( J84 ) 



It admits of no doubt that the highefl 

 mountains of America, as Chimboraco, Col- 

 topaxi, Sangai, Pichencha, &c. form a chain 

 of burning volcanos, the largeft exifting in 

 nature. We are indebted for the accounts 

 we have of them to M. Bouguer ; but thefe 

 are fuch as only tend flrongly to excite 

 our curiofity without gratifj^ing it. With 

 refped: to what relates to our prefent en- 

 quiry, we only learn from this writer, that 

 " fome mountains in the vicinity of Quito 

 " are compofed entirely, to a great depth, 

 " of fcorise, pumices, and fragments of 

 " burnt ftones of every fize *." As to 

 volcanic glaffes, he does not make the flight- 

 eft mention of them ; though it is well 

 known that the famous gallinaceous ftone, 

 which is univerfdly acknowledged to be 

 a moft beautiful American volcanic glafs, 

 of a black colour, is found in Peru, and 

 that, according to M. Godin, there is a 

 mine of it, feveral days journey from 

 Quito. 



* Acad. Royale des Sciences, J 7 44. 



If 



