The photographic news

• Bandzählung: 13.1869
• Erscheinungsdatum: 1869
• 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-id1780948042-186900000
• PURL: http://digital.slub-dresden.de/id1780948042-18690000
• OAI: oai:de:slub-dresden:db:id-1780948042-18690000
• Sammlungen: LDP: Historische Bestände der Hochschule für Grafik und Buchkunst Leipzig
• Sammlungen: Fotografie
• Bemerkung: Heft 545 (S. 73-84), Heft 547 (S. 97-108), Heft 589 (S. 599-610) fehlen in der Vorlage. Paginierfehler: Auf Seite 444 folgt Seite 443
• Strukturtyp: Band

• Digitalisat: SLUB Dresden
• Strukturtyp: Ausgabe

[June 11, 1869. POrsoNIe BY Cyanide of Potassium.—A melancholy in stance of poisoning by cyanide of potassium has just occurred in Dublin. The evidence given at the inquest upon the re mains of Mr. Frederick Darley Grattan Guinness estab lished that his death was caused by cyanide of potassium being substituted for carbonate of ammonia in a tonic stimu lant prescribed for him to relieve heart disease, with which he was afflicted. The poison had been placed in the dispensing bottle bearing the label “ Carbonate of Ammonia.” The dose taken by Mr. Guinness was more than sufficient to kill the strongest man Immediately he had swallowed it, he exclaimed, “I am choking!” and was dead before medical assistance arrived. It was proved that on Friday evening, owing to hurry of business, the ammonia bottle was given to be refilled to a young lad, only seventeen years of age, employed as a store keeper in the establishment, and he, unfortunately, filled it from ajar containing the cyanide, which closely resembled that in which the ammonia was kept, and which, in contravention of very stringent rules for the care of dangerous drugs, had been left out unlabelled. Silvering Cast Iron.—M. Bcttger recommends the use of a bath prepared in the following manner:—Fifteen grms. of nitrate of silver are dissolved in 250 grms. of water, and 30 grms. of cyanide of potassium are added; when the solution is complete, the liquid is poured into 750 grms. of water wherein 15 grms. of common salt have been previously dissolved. The cast iron intended to be silvered by this solution should, after having been well cleaned, be placed for a few minutes in a bath of nitric acid of 1-2 sp. gr., just previous to being placed in the silvering fluid.—Chemical News. Fixing Negatives.—Mr. Carey Lea, referring to the recent discussion bn cracked films, says :—“ As some have complained of the destruction of negatives fixed with hypo sulphite of soda by time, a correspondent of the News brings forward a case in which a set of negatives, ten years old, fixed with hypo, were found in excellent order. No possible danger can arise from fixing with hyposulphite, if it be perfectly washed, and this washing out will always require a certain time, no matter how rapid the current of water may be. When water is scarce, so that a stream cannot be kept up for the needful time (five to ten minutes, according to size), it is better to distribute the water into four or five pans, and let the nega tive lie five or ten minutes in each in succession. The last pan, or even two pans of one negative, might be used to begin the next with. Where a stream is used, of course particular care must be taken that a ripple forms on every part of the film, to make sure that the water is everywhere in active motion. Even with this precaution, however, time is needed, because the film is not like blotting-paper, for which solutions can be ‘ displaced,’ but it is like membrane, from which liquids must be removed by osmose, which is always far slower in its action than displacement.” o Uo Corresyondents, E. D. S.—The cause of the albumen being dissolved from the paper by the silver bath is the weakness of the latter. In using a weak bath like that you describe, especial care is necessary to replenish it with silver from time to time, otherwise, when it becomes a little weaker than the standard strength, it readily dissolves the albumen. The substitution of about one-sixth of alcohol for water is desirable in a bath as weak as that you mention, and it is im portant to replenish with silver systematically, so as to provide for the constant waste of silver. Yardley Slick.—Backing transparencies with plain white paper is not an infringement of Mr. Sarony’s Patent. 2. We cannot tell you which. There are various modes of preparing the material for ornamental corners and mouldings; we believe that a mixture of plaster of Paris and size is often used. 3. It is probable that your bath requires a little more acid. Add to each pint one drop of nitric acid. 4. Read an article on the Emolliotype process, by Mr. Nettervillc Briggs, in our last Year-Book, for full instructions. Novus.—Take the starch—Glenfield starch is best—and mix it into a paste with the smallest possible quantity of cold water; then pour boiling water upon the paste, stirring briskly until the right thickness is attained. About a teaspoonful of powdered starch will make a teacupful of paste, as it swells up enormously, and becomes very glutinous on adding the boiling water, 2, We do not know of any mode of protecting the surface of Obernetter prints; we have not found such prints peculiarly liable to injury. 