CORKTREE. 217 
pieces of wood, or heavy stones, on purpose to flatten 
them. 
Cork is sometimes prepared without burning, and 
in this case it is merely soaked in water to straighten 
it. But this preparation, which is called white 
cork, is by no means so much esteemed as the black. 
Good cork ought to be supple, elastic, neither ligne- 
ous nor porous, and of a reddish colour. That 
which inclines to a yellow tint is not of so good 
a quality, but the white is by far the worst of any. 
The cork, when burnt in close vessels, yields a 
black powder, called noir d' Espagne, which is em- 
ployed in the arts. 
