12 USES OP MALLEABLE ZINC. 



possessed by that metal, though I could fully speak to the 

 facility with which it eoulcl be worked into vessels, and of its 

 application to other purposes. I was still, for want of longer 

 experience, not decided as to its changeability when exposed 

 to the action of water and air. 

 Zinc might be From the great affinity which zinc possesses for oxigen, it , 

 supposed ea- might be expected to oxidate with great avidity, and on that 

 account be rendered useless in the situations above alluded 

 Put it is not, to; but, to the astonishment of most theorists, the contrary 

 proves to be the case. Many specimens of zinc, both in 

 the state of sheets and wire, have been exposed in the open 

 air, as well as in damp rooms, without undergoing any other 

 change than that of colour. Indeed it appears, that a piece 

 of polished zinc will lose its lustre, and assume a blue gray- 

 colour, when exposed in a damp room for the space of a few 

 except super-. *ce*8. An oxide is formed upon the surface, which, though 

 fccially. of an imperceptible thickness, is so exceedingly hard, and at 



the same time so insoluble, that it resists ail the future at- 

 Less affected tacks both of the air and of water. From numerous expe- 



tUan copper by riments I have ascertained, that copper is much more liable 

 seawater. . 



to waste than zinc in sea water, and even in strong solutions of 



muriate of soda. There cannot be therefore a doubt of its 



ready application to the sheathing of ships. 



Its superiority For the purposes of roofing houses, forming cisterns, 

 over lead or Q . i » . 



copper for ra- P um P s > pipes, &c, it possesses many advantages over lead 



rio us purposes. an d copper. In the first place it is equally durable with those 

 metals, without possessing any of their deleterious effects. It is 

 also capable of being lapped and soldered with the same faci- 

 lity as sheets of copper, lead, or tinned iron plates ; and may be 

 worked to advantage equally by the brazier, the plumber, and 

 the tinman. Its little specific gravity, which is to that of lead 

 as 7 to 11, compared with its greater strength, which is 15 

 times that of lead, gives it a decided advantage over that 

 metal in point of price. Allowing the sheets of zinc to be 

 only |th the thickness of lead, the zinc will come in at one 

 third the price of that metal. Its advantage in a similar 

 point of view over copper will not admit of a question. 

 fTeneral size of The sheets arc generally made 2 feet by 4, and can be 

 the sheets. xo \\^ { \ as thin as G ounces to the square foot. 



Sheets 



