I 



Geological Obfervatlons. 397 



There is no matrix peculiarly appropriated 

 to any metal; it has only been remarked, 

 that tin is generally found among ftones of 

 the filiceous genus, and lead very frequently 

 among thofe of the calcareous. 



There is no certain fign from which the 

 exiftence of an ore in any mountain may be 

 inferred, except the veftiges of it in the beds 

 of torrents or mineral waters, anc) the ftruc- 

 ture of the mountain itfelf, of which enough 

 has been already faid. 



Of Hof Springs. 



Mr. Tifflngton has remarked, that waters 

 flowing through a blue marl filled with no- 

 dules of pyrites are warm; Mr. Guettard 

 has alfo obferved, that all the hot mineral 

 fprings of France flow from ihiftus : hence 

 there is no occafion to derive their heat from 

 fubterraneous volcano. 



TABLE 



