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
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• PURL: http://digital.slub-dresden.de/id1780948042-18680000
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• Sammlungen: LDP: Historische Bestände der Hochschule für Grafik und Buchkunst Leipzig
• Sammlungen: Fotografie
• Strukturtyp: Band

• Digitalisat: SLUB Dresden
• Strukturtyp: Ausgabe

540 THE PHOTOGRAPHIC NEWS. [NOvEMBER 6, 1868. Venator.—The exhibition will remain open for a week, and the public, after Tuesday evening, will be admitted free. 2. The best remedy we can suggest for turbid collodion is to allow it to stand, and then decant off the top portion. 3. When wax is applied to a plate of doubtful cleanliness to give it a thin film of a neutral substance, it is simply necessary to apply the wax solution, and then rub it nearly all off with a clean cloth. After it is so treated, it will generally yield a clean negative, although it will not look even and clean when breathed upon. A preliminary coating of albumen causes risk of injury to the silver bath. Peter Simple.—Without some slight preliminary knowledge of the subject—such, for instance, as a knowledge of what an enamel is— we fear that you will not succeed in producing bumt-in pictures. An enamel picture is a picture formed of vitreous colours which have been submitted to sufficient heat to slightly fuse them. A <{ flux” consists of a mixture of powdered flint and borax, or similar materials, which readily vitrify under the action of heat. A flux is added at times to the colours used to aid in the process of vitrifying. Porcelain colours generally consist of metallic oxides, which assume a vitreous form under the action of heat. Vitreous colours, fluxes, and enamel tablets can be purchased ready for use. We cannot tell you where; but your London dealer will doubtless procure them for you. Our Fifth Volume contains a good deal of information on the subject of enamels Wm. Cobbold.—The pinholes in your case most probably proceed from excess of iodide of silver in the bath. To test this, take an ounce of the bath and add half an ounce of distilled or boiled rain water. If your silver bath be already saturated with iodide of silver, this addition will make it turbid. The remedy is to dilute the whole bath with an equal bulk of water, and then, after filtration, add sufficient nitrate of silver to bring the solution to the proper strength. W. J. A. G.— You will best understand the directions for deve loping the dry plates if you bear in mind the respective offices of solutions 1, 2, and 3. No. 1, the pyro solution, is the developer propei ; No. 2, the ammonia, aids the action of the pyro; whilst No. 3, the bromide, retards somewhat, its especial function being to prevent fog. These are mixed in the proportions indicated for the purpose of bringing out the image; and when this is effected the pyro and ammonia are used to secure intensity. The bromide will not aid in this, and should not be used unless there is some tendency to abnormal deposit on the shadows, in which case a little of it may be added. We have found, as a rule, that dry J. T. (Fife).—Either Mr. Bovey’s toning bath, the lime bath, or the acetate bath will, as a rule, answer; but double albuminized paper is generally somewhat slow in toning. If you immerse the prints in the toning bath without previous washing, or with but slight washing, they will tone more readily. Z. H. A.—The formula you state will yield you a good solution of chloride of gold; but as it contains a large proportion of acid, it will not be suitable for use with an acetate bath. Your best plan of using it will to be neutralize the portion required with chalk, whenever you wish to use it, a few hours or a day beforehand. If you want it for immediate use, neutralize with chalk, and add to an ounce of the solution 5 ounces of hot water; when cool, it will be fit to use. It will always require a few ounces of water adding to each ounce, as the strength you name, 1| grain per ounce, is much too strong for toning purposes. 2. The story is a myth. Publishers of engravings generally get as good a sub scription list as they can before publishing a costly plate; but they are under no legal obligation to destroy the plate at any time. They sometimes make a compact with subscribers that the plate shall be destroyed after a certain number have been printed, with a view to prevent the subject becoming too common; but this is purely a matter of choice. The notion that Graves and Co. make money by prosecuting pirates is very foolish. They have been, perhaps, a little vindictive in these prosecutions because they have been much wronged, and suffered much loss. plates were not satisfactory with any amount of exposure in a bad light, and we should recommend you not to waste time and court disappointment by exposing dry plates except when the light is clear and bright. GULIELMUS.—As you have, as you state, carefully read all that has appeared in the News on the subject of pinholes, it is difficult for us to give you any fresh information. Your remark that your difficulty generally occurs during the process of intensifying sug gests a possible remedy. We have found pinholes occur in inten sifying from several causes : where, from thinness in the image, or from under-exposure, the intensifying has required pushing con siderably ; where a portion of the nitrate bath is added to the pyro instead of a fresh solution ; and where excess of nitrate has been added to the pyro. Aim, by the use of suitable materials and full exposure, to get a good image in the first process of develop ment, and the risk of pinholes will be much reduced. Either citric or acetic acid may be used; but we are not aware that any difference in the result, as regards pinholes, will follow. 