( '85 ) 



If we now confider thofe parts of thefc 

 imperfecl accounts which relate to glaffes 

 and pumices, we fhall find, with refpedl to 

 the former, that the much greater part of 

 volcanos produce none, and that thofe 

 which do produce them, as in the Neapoli- 

 tan territory, Iceland, and Peru, are by no 

 means to be compared in this refpe£t with 

 Lipari and Vulcano. The fame may be 

 aflerted of Alicuda and Felicuda, the glafles 

 of which, though abundant in many parts 

 of thofe illands, are only found in flakes and 

 fragments. Thefe obfervations might like- 

 wife be applied to the pumices, did not the 

 immenfe quantity of them in the ifland of 

 Santorine equal, if not exceed, that of the 

 two Eoljan iflands above mentioned. 



If we confider the volcanos known to us 

 under one general point of view, we fiiall 

 find that, though they have changed into 

 lavas an infinity of rocks, by which they 

 have produced mountains and iflands very 

 confiderable both in number and dimen- 

 fi ons, it is very rarely that they vitrify the 

 7 fubftances 



