PEWTER is a generic term for a variety of alloys, which all agree in this, that tin forms the predominating component. The finest pewter (sometimes called “tin and temper ”) is simply tin hardened by the addition of a trifle of copper. Ordinary pewter is tin alloyed with lead, which latter ingredient is added chiefly on account of its cheapness, and therefore often in excessive proportion. The law of France restricts the percentage of lead to 16*5, with a toleration of 1'5 per cent, of error, an alloy of this or a higher degree of richness in tin being, according to an old investigation by Vauquelin, as proof against sour wine or vinegar as pure tin is. Higher percentages of lead are dangerous, and besides spoil the appearance of the alloy. The composition of an alloy containing only these two components can be ascertained approximately by determining the specific gravity (see Metals, vol. xvi. p. 67 sqf. Plate pewter is a hard variety much used for plates and dishes; a good quality is composed of 100 parts of tin, 8 of antimony, 2 of bismuth, and 2 of copper. Closely allied to it is the silver-white alloy called “Britannia metal,” which is much used in Great Britain for the making of teapots more especially. To give an idea of its very variable composition the following two analyses may be quoted :— [table]...
Pewter wares are shaped chiefly in three ways. Measures and spoons are cast in moulds of brass made of two closely-fitting but detachable halves, the surface of the mould being powdered over with sandarach, or painted over with white of egg or oil, before use to prevent adhesion. Plates and dishes are made preferably by hammering. In large establishments milk-jugs and similar articles are often produced by “spinning,” i.e., by pressing a flat plate of pewter against a rapidly-revolving blunt tool, and thus raising it into the desired shape. (Cf. Lead, vol. xiv. p. 378.)
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