improvement in the Asphalt Process 417 Blanchard’s Instantaneous Views on Wet Collodion Plates 417 The Antwerp International Exhibition 419 Action of C loured Substances upon the Colour Sensitiveness of Bromide of Silver in Gelatine. By Dr. J. M. Eder 420 On the Work of a Local Photographic Society. By W. Jerome Harrison. F.G.S 421 Maaking Lantern Slides. By A. B. Benjamin 422 Isochromatic Photography. By Fred. E. Ives 423 Notes TASK .. 424 Patent Intelligence 426 Positives on Gelatino-Chloride of Silver. By W. M. Ashman and R. 42G The Photographic Society of Philadelphia 428 Correspondence 428 Proceedings of Societies 430 Talk in the Studio 431 Answers to Correspondents 432 RECENT IMPROVEMENT IN THE ASPHALT PROCESS. Prof. J. HUSNIK has recently worked out an improve ment which forms a genuine advance in the asphalt pro cess as applied to photo-zincography. This he describes in the Photographische Mittheilungen, from which we abstract the following particulars of the process. In working the asphalt process it is desirable to separate from the bitumen the portion which is soluble in ether, that portion being insensitive to light. ‘To bring this about, it has been customary to powder the bitumen, to pass it through a fine sieve, and to pour ether over it. This process has been only partially successful, a con siderable quantity of the insensitive bitumen remaining undissolved after any reasonable time of the action of the ether. Herr Husnik get, over the difficulty in the following ingenious manner. . The bitumen is reduced to a coarse powder, and is dissolved in rectified turpentine. By allowing sutlicient time, a very large proportion of the bitu men may be thus dissolved. Herr Husnik states that with occasional stirring during three days the turpentine can be caused to take up one-third of its weight of bitumen. When a saturated solution of bitumen in turpentine has been made, the liquid is diluted with ether. This process now precisely corresponds with the precipitation of a gelatine emulsion by the use of alcohol, except that in the latter case it is usual to pour the emulsion into the alcohol — that is to say, into the precipitating fluid ; whilst in the case of the bitumen process the solution, corresponding to the emulsion, has the precipitating fluid—the ether—poured into it. The reason for adopting this course will soon be made evident. As ether is poured into the solution of bitumen in turpentine, the first effect is merely to cause the fluid to become less viscous ; but after the solution has been about three times diluted, a doughy precipitate is thrown down. To discover now whether the ether has thrown down all the insoluble asphalt, a portion of the upper stratum of the liquid is placed in a small vessel. If an addition of ether to this small portion of the liquid causes the precipitation of any bitumen, it shows that sufficient ether has not been added to the turpentine solution. Further additions are made, a test being performed after each, as just indicated, till no further precipitate takes place. It will now be evident why the ether is poured into the bitumen solution, and not vice versa. It enables the quantity of ether necessary to be accurately guaged, so that there is no waste. The solution is allowed to stand for twenty-four hours, when the supernatent fluid is poured away. Theprecipi- tate which remins behind amounts to about half the original bitumen. Fresh ether is poured over the precipi tate, which is occasionally stirred up during two or three days. This causes it to become considerably firmer, on account of the removal of almost the last trace of the tur pentine, and also of the last of the bitumen soluble in ether. The last portion of ether is retained to be used again. The precipitate is removed with a bent strip of zinc from the vessel in which it was thrown down ; it is placed in a porcelain dish, and is allowed to remain in a warm place for several days, with occasional stirring to secure the complete removal of the ether, when there remains a “ hard, ex tremely brittle, glittering black mass, which is readily re duced to powder by hand.” After the bitumen has been thoroughly freed from ether as described, it is dissolved in benzol (not benzine) free from water. Then is added to each 100 parts of the bitumen 1} parts of Venice turpen tine. This renders the film more pliable, and less liable to scale off than it would be without the addition. If, as is common with commercial benzol, there is a trace of water, the solution of bitumen cannot be caused to flow evenly over the zinc plate, but runs into lines and drops. This defect can be overcome by a free addition of chloro form. With films made from bitumen prepared as described, the exposure necessary with a clear negative is only ten minutes in bright sunshine, or one to two hours in diffused light, and development is complete in four minutes. BLANCHARDS INSTANTANEOUS VIEWS MADE ON WET COLLODION PLATES. Our supplement of this week consists of some examples of the extensive series of instantaneous pictures made by Mr. Blanchard nearly a quarter of a century ago, and which pictures are now in the historical collection of the Photographic Society, at the Inventions Exhibition. With respect to these pictures Mr. Blanchard says :— Nearly all the river and street scenes were made between the years 1861 and 1867, and the lower Thames view—one of the four illustrations—was taken exactly twenty years ago this spring. In an art so comparatively new as photo graphy, this is a period sufficiently long ago to have earned for it the mellow expression, “the good old days.’’ It cannot be other than interesting, therefore, to a new gen-ration of photographers to know how rapid pictures were made by the antique methode. In this age of prodigious mechanical appliances and chemicalwonders—when, with snap shutters and pneumatic triggers, not only can a picture be produced in the 100th part of a second, but it can almost be made in five minutes less than no time—in such an age, th n, as this, it is some thing to remember that just a quutar of a century ago the