Tin combines with two proportions of oxygen, thus forming two oxides. The yellow oxide, which has the smaller pro portion of oxygen, may be prepared by dissolving tin in nitric acid diluted with water, without the aid of heat. fly pre cipitating the oxide with pure potash, it is obtained in the form of a yellowish powder. Its component parts are, Oxygen 20 Tin 80 .• 100 By dissolving tin in concentrated nitric acid, with the assistance of heat, the whole is converted with effervescence into a white powder, which falls to the bottom of the vessel. The component parts of this oxide are 28 oxygen, and 72 of tin.
Phosphorus combines very readily with tin, by projecting bits of phosphorus on melted tin in a crucible. A phosphuret of tin is thus Obtained, which crystallizes on cooling. This compound is of a silvery white colour, may be cut with a knife, and extended under the hammer, but soon separates into plates. Sulphur com bines very readily with tin, by adding the sulphur to the metal while in a state of fusion. This compound forms a grey ish or blui,sli matter, which has a metallic lustre, a lamellated structure, and crys, tallizes in cubes, or in octahedrons. It is decomposed by acids with effervescence. The component parts are, according to Bergman, Tin 80 Sulphur 20 100 If equal parts of oxide of tin and sul. phur be fused together in a retort, sul• phurous acid, and some sulphur, are dis• engaged, and there remains in the vessel a compound of a brilliant, golden colour. It crystallizes in six-sided plates. It is not acted on by the acids. When it is strongly heated, it gives out sulphurous acid and sulphur, and there remains behind a black mass, which is stilphuret of tin. This compound, which is a sulphurated oxide of tin, was formerly distinguished by the name of aurum, musivum, musi cum, or mosaicum. The component parts of this sulphurated oxide of tin are, Oxide of tin 60 Sulphur 40 100 Tin enters into combination with many of the metals, and forms alloys with them, some of which are of great import ance. It also combines with acids, and forms salts.
Of the alloys, the most important is that of tin and copper, with some other addi tions, which forms bronze, bell-metal, spe culum metal, &c. The alloy of tin and lead, in equal parts, forms plumbers' sol der. The alloy of tin, lead, and bismuth, in the proportions of 3, 5, and 8, forms a compound that melts in a heat somewhat less than that of boiling water: The amal gam of mercury with tin is used in sil vering of mirrors. Pewter is an alloy of tin and lead, which was formerly very much used, more so than any other me tallic alloy, being the common material for plates, dishes, and other domestic utensils. Its use now is almost universal
ly superseded by pottery, which is light er, more readily kept clean, and much cheaper, though certainly less durable, on account of the brittleness of the latter. The name of pewter has been given to any malleable white alloy, into which tin largely enters ; and its composition is so various, that hardly any two manufactur ers employ precisely the same ingredi ents, and the same proportions. The finest kind of pewter contains no lead whatever, but consists of tin with a small alloy of antimony, and sometimes a little copper, and in all the superior kinds of pewter, the tin forms by fir the greater part of the mixture. Pewter may be used for vessels containing wine, and even vi negar, provided there be from 80 to 82 parts of tin in the alloy, without the smallest danger ; hence its use as a mea sure. The specific gravity of a mixture of tin and lead is less than the mean spe cific gravity of the two metals separate ly.
Tin is much used, particularly in the state of very thin leaves : it is then called tin-foil. This is made from the finest tin, first cast into an ingot, then laminated to a certain extent, and afterwards beat out with a hammer Tin is used for tinning copper, iron, &c. and the salts of tin are employed in dying.
T;-: plate, tinning.. Tin combines with iron, and adheres strongly to its surface, forming a thin covering. This is one of the most useful combinations of tin, for it renders the iron fit for a great many valu able purposes, for which, otherwise, on account of its strong tendency to oxida tion, or rusting, it would be totally inap plicable. This is well known by the name of tin-plate, or white iron. The process of tinning iron is the following: the plates of iron being reduced to the pro per thickness, are cleaned, by means a weak acid. For this purpose the sur face is first cleaned with sand, to remove any rust that may have formed. They are then immersed in water, acidulated with a small quantity of sulphuric acid, in which ' they are kept for twenty-four hours, and occasionally agitated. They are then well rubbed with cloths, that the surface may be perfectly clean. The tin is fused in a pot, the surface of which is covered with an oily or resinous matter, to prevent its oxidation.
The plates of iron are then immersed in the melted tin, and are either moved about in the liquid metal, or are dipped several different times. They are then taken out, and rubbed with saw-dust or bran, to remove the impurities from the surface.