the Congelation of Vitriolic Acid . . 281 
does not proceed from fome marine or other volatile acid, 
which may be contained in the martial vitriol, whence the 
vitriolic acid is obtained. 
Philofophy, vol. I. p. 26. and 450. M. Cornette has alfo effe&ed the cry- 
flallization of vitriolic acid by drilling it with nitrous acid and charcoal.. Me- 
moir. de l’Acad. des Scienc„ Paris, pour 1779. 
