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

ject would be difficult to discuss satisfactorily in the absence of more evidence than was before the meeting. One or two others present and himself were in possession of many details they were not at liberty at present to make public ; but he thought Mr. Shadbolt would agree with him that they might state thus much, that some of the pictures were labelled “ Sun pictures by J. W.” which seemed to settle that part of the question in favour of Watt. Mr. Shadbolt said there was even more evidence than that. The SECRETATY referred to a process of copying mezzotint engravings by Mr. Bolton, which produced such accurate imitations they could scarcely be distinguished from the originals. Mr. Malone had examined the specimen before them, and could not help expressing great surprise that any one should take it for a photograph. It had more of the character of a drawing in liquorice, and had no resemblance whatever, that he could see, to a photograph. After some further remarks, Mr. Simpson said if the matter were discussed it should be distinctly borne in mind that it was not asserted that these were photographs by any process now known. It was simply stated that they were sun pictures, obtained in some way by the agency of light. Any deduction drawn from a comparison of these with ordinary photographs would be very likely to lead to error. The Chairman said this was undoubtedly true, but still it might be possible to arrive at some conclusion from an ex amination of this picture as to whether it was produced by chemical action or hand labour. Mr. Malone said they could only examine it by the evidence before them, and on that evidence he affirmed that there was no reason to believe it to be a photograph. The SECRETARY said perhaps he was to blame to bring this picture before them without being permitted to bring other evidence. There were, however, two Daguerreotypes, in all respects resembling the early pictures of Daguerre, but these were taken as early as 1791, one being a picture of Mr. Bolton’s house before the alteration in 1791, and the other, which at first appeared to have nothing on it, was found, on careful examina tion, to be a picture of the house after the alteration. It was not until, in company with Mr. Thurston Thompson, he examined this in a strong light that he discovered anything on the plate at all. Dr. Weight called attention to the paper being common writing paper with a water mark, such as no one would have used for producing a finished drawing upon; if the picture before them were not a photograph it was an exquisitely finished drawing. Mr. DEBENHAM said there were some minor stains and imperfections in the print before them which looked marvel lously like those which would arise in photographic manipula tion. After some further conversation, Mr. Allen said that the print showed decided signs of being produced by the hand of man, all the touches of the brush were quite apparent. Mr. Simpson said he was afraid that some members were looking at the picture as a photograph from nature, whereas it was a reproduction, a copy of a picture, and as such should of course accurately reproduce the touches of the brush. Mr. Henry White expressed a decided conviction that it was a photograph. On examining it carefully it would bo seen that the original from which this had been copied had a rough sur face, and the small protuberances or excrescences each cast a shadow which was here accurately reproduced, showing that it had been taken by light. It would have been scarcely possible to produce such an effect by hand if it had been tried. Mr. Brookes had noticed the same fact and drawn the same conclusions. Mr. Shadbolt said that although they could not discuss the matter in its entirety, it might be interesting to restate the particulars which had already been published. (He here de- tafit? the particulars which appeared on p. 193 of the PHOTO- GRAPHI News, vol. 7, April 24th.) The evidence so far as it had gone was quite sufficient, he thought, to prove in a court of law that these were photographs taken by James Watt; but Mr. Smith thought he could make it better, or even indisputable. He (Mr. S.), as a photographer ever since the introduction of the collodion process, felt convinced that these were photo graphs in the most complete sense of the term, produced by the action of light. Mr. Malone reiterated his conviction that there was nothing to prove that these were photographs at all. The prominences referred to might bo roughnesses in the paper where the colour had not taken well. Tho Chairman referred to the fact that the pictures were not upon the paper itself, but upon some varnish or medium. Possibly some artist could help them by saying if any method of working on such a surface so perfectly were known. Mr. Debenham said if the prominences were, as Mr. Malone said, roughness in the paper, that might bo ascertained by look ing through. (This being done it was found that the pro minences were not in the paper.) Mr. Brookes suggested that they might have boon drawn by tho aid of tho camera lucida, and then both tho correctness of the drawing and its reversed character would be accounted for. After some further desultory conversation on the subject, it dropped. Tho Secretary showed some instantaneous stereographs, by Mr. Davenport, of London Bridge, on the entrance of the Princess Alexandra. Mr. Brookes then read a paper on the action of the blue ray on the iodide, bromide, and chloride of silver, in producing the photographic image. The argument advanced was an ingenious one, but appeared to us to be based on a misconception of tho exact meaning of some terms in chemical nomenclature.* He argued that as phosphorescence was the result of the blue ray it contained phosphorus, and that photogenic action was the result of minute particles of phosphorus in tho blue ray diffused through the universal ether. To illustrate this he dissolved phosphorus in ether, and exposed an excited collodion plate to the vapour, he then developed it, and obtained a reduction similar to that produced by light. Mr. Debenham asked Mr. Brookes if he imagined the ether of the chemist was the same substance as that diffused through space. Mr. Brookes said “ No,” he had used tho phrase rather as an illustration than as a statement of a fact. Mr. Debenham thought that all which had been proved by the experiments detailed was that phosphorus would fog an excited plate. Mr. Brookes said that he was merely quoting Dr. Phipson in ascribing phosphoresence to the action of the blue ray. If paper were treated with tartaric acid and then submitted to the rays of the sun, it would absorb light, which would after wards have chemical action. Mr. Debenham said that M. Niepce de St. Victor’s idea of bottled light was exploded. The Chairman moved a vote of thanks to Mr. Brookes for his paper, and invited further comment. Mr. Malone remarked that Mr. Brookes laboured under a fundamental error of judgment in supposing that phosphorus existed in light, and in imagining that his experiment proved such a thing. Because he had produced a body resembling the photographic image by tho use of phosphorus, he argued that light contained phosphorus. However plausible sucli an argu ment might appear at first glance, it was altogether fallacious. The salts of silver could be reduced by many agencies. Tho oxide could be reduced by heat; tho chloride by heat and hydrogen, and also by light. But because phosphorus and other agents would reduce silver, was it to be argued that those agents were all present in light? He had used phosphorus for re ducing silver, at a former meeting, but for illustrating a very different point. Mr. Malone then referred to Mr. Glaisher's experiment, and remarked that the result was most probably due to the dryness, as chemists had an axiom that without solution there is no chemical action. Ho then' proceeded to describe some further experiments he had made, in verification of the theory he held that the photographic image was simply, metallic silver in an amorphous condition. When chloride of silver without organic matter was reduced by light, it resembled the photographic image, but when treated with hypo it lost something of that appearance, and therefore some persons denied that it was the same substance as that in tho fixed photographic image. He had contrived to mix it with gelatine and then reduce it by light, and ho thus produced amorphous silver, and this, when treated with hypo, retained its amorphous form. He then mixed it with alcohol and other, diluted with water, to get it into a thin solution, such as ho now held in his hand. It now only remained to analyze it by first weighing * See a letter from Mr. Brookes on another page.