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Simple Method of Copying II

Cooper, Jr., of England, gives the follow- Drawings, Etc. Silvered albumen paper, ing formula for a preservative varnish which after being washed, may be conveniently is stated to be an entire protection against used for copying negatives as well as posi- fading: 1 drachm gum damar dissolved in 1 tives. It keeps for weeks, and becomes ounce benzole. 1 drachm paraffine, dissolved sensitive to light only after exposure to the in 1 ounce benzole. Mix 4 parts of the vapors of aqua ammonia, technically termed paraffine solution with 1 part of the damar smoking with ammonia. Dr. H. Vogel has solution. Photographic prints covered with greatly simplified the latter process by substi- this varnish are impermeable to water. A tuting for the liquid ammonia the powder of solution of the paraffine only will do; but it carbonate of ammonia. He thoroughly im- is better with the gum damar. pregnates a piece of felt or cloth with this 3164. Everlasting Photographs on powder, and lays it under the silvered sheet, Enamel. First-class photographs, either separated from it by a piece of blotting-paper. negatives or positives, may be taken on He places the silvered paper, with the sub- Duchemin's enamel (sce No. 2402) without stratum of carbonate of ammonia and the collodion, by using bitumen, or citrate of drawing on top, between two plates of glass, iron, or perchloride of iron and tartaric acid, and, exposing it to the light of the window, or bichromate, or any other salt. A good obtains a copy quite distinct in all its details. solution for this purpose is, water, 100 parts The copy obtained is, of course, in white lines by weight; gum, 4 parts; honey. 1 part; upon black ground. Such photographs re- pulverized bichromate of potash, 3 parts quire to be treated with soda when intended Filter the liquid, spread it over the enamel, for long preservation. and let it rest, after which, expose it to the