The photographic news

• Bandzählung: 12.1868
• Erscheinungsdatum: 1868
• 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-id1780948042-186800009
• PURL: http://digital.slub-dresden.de/id1780948042-18680000
• OAI: oai:de:slub-dresden:db:id-1780948042-18680000
• Sammlungen: LDP: Historische Bestände der Hochschule für Grafik und Buchkunst Leipzig
• Sammlungen: Fotografie
• Strukturtyp: Band

• Digitalisat: SLUB Dresden
• Strukturtyp: Ausgabe

12] THE PHOTOGRAPHIC NEWS. [January 3, 1868. sliding from front to back ; a cord running through the rings attached to each, and hanging down from the higher end, to be either attached to a hook to hold the blinds in position and pre vent them sliding down the rod, which, of course, must be on an incline, or to be furnished with a counterpoise weight for the same purpose. Camera.—“The Photographer ” is an amateur magazine, as we described in our last, and is only circulated amongst the con tributors and their friends. Anything of interest it may contain will be published in our pages. W. Bartholomew.—Of course the character of the sitter mate rially affects the possibility of producing pleasing portraits ; and the more graceful, striking, or beautiful the model the better will be the picture. The more plastic the model the more easily will the capable artist produce good results ; and the more awk ward and intractable, the greater will be his difficulty. The more skill and knowledge a photographer possesses the more control he will have even over ungainly and intractable sitters. We have seen many of M. Salomon’s portraits of Englishmen, all very excellent pictures. Two of the five gentlemen’s por traits we exhibited at Conduit Street were Englishmen. We shall be glad to hear more of the idea to which you allude. Waterloo.—We are glad to learn that you have found the partial obscuring of your top-light by stippling with white paint pro duce such a marked improvement in your pictures. Non-Chemicus.—A combination of oxide of gold and ammonia j forms fulminating gold, which is highly explosive and I dangerous. Whether any trace of this may have been formed in precipitating your old toning baths with ammonia-sulphate of iron is difficult to say. You may obviate all risk by avoiding drying by heat. A trace of moisture left in the black precipitate will not be a disadvantage in making it into chloride of gold by means of nitro-hydrochloric acid. You will only need to add a little less water with the mixed acids. Thomas Stothard.—The addition of gelatine or of iodine to the developer will not prevent the over-action of light in a window directly opposite your lens in a dark interior. If you cannot cover the window for a time during the exposure, the best remedy will be to paint the back of the plate with red paint, or press a piece of damp red blotting-paper at the back. This will prevent the spreading of the light over the edges of the window. 2. In crystallizing after evaporating by heat, set the solution in a state of super-saturation in a cool place to crystallize; then pick out the largest crystals as they are formed, and repeat the process. An Old Subscriber.—Pure gelatine (Nelson’s, for instance) is nearly free from colour, and, in thin layers like varnish, or in tolerably thin solutions, it is practically colourless ; but when you speak of a sample “ perfectly colourless,” we cannot say that we have ever seen such a sample. 2. Chrome alum you can best obtain by writing to Mr. Swan, Mosley Street, Necastle-on-Tyne. The exceedingly minute trace of it used to render gelatine in soluble renders the colour inappreciable. Common alum, or sulphate of alumina, will render gelatine insoluble. X. Y. Z.—Enlargements by the enlarged negative process can be obtained as sharp as enlargements by the solar camera. 2. Various fluxes may be used with chloride of silver. Mr. Hart’s plan of adding half the weight of powdered resin and a little borax is good. That most commonly used is a mixture of the carbonates of soda and potash, twice the weight of this being added to the chloride of silver. It is not very important that every particle of filtering-paper should be picked out. 3. There is no method of saving the gold better than that described by Mr. England, which you will find in our Year-Book for 1867. It consists in precipitating with sulphate of iron, and boiling the precipitate with nitric acid. Kent.—It is well, for keeping purposes, to preserve your albu minized paper quite dry; but the stock for immediate use may be kept in a dampish place, as over-dessication is attended by many troubles. 2. Waxing prints should be effected after mounting. The wax should be used in a state of thick paste made with an essenvial oil, such as that of lavendar or rosemary. It is roughly applied in places over the print, and then rapidly spread by means of friction with a clean piece of woollen cloth. It is not necessary to have a perceptible coating of it on the face of the print; but if you leave half a print undone, you will quickly perceive the additional richness in the shadows of the part treated. An enamel or encaustic paste for the purpose is prepared by some houses. Newman’s have a very good article. 3. in excess of water, chloride of silver is apt to remain sus pended a long time. Use as little water as possible, and now and then add a little hydrochloric acid, as chloride of silver is partially soluble in solutions of alkaline chlorides. 