Stannic Sulphide. SnS2. Syn. Bisulphide of tin, Bronze powder, Mosaic gold; Aurum musivum, Aurum mosaicum, Stanni bisulphuretem, L. Prep. 1. To pure tin, 12 oz., melted by a gentle heat, add of mercury, 6 oz.; to the powdered mass, when cold, add of chloride of ammonium, 6 oz.; flowers of sulphur, 7 oz; and after thorough admixture place the compound in a glass flask or matrass, and gradually heat it, imbedded in sand, to low redness, and continue the heat for several hours, or until white fumes cease to be disengaged; the ‘aurum musivum’ remains at the bottom of the vessel, under the form of soft and very brilliant gold-coloured flakes.
2. (Berzelius.) Stannic oxide and sulphur, of each 2 parts; chloride of ammonium, 1 part; mix, and expose it to a low red heat, in a glass or earthenware retort, until sulphurous fumes cease to be evolved.
Used as a metallic gold colour, or substitute for powdered gold, in bronzes, varnish work, sealing-wax, &c.
TIN FI′LINGS. See Tin powder (below).
TINFOIL, Lead in. Tinfoil very rarely consists of pure tin; generally it contains more or less lead. According to the recent analysis of August Vogel, who has examined a great number of samples from very different sources, it contains from 1 to 19 per cent. of lead. There are, however, specimens of tinfoil which
contain so little lead that it hardly gives a reaction with the appropriate tests.
Since tinfoil is so much used for covering articles of diet, or of confectionery, or of perfumery, it was a matter of some interest to determine whether or not there was any danger of transference of lead from the wrapper to the contents. A number of experiments upon soap, chocolate, and different kinds of dry sugar, which had been enveloped in tinfoil very highly charged with lead, showed that there was no contamination with lead. Cheese, on the other hand, on account of its being moist, and being closely in contact with the foil, did take up lead.
Of course the lactic acid of the cheese would also favour the taking up of the metal. A point worthy of being recorded in connection with this matter is the rapid diminution of the lead toward the centre of the cheese. Often plenty of lead was found in the rind, and none a little way in the cheese.[233]
[233] ‘Repertorium für Pharmacie,’ Von Buchnee.
TIN GLASS†. See Bismuth.