C 343 ) 



fafe this glafs, but not to convert It Inro 

 gas. The chemical furnace, being more 

 adlve, rendered it gafeous. Hence arofe 

 that violent tumefadion ; though the adion 

 of the fire having afterwards diminiflied, 

 the glafs confequently paifed from the aeri- 

 form to the liquid ftate, and defcended to the 

 bottom of the matrafs, where it congealed. 

 That no permanent gas had any part in 

 this ebullition is proved by the mercurial 

 pneumatic apparatus, in which it muft have 

 collected, more or lels, above the mercury : 

 but nothing was found except common air, 

 as in the other experiments. 



Fitherto I had only ufed thofe volcanic 

 products, which, in the furnace, are filled 

 Vv'ith bubbles more than others ; being de- 

 fu'ous to obferve whether the f.ime effedl 

 would take place in the matralTes, as was 

 in fad the cafe. I afterwards refolved to 

 make experiments on others lefs liable to 

 inflate in bubbles. To avoid needlefs pro- 

 lixity, however, I fhall only ftate the qua- 

 Z 4 llties 



