i8b Vfe of Tin in Arts and Medicine. [Book VI. 



We have three forts of pewter in common life; they 

 are diftinguifried by the names of flats ; trifle ; ley. 

 The plate pewter is ufed for plates and diflies ; the 

 trifle chiefly for ale pints, quarts, &c. and the ley- 

 metal for wine meafures and other coarfer ufes. Our 

 very beft pewter is faid to confift of one hundred parts 

 of tin to from ten to feventeen of antimony. To this 

 compofition the French add a little copper. In general 

 the lighted pewter is the beft. The inferior kinds are 

 heavier and ibfter, from a quantity of lead with which 

 they are adulterated. Putty is prepared from the 

 white calx of tin. The folution of tin in aqua regia has 

 been already mentioned as uleful in dying. When it 

 is mixed in the dyer's bath it forms a precipitate, which 

 carries down the colouring matter, and depofits it on 

 the fluff which is to be dyed fcarlet. The operation 

 of tinning copper will be afterwards defcribed. The 

 powder of tin has been ufed as a remedy againft worms 

 in large dofes, and therefore the fcruples which have 

 been entertained againft the ufe of veffels lined with 

 tin muft be wholly without foundation. Tin has been 

 analized by many chemifts, with a view to difcover the 

 quantity of arfenic contained in it. The refults of thefe 

 experiments have been by no means uniform. The 

 largeft proportion, however, which has been detected 

 in any tin ufed in commerce, is a grain in an ounce, 

 or one five hundred and feventy-fixth part of the com- 

 pound j but more frequently no arfenic whatever has 

 been difcoverecl. 



