PHYSICAL anv LITERARY. 235 
order to expel a larger quantity of air, and 
render it more remarkably cauttic ; but. 
the whole of it was diilipated by the 
force of the heat, and the black lead, 
which ftill retained the form of a loof 
and fubtile powder, Goer d little or no- 
thing to water. 
We learn then from the above experi- 
ment the reafon why the alkali newly ob- 
tained from the afhes of vegetables is ge- 
nerally of the more acrid kinds of that 
falt. It never appears until the fubject 
be converted into afhes, and is fuppofed 
to be formed by the fire, and to be the re- 
fult of a particular combination of fome 
of the principles of the vegetable ; one of 
which principlés is air which is contained 
in large quantity in all vegetable matters 
whatever. But, as foon as the {mallet 
part ofa vegetable is converted into athes, 
and an alkaliis thus formed, this falt ne= 
ceffarily fuffers a calcination, during 
which itis kept in a fpongy form by 
_ the afhes, and fhews a very confiderable 
£ Bie ice of acrimony, if immediately ap- 
_ Pied to the body of an animal ; but, if the 
afhes 
