r Ys2*) 
Paris. ~Vitriolic acid extracts from 
calcareous earth, fixed air, and from 
fome kinds of fparrs an air of a 
wonderful quality, corroding glafs 
itfelf, which feems to be almoit an — 
incorruptible fubftance, and reduc- 
ing it into duft by its contact only 5 
and this air, fo active upon glafs, is 
yy the firft approach of water im- 
mediately reduced again into the 
form of the ftone out of which it 
was extracted, 
Confidering all what is faid be- 
fore, incline much to the opinion, 
that the various kinds of air extracted 
from the different bodies owe, for 
a great part, their {pecific nature ta 
the tranfmutation which they un- 
dergo in the operation by which 
they are obtained; and that they 
cannot, at leaft not all, be faid to 
exift in the body in a contraéted 
ftate 
