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238 THE PHOTOGRAPHIC NEWS. [May 16,1862 Mr. Whakton Simpson said he understood that the bath Mr. Blanchard had used in the majority of the experiments was one in the most sensitive working condition, such as he would use in his practical, instantaneous operations, and such, therefore, as should give fair play to any collodion. Mr. Blanchard had referred to some recent experiments made by Mr. Sutton, which it might be interesting to state. Most of the members knew that Mr. Sutton was an authority on the manufacture of collodion, and photographic matters generally, worthy of much respect, although in the matter of bromides, ho held some views which his (Mr. Simpson’s) experience did not confirm. Mr. Sutton had recently detailed a series of experi ments for testing tho value of bromides, in which, however, they were used alone, and not in conjunction with an iodide. He stated, that a plate coated with collodion containing five grains of bromide when immersed in the bath, and withdrawn in tho usual time, presented a thin blue film, and that it required some hours’ immersion before it became creamy, and hence he argued, that when a large quantity of a bromide was used in conjunction with an iodide, and the plate only loft the usual time, a large portion of the bromide remained unconverted into bromide of silver. If this were so, it was unquestionably an important consideration. His (Mr. Simpson’s) experience did not entirely confirm this. A bromized plate left the usual time —say two or three minutes—in the bath, certainly gave a thin blue film, but on leaving it double that time it was much more dense, and he had no reason to believe from its appearance that tho whole of the bromide was not converted into bromide of silver. Still, that the change was slower seemed evident, and the subject was worthy of further attention. Mr. Sutton’s con victions were very strong in tho matter, he even regarded bro mides as retarders—useful to hang on to tho wheels of the iodide as a drag, when it was running too fast. The whole of Mr. Blanchard’s experiments tended to prove an opposite con clusion. He (Mr. Simpson) had tried similar experiments scores, he might say hundreds of times, and always with similar results. The use of a bromide alone, unquestionably, gave slower results than the use of an iodide, but the combination of the two he had always found most rapid, most clean, and most satisfactory. Mr. Blanchard had referred to the universal reduc tion, in one experiment, with iodide alone, as possibly indicating a very high and almost unmanageable state of sensitiveness. If it were so, some trace of an image would have been found, however buried in fog; it only appeared to indicate over- readiness to reduction or decomposition, under tho influence of a developer, and would probably have been found the same without the action of light at all. He might mention, in con clusion, as interesting, that Mr. England, whoso instantaneous pictures everyone was familiar with, had recently told him, that after many mouths of the most careful experiment, ho had come to the conclusion that bromo-iodized collodion, with iron deve lopment, was three times as sensitive as simply iodized collo dion with pyrogallic acid development. Mr. Wall suggested that the universal use of bromides by the best photographers, was a strong argument in their favour. Mr. Harmer and Mr. Lane had both noticed the fact that a bromo-iodized collodion required a somewhat longer immersion in the silver bath, and that if it did not receive that, it looked creamier after coming from the camera, than when taken from the bath, showing that the reaction had been going forward with tho free silver on the plate. The Chairman thought the fact mentioned by Mr. Sutton as to the slower reaction between a bromide and the silver bath, worthy of further attention, as any unconverted bromide in the film would probably act as retarder, and referred to a practice which once obtained, of pouring a solution of a bromide over the plate, to prevent the further action of light. After some further conversation on the subject, Mr. Fry, in answer to the Chairman, said he had not a shadow of a doubt as to a bromo-iodized collodion being the best possible for rapid results, giving the highest possible degree of sensitiveness, and the maximum of delicacy and cleanness. He could scarcely understand how the matter could be brought into discussion, the thing seemed so palpable. He regarded bromo- iodized collodion, as one of the photographer’s greatest boons. Whereas, at one time, a certain sample must be kept for land scape, another for portraits, another for copying, another for dry plates ; he now found that one good bromo-iodized collodion was, with slight modification in the treatment, available for all purposes. It seemed to combine all the advantages which had before belonged to several. After some further remarks, the thanks of the meeting" given to Mr. Blanchard, who was requested to continue# experiments. The Chairman showed a dry plate, prepared with albuEa and glucose, developed with pyrogallic acid, without anya acid, and a single drop of silver solution. The result " good negative, with a much shorter exposure than usual. Mr. Simpson showed an experimental negative takeup honey and tannin, in seven seconds, lens six inches focus,* half-inch stop. , a The presentation print, Robinson’S exquisite vignetted" scape, “ Early Spring,” was delivered to members. , After some further routine proceedings, and the electiona Messrs. Brookes, Clifton, and Cornish, as members of ' society, the proceedings terminated. Amateur PIOTOGRAPHIC Association. A meeting of the Committee of the Amateur Photogn Association was held on Monday, the 28th April, at 26, market, Mr. G. Shadbolt, in the chair. The minutes w last meeting having been read and confirmed, the Secretary’ before tho meeting the printed catalogue of the As9oc” pictures, with which the committee expressed their del5 approval. A question having been raised by the Secretary * tive to the price which should be charged to members au“ scribers for the prize pictures (now the property of the5 lishers), it was decided, with their consent, that each me and subscriber should be entitled to select one copy of 6 tho prize pictures at the same rate as the other Assod prints, but that for any further copies it should be left t publishers to regulate the prices to be charged. The subject of a Photographic Art Union, in connectiol" the Association, was again discussed and adjourned. . • The Secretary, having pointed out to tho meeting unavoidable delay which had occurred in obtaining tb year’s negatives, and consequently in the award of theP the preparation of the catalogue, and the distribution d prints, it was decided that the Association year shall hend commence the 1st of June, instead of the 1st of May, and subscriptions for the ensuing year will, therefore, not M until tho 1st of June next. It was also decided in referel the selection of prints by members and subscribers, tha may select them from any of the Association negatives, the publishers may have in hand, irrespective of the S which they may have been received; and further, thatal payment of the subscription, members and subscribers! once select thoir two or one guinea’s worth of prints, as th may be. The proceedings of the meeting then terminated. ♦ Correspondence. FOREIGN SCIENCE. [pnor OUR SPECIAL COnnESPOXDEXT.] 88 Paris, 14th May, 1 f Positive printing with nitrate of uranium has St advocates. M. Hermann Krone states that the b5, quickest papers, which give the most brilliant I under good negatives, are those which are first well 15 noted with the solution of nitrate of uranium (1 part Q to 7 parts of water), quickly dried, and then again V for a minute only on the same nitrate solution. PaPM prepared retains its good qualities a very long time, in a dry dark place. After the lapse of a year, they great part their sensitiveness; they then yield P ro j W vigour with a yellow ground, which in a diffused 00 becomes of a brownish red in the course of a dev These proofs cannot be fixed by the usual washinsd. those taken upon paper recently prepared. In 0 1 obtain the most vigorous and beautiful proofs, We r • the exposure in the sun, under a negative, and dev ef a solution of nitrate of silver, of the strength of hafFd • slightly acidulated with nitric acid, and alcoholtmd ten per cent. Wash the proofs in distilled water, 8 May in a ba water; and as s it must of water is retail proof rr yarnishi On tl the folk “Am accustor acetates acetic t sence of fluence of need cither o negativ “Th: (lances to guar ral day: tate; tl paper < Weak, i paper i trated this ba negativ were e blacker all my ing the of silve the pre could t the ter gave n I had • reason of the is muc and tl fatura concer diate । Wards We fir '"list, dtenp nitrat in the bath, then first 1 great when crysti W M. K ject 1 serve necei chlol redu been sens box< satis will