( 3^9 ) 



thus glafs which does not produce gas 

 in the furnace^ but njuhich produces it, 

 <withtn matrajfes, in ajlrong heat — Expe- 

 riments on fix other volcanic bodies^ which 

 produce little or no gas in the furtiace^ but 

 a confiderable quantity in matrajfes^ with' 

 cut a?iy appearance of permanent gas — 

 Concltfion that the bubbles and inflations of 

 various ft%es, which we fo frequently ob- 

 ferve i?i the produ&ions of volcanos^ arc 

 not the effeSi of afiy permanent gas which 

 has aEled on them, but of an a'iriform fluid 

 proceeding from the excejive fubtilization 

 of thofe produ&ions by means of beat — 

 Not but that volcanic produBs, expofed to 

 our common fire, fometimes emit perm afient 

 gas — -Proofs, deduced from faEis on v 

 f mailer fcale, that this a'eriform fluid, in 

 the deep receffes of a volcanic crater, being 

 abundantly mixed with tfoe liquid lava, 

 and flrongly excited by the fubterranean 

 conflagrations, may, by its violent force, 

 raife the lava to the fummit of the crater, 

 and compel it to flow over the fides and 

 form cur rents-'-^ Another proof of this fa£l, 



'which 



