coating of tin, by dipping it into a bath of that metal.
TIN POW′DER. Syn. Tin filings, Tin dust; Stanni pulvis (Ph. E & D.), L. Prep. 1. (Ph. E.) Melt grain tin in an iron vessel, pour it into an earthenware mortar heated a little above its melting-point, and triturate briskly as the metal cools; lastly, sift the product, and repeat the process with what remains in the sieve.
2. (Ph. D.) Melt grain-tin in a black-lead crucible, and, whilst it is cooling, stir it with a rod of iron until it is reduced to powder; let the finer particles be separated by means of a sieve, and when, after having been several times in succession shaken with distilled water, the decanted liquor appears quite clear, let the product be dried for use.
Obs. Powdered tin is also prepared by filing and rasping.—Dose, 2 to 4 dr., as a vermifuge. Polishers’ putty, coloured with ivory black, is frequently substituted for this powder, and hence arises the ill effects that sometimes follow its use.
TIN′NING. Proc. 1. Plates or vessels of brass or copper, boiled with a solution of stannate of potassa, mixed with turnings of tin, become, in the course of a few minutes, covered with a firmly attached layer of pure tin.
2. A similar effect is produced by boiling the articles with tin filings and caustic alkali or cream of tartar.
Obs. By either of the above methods chemical vessels made of copper or brass may be easily and perfectly tinned.
3. The following method for tinning copper, brass, and iron in the cold, and without apparatus, is by F. Stolba.[234]
[234] ‘The Pharmacist,’ iv, 86.
The requisites for accomplishing this object are:—1st. The object to be coated with tin must be entirely free from oxide. It must be carefully cleaned and care be taken that no grease spots are left; it makes no difference whether the object be cleaned mechanically or chemically. 2nd. Zinc powder; the best is that prepared artificially by melting zinc, and pouring it into an iron mortar. It can be easily pulverised immediately after solidification; it should be about as fine as writing sand. 3rd. A solution of protochloride of tin containing 5 or 10 per cent., to which as much pulverised cream of tartar must be added as will go on to the point of a knife. The object to be tinned is moistened with the tinned solution, after which it is rubbed hard with the zinc powder. The tinning appears at once. The tin-salt is decomposed by the zinc, metallic tin being deposited. When the object tinned is polished brass or copper, it appears as beautiful as if silvered, and retains its lustre for a long time. 4th. (C. Paul.)[235] The zinc or iron articles are immersed in a mixture of 1 part sulphuric or nitric acid with 10 parts of water; a solution of copper sulphate