4121. Binoxide or Peroxide of Tin

4121.    Binoxide or Peroxide of Tin. Obtained by adding potassa, or an alkaline carbonate, to a solution of perchloride of tin. Thi3 substance is also known as Stannic acid; hence, its compounds with alkalies are sometimes called StaNNAtes. It is soluble in acids, and in pure alkalies. If grain tin be heated in a test tube with nitric acid, the tin is converted, with evolution of yellow fumes, into a white powder, peroxide of tin. The nitric acid will convert the tin into an oxide, but it cannot combine with the oxide produced. (Stbckhardt.) From this it appears that nitrate of tin is a misnomer.

4122. Tin or Polishers' Putty

4122.    Tin or Polishers' Putty. Melt tin with rather more than an equal quantity of lead, then rapidly raise the heat till the mixture is red hot; the tin will then be thrown off in dross, which should be removed as it forms. This dross is the peroxide of tin, or tin putty; the dross may be calcined until it becomes whitish, and then reduced to powder.

4123. Protochloride of Tin

4123.    Protochloride of Tin. Muriate of tin is obtained by distilling a mixture of chloride of mercury and tin in fine powder. It is grey, solid, resin-like, fusible, and volatile. (Cooley.)

4124. Perchloride of Tin

4124.    Perchloride of Tin. Called also Bichloride and Permuriate of Tin. The pure bichloride is obtained by heating the protochloride in chlorine gas, or by distilling a mixture of 8 parts of grain tin with 24 parts of corrosive sublimate, when a very volatile, colorless liquid comes over, which was formerly called Libavius' fuming liquor. A solution of the bichloride or Permuriate of tin is obtained by dissolving tin in nitromuriatic acid. This solution is much used by dyers, under the name of Spirits of Tin, Dyers' Spirits, etc.. (See Nos. 107 (Acid Preparations of Tin), etc..) For this purpose, the acid is best made by mixing 2 parts of muriatic acid with 1 part each of nitric acid and water, all by measure. (Liebig). The tin should bo added by degrees, one portion being allowed to dissolve before adding another; as, without this precaution, the action is apt to become violent, the temperature rise, and peroxide of tin to bo deposited. (See No. 108 (Red Spirits).) A process which has been highly recommended, is to prepare a simple solution of tho protochloride, and to convert it into tho bichloride, either by the addition of nitric acid and a gentle heat, or by passing chlorine through it.

4125. Tests for the Salts of Tin

4125.    Tests for the Salts of Tin. The salts of tin are characterized by the following general properties: Ferroprussiate of potash gives a white precipitate. Hydrosulphuret of potash, a brown-black with the protoxide, and a golden - yellow with tho peroxide. Galls do not affect tho solutions of these salts. Corrosive sublimate occasions a black precipitate with the protoxide salts; a white with tho peroxide. A plate of lead frequently throws down metallic tin, or its oxide, from tho saline solutions. Chloride of gold gives, with tho protoxide solutions, the purple precipitate of Cassius. Chloride of platinum occasions an orange precipitate with the protoxide salts. (Cooley.) ■