The photographic news

• Bandzählung: 7.1863
• Erscheinungsdatum: 1863
• Sprache: Englisch
• Signatur: F 135
• Vorlage: Hochschule für Grafik und Buchkunst Leipzig
• Digitalisat: Hochschule für Grafik und Buchkunst Leipzig
• Digitalisat: SLUB Dresden
• Rechtehinweis: Public Domain Mark 1.0
• URN: urn:nbn:de:bsz:14-db-id1780948042-186300004
• PURL: http://digital.slub-dresden.de/id1780948042-18630000
• OAI: oai:de:slub-dresden:db:id-1780948042-18630000
• Sammlungen: LDP: Historische Bestände der Hochschule für Grafik und Buchkunst Leipzig
• Sammlungen: Fotografie
• Strukturtyp: Band

• Digitalisat: SLUB Dresden
• Strukturtyp: Ausgabe

[March 20, 1863. Proceedirgs ok Sotiteties, South London Photographic Society. The usual monthly meeting of this Society was held on the evening of Thursday, the 12th inst., in the City of London College. F. F. Statham, Esq., M.A., F.G.S., in the chair. The minutes of a previous meeting having been read and confirmed, Mr. Cl. WHARTON Simpson called attention to a couple of large photographs by M. Jeanrenaud, one of the ablest land scape photographers in France. They were worthy of exami nation, he remarked, for their excellence, but the especial object for which they had been forwarded by that artist was to illustrate the very great amount of angle he had been able to include with satisfactory definition by using Dallmeyer’s No. 4 triple lens. M. Jeanrenaud had marked on the picture the amount of subject included by one of the best French landscape lenses of similar focus, which was about one-third of the picture less than was given with the triple. There was, moreover, considerable depth of definition. The photographs, which were from dry plates, by M. Puech’s dry collodion, were very fine. Mr. Simpson also announced that the prints by Mr. A. Burns were now ready for distribution. He had written, asking Mr. Burns for a few particulars of his method of working in producing such views, in the form of a short paper for the Society. He would read the part of his letter referring to the subject, which was as follows ;— “ With regard to a paper for the Society on obtaining cloud negatives and printing in skies, I fear I cannot do anything in that way. What little I do know on the subject is just what has appeared in the News and other journals, and a mere compila tion by such an indifferent hand would not profitably occupy the time of the South London Photographic Society. “ The card picture is printed from a stereo negative obtained by the ordinary Fothergill process, very early (about 5 a.m.) one morning in June last, the exposure with a pair of Horne and Thornth waite’s small new lenses and smalls top, from beginning to end occupied 60 seconds, but the whole plate did not receive so much time, the lens being opened and closed very sloivly by a shutter inside the camera, so that the immediate foreground would receive at least double the exposure of the distant castle &c. In this way I sometimes manage so as to obtain natural skies, and in the negative referred to, all the clouds present at the time may be seen in the negative, but too dense to print with the rest of the picture.” Mr. G. Price then read a paper on “ The Theory of Positive Printing.— Albumenized Paper, and the Action of the Sensitizing Bath ” (see p. 126 and p. 137). After which the Chairman, in moving a vote of thanks to Mr. Price for his very able paper on a subject of great interest and importance. If the question were thoroughly examined, it opened a very considerable scope for inquiry. It was perhaps a matter for a little regret that any subject of personal antagonism had been introduced into the paper, and he would suggest that this part of the paper was scarcely suitable for discussion in a society’s meeting. The subject presented ample field for discussion, however, and had been most comprehensively treated. There was first the general question, and then the distinctive pro positions with which Mr. Price concluded his paper, which he (the Chairman) again read to bring them under the immediate attention of the meeting. Mr. Price explained that the observations in his addendum were not intended for discussion. There was, however, neither personality nor antagonism intended. He had felt it important to clear the subject of certain mis-statements, and he had taken the advice of several unprejudiced persons and some friends of the British Journal, who all had concurred in the recommen dation that they should be rebutted in this way. He had felt no antagonism, intended no personality, and only wished an important subject to be cleared from misleading statements, that the