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380 THE PHOTOGRAPHIC NEWS. [June 12, 1885. in contact with it, and which is also acted upon by rays of the same refrangibility. Now no mere physical theory of the photo graphic image would account fur this. Instead of the developed image being almost nil at this particular part of the spectrum, it would be increased in intensity, and such increased intensity is to be found if the two be exposed in the presence of silver nitrate, which will take up the bromine and iodine liberated by light. (To be Continued.'} Oorxespondence. MR. A. PRINGLE ON JUDGING PHOTOGRAPHS. Sir,—Sarcasm, used skilfully, and on appropriate sub jects at fitting times, is certainly a powerful weapon in the hands of the journalist. When sarcasm is crude, inappro priate, and misplaced, it becomes mere buffoonery, and the wit of your correspondent, “ A Member, &c.,” in your issue of yesterday, is a very fair sample of the latter phase of sarcasm. The very “oblique ovation” of your correspondent con veys to the reader ignorant of the facts, several impres sions of my first letter’ grossly exaggerated, and several absolutely false. This writer’s style, coupled with his hiding under a general name, precludes the idea of my attempting to answer him further. It is significant, or seems so to me, that the two persons who have attacked me and posed as defenders of the exist ing system of judging, one in your columns, the other in those of your contemporary, have both of them shone by reflected light; in other words, have taken refuge in names by which they cannot be identified. Does it mean that no one approves of the existing system sufficiently to say so boldly and openly? It looks like it. I anticipate opposition, but I hope for manly, open, and gentlemanly opponents.—I am, yours, &c., Andrew Pringle. Aroceedings of Sotieties. Photographic Society of Great Britain. The last ordinary meeting of this Society for the present session was held on Tuesday evening last, the 9th inst., at the Gallery, 5a, Pall Mall East, James GLAISHER, Esq., F.R.S., President, in the chair. The minutes of the previous meeting having been read and confirmed, The Chairman called upon Mr. J. R. Sawyer to re-open the discussion upon Mr. W. S. Bird’s paper “ On the Reproduction of Pictures in the National Gallery,” and exhibit illustrations of recent discoveries in the photographic reproduction of colour. Mr. Sawyer commenced by saying that it was quite un necessary to insist on the importance of the subject referred to in Mr. Bird’s paper, as the examples which had been shown roved that a real and substantial advance had been made. Mr. ird had mentioned that he went to head-quarters for particulars, and Messrs. Braun refused to give any information beyond the letter which had been read. This he had analysed, and could get nothing out of it, beyond certain additions to collodion, and the employment of light of a complementary colour. He thought it was usual to add several substances to collodion for certain purposes. Then they declared that there was no re touching whatever employed, except a few touches, thus imply ing that the results were due to a secret substance in the film. There was certainly an advance ; at the same time, it must not be supposed that it was entirely the outcome of an alteration of the sensitive condition of collodion. They had a proper studio, fitted with every appliance for the work in hand ; the glasses could be removed from the pictures, and no pains were spared to thoroughly utilise any advantages the trustees had granted. The Berlin Company, who previously photographed the same subjects, had not similar facilities. Speaking of the influence of isochromatic plates, he said, scarlets remain unchanged ; one great point seemed to be a retarding action upon blues, which he thought enabled a longer time to be given to the yellows; this would also account for the greater smoothness discernible. Dr. Vogel had spoken of eosine producing smoothness, and he (Mr. Sawyer) found that whether it be used in collodion or a dry plate, this peculiarity was very noticeable. He did not think it likely that colour value would be gained in photography in the manner advocated by Mr. Werge, and some difficulty might be experienced in preparing and working plates sensitive to every part of the spectrum ; still, while every nerve should be strained to improve the work by chemical means, yet some art would always be necessary. Mr. Sawyer then exhibited two carbon transparencies of large size, forming a scale of twelve tints each, ranging from vermilion to indigo: one produced from an ordinary wet plate negative, and the other from a Clayton and Tailfer isochromatic gelatine plate, wherein it appeared that the green and vermilion showed no difference in either plate ; but there was considerable difference in the case of blues and yellows. In the Clayton and Tailfer plate the three tints of yellow were exactly the same ; not so with the wet collodion ; and this want of distinguishing degrees or shades of colour accounted for some of the failures in the reproduction of the pictures in the National Gallery. Several examples were then shown, among which were three reproductions of a coloured print: one by the wet process, direct and untouched ; another reduced by the wet process ; and a carbon transparency taken which had been carefully retouched, and then a carbon negative made from it, and a third made direct on an isochromatic plate (untouched). There was very little difference between the results of the two last named, but the details were pointed out, as also were similar peculiarities in Messrs Braun’s reprodudtion of a Raphael and a Rubens recently photographed. Certain evidence of retouching was then alluded to, also the effect of eosine in emulsions and collodion. Coloured glass as a medium Mr. Sawyer did not think practical when large pictures had to be dealt with. Mr. Sawyer having concluded, the Chairman invited remarks. Colonel Stuart WOnTLEY had listened carefully to Mr. Sawyer’s paper, and he had not discovered any evidence to show that Braun’s results had any advantage whatever over isochro matic plates carefully retouched, or what had been done tv.enty years ago with wet collodion by Dr. Diamond. He had been to the Gallery that afternoon to compare a print from Dr. Diamond’s negative, and one of the same subject recently made by Braun, with the original painting (one of Turner’s). In the latter the yellows were all of the same tint; the old negative he considered perfect in that respect. The blue of the sky was rendered by comparison ; in the new negative it was all white. The masts of the vessel had been carefully put in by the retouchers, and Turner had purposely left part of them out. Again, they had completely changed the shape of a cloud ; and he would meet any committee the Society might appoint, and prove to them in the most emphatic manner that Braun’s pic ture had been retouched enormously. Mr. J. Werge said both Mr. Sawyer and Colonel Wortley had strengthened his arguments. The reds were not produced any better than formerly, and the claim advanced by Messrs. Braun was entirely due to retouching. Mr. W. E. Debenham: Mr. Sawyer referred to coloured mediums as an objection. For large surfaces or for a number of different coloured mediums it would be an insuperable objection. The use of coloured illumination iu a box or in the room, of any particular colour, would not be disadvantageous, and he had been working in that direction. Ives, Vogel, Eder, and others introduced dyeing films, and some thought they acted as optical sensitizers ; but he thought it better to employ coloured illumi nation. Mr. Sawyer’s experiments led him to prefer placing the coloured medium over the sensitive plate. Mr. W. L. Bird was glad to find his paper had elicited so much interest. Did the Colonel admit that the blues and yellows were affected in the specimen of Messrs. Braun ? Col. Wortley : Yes. Mr. Bird had taken the opinion of Mr. Eastlake, the Keeper of the National Gallery, and he said the advance was very decided ; also that of Sir F. Burton, who held that the point was beyond discussion. A month ago Mr. Sawyer held opinions something like those stated by the Colonel, that there was nothing new. Col. Wortley : There is no novelty beyond what isochromatic plates could do with retouching. Mr. Bird ; Well, Mr. Sawyer was of the same opinion as Mr.