( "5 ) 



that it was thrown out from the mouth of 

 the volcano in the fame ftate in which it is 

 now feen ; fince it is only found in plates 

 or flakes, and with thofe points and (harp 

 angles, thofc cutting edges and waving 

 ftreaks, which we obferve in glafs, whether 

 volcanic or fad:itious, when it has been 

 broken and^ divided into fragments by a 

 hammer, or other heavy body. We muft 

 therefore conclade, that after the fubterra- 

 nean conflagrations had reduced the ftony 

 fubftance to glafs, this glafs has been thus 

 broken and fhivered by fome convulfion of 

 the earth, or by fome violent and tumultu- 

 ary agent. 



The larger pieces are about five inches 

 and a half over, and two in thicknefs. 

 Many of them are not inferior in clearnefs 

 and brilliancy to the fineft and brighteft 

 glades of Liipari ; others are lefs tranfparenr, 

 and of a cinerltious, or grey, colourj while 

 others are almoft entirely opake; and'thefe 

 approach nearer to the nature of enamels 

 than to that of glalTes. They are all, how- 



I 3 ever, 



