The photographic news

• Bandzählung: 29.1885
• Erscheinungsdatum: 1885
• 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-id1780948042-188500006
• PURL: http://digital.slub-dresden.de/id1780948042-18850000
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• Sammlungen: LDP: Historische Bestände der Hochschule für Grafik und Buchkunst Leipzig
• Sammlungen: Fotografie
• Bemerkung: Seite I-II fehlen in der Vorlage. Paginierfehler: Seite 160 als Seite 144 gezählt.
• Strukturtyp: Band

• Digitalisat: SLUB Dresden
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304 THE PHOTOGRAPHIC NEWS. [May 8, 1885. thousandths of 1 per cent. — Journal of the Chemical Society. PHOrOGRAPHIC Club.—The subject for discussion on May 13th will be “ Transparencies for Enlargements.” The Saturday outdoor meeting will be held at Eltham. Death of Mr. Chaffin, of Taunton, and of Herr HAUT- STAENGL, OF Berlin.—Two gentlemen well known in photo graphic circles have passed away. Mr. Chaffin died last week, axd Herr Haufstaengl expired at Berlin on the 8th of last month. ELECTRO-CHEMICAL Equivalent of Silver.—By Lord RAY- LEIGI and Mrs. SIDGWICk {Proc. Roy. Soc., 36, 448—450, and 37, 142—146.)—Tn these papers, an account is given of experiments made with a view of determining the electro-chemical equiva lent of silver in terms of practical units. The final number expressed in C.G.S. units is 1118X103, a value in accordance with that determined by Kohlrausch ; thus in practical units the quantity of silver deposited per ampere per hour is 4'0246 grams. With a view of obtaining a convenient standard of E.M.F., the authors have made a detailed examination of Clark’s cells, which possesses the advantage of standing ready for use, and not polarising greatly on the passage of small currents. The value for the E.M.F., that of the B.A. unit being 0'9867 ohm, is equal to 1'435 volt, with an extreme range of 106 during six months, although about ten days are required before the cell reaches its permanent condition.—Abstracts of the Chemical Society. Composition of “ Mystery GoLp"—An alloy containing enough platinum to enable it to resist the action of nitric acid is now being extensively used as a means of defrauding buyers of trinkets, and Mr. W. F. Lowe, who has analysed the alloy in question, gives, in the Chemical News, the following particulars. The alloy, after the gilding had been scraped off, had about the colour of 9 carat gold. Qualitative analysis proved it to consist of platinum, copper, and a little silver; and quantitatively it yielded the following results Silver 2'48 Platinum 32'02 Copper (by difference) ... 65'50 100'00 Strong boiling nitric acid had, apparently, no action on it, even when left in the acid for some time. Influence of Light on the Course of Chemical Reactions in the Bromination of Aromatic Compounds.^—J. Schramm finds that bromine has no action on parabromotoluene in the dark at ordinary temperatures, but on exposure to light, converts it into parabromobenzyl bromide; the rapidity of the reaction is directly as the intensity of the light. On ethyl benzene, also, bromine has no action in the dark; on exposure to the light, a-phenylbromethane is formed. When a mixture of a-phenyl- bromethane with bromine (1 mol.), or of ethylbenzene with bromine (2 mols.), is exposed to direct sunlight at the ordinary temperature, phenylbromacetole is formed; whilst if the mixtures are exposed to diffused daylight, the reaction is very slow, and the isomeric cinnamene dibromide, CHBrPh.OH,Br, is obtained.— Journal of the Chemical Society. Exposure to White Light before Fixing.—Mr. H. M. Park hurst, writing in Photographic Times, says :— 11 In the early in structions we were told never to expose a plate to white light until afterit was fixed. In order to test this matter, I developed a plate, washed it, placed a penny upon it, and exposed it to the fullness of a bright sun for some seconds. It was then put into the hypo, and when fixed I could not perceive any effect what ever from the sun’s rays. I have never since feared exposure to white light after the developer is thoroughly removed.” One Thousand Photographs of Sculpture.