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726 THE PHOTOGRAPHIC NEWS. LOCTOBER 16, 1891. Corresponenre. LANTERN SLIDE EXHIBITIONS. Sir,—I think it my duty to inform hon. secretaries of the photographic societies of the United Kingdom who are making arrangements for lantern slide exhibitions during the coming winter, that the Boston Camera Club, U.S.A., have sent us another lecture, entitled « The Yosemite Valley,” prepared by members of the California Camera Club. This is a gift to the amateur photographic societies of Great Britain on the same terms as “ Illustrated Boston,” “ The White Mountains of New Hampshire,” and “In and about Columbus. ” There are now four complete lecture sets of about eighty slides each, with accompanying lecture neatly mounted in type, of American scenery, in free circulation among photographic societies in this country, and which can be lent on application to me. The only conditions are, that the carriage of the boxes be paid at least one way ; that an account of the lectures and press notices of the same be posted by societies at once to Wm. Garrison Reed, 25, Kilby Street, Boston, U.S.A., the manager of the “ Interchange of Illustrated Subjects” ; and that the greatest care be taken of the slides, any accidents to which, as far as possible, to be made good, and the same reported to me immediately. E. M. Tunstall, Hon. Sec. Liverpool Amateur Photographic Association, 3, Lord Street, October 10th. Proceedngs of Soctettes. London and Provincial Photographic Association. At the meeting of this Society held on the 8th inst., Mr. J. Barker occupied the chair. Mr. J. S. TEAPE said that at a former meeting a plate which he had shown, illustrating the effects of several backings, was objected to on the ground that the caramel backing was not dry when exposed. He now brought forward a plate exposed in the same manner, but prepared in three divisions. One part had been coated with caramel and dried ; another had been backed with burnt sienna and dextrine and dried ; and the third backed with caramel and not dried. He found that part coated with caramel to be free from halation, whilst the burnt sienna showed a little, and the wet caramel rather more hala tion. He found, therefore, that his failure to get the best result with caramel was due to his having exposed before the backing was dry. Mr W. E. DEBENHAM said that this result was in accordance with his own experiments, the high refractive power of caramel rendering it especially efficient. Mr. Teape also showed some plates which had been exposed under negatives, and completely reversed merely by over-expo sure. They were exposed to the light from 30 inches of mag nesium wire burned at a distance of 12 inches. They were developed with hydrokinone by Thomas’s formula, except that 11 ounces of the hydrokinone solution had been taken, and 5 ounces of the soda solution. As soon as the image began to appear he had added 4 grains of potassium bromide to the developer. The resulting negatives were con sidered by several members to be the best instances of reversed negatives obtained by simple over-exposure that they had seen. Mr. Atkins showed an iris diaphragm which he had made. He dissected it to explain its working. A model in paper showed by its translucency the position of the several leaves at all stages of aperture. The Chairman hoped that this and other societies would stir in the matter of the new impurities now added to methylated spirits. He thought it a serious drawback to several photo graphic processes, and that something might be gained by proper representations to the authoiities. Mr. Howson then showed a number of prints on gelatino- chloride printing-out paper, manufactured at Ilford, and demon strated the toning and fixing of the prints. The photographs were of several kinds of surface, from the matt effect pro duced by stripping from ground-glass, to the enamel glaze obtained by drying in contact with ordinary glass. The toning used and recommended was the sulpho-cyanide bath contain ing 2} grains of chloride of gold, and 30 grains of sulpho cyanide of ammonium to 16 ounces of water. A combined toning and fixing bath was also described, but there seemed to be doubts as to the permanency of the prints compared with those toned in the separate sulpho-cyanide solution. The Chairman considered that thorough fixing was essential to permanency. He showed some prints made by the gelatino- chloride process which he had introduced at the Society in March, 1885, and which he then exhibited. They did not now show any trace of fading. PHOTOGRAPHIC Society of Ireland. The first meeting of the session was held on the 9th inst. at 15, Dawson Street, Dublin, Mr. George Mansfield, J.P. (president), in the chair. After the usual formal business, the President read his open ing address, in the course of which he said that it was pleasant to meet again after another year, and, above all, to find then that the Society had continued to progress. Of course, to the out door photographer, who sought his pleasure in the presence of nature, the endingof the sunnydays and the rapid closing in ofthe chilly evenings brought a pang of regret. There was, however, plenty for him to do during the winter season, were it only to bring before the Society’s meetings some of the useful experi ence he had acquired during his summer work. The field of photography was a large one ; there were paths of research in it suited to all tastes. He thought an error had been largely committed during the past two years by the overwhelming amount of encouragement given to the art side of photo graphy. He was a firm believer in the art future of photo graphy, but he was also convinced that, as in other forms of the art of delineation, so also in photography, artists in the true sense of the word have been, and always will be, few and far between. The other uses of photography, therefore, equally deserved their attention, and they were bound to welcome the many who, neglecting the higher walks of art photography, regarded it solely from a scientific point of view, whether as a mere branch of physical or chemical science, or as applied to some of the arts or sciences—such as astronomy, microscopical research, architecture, or archology. Mr. Mansfield men tioned the fact that an exhibition of members’ work would take place in the rooms in December. Speaking of the more general adoption of eikonogen as a developer, particularly for instantaneous exposures, the President’s own experience was that for short exposures it was unsurpassed. In printing there had been an increase in the employment of gelatino-chloride printing-out papers. The chairman concluded his address by pointing out that celluloid films had come into more general use, and that where it was necessary to reduce weight they were invaluable. The meeting then became conversational. Holborn Camera Club. October ^th.—Mr. Jambs Rennie, jun., in the chair. Mr. Ernest Benest gave a lecture, with experiments, on “Light and its Action on the Haloid Salts.” His reason for treating on this subject was due to the fact that he thought a large number of practical workers were very careless about the fundamental principles upon which their art or craft depended. He divided his paper into two sections and an appendix. In the first section he treated of the conditions and materials necessary for receiving the latent image, by noting the various processes, viz., the Daguerreotype, the wet plate process, the gelatino-bromide process, and the collodion process. In section two he dealt with the action of light on these sub stances. He thought it would be well to consider in the first place :—Is the action of light on the haloids chemical or physical ? The general opinion on the action of light was rather favourable to what was known as the sub-haloid theory. He gave various reasons which tended to confirm this theory, as against the theory of a physical change. He then