The photographic news

• Bandzählung: 6.1862
• Erscheinungsdatum: 1862
• 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-id1780948042-186200003
• PURL: http://digital.slub-dresden.de/id1780948042-18620000
• OAI: oai:de:slub-dresden:db:id-1780948042-18620000
• Sammlungen: LDP: Historische Bestände der Hochschule für Grafik und Buchkunst Leipzig
• Sammlungen: Fotografie
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• Strukturtyp: Band

• Digitalisat: SLUB Dresden
• Strukturtyp: Ausgabe

262 THE PHOTOGRAPHIC NEWS. [May 30,1862. Mr. Martin suggested that, probably, the baths referred to were purchased many years ago, before gutta-percha was so largely adulterated. Manufacturers of photographic vessels of gutta-percha were dependent upon the purity of the sheet gutta-percha they bought for the purpose. Mr. Simpson said, the purity of sheet gutta-percha was chiefly a matter of price. Manufacturers of photographic vessels would, doubtless, be able to obtain a pure article if they would pay the price. Pure sheet gutta-percha, of a thickness suitable for photographic vessels, was, he believed, worth about four shillings per pound, whilst an article of similar substance and appearance, but not pure, could be bought for eighteen pence a pound. The latter, he feared, was too often made into photographic baths by some makers. Mr. Dawson said he had long held the opinion that gutta percha might be used withimpunity, but a careful examination of the matter had convinced him that he was wrong. He had made ten ounces of bath solution, and put half of it into a gutta percha bath for a short time ; he then applied Barber’s test for organic matter, making the solution slightly alkaline, and ex posing it to the light. That which had been in the gutta percha turned black and turbid, whilst the other was un changed. Mr. Simpson had some years ago given a good deal of atten tion to the subject, and he then applied a test of a similar character, but, he thought, even more severe. He made a new neutral bath of nitrate of silver, and placed it in a bottle ; he then cut up some very' pure gutta-percha into fine shreds or shavings, and put a large quantity into the solution, so as to secure as large a portion of acting surface as possible. The hottie was then placed in the light for a few days, without any blackening or change taking place. Mr. Dawson asked if the solution was made alkaline? Mr. Simpson said it was nearly neutral, just in fact, in good working condition. A picture was taken with it before this treatment, and another after, without the slightest apparent change in the condition. A eonversation on the subject followed, in which Mr. Sang’s suggestion of varnishing the interior of gutta-percha vessels with shellac was referred to. Mr. Bingham said that the shellac in such cases was apt to crack. Mr. Moens asked what was the best method of preventing the india-rubber lining of the top from sticking to gutta-percha baths, with watertight tops. Mr. Simpson suggested the uso of vegetable parchment over the india-rubber. Some further conversation followed on the uso of gutta percha dippers with iron supports, &c., after which the subject dropped. Mr. Barber exhibited a bottle of a collodion, which was usually known to be quite colourless, and was thought to be a cadmium collodion. This was, however, quite red. He showed this to illustrate the uncertainty of organic chemistry, and the diffi culty of making in collodion a perfectly uniform article. After some conversation on the subject, Mr. Seely showed some negatives recently taken on tannin plates, ilfter some conversation on the subject, The Chairman asked if any ono had tried honey and tannin, as suggested by Mr. England? Mr. Seely had tried it, but could not get such clean nega tives as without the honey. Mr. Simpson had tried about a dozen experimental plates with honey and tannin, and was highly gratified by the results. The plates were extremely sensitive, and the quality of the negatives was excellent. The manipulation was eztremely simple, less than usual care being required apparently in the preparation of the plates. Mr. Barber could fully bear out Mr. Simpson’s remarks. He had added a little methylated finish (methylated spirit with shellac, about an ounce to the gallon added) to the solution of honey and tannin to make it keep better, and ho thought the quality of the negative was better for the addition. Ho had tried a solution of sulphate of quinine, instead of tannin; the results wore very similar. Ho had tried tho iodido of quinine without perceiving any advantage. Mr. Simpson asked tho Chairman if his experience in tho honey process had led him to the conviction that it exercised a chemical influence on the preserved plate, or merely a me chanical action. It certainly seemed to accelerate materially in the tannin process. Correspondente. Tho Chairman said his conviction was that the effect decidedly chemical as well as mechanical. He had kon plates, when kept some little time after exposure, show a loped picture, which proved that tho honey had a redud action. J Mr. Simpson exhibited a print from a negative taken by, Underwood to illustrate the influence of a hot developer. Ta negative was collodio-albumen, exposed for 45 seconds ats o’clock in the evening, a few weeks previous. The result was regarded as very satisfactory. A convey tion on hot development followed, in which a general con" tion was expressed that the term warm development was •O safe and correct than hot, as the temperature should not rally exceed 100° Fah. Mr. Simpson exhibited an iron print on albumenized PoDd toned with pyrogallic acid, which ho had received fromB Liesegang. The print very much resembled a silver PPP with gold toning. He also exhibited a print from a negattn by Mr. Penny, to show the injury of delaying the develop® 1 ' of tannin plates long after exposure. The Chairman called attention to a portfolio, contain* some very excellent prints by the members of the Amat Photographic Society. • Mr. King presented some prints to the portfolio of the So®” The proceedings then terminated. NITRATE OF MORPHINE DRY PROCESS. ■ the Sir,—The solutions used by the Rev. Mr. Law in S Morphine Process are, I think, unfavourable for the att ment of the maximum sensitiveness; he has used an 0 negative bath, with (it appears) strong nitric acid readta and a weak pyrogallic developer. If nitric acid is used ( the bath, it should be a very small excess, and the develo a 3-grain one, applied first without silver or acid, to " the image visible, and then with silver and acid to intense then, I think, the sensitiveness is considerably mow t twice that of Fothergill’s. There need be no fear of taminating the bath for the usual wet process ; I have L the same one for some months, and a few days since I P pitated about } drachm of carbonate of silver in it, and took several negatives clear, dense, and with remark short exposures; this exactly parallels Mr. Blanchards, pcriments. Hardwich says, carbonate of silver is solub I water, sufficiently to react on litmus —can it be so i, silver solution? Carbonic acid cannot neutralize it," were soluble, itself producing an alkaline salt. It has appeared to me that the higher atomic weight the io and bromizer possesses, the more sensitive is the res' 1 U collodion, and so if a still greater atomic weight than lit or cadmium could be used, we might reasonably en greater sensitiveness. May I suggest the use of Mr. England’s tannin and solution on the morphine plates; for if the sensitivenv increased by it pro rata, as in the plain tannin proceSsa V exposure would be reduced to instantaneity ; they wolly eligible for the hot water as well, either plain morPy plates, or tannin and honey combined with the motP process. . 30) I recommend "Qusitor" to dissolve the gelatine J J. grains per ounce, and put the subcarbonate of sodattoV 1 or 2 grains per ounce, and apply at ono operation ib plate. Of course, no image will develop on them "J r the addition of silver to the developer, unless a solutg pyrogallic acid is applied first without acid on.1 Feeling I have taxed your space more than I ought, s sir, yours respectfully, War. BanriroLo" Alum Bay, May 2^th, 1802. 10 P.S. Whilst writing, I will mention that it occuttb me that possibly a little gallic acid added to thecepi it solution would get over Mr. Penny’s difficulty in " exposed and non-developed tannin plates.