PEWTER, PEWTERER

(Potier d’étain , Fr.) Pewter is, generally speaking, an alloy of tin and lead, sometimes with a little antimony or copper, combined in several different proportions, according to the purposes which the metal is to serve. The English tradesmen distinguish three sorts, which they call plate, trifle, and ley pewter; the first and hardest being used for plates and dishes; the second for beer-pots; and the third for larger wine measures. The plate pewter has a bright silvery lustre when polished; the best is composed of 100 parts of tin, 8 parts of antimony, 2 parts of bismuth, and 2 of copper. The trifle is said by some to consist of 83 of tin, and 17 of antimony; but it generally contains a good deal of lead. The ley pewter is composed of 4 of tin, and 1 of lead. As the tendency of the covetous pewterer is always to put in as much of the cheap metal as is compatible with the appearance of his metal in the market, and as an exce of lead may cause it to act poisonously upon all vinegars and many wines, the French government long ago appointed Fourcroy, Vauquelin, and other chemists, to ascertain by experiment the proper proportions of a safe pewter alloy. These commi ioners found that 18 parts of lead might, without danger of affecting wines, ., be alloyed with 82 parts of tin; and the French government in consequence pa ed a law, requiring pewterers to use 83 1 ⁄ 2 of tin in 100 parts, with a tolerance of error amounting to 1 1 ⁄ 2 per cent. This ordonnance, allowing not more than 18 per cent. of lead at a maximum, has been extended to all ve els destined to contain alimentary substances. A table of specific gravities was also published, on purpose to test the quality of the alloy; the density of which, at the legal standard, is 7·764. Any exce of lead is immediately indicated by an increase in the specific gravity above that number. The pewterer fashions almost all his articles by casting them in moulds of bra or bronze, which are made both inside and outside in various pieces, nicely fitted together, and locked in their positions by ears and catches or pins of various kinds. The moulds must be moderately heated before the pewter is poured into them, and their surfaces should be brushed evenly over with pounce powder (sandarach) beaten up with white of egg. Sometimes a film of oil is preferred. The pieces, after being cast, are turned and polished; and if any part needs soldering, it must be done with a fusible alloy of tin, bismuth, and lead. Britannia metal, the kind of pewter of which English tea-pots are made, is said to be an alloy of equal parts of bra , tin, antimony, and bismuth; but the proportions differ in different workshops, and much more tin is commonly introduced. Queen’s metal is said to consist of 9 parts of tin, 1 of antimony, 1 of bismuth, and 1 of lead; it serves also for teapots and other domestic utensils. A much safer and better alloy for these purposes may be compounded by adding to 100 parts of the French pewter, 5 parts of antimony, and 5 of bra to harden it. The English ley pewter contains often much more than 20 per cent. of lead. Under Tin , will be found the description of an easy method of analyzing its lead alloys.