OF THS ASBESTINE EARTH. 199 



ted fome magnefia diflblvcd in the acrid acid; 

 and, if there was flill any quantity of aerated 

 chalk, it would be cafily feparated by means of 

 the vitriolic acid. The two precipitations a- 

 bovc related were found ufeful folutions in the 

 vitriolic acid, for the purpofe of expelling the a- 

 qua regia, and depoiiting the alum in its turn. 

 The new folution in the vitriolic acid is there- 

 fore firft to be precipitated by the phlogiftic al- 

 kali, and then, the i'ruilian blue being collccl- 

 ed, the alum may be dcpofitcd in the remain- 

 ing clear liquor, by means of the aerated mag- 

 ncfia. 



xv. Corollary. 



In order to Icficn the difficulty of comparing 

 together the fevcrai varieties examined, we 

 have exhibited here at one view the proportion- 

 al contents of a centenary of each of them. 



N 4 



