( ^jo ) 



of volcanos be found in abundance, and be- 

 come inflamed, in feparate heaps, burning 

 mountains would arife, in a diredt line, and 

 more or lefs large, according to the quantity 

 of the ejeded matters. 



From the particular defcriptions of the 

 iflands of Lipari, we Jiave feen that the 

 combuftible fubftances which have produced 

 them have fometimes been contained within 

 granite, as at Panaria and Bafiluzzo, but for 

 the moft part within rocks which have for 

 their bafe the petrofilex, the horn-ftone, and 

 the fcltfpar. It likewife appears, from the 

 obfervations made at Stromboli, that, even 

 there, thefe burning fubftances have their 

 feat in the horn-ftone rock, though, from 

 the fize of the ifland they have produced, 

 they muft undoubtedly be buried at an im- 

 menfe depth. If we would fimplify the 

 fads relative to the materials of ail thefe 

 illands, we (hall find that they are for the 

 greater part porphyritic ; as are likewife 

 foine of thofe fubmarine trads, apparently 



not 



<*a. 



