Assay. Each grain of stannic oxide (see above), after being washed and gently ignited, is equivalent to ·78365 gr. of pure tin. The loss of weight represents the impurities. Each gr. of sulphate of lead, so treated, is equiv. to ·683 gr. of metallic lead (nearly).
Uses. The uses of tin in the arts are well known. In medicine, 1 to 3 dr. of the filings or powder, made into an electuary with treacle, are sometimes given in tapeworm, for 2 or 3 successive mornings, followed by an aperient.
Stannic Chloride. SnCl4. Syn. Bichloride of tin, Tetrachloride of tin, Perchloride of tin, Permuriate of t.†; Stanni bichloridum, Stanni permuras, L. Prep. 1. (Liebig.) By dissolving grain tin in a mixture of hydrochloric acid, 2 parts; nitric acid and water, of each 1 part (all by volume); observing to add the tin by degrees, and to allow one portion to dissolve before adding another, as without this precaution the action is apt to become violent, and stannic oxide of tin to be deposited.
2. (Anhydrous; Libavius’s fuming liquor.) By heating stannous chloride in chlorine gas; or, by distilling a mixture of powdered tin, 1 part, with corrosive sublimate, 3 parts (5 parts—Fownes). A very volatile, colourless, mobile liquid, which fumes in the air, and boils at 248° Fahr.; when mixed with 1-3rd of its weight of water, it solidifies to a crystalline mass.
Obs. Solution of stannic chloride is much
used by dyers, under the names of ‘SPIRITS OF TIN,’ ‘DYERS’ SPIRITS,’ ‘TIN MORDANT,’ &c., the proportions of the ingredients and the state of dilution being various, according to circumstances or the caprice of the manufacturer. A process, which has been highly recommended, and which seems preferable to all others, is to prepare a simple solution of the stannous chloride, and to convert it into a solution of the stannic chloride, either by the addition of nitric acid and a gentle heat, or by passing chlorine through it. See Tin mordants.
Stannic Hydrate. Sn(HO)4. Syn. Hydrated peroxide of tin, Stannic acid. Prep. By adding hydrate of potassium or an alkaline carbonate to a solution of stannic chloride. Soluble in acids and pure alkalies. Its compound with the latter are sometimes called STANNATES.
Stannic Iodide. SnI4. By dissolving stannic hydrate in hydriodic acid. Yellow, silky crystals.
Stannic Oxide. SnO2. Syn. Binoxide of tin, Peroxide of tin. Prep. By the action of nitric acid on metallic tin, the resulting white powder being well washed with water; or, by heating metallic tin above its melting-point, in the air. Yellow; anhydrous; insoluble.
Obs. Frémy has given the name of Metastannic acid to the oxide prepared by the action of nitric acid on metallic tin; the hydrate he calls STANNIC ACID. See Polishers’ putty.