truth might bo established. Mr. Sebastian Davis asked Mr. Price whether he had formed any opinion as to the constitution of the salts formed by weak solutions of nitrate of silver and albumen as compared with those formed by strong solutions. Did he regard them as differing in chemical character ? Mr. Price had, in his paper, simply referred to Messrs. Davanne and Girard’s statements on the subject, in which they repeated a fact well known before. Mr. Davis was not aware that it was known that a precipi tate of different character was formed. Mr. Price said they did not say that, neither did he; but, nevertheless, there must be a difference in the chemical con stitution, or there could be no difference in the character of tho precipitate. Mr. Davis said the subject was a difficult and complex one, and considerable doubt existed as to the calculation of the equivalent of albumen, as it was necessary to multiply the different elements in order to state tho proportion of sulphur and phosphorus. Mr. Martin said that from analogical cases he would lead to the conviction that a definite chemical compound would be formed, whatever .the strength of the solution—the difference in physical appearance, described by MM. Davanne and Girard, arising in his (Mr. Martin’s) opinion solely from the variable state of agglomeration of the particles ; that, in short, a definite compound of albumen and nitrate of silver was formed in each case, just as gelatinous alumina and pulverulent alumina—tho one obtained from a cold solution and the other from a hot solution—were nevertheless both alumina. Mr. Price hold that all combinations below that which pro duced complete saturation were imperfect albuminates. Mr. Davis asked what Mr. Price understood by imperfect albuminates. Mr. Price said that by the term albuminate or perfect albu minate of silver he meant the highest or most complete combi nation, which produced what was termed complete coagula tion. Combinations below that he would call imperfect albu minates. After some further conversation on the subject, Mr. Hart thought that precipitates produced by weak or strongs olutions were identical in constitution, albumen being a highly colloid substance, the more dense the solution tho more firmly it hold any salts of silver, so that a higher amount of silver was found in tho dense precipitates than in tho light precipitates. Mr. Price asked Mr. Davis if he considered the albuminate of silver a combination of albumen with nitrate of silver, as a whole, or as a phosphate, carbonate, &c. Mr. Davis was uncertain, but should say it combined as a whole. Mr. Hart had analysed tho ashes of some albumenized papers after burning and found them to contain sulphide of silver. Mr. Davis expressed surprise that Mr. Price should imagine that it was not generally known that the base of tho chloride used, and the nature of the nitrates formed affected tho tone of the print. The idea that they did affect the print had been held for years. Ho remembered that some years ago Mr. Heath brought the subject under the attention of the parent society. Mr. Price said that so far as he had been able to ascertain the notion had not been commonly held. An article which appeared in the journal of the Photographic Society referred to that idea as having recently gained some attention. He knew that it had been held by some that barium affected the colour of the print, because of a combination between tho albumen and the barium ; but he had tried everywhere almost in London without being able to meet with albumenized paper salted with barium. A conversational discussion arose on the question whether the action of the nitrates had been recognized, and upon the use of barium paper and the difficulty of obtaining it. Mr. Harman thought chloride of ammonium was tho best salting chloride ; and tho reason was, that the prints wore always red in the pressure-frame, so that there was more control and certainty in toning them. Mr. Howard thought that one of the advantages of ammo nium arose from the fact that it was a ready solvent of salts of silver, and thus aided in producing oven homogeneous film of silver on the albumenized paper, by the more ready assimila tion as it were. Mr. Price asked Mr. Harman if the redness in the pressure- frame was not rather duo to tho proportion of albuminate of silver than to tho base of the chloride. Mr. Harman said that some samples of albumenized paper would print black, no matter how much albumen there might be. Mr. Price said that was a question of tho proportion between tho two; if the chloride wore in greater proportion it would print dark.