56 Elements of Mineralogy. 



Mr* Morveau obferves that it accompanies 

 the ores of moft metals. Mr. MargraafMo 

 frequently found maflfes of it mixed with 

 gypfum. i Margr. 332. 



\The eafieft method of decompofing it, is 

 that praftifed by Mr. Wolfs and Mr. Wiegleb^ 

 viz. by calcining it in a ftrong red heat for i 

 or 2 hours, with i i or twice its weight of 

 fixed alkali ; the neutral fait and fuperfluous 

 alkali are then wafhed of, and the Jtarth is 

 found combined with fixed air. Mr. Afor- 

 *ueau y s method is cheaper. He calcines the 

 ponderous fpar with of its weight of char- 

 coal for i hour, in a crucible, well luted, and 

 a ftrong red heat : he then diflblves the Earth 

 in the acetous acid. The fulphur is thus fe- 

 parated. Mem. Dijon, 1782. Mr.Margraqf 

 decompofed it in the liquid way, by mixing 

 two parts of the ftone with one of fixed al- 

 kali ; then pouring hot water on it, and keep- 

 ing it boiling for iome hours, i Margr. 366. 

 The decompofed part, well edulcorated, is 

 foluble in acids. 



This fpecies often forms the ftony matter of 

 petrifactions, Mem. Dijon, 1782. i Seme/I. 

 P. 163. 



According to Mr. Bergman, 100 parts of 

 it contain 84 of Earth, 13 of the moft con- 

 centrated 