4. The decomposition which you describe in the gelatino-iron developer is due to lack of acid, or, possibly, to the use of an impure sample of acetic acid. See Mr. Spiller’s article in our Year- Book in reference to testing acetic acid. Thanks. W. F.—Your phrase, an “illuminated photograph,” is scarcely sufficiently definite to enable us to advise you, and your account of the purpose for which it is intended is not sufficiently clear. An illuminated photograph may either consist of positive trans parency on glass, or of a positive on paper, made transparent by wax or varnish, and brilliantly coloured. We should fancy you want the latter. 2. The question as to enlarging must depend on the size of the negative and of the print required. 3. In any case, if used by artificial light, it should be placed facing the gas, and be screened a little from light on the side at which it is examined. W. J. A. G.—Hyposulphite will keep in solution before it has been used; but when once it has been used for fixing prints it is liable to change, and should not be used afterwards. 2. You can take open-air groups with your Ross’s single lens; it will give you perfectly good and sharp results. For interiors, all single lenses will, however, give curved lines; a double or triple combination is necessary. 3. For interiors or architec ture we should prefer No. 2 ; for landscape and general purposes No. 3 would be better. 4. We prefer a bellows camera. 5. In making or renewing the acetate of soda and gold toning bath no carbonate of soda should be added. 6. Both the samples of cloth are poor, thin, and open. It is possible to get both the twill and the yellow calico closer and better, so that a thickness of each would be opaque enough for a tent. If these are of the ordinary width (that is, three-quarters of a yard wide), they are worth, perhaps, half the price you quote. 7. As a rule, less acid is required in a strong iron developer, because its action being less prolonged, less restraining agency is necessary. If it were necessary to force development by prolonged action of a strong developer, then it would require more acid in proportion to its strength. M. G.—A little thought will satisfy you that when you arc using an artificial light to illuminate any single object you waste a large quantity of light, unless you use a reflector, as the light radiates in all directions, only a small portion falling on the object. By using a suitable reflector yon concentrate the chief part of the light on the object to be illuminated. To succeed satisfactorily with the magnesium wire you undoubtedly should use some kind of reflector. G. G. G.—The changes which take place in the production of a print by the oxy-hydrogen light are the same as those which take place in the same operation by sunlight. When iodized paper is brought into contact with the bath of nitrate of silver, a process called double decomposition takes place, and iodide of silver is formed in and on the surface of the paper. The action of light upon this sensitive paper is to set up incipient reduction of the iodide of silver, which reduction is completed, in the ratio in which light has acted and commenced it, by the gallic acid, which is in itself a reducing agent, or an agent tending to reduce salts of silver to their metallic form. The object of immersing the print into the hypo solution is to remove all un. changed iodide of silver, which, being still sensitive to light, would, if not removed, cause the whole of the paper eventually to become darkened. The quantity of hypo necessary to fix a print ■ depends, of course, on the size and upon the quantity of silver salt to be dissolved. Speaking roughly, about two sheets of paper may bo fixed with one ounce of hyposulphite of soda in five ounces of water. The time of immersion depends somewhat on whether the paper be thick or thin, and the weather cold or hot; but from ten to twenty minutes will generally suffice. W. P.—The diagram E indicates the saucer containing chloride of calcium. Gutta-percha grooves might do, but if much heat were applied they would soften and lose form. Plates should be well drained before placing in a drying box. Thanks. James Andrews.—The mistake is doubtless a very troublesome one. The only thing you can do is to get it rectified as early as you can, and avoid using as far as possible the incorrect cards. A Dabbler in the Art.—We published all the particulars of the Chassis-Cuvette in our possession. It is not, that we are aware of, made or sold in this country. G. M. (Amsterdam) — The firm you mention sells colour for colouring transparencies, and the work contains hints for colour ing glass positives. We do not consider the second work you name trustworthy, especially on the point in question. 2. So far as evidence reaches us, the second you name is as good as the first. Yes; we think so. Received, “ Leaf Prints, by C. F. Himes, Ph.D.” Some Articles and Critical Notices are compelled to stand over until our next. Several Correspondents in our next. *,* All photographs forwarded to the Publisher for registration receive attention at once ; but the pressure on our space sometimes compels us to defer the acknowledgment in this column. Itashould be borne in mind, therefore, that non-acknowledgment at once does not necessarily imply non-receipt or non-registration.