The principal constituents of pewter are lead and tin; the proportions of the two metals depending somewhat on the use to which the alloy is put. The best contains but 16 to 20 per cent, of lead. Of this plates and dishes are made, which look like block tin, and can be brightly polished by rubbing. The addition of more lead cheapens the commodity, and gives it a dull bluish appearance. In France pewter vessels for wine and vinegar contain 18 per cent, of lead. It has been found that a larger proportion of that metal in utensils for this purpose is liable to result in the formation, in the liquid, of the poisonous acetate or sugar of lead.
A Little copper added in making pewter hardens the compound and renders it sonorous, so that toy trumpets and other rude musical instruments can be made of it. If the copper is replaced by antimony, hardness and a silvery lustre are the result. If the contents of the melting pot are stirred with a strip half of zinc and half of tin, or if a lump of zinc is allowed to float on the melted metal during the casting, the vaporized spelter seems to protect the fluid mass from oxidation, and prevents the formation of dross. Hence it is said to " cleanse " the mass.
Jewellers use polishers and laps of pewter, and sheets of the article are to some extent used for cheap engraving, music notes, or other figures being stamped upon it instead of being cut with a burin or graver. The ease with which it melts causes it to be employed by tinsmiths and tinkers for solder. Care must be taken not to set pewter dishes, mugs, spoons, lamps, etc., on stoves or other hot bodies, as, if left for any time, they are liable to settle into shapeless lumps.