3. To 6} drachms of water add 1| drachms of a saturated solution of protosulphate of iron, and you will obtain a 30-grain solution. 4. It is alleged that the use of ammonia-sulphate of iron, and also of sulphate of copper, in the developer, tend to the production of harmonious negatives. 5. It is probable that with Obernetter paper hypo as weak as one in ten might be used, but we generally use the ordinary strength of one in four, and immerse for a shorter time. 6. The numbers of the Photographic News containing Lake Price’s articles on Composition and Chiaroscuro are out of print. George Restall.—Undoubtedly ; but wo presume the matter is long past and done. We are glad to hear of your success, and sorry to hear of your bereavement. T. Mitchell.—We have not had any personal experience with the rapid plates of the Birmingham Dry Plate Company; but wo found, when we tried them some years ago, that, when in good condition, they were little inferior in sensitiveness to wet plates; and in the recent trial of various dry plates by Mr. Gordon and others, these plates were found to be as sensitive as wet plates. We do not remember precise particulars of the developer, but the formula you quote scarcely seems well suited to form a good deve loper, and the fact that it turned turbid confirms our view. Instead of adding 8 drops of 60-grain plain silver solution to 2 drachms of 30-grain iron solution, we should not have commenced with more than 1 or 2 drops at most of such a silver solution. After it had turned turbid, if it were then poured on the plate, being somewhat acid and inert for development purposes, it would tend to destroy the latent image, after which no subsequent application of deve loper would bring out an image. R. S.—The probable cause of the sunken character of tho image in your developed prints is the use of soft, absorbent paper, instead of a hard, non-absorbent sample. In printing by development, very much depends on this. We prefer a formula into which a chloride enters, as generally giving a cleaner, more vigorous image; but with the formula you quote, if you use a hard-surfaced paper, floating it only a short time on the salting solution, a short time on the silver solution, and avoiding over-exposure, we have no doubt you will obtain vigorous prints. 2. Card lenses will do well for instantaneous stereo work. J. F. F.—The article on enlarging in our last Year-Book is de voted rather to the consideration of various formulae than to initial instructions on the subject, as it is presumed that the reader knows how to set about the work. When you tell us that you do not understand how to enlarge, without telling where your special difficulty is, we scarcely know how to help you, because we do not know how much or how little you know of the subject, and it would be impossible in this column to give you full instructions. As a rule, in purchasing a solar camera, you should receive printed instructions for arranging it and setting about your work. We may very briefly indicate what must be done. The solar camera should be fixed to the window of a room with a south aspect, capable of having all light excluded except that passing through the camera. The reflector should be arranged so as to throw the image of the sun direct on the condenser. Tho latter should be placed so as to bring its focus, forming a sharp image of the sun, on the front lens of the enlarging lens. The negative should be placed in its groove, and an imago thrown on the screen placed at the proper distance. When a sharp image is obtained, place the sensitive paper on the screen, expose until a trace of an image is obtained, and then proceed to develop. If you have any special difficulty on any special point, describe it clearly, and we will endeavour to help you. North and South.—Your general plan and proportions seem good. We should prefer, if circumstances permit, to have two or three feet more in width of room, and one or two feet more of glass in length of side-light, at least on the north side and top. The angle of roof 'will do. John Otto.—Thanks for the excellent transferred negative and the description of the mode of intensifying, which shall appear in our next. Which mode of transferring do you employ ? A few of the Year-Books for 1861, 1864, 1866, 1867, are in print; the remainder are, unfortunately, out of print. Wo can let Messrs. Longman know which copies are in print, but it would be a simpler plan to send them to you by book-post. We are glad to hear from a Danish subscriber, and gratified to know that the News has been of service to you. Your English is very excellent. An Amateur.—Thanks. The diagrams have been slightly reduced to scale, to make them fit our space. Received : Pepper’s « Science Simplified.” Several Reviews arc compelled to stand over at present. Several Correspondents in our next.