Anal)fis of Earths and Stones, 163 



SECTION III. 

 Of the Analyfis of Earths and Stones. 



The beft general folvent for Stones or 

 Earths feems to me to be Aqua Regia, com- 

 pofed of two parts nitrous, and one of marine 

 acid : if the ftone or Earth effervefees ftrongly 

 with acids, no other preparation is requifite 

 than a feparation of fuch parts as are vifibly 

 heterogenous, and pulverization ; the folution 

 is then eafily performed in a digefting heat, 

 if requifite. The undiffolved refiduum, if 

 purely filiceous, will melt into a tranfparent 

 glafs with about \ its weight of mineral al- 

 kali > if not, it is ftill compounded, and its 

 foluble parts will yield to a reiterated di- 

 geftion. 



If the ftone does not effervefce, or eafily 

 diffolve in acids, after pulverization and di- 

 geftion, but leaves an infoluble refiduum 

 evidently compound, or but flightly altered, 

 it will require to be pulverized and mixed 

 with twice or thrice its weight of mineral 

 alkali, and to be expofed to a low red heat 

 for one or two hours. I found mica to re- 

 quire a mixture of 4 times its weight of 

 mineral alkali ; after which it is to be fepa- 

 rated from the alkali by lixiviation and filtra- 

 tion, wafliing it with diftilled water until the 

 M 2 water 



