OXISALTS Or TIN.
Protonitrate of Tin is formed by dissolving either the metal or tho protaxide in dilute nitric acid. A yellow uncrystallisable solution is obtained by exposure to the air it absorbs oxygen, and peroxide of tin is precipitated.
Pcrnitrato of Tin.—When tin is acted upon by strong nitrio acid, the peroxide fonued remains entirely insoluble in the acid ; to procure the pernitrato it is best to cause the hydrated peroxide to dissolve in dilute nitric aoid. The solution is colourless, and yields no crystals; when diluted or heated, it is rendered turbid.
Sulphates of Tin.-11y boiling excess of tin in eitiplittrie acid, a solu tion is obtained front which colourless !wielder crystals of sulphate of tin (SnO, S0,) are deposited. \Viten, on the other hand, tin is boiled iu excess of sulphuric, acid, or hydrated peroxide of tin is dissolved in the acid, persulphato of tin i4 obtained iu solution, but it cannot be macho to crystallise.
./Itosp/mla of Tin.—When phosphate of soda is added to a solution of protochlorido of tin, an insoluble white precipitate of protophoaphate is obtained ; the perphosphate, also an insoluble colourless preeipitato, may be procured by adding the phosphate of soda to a solution of perchloride of tin.
The characters of the salts of tin are as follow :—The protosalts are white, and tho solutions of them are usually colourless; their taste is astringent and metallic, and highly disagreeable; when in solution, they rapidly absorb are converted into the correspcanling parsalts.
When a plate of lead or zinc is put into a solution of tin, the latter is thrown clown in the metallic state. Ferrocyanide of potassium occa sions a white gelatinous procipitate whoa dropped into those solutions, and sulphide of potassium or sodium or eulphuretted hydrogen occa sions a coffee-brown precipitate in the Bate of the protoxicle of tin ; noither gallic acid nor infusion of galls occasions any precipitate. Wheu chloride of gold is poured into solutions of protoxide of tin, a purple-coloured precipitate falls. A solution of potash or soda throws down a white precipitate, which dissolves in excess of tho alkali. If the solution be boiled, a black powder falls, which is metallic tin ; while a compound of peroxide of tin and potash remains in solution. Ammonia throws down a white precipitate, nut soluble in excels of the alkali.
Permits' of tin give a white precipitate with caustic, alkalies, solublo in excess, the solution not being decomposed on boiling. Suiphurettod hydrogen and aulphide ammonium give a dirty yellow precipitate, soluble in excess of tho alkaline sulphide or in caustic alkalies. Before the blowpipe on charcoal, salts of tin give, in the reducing flame, a white malleable globule of metal.
atiegation of Tin.—This is usually effected in the state of bluoxide, of which 78.66 per cent. is metal.
Attors Of Tie.
Most of the malleable metals are rendered brittle by alloying with , tin ; it cumbhuse roatlily with prtaasinn and sodium, funning brilliant white alloys, which are less fusible than tin ; the potassium alloy burns ' readily when it contains more than one-fifth of potassium. With arsenic it forms a metallic mass which is whiter, harder, and more sonorous than pure tin. With antimony tin forms a white, hard, and sonorous alloy. Bismuth forms with tin an alloy which is more fusible than either of the metals separately, a mixture of equal weights melt ing at 212'; this compound is hard and brittle. Copper and tin form alloys which are well known and highly useful : they are BELL-METAL and BRONZE. [See, also, BRITANNIA-METAL ; PEWTER ; SOLDER ; and Gusr-Mssar..] With mercury tin readily amalgamates, and the com pound is used for silvering mirrors. With iron, tin forms white com pounds, which are more or less fusible according to the proportion of iron they contain. Tin-plate is of all the alloys of tin the most useful, and the preparation of this and of pewter are the most extensive appli cations of this very valuable metal.
In making tin-plate the best iron is employed, and, after being tho roughly cleansed from oxide and grease, by immersion in dilute sul phuric acid and scouring, the plates are dipped into a vessel containing melted tin, on the surface of which tallow floats. These and other similar precautions are necessary to secure the uniform adhesion, or rather alloying, of the two metals. Copper may be tinned by a some what similar process.
Moira ma allique is tin-plate to which a beautifully crystalline appearance has been given by moistening the warmed plate with a mixture of equal parts of nitric and hydrochloric acids diluted with its own bulk of water. [1forai.]