The photographic news

• Bandzählung: 35.1891
• Erscheinungsdatum: 1891
• 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-id1780948042-189100009
• PURL: http://digital.slub-dresden.de/id1780948042-18910000
• OAI: oai:de:slub-dresden:db:id-1780948042-18910000
• Sammlungen: LDP: Historische Bestände der Hochschule für Grafik und Buchkunst Leipzig
• Sammlungen: Fotografie
• Strukturtyp: Band

• Digitalisat: SLUB Dresden
• Strukturtyp: Ausgabe

532 THE PHOTOGRAPHIC NEWS. [July 24, 1891. can be returned to you, and a goodly part of the gold, if you will carefully follow the directions given below. A. Developer Drippings.—Enough protosulphate of iron remains in the drippings from the development of wet plates to precipitate the silver. What is needed, then, is to carefully catch what goes off the plate in a proper vessel, and allow it to settle. Pour off the clear water once a day. This last is important, for when the water is allowed to remain for some days the recovery of the silver becomes more difficult, and therefore the amount recovered is much lessened, owing to the large quantity of iron present. If left any length of time, then test with salt; if same show a precipitate, then proceed as follows:—A small quantity of salt in solution should be stirred into the drippings before the water is poured off, and until the water appears clear. Take time and do the work thoroughly. The precipitate is rich in chloride of silver. Add the salt gradually, stirring up the solution until it no longer forms a precipitate, which you may easily determine by taking a sample of it in a tumbler or white bottle, holding it up to the light when adding a little salt. Don’t add too much, as an excess will redissolve the chloride. When the silver is all down, pour in a little acid, either nitric, sulphuric, or muriatic, which will clear the solution; allow it to stand for about twenty-four hours, then draw off your clear water and you have the chloride on the bottom of the vessel. B. Fixing Solutions are very rich in silver. They should be precipitated with sulphuret of potassiums previously dissolved in water, also adding it as long as it will form a precipitate. The latter, when down, may be thrown on a plain muslin filter to allow the water to drain off. Such a filter may be readily constructed by taking a piece of common unbleached muslin, say a yard square, tying loops to the four corners, and hanging it up on sticks. A good many photographers are in the habit of pre cipitating their washing solutions with metallic zinc sus pended in sheets therein. The action of zinc, however, is slow, and must be accelerated by acidifying the solution. Now it frequently happens that the fixing solution is allowed to run into the same vessel, and the hypo, being an alkali, suspends the action of the zinc. In the course of time a deposit out of the water is formed, but the happy proprietors of the “ mud ” are sadly disappointed in its value, as it is sometimes even so poor as not to pay for the trouble of refining. All hypo fixing solutions may be treated together in this way. A large barrel serves as the best receptacle for them. Insert a spigot about six inches from the bottom. It has been found economical to use a large crock or stone jar—or it may be glass—for the negative fixing solution; you can use a dipper with it, or let a strong strip of glass remain in and across it at an angle to prevent the smaller plates from going flat to the bottom of the vessel. Once in a while the solution may be emptied into the barrel. The precipitate which results is sulphide of silver. C. Impure Solutions and Used Baths.—Besides salt, muriatic acid, sulphuret of potassium, protosulphate of iron, or sheet copper may be used for the precipitation of silver from any solution very rich in silver ; and they should be used, or else the solution boiled down to dry ness, when the wastes are sent to the refiner. The reasons are obvious; the freight is less, and the danger of loss from the breakage of bottles and leakage is insured against. See instructions for saving print washings (E). The same course may be followed here. D. Silvered Paper. —All prints should be trimmed before toning, as it saves gold, and besides, toned paper is of hardly any value. Keep the untoned clippings and filters clean, by themselves; do not throw sweepings, pieces of glass, and spoiled ferrotype plates among them, as their bulk only decreases the real value. If you wish to burn the paper, have your stove cleaned of cinders and ashes, and proceed slowly, for a good draught will carry many particles of silver through the flue. Every inch of silvered trimmings is valuable, and should be kept in a box sepa rately. Do not tread them under foot and allow them to become mixed with dirt and grit and dust on the floor. Keep a cover on the box, and do not allow anything but clean, untoned paper trimmings to go into it. We prefer to burn the paper, but if you attempt it, see that every bit of the paper “ cinders” is consumed before the ashes are taken from the stove. E. Print Washings may be treated the same as A, only it is best to keep them separate. You save enough extra to more than pay you for the additional trouble. Add the salt gradually, and watch the effect. If precipitation is slow and the solution remains milky in appearance, the addition of a little of the protosulphate of iron solution is of good service. Some workers prefer a mixed solution of salt and alum—say twelve ounces of each ingredient dissolved in two quarts of hot water—for a stock solution. Add this carefully, and not too much of it. F. Toning Solutions.—Precipitate these with protosul phate of iron, but be sure and have the solution “ acid,” as otherwise the iron will be precipitated, and your gold will be lost. Old toning baths, and the precipitates which form when the toning bath is being neutralised by bicar bonate of soda or other alkali, should all be saved, and separately from any other wastes. G. Toned Paper Clippings.—In a small business it hardly pays to save these, but where quantities are large and fuel and time are cheap, it often does. Printers for the trade, publishers of photographs, and those whose business is large, have found the recovery of gold from these clippings well worth looking after. H. Old and Spoiled Dry Plates are likewise worth taking care of. The emulsion from all such can be best removed by soaking them in a strong hot solution of carbonate of soda (washing soda). When a quantity is collected, strain it through a muslin filter, allowing the solution to drain off. A stone jar is excellent for this work. After filtration the precipitate should be allowed to dry spon taneously, after which it is ready for the refiner. I. Barrels, Floors, and Old Hats.—We have likewise found that the wood of barrels which contained waste solutions for a number of years was quite impregnated with silver, some barrels yielding as many as thirty ounces of metal; so when yours are unfit for further use you know what to do with them. The same discovery has been made as to the floors of long-used dark rooms and of rooms where the paper is silvered and drained and fixed. Old felt hats are used for developer drippings by some. These with the deve loper, skins, fragments, and emulsion from dry plates, as well as blotters and filters, are well worth saving. J. Aristotype Paper Wastes should be treated the same as other paper wastes (D). They may go together, but in everything like “ wastes ” the separate plan is preferable.