Composition of the Rougie

| Names of the Authors. | Starch. | Cream of Tartar. | Cochi- neal. | Solution of Tin. | Common Salt. | | lb. | oz. | lb. | oz. | lb. | oz. | lb. | oz. | lb. | oz. | | Berthollet | 0 | 0 | 0 | 0 | 5 | 8 | | 14 | 0 | 0 | 0 | | Hellot | 3 | 2 | 0 | 0 | 7 | 4 | | 12 | 8 | 0 | 0 | | Scheffer | 3 | 2 | 3 | 2 | 5 | 7 | 1⁄2 | 4 | 11 | 0 | 0 | | Poërner | - | | | 0 | 0 | 1 | 8 | 6 | 4 | | 6 | 4 | 0 | 0 | | 0 | 0 | 0 | 0 | 6 | 4 | | 12 | 8 | 0 | 0 | | 0 | 0 | 1 | 8 | 6 | 4 | | 6 | 4 | 12 | 8 | M. Lenormand states that he has made experiments of verification upon all the formulæ of the preceding tables, and declares his conviction that the finest tint may be obtained by taking the bouillon of Scheffer, and the rougie No. 4. of Poërner. The solution which produced the most brilliant red, is that made according to the proce of mordant B ( Tin ). M. Robiquet has given the following prescription for making a printing scarlet , for well-whitened woollen cloth. Boil a pound of pulverized cochineal in four pints of water down to two pints, and pa the decoction through a sieve. Repeat the boiling three times upon the residuum, mix the eight pints of decoction, thicken them properly with two pounds of starch, and boil into a paste. Let it cool down to 104° F., then add four ounces of the subjoined solution of tin, and two ounces of ordinary salt of tin (muriate). When a ponçeau red is wanted, two ounces of pounded curcuma (turmeric) should be added. The solution of tin above prescribed, is made by taking—one ounce of nitric acid, of specific gravity 36° B. = 1·33; one ounce of sal ammoniac; four ounces of grain tin. The tin is to be divided into eight portions, and one of them is to be put into the acid mixture every quarter of an hour. A solution of chlorate of pota a (chloride?) is said to beautify scarlet cloth in a remarkable manner. Bancroft proposed to supplant the nitro-muriatic acid, by a mixture of sulphuric and muriatic acids, for di olving tin; but I do not find that he succeeded in persuading scarlet-dyers to adopt his plans. In fact the proper base is, in my opinion, a mixture of the protoxide and peroxide of tin; and this cannot be obtained by acting upon the metal with the murio-sulphuric acid. He also prescribed the extensive use of the quercitron yellow to change the natural crimson of the cochineal into scarlet, thereby economizing the quantity of this expensive dye-stuff. See Lac Dye . SCHEELE’S GREEN, is a pulverulent arsenite of copper, which may be prepared as follows:—Form, first, an arsenite of pota a, by adding gradually 11 ounces of arsenious acid to 2 pounds of carbonate of pota a, di olved in 10 pounds of boiling water; next, di olve 2 pounds of crystallized sulphate of copper in 30 pounds of water; filter each solution, then pour the first progre ively into the second, as long as it produces a rich gra -green precipitate. This being thrown upon a filter-cloth, and edulcorated with warm water, will afford 1 pound 6 ounces of this beautiful pigment. It consists of, oxide of copper 28·51, and of arsenious acid 71·46. This green is applied by an analogous double decomposition to cloth. See Calico-printing .