( 2S-^ ) 

 the matrafs at length was forced to open* 

 I find, therefore, no difficuky in beUeving 

 that fuch a vapour may produce fimilar 

 effecls, on a larger fcale, within the* earth, 

 when it meets any obllacle to its expanfion. 



I cannot, however, fo eafily admit that 

 the fame vapour is the caufe of the f ery 

 hail or eje£lions of volcanos, as the break- 

 ing of the matraffes happens without the 

 leaft noife, and without the ejedlion or fcat- 

 tering of the contained matter. I atten- 

 tively watched two matraffes placed in the 

 furnace when they began to open, and I 

 obferved that the apertures enlarged infen- 

 fibly ; which proves that the power of this 

 vapour, though fuperior to the refiftance of 

 the matraffes, acts neverthelefs