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

such is the perfection of tho work, it has been remarked that one might as well gild refined gold, or paint the pure lily, in expectation of improving them, as attempt to add aught to the beauty or finish of these pictures by retouching.” It should be remembered that Mr. Pollock here speaks of his own portraits, the negative of which, as well as the prints, he has in his possession. Antidote fob External Poisoning by Cyanide of Potassium.—This substance is extensively used in electro plating and other arts, where its external poisoning effects pro duce many painful and troublesome ulcers on the hands of the workmen. The foreman of the gilding department of the American Watch Works writes to the Boston Journal of Chemistry that experience has taught him the most effectual remedy that can be employed in such cases, which is the proto- sulphate of iron in fine powder, rubbed up with raw linseed oil.—Scientific American. Photography and PARKESINE. — Parkeseine, originally described in the pages of tho News, is now being introduced in commerce as a substitute for ivory; and, as photographing on ivory can be readily done, and elegant results obtained, it may possibly be found advantageous to try its effects on the now material, which will be extensively used for many articles of domestic and ornamental use in lieu of tho scarce and costly tusk of tho elephant. U0 Correspoudents, W. J. A. G.—Black is very dismal and uncomfortable-looking for any portion of the interior of a studio. A dark warm grey, a chocolate brown, a port wine colour, a dark crimson or maroon, or an olive green, will all be suficiently non-actinic in their reflections, and much more pleasant to look at. 2. There is no patent for Mrs. Cameron’s process. The black colour is easily obtained by deep printing and toning. The reason they look unlike photographs is two-fold: first, they do not possess, but absolutely ignore, tho sharpness and detail which is the especial characteristic of photo graphy, and in which it excels other modes of delineation; and, second, because there is really a large amount of artistic feeling displayed in the selection and management of each subject. As a rule, a free and artistic style of treatment, a lack of definition, and prevalence of deep shadow, characterize all her pictures. 3. A rising front docs not give you the same advantages as a swing back. By moans of a rising front you can regulate the amount of foreground, sky, &c., to be included in your picture; by a swing- back you can do this to some extent also; but its especial purpose is, when it is necessary, to tilt the camera to secure the roof in an interior, or a spire or tower in an exterior view of a building, to enable you to keep tho sensitive plate parallel with the subject depicted, and so prevent the effect of converging perpendicular lines. 4. For general work, No. 3; for architecture, No. 1 is best. 5. Tho quality of the tone of a print depends very much upon tho quality of tho negative ; but it is chiefly from the amqunt of reduc tion which the negative permits in the shadows without over-print ing the lights. It is quite possible to got brown tones with tho acetate bath, and a very short immersion is sufficient to secure it. Our choice of a toning bath much depends on the kind of results we desire, some tones suiting one subject, some another. For a rich, warm, purple brown nothing is better than tho acetate bath ; for black tones, the lime bath. We very frequently improvise a bath if we require to use it at once, and have none ready, by adding a little chalk to a concentrated solution of chloride of gold, diluting with hot water, and using when cool. 6. No. 1 undoubtedly. A Stranger.—There is no association or benefit society composed of operators in London or elsewhere, that we know of. Argent.—In producing a transparency by tho process we described, the negative is placed in the outer groove of the copying-box, as indicated at C, on p. 73 of our Year-Book, the lens being in the centre and the ground glass at the opposite end. If convenient, it is better to work in the open air, or with the end of the copying box containing the negative placed out of a window, simply because more light is secured. II. Berton.—The colour test of alkaloids is an exceedingly falla cious means of detecting poisons, and, if relied upon, will frequently load to error. For instance, iodic acid and starch form tho colour test for morphia ; and Orfilla mentions a case in which the viscera of a healthy calf gave, with the test, exactly the same reaction in colour as the viscera of one which had been poisoned with morphia. This led to the discovery that lithic acid or tho lithate of ammonia (constituents of healthy urine) gave the same colour with morphia as the recognized test, iodic acid. Another eminent French autho rity, writing on the subject, remarks that nothing is so deceitful as a reliance on colour tests. R. B.—A thick solution of india-rubber in benzoic, from 20 to 30 grains to the ounce, is the best thing for mounting photographs in an album, as then all risk of cockling is avoided. 2. You can pro cure iodized negative collodion of any photographic dealer. 3. Float on the salting solution about three minutes, and on the silver solution three minutes. The question whether acetic acid is to bo added to the gallic acid depends for its answer on whether it is present, and in what proportion, in the silver bath. Painting a negative at the back to prevent " blurring” is done, of course, after the plate is prepared. A piece of red blotting-paper, moistened and pressed to the back of the plate, answers well. B. B.—Tho address of Messrs. Foster, Auctioneers of Works of Art, is 54, Pall Mall. The address of Messrs. Christie and Co. is King Street, St. James’ Square. Wo are glad to hear of your continued success with tho modified collodio -albumen process. Thanks for your kind remarks about tho Year-Book. A Provincial Photographer.—Judging from the print you forward, the negative is fogged, probably by diffused light having reached the plate. Tho lights may be dense, but we should say that there is considerable deposit on the shadows; hence the want of depth in the shadows. We can only tell certainly on seeing tho negative. Mrs. II. West.—The bleached or white bees’-wax is used for waxing photographs ; paraffine is equally good, or better for tho purpose. 2. The effect of adding cyanide of potassium to a solution of nitrate of silver is to cause a precipitate of cyanide of silver, which, when filtered out, will not cause further injury. Neu tralize the nitric acid in your printing bath with ammonia, and try again. 3. Tho price of Mr. Edge’s card pictures is Is. 6d. each. A letter addressed Preston will find him. Young.—Tho light entering above A.B. in your diagram, at an angle of 45 degrees, would not reach the sitter; but you forget that all the light docs not enter at an angle of 45 degrees, but a great many angles besides, and therefore some of it will reach the sitter. A very simple plan will enable you to ascertain how much light reaches the head of the sitter. Place yourself in that posi tion, and cast your eyes around : from every point at which you can see the sky direct light will reach the sitter. All glass through which you cannot seo the sky may with advantage bo covered or obscured. 2. All light which docs not reach the sitter is mis chievous. 3. In a lofty room it is often advisable to have curtains which can be arranged near the head of the sitter for occasional use. Blue calico is a good material. 4. Portrait lenses rarely cover so evenly or illuminate so perfectly to tho edges as view lenses; and in order to got all parts defined, very small stops must bo used : nothing is gained in using them for ordinary land scape work, whilst something is lost. 5. About equal. Alex. AYTON.—Thanks for the excellent examples of card por traiture. Wo shall have pleasure in learning the result of your contemplated modification. We arc glad to learn that your visit to M. Salomon was so pleasant and so satisfactory. Engineer.—It seems probable that what you call fog in the trans parencies produced by the method in question is really increased action of light, as it often happens that a thick film is more sensi tive than a thin one. In some cases a little dilution of tho collo dion may be desirable. A good iodizer for the purpose will consist of two grains each of iodide of ammonium and iodide of cadmium, and one grain of bromide of cadmium. X. L.—We do not know in whose possession tho original painting of “ Belshazar's Feast,” by Martin, now is. There is an engraving of it published, but we do not know of any photographic copies to the engraving. A Young Beginner.—So long as you take care to have your yellow light in your dark room thoroughly non-actinic, there is no danger in having a sufficient amount of it to make working easy and pleasant. It is a bad thing to have too little, as you cannot then properly sec what you are doing. In such a room as you describe, a window three feet by three feet will probably answer. We arc glad to learn that you are well pleased with the-paper. CHEMIICUS.—It appears to us that the lenses you have in your pos session ought to answer well for the purposes you mention. What difficulty have you in using them ? No. 3 is a capital lens, but not sufficiently long in focus for standing card pictures. J. A. Reed.—When the term parts is used, the formula) may be made up in grains, scruples, drachms, or ounces. Thus, if you make up the formula you mention in scruples, you will have 1 scruple of pyro and 1 scruple of citric acid in about 13 ounces 0 water, or something like Ingrains of each to an ounce. A 3 Per cent, silver solution is a solution containing 3 grains of silver 1 100 minims of water, or a fraction under 15 grains to the ounce10 water. 2. It is the collodion containing nitrate of silver whic has turned rod. It may not necessarily bo spoiled: try it. - any case, tho collodion containing chloride is good still. Wo arc again compelled to leave over much interesting matter, oWl to the pressure on our space ; and many Correspondents also stan over until our next.