Argillaceous Genus. 83 



that the fire had ated upon, but not in any 

 other. Mem. Par. 1769, p. 276. 



The rotten Jlone of Derbyfhire is, according 

 to Mr, Ferber^ a tripoli mixed with calcareous 

 Earth. 



SPECIES III. 



Barely fat ur ate d 'with Vitriolic Acid. 

 Embryon Allum. 



This fpecies was firft difcovered by Mr. 

 Beaume ; it forms fmall fcaly chryftals like 

 mica, which require 1450 times their weight 

 of water to diffolve them in the temperature 

 of 60? It is no where found fingle, but ge- 

 nerally mixed with clays, from which it may 

 be feparated by boiling, and diffolved in water, 

 to which it gives an earthy tafte, and is fepa- 

 rable by the affufion of lime water, which 

 precipitates the argill. 



SPECIES IV. 

 Barely fat ur at cd 'with Marine Acid* 



Embryon Marine Allum. 



As a folution of marine alum, completely 

 faturated with argill, forms alfo a very diffi- 



G 2 culcly 



