TIN has a silvery white colour with a slight tint of yellow; it is malleable, though sparingly ductile. Common tin-foil, which is obtained by beating out the metal, is not more than 1-1000th of an inch in thickness, and what is termed white Dutch metal is in much thinner leaves. Its specific gravity fluctuates from 7.28 to 7.6, the lightest being the purest metal. When bent it occasions a peculiar crackling noise, arising from the destruction of cohesion amongst its particles.

When a bar of tin is rapidly bent backwards and forwards, several times successively, it becomes so hot that it cannot be held in the hand. When rubbed it exhales a peculiar odour. It melts at 442o, and, by exposure to heat and air, is gradually converted into a protoxide. (Brande, 779.)

Pure tin is commonly used for dyer's kettles; it is also sometimes employed for the bearings of locomotivo carriages and other machinery. This metal is beaten into very large sheets, some of which measure 200 by 100 inches, and are of about the thickness of on ordinary card; the small sized foil is stated not to exceed one-thousandth of an inch in thickness. The metal is first laminated between rollers, and then spread one sheet at a time upon a large iron surface or anvil, by the direct blows of hammers with very long handles; great skill is required to avoid beating the sheets into holes. The large sheets of tin-foil are only used for silvering looking glasses by amalgamation with mercury, See Mr. Farrow's apparatus, Trans. See of Arte., vol. 49, p. 146. Tin-foil is also used for electrical purposes. The amalgam used for electrical machines, is 7 tin, 3 zinc, and 2 mercury.

TIN is drawn into wire, which is soft and capable of being bent and unbent many times without breaking; it is moderately tenacious and completely inelastic. Tin tube is extensively used for gas fittings and many other purposes; it has been recently introduced in an ingenious manner for the formation of very cheap vessels, for containing artists' and common colours, besides numerous other solid substances and fluids, required to be hermetically sealed, with the power of abstracting small quantities. Rand's Patents.

Tin plate is an abbreviation of tinned iron plate; the plates of charcoal iron are scoured bright, pickled, and immersed in a bath of melted tin covered with oil, or with a mixture of oil and common resin; they come out thoroughly coated. Tinned iron wire is similarly prepared; there are several niceties in the manipulation of each of these processes which cannot be noticed in this place.

Tin is one of the most cleanly and sanatory of metals, and is largely consumed as a coating for culinary vessels, although the quantity taken up in the tinning is exceedingly small, and which was noticed by Pliny.

Tin imparts hardness, whiteness, and fusibility to many alloys, and is the basis of different solders, pewters, Britannia metal, and other important alloys, all of which have a low power of conducting heat,

Pewter is principally tin; mostly lead is the only addition, at other times copper, but antimony, zinc, etc, are used with the above, as will be separately adverted to. The exact proportions are unknown even to those engaged in the manufacture of pewter, as it is found to be the better mixed when it contains a considerable portion of old metal to which new metal is added by trial.

In order to regulate the quality of pewter wares, the Pewterers' Company published in 1772 "A Table of the Assays of Metal, and of the Weights and Dimensions of the several sorts of Pewter Wares," and they threatened with expulsion from their guild, any who departed from the regulations given in this now scarce and disregarded pamphlet.

The assay is made by casting a small button of the metal to be tried in a brass mould, which is so proportioned that the button if pure tin weighs exactly 182 grains; all the metals added to the tin being heavier than the latter, the buttons or assays are the heavier the less tin they contain, and at page 14 of the pamphlet the following scale is given: -

Assay of pure tin ................

182

grains.

Ditto of fine or plate metal 1 1/2 grains heavier than tin or . . .

183 1/2

,,

Ditto of trifling metal

3 1/2

_____________

185 1/2

,,

Ditto of ley metal

16 1/2

___________________

198 1/2

,,

and it may be added although an unauthorised addition, that equal parts of tin and lead are about fifty grains heavier than tin or 232 grains.

Some pewters are now made nearly as common as the last proportion; when cast they are black, shining and soft; when turned, dull and bluish. Other pewters only contain 1/5 or 1/6 of lead; these when cast are white, without gloss and hard; such are pronounced very good metal, and are but little darker than tin. The French legislature sanctions the employment of 18 per cent of lead with 82 of tin as quite harmless in vessels for wine and vinegar.

The finest pewter, frequently called "tin and temper," consists mostly of tin, with a very little copper, which makes it hard and somewhat sonorous, but the pewter becomes brown-coloured when the copper is in excess. The copper is melted, and twice in weight of tin is added to it, and from about 1/2 to 7 lb. of this alloy or the " temper," are added to every block of tin weighing from 360 to 390 lb.

Antimony is said to harden tin and to preserve a more silvery colour, but is little used in pewter. Zinc is employed to cleanse the metal rather than as an ingredient; some stir the fluid pewter with a thin strip, half tine and half tin; others allow a small lump of sine to float on the surface of the fluid metal whilst they are casting, to lessen the oxidation.

Britannia metal, or white metal, is said to consist of 3 1/2 cwt. of block tin, 28 lb. antimony, 8 lb. copper, and 8 lb. brass; it is cast into ingots and rolled into very thin sheets. This manufacture was introduced in about the year 1770, by Jessop and Hancock. - (Lardner's Cyclopaedia. See page 811.)

Tin solders are very much used in the arts, and according to Dr. Turner

1

tin

3

lead,

the coarse plumber's solder, melts at about

500 F.

a

-

1

-

the ordinary or fine tin solder -

360 F.

See also Bismuth, and the chapter on soldering. ZINC is a bluish-white metal, with considerable lustre, rather hard, of a specific gravity of about 6.8 in its usual state, but, when drawn into wire, or rolled into plates, its density is augmented to 7 or 72. In its ordinary state at common temperatures, it is tough, and with difficulty broken by blows of the hammer. It becomes very brittle when its temperature approaches that of fusion, which is about 773°; but at a temperature a little above 212°, and between that and 300°, it becomes ductile and malleable, and may be rolled into thin leaves, and drawn into moderately fine wire, which, however, possesses but little tenacity. When a mass of zinc, which has been fused, is slowly cooled, its fracture exhibits a lamellar and prismatic crystalline texture. (Brande, 770.)