2. The different statements you find as to the proportion of silver taken up by a sheet of albuminized paper doubtless arise from the use, in the experiments recorded, or different samples of paper, in which different proportions of salt have been used. The proportion of silver absorbed is chiefly regulated by the proportion of salt added to the albumen; and as the proportions used by different persons vary from 5 grains per ounce to 20 grains per ounce you will see how impossible it is to give any general statement on the subject. The following calculation may help you:—One sheet of paper takes up nearly an ounce of albumen solution. Suppose it contains a proportion of 8 grains of chloride of ammonium, the salt on a sheet of such paper will take up about 25 grains of nitrate of silver, the albumen will take up a little, and the solution on the surface, suppose it to be a 40-grain bath, will amount, probably, to 10 grains more. In such a case you would have nearly 40 grains of nitrate of silver consumed by one sheet of such paper. We are glad our last advice enabled you to remove your difficulty. J. Smith (Halifax).— Grasshof's Manual of Instruction for Re touching Photographs is published in German, by L. Gerschel, Berlin. M. A. Wanderson.—We do not know of any one who makes a collodion specially for enamelling photographs, except Mawson and Swan. To make some for yourself you would probably require to make the pyroxyline also, as toughness much depends on the character of the pyroxyline. It should be made with moderately weak acids, and at a low temperature. Lux et Salus.—Thanks. You will probably have opportunity of calling on some other occasion. Your letter in our next. Photo.—Marion and Co. are the largest photographic publishers. The Stereoscopic Company also publishes largely. C. E. Elliott, Spooner and Co., and some others, both publish photographs and deal in them; but we cannot furnish you with anything like a complete list of such publishers. 2. If you develop your solar camera image sufficiently, then wash, and immerse in an ordinary hypo bath, you will not lose the image. W. T. Watson.—Received. Your request shall have our attention. The specimens are very good. We shall have pleasure in learning further particulars of the mode of producing them. B. A. Gilbert.—Acetic acid once added to a silver solution is very difficult to remove. Nothing short of boiling to dryness will effect it thoroughly. E. Sawyer.—We ascertain from our correspondent that your pic tures arrived at Falmouth two days after the opening of the Ex hibition, and as his notice was written on the first day, no notice of your contributions was possible. Those to which you refer as possibly yours were both by Mr. Douglas, of Edinburgh. Our correspondent, speaking of yours, states that they are superior to the average of coloured enlargements, and that the likeness is admirably preserved. ‘‘Permanent Photography.”—A correspondent has sent us a paragraph cut from the Daily Telegraph with this heading, with some severe strictures upon what ho terms a “ shameless puff o Pouncy's process,” and his claims to the origin of carbon printing. The subject is not worth re-discussion. It has been thoroughly canvassed in our pages more than once, and we have shown that M. Poitevin produced carbon pictures and patented his process three years before Mr. Pouncy was heard of. The oil or print ing-ink process has many good features, and we have seen good results produced by it. It is a pity that a good process should be prejudiced by the injudicious claims of its inventor. Six hours’ boiling, and six days’ baking in a furnace, are burlesque tests, and are of no value if true. F.—Thanks: in the main you are correct. We simply answered two specific points raised by our correspondent; we have no concern with common gossip or its retailers, nor should we dream of having any discussion with persons who do not hesitate to invent their facts and their correspondents to meet any case. We are familiar with the aliases you mention, and many more; but neither they nor their owner possess any interest for the public. A. B.—The plan of iodizing by the addition of a little collodion to the bath is not to be commended. The pinholes in your first essay are probably due to that. So far as we can see, there is not much defect about the second bath. It is difficult to say from which o two or three causes the fog may arise. It maybe that a little more nitric acid may be required in the bath ; there is not much danger of adding excess when you are using bromo-iodized collodion. may be the want of a little more acid in the developer. Possibly the use of the gelatino-iron developer would meet the case. The fog may possibly be due to the presence of a little white lighti the camera or dark room. It has somewhat of that effect. I excluding white light carefully, and try the gelatino-iron developer and let us know the result. We are glad our advice helped Y°" out of toning difficulties. Dealer.—You need be under no apprehension. The first clause 1 the new Act, from which we made an abstract some months,88° for our readers, distinctly states the date of its operation as " fro 1 ' and after the 31st of December, 1868;” and no "judge" 11 stated anything to the contrary. A blunder on the subject W made in a police court, which has been perpetuated by some of t more careless or less informed portions of the press Several Correspondents in our next.