Chap. 27.] Ufe of Zinc in Pewter. 153 



that of arfenic, but it more readily unites with arfenic 

 in its calciform ftate. Zinc diflilled with white arfe- 

 nic deprived it of part of it5 oxygen, and was con- 

 verted into a calx, while a correfponding quantity o 

 arfenic was reduced to a regulus. 



Zinc does not combine with bifmuth, and when 

 thefe two metals are fufed together, the biftnuth takes 

 the lower \ lace on account of its greater gravity, and 

 may be feparated by a flroke of the hammer. It 

 will not unite with nickel. Its volatility renders it 

 extremely difficult to combine it with metals which 

 are of difficult fufion, as iron and copper. It is, how- 

 ever, united to feveral metals for particular purpofes 

 in the arts. It is added in fmall quantities to tin, 

 or to a mixture of tin and lead, in the compofition of 

 pewter, which it improves both in adding to the white- 

 nefs and brilliancy, and increafing the hardnefs. It is 

 employed in many alloys, particularly in tombac, 

 prince's metal, and the various kinds of brafs. Fine 

 filings of zinc are ufecl to produce brilliant fparks in 

 fire-works. Some perfons have propofed to fubfti- 

 tute zinc for tin in lining copper veffels; the latter 

 metal, in conjunction with lead, having been fuppofed 

 jnfufficient to prevent the dangerous effects of the lead. 

 Macquer allows that this metal fpreacls more evenly 

 pn the copper, is much harder, and lefs fulible, than 

 the lining of tin, but objects to it, becaufe it is foluble 

 in vegetable acids, and has a confiderable emetic 

 power. Mr. De la Plance, however, has taken the 

 falts of zinc, formed by the vegetable acids, in greater 

 quantities than they can be contained in aliments which 

 "have been dreffed in veflels lined with zinc, without 

 experiencing any dangerous effect Experiments are 

 yet wanting to prove the fuperiority of zinc lining 

 pver that of tin, 



Zinc 