—We learn in The Nation, from a letter of Mr. J. C. Rowell, that Mr. John S. Hittel has placed in charge of the University of California a collection of nearly one thousand photographs, normal size being 8 by 10 inches, of the masterpieces of ancient and modern sculp ture, for the use and pleasure of the public. The fact that sculpture yields itself to the photographer’s art readily and with fine results, and, further, that excellent photographs may be gathered at slight expense compared with the cost of casts, should lead to the formation of similar collections throughout the country. Influence of Light on the Electrical Resistances of Metals. —By A. E. Bostwick {Amer. J. Sci. [3], 28, 133—145). — From a series of elaborate experiments made in the Yale Col lege Laboratory on plates of platinum, gold, and silver, the author concludes that if light causes any diminution in the electrical resistance of metals, it probably does not exceed Uo Uorxespondents. *,* We cannot undertake to return rejected communications. Thos. Sansom.—A strong aqueous solution of sulphocyanate of ammonium will dissolve it in the cold. H. Foss.—The address has been posted to you. Rogation.—1. See vol. for 1881, page 563. 2. They are usually sunlight pictures printed on paper of a greenish tint (or what comes to the same thing, they are stained afterwards) ; but some working up of the original negative is required. 3. By giving a decidedly full exposure and developing accordingly. A. T. G.—1. We should certainly consider that a person who en gages to “ assist generally ” may fairly be regarded as a general assistant. 2. Heigh way’s “Posing and Lighting,” published by Piper and Carter, will perhaps serve your purpose ; but a far more comprehensive book is in the press, “ The Studio, and what to do in it,” by H. P. Robinson, 3. It is better to cast it on one side under the circumstances; but of course you will take care to re cover any gold which may be present. 4. He is supposed to be able to take a negative, and if he make good use of his opportuni ties he may soon learn to do high-class work. W. E. Price.—1. It is possible; but you will find it very much better to make a negative in the ordinary way, and then make a contact transparency from it. 2. As tar as we know, it is a satisfactory instrument, and will serve for all the purposes you mention. 3. Yes, provided the light is moderately good. Spots.—They arise from air-bubbles adhering to the paper in sen sitizing. Lift the sheet from the sensitizing bath and replace it; this operation may be repeated if necessary. Vero C. Driffield.—Thank you for the block, which we hope to use next week. Chas. H. Grant.—This correspondent writes as follows:—“I shall be much obliged if any of your subscribers could give mo their experience as to th best method of carrying my photo graphic gear (a whole-plate camera, three dark slides, and tripod) on a Singer’s Challenge rear-steering tricycle of the old type.” Perhaps some reader can speak from experience. Lussac.—It is a well-recognised defect of the printing process you refer to, and we have an article in type which throws some light upon it. W. F. Mitchell.—1. From Messrs. Houghton and Sons, of High Holborn, or Marion and Co., of Soho Square. 2. We do not khow the price. H. Field.—Nothing better than the ordinary Brunswick Black. Belfast.—We would obtain it for you you with pleasure, but it is a rule with us not to take part in such agency business. Write to the photographic publishing house to which you refer. G. George.—Cement them to the glass with the varnish known as “ crystal paper varnish.” „*, Several answers are unavoidably postponed until next week. Uhe Ahotographit Jews. subscriptions. Including Postage to any part of the United Kingdom:— Yearly ... 15s. Od | Half-Yearly ... 7s. 8d. I Quarterly ... 3s. 1d To the United States, the Continent, and the Colonies:— Yearly ... 17s. 4d. I Half-Yearly ... 8s. 8d. | Quarterly ... 4s. 4d To India (Yearly) 19s. 6d. ADVERTISEMENTS in column. Not exceeding Five Lines (36 words)... 3s. 0d. Each Additional Line 0s. 4d. Repeated insertions, and special positions or style, by contract. Advertisements should be forwarded (prepaid) to Piper and CARTE 5, Castle Street, Holborn, E.C., to reach the office not later than noon Thursday. A fee of 6d. must be forwarded when the Pub lishersLeF expected to receive and forward replies to Advertisements; and Whene undertake the receipt of replies, they must be entrusted with the n and address of advertiser, for revelation to applicants, in case they J deem it necessary.