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
• OAI: oai:de:slub-dresden:db:id-1780948042-18850000
• 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
• Strukturtyp: Ausgabe

240 THE PHOTOGRAPHIC NEWS. LAPRIL 10, 1885. Aniline Company (Actien-Gesellshaft fur Anilinfarben-Fabrica- tion zu Berlin) is to be preferred. Half-a-gramme of aurantia is shaken with 100 cubic centimetres of plain collodion, and after the insoluble matter has settled down, the glass (patent plate) is coated. The plate may be placed inside the camera, or may be used as a cover to the object to be copied. Influence of Light on the Germination of Seeds. By A. Cieslar.—The author finds that many seeds hitherto thought to germinate in light only, will do so equally well in darkness. Small seeds with poor reserve of material germinate better in light, whilst those with a large reserve do so equally well in darkness ; he did not find any seeds which grew better in dark ness than in light. Yellow light accelerated, violet retarded germination, and the latter at a low temperature almost rendered growth impossible. In white light there was greater energy of growth, a higher percentage ef buds, and generally more activity than with coloured lights ; the author thinks this due in part to the transformation of light into heat.—Journal of the Chemical Society. Standard of Illumination.—By W. H. Preece [Proe. Roy Soc., 36, 270—275).—-After alluding to the unsatisfactory methods in vogue for measuring the intensity of illumination, the author suggests as a standard the space illuminated by a standard candle at 12’7 inches distant. For a comparison of the relative illumination of surfaces, use is made of a Swan’s incandescent lamp, giving a light of 2] candles with a current of 5 volts, enclosed within a box with blackened walls, over the end of which is stretched a diaphragm of paper; the latter has a grease spot at its centre. At about 12 inches from the tube is a screen of paper as a reflecting surface. The current is supplied from a secondary battery. From experiments detailed in the paper, it appears that the iliumin ding power of the glow lamp increases in the ratio of the sixth power, of the current: hence a determination of its strength gives the necessary equivalent for ascertaining the degree of illumination. Though there are certain difficulties arising from alteration of the glass envelope of the lamp, deterioration of the carbon fibres, and failure of vacuum, yet the light emitted from the passage of a given current is more easily reproducible, and probably more uniform than any other artificial standard.—Journal of the Chemical Society. Photographic Club.—The subject for discussion on April 15 th will be on “ Reducing and Intensifying of Gelatine Negatives.” Uo Uortespondents. *.* We cannot undertake to return rejected communications. William Goode.—1. We have found those by all the leading makers to be excellent as a rule, but of course there is nothing to be surprised at in an occasional failure to quite reach the standard. 2. Get a few of each, and judge for yourself. M. D.—Within anything like reasonable limits the larger the better, aud we would suggest that you should try and get a second-hand cast iron "‘imposing slab” such as is used by printers. A slab about two feet square would not only do well for the size you mention, but also for larger plates. You may perhaps get one by writing to Taylor, printer’s broker, Little Parker Street, Drury Lane. A. R.—1. The plates have probably been damaged by fumes which the packing material did not effectually exclude, or by some emanations from the packing material itself. 2. It is less likely to happen if you use a non-ammoniacal developer. Broad Arrow.—Husnik’s " Lichtdruck; ” it is published by Hartleben, of Vienna, and can be obtained through any foreign bookseller—Trubner, of Ludgate Hill, for example. Alfred Dando.—Not many weeks; your best way will be to ad vertise for an instructor. Trombone.—Try Beach’s soda and potash developer, and do not under-expose. The formula is to be found on page 194 of the Year-Book. X. M. N.—They are due to minute metallic particles in the original paper, and the only thing you can do is to obtain another sample. H. P.—If you want to take out a weight of 100 lbs. on rough and hilly roads, you had better get one of the specially-made parcel cirrying tricycles, and at the sams time prepare yourself for hard work, W. North.—It is not a very convenient operation to carry out when on a journey. Clean some glass plates, and rub one side over with powdered French chalk, taking care to dust off the excess ; after which coat the chalked side with collodion, and when this is dry, all is ready for mounting the prints on the glass. Allow the prints to remain for a few minutes in a warm solution of one part of gelatine in twenty or thirty parts of water, and after having flooded the collodionised surface of the glass with the same solu tion, place one of the prints face downwards upon it. Now expel all excess of gelatinous solution by gently stroking the back of the print with a squeezee. When quite dry, the print can be stripped from the glass. See p. 173 of the Year-Book. J. II. B.—The process you mention, if not the best, is so good that we cannot suggest anything that is more likely to suit you. H. S.—1. There is not any apparatus of the kind which gives accurate results, but the minute variations may be disregarded in actual practice. 2. Certainly not for every-day work, but possibly it might prove of value in certain scientific investiga tions. 3. That described on page 163 of the Year-Book is equally good for prints or for negatives, while if you want one for plates only, get a tinman to make one according to the directions of Mr. McKellen, who writes on page GO of the same volume. If you have not a copy of the Year-Book, send us a post card, and we will forward one to you. 4. Most likely—indeed, almost certainly—the result of insufficient washing. 4. Thank you for your promise ; we shall write to you. Amateur.—You have been misinformed ; nothing of the kind is being done. Your inform ant should make further enquiries, and he will find that he is mistaken. Typographer.—1. Work from a transparency instead of from a negative, but take care that the transparency is not too dense. 2. Oue part of gelatine and ten of water. When dissolved, allow the mixture to cool to about 100° Fahrenheit, and then stir in one-fourth part of ammonium bichromate. 3. Your account is not quite clear, but we imagine you refer to the old process of etching with a solution of perchloride of iron. W G. S.—Hardly a matter for discussion in the News : or, if dis cussed, the matter should be made less personal. Sigma.—Only by very hard rolling. D. Cunningham.—See article on the subject in the “ Dictionary ” this week. A Young Beginner.—You do not make an ordinary etching ground sensitive, but use sensitive materials to make an etching ground. See the first article in the present number. Ed. Wheeler.—Your failure is probably duo to the use of impure cyanide of silver. Monckhoven’s proportions, given in answer to “ Forrester,” in the News of last week, answer well. Morrison.—1. It is the most remarkable case of reversal which we have seen, and we will make some experiments with the view of throwing light upon it. 2. We do not think it has been patented in this country; but, at any rate, you would be safe in making one for your experimental purposes. 3. That described in our first leader of this week. J. P.—From Law, Sons, and Co., Windsor Court, Monkwell Street E.C. J. E. Ford.—An article on the subject shortly; but in the mean time, read the account of the direct method, described in our pre sent issue. Litho.—The collodion process is usually employed. Amateur.—Perhaps you have under-exposed, or used a developer containing too large a proportion of bromide. Uhe A9hotographit SUBSCRIPTIONS. Including Postage to any part of the United Kingdom:— Yearly ... 15s. Od | Half-Yearly ... 7s. 8d. | Quarterly ... 3s. 10d To the United States, the Continent, and the Colonies:— Yearly ... 17s. 4d. I Half-Yearly ... 8s. 8d. I Quarterly ... 4s. 4d To India (Yearly) 19s. Gd. advertisements in column. Not exceeding Five Lincs (3G words)... 3s. Od. Each Additional Line 0s. 4d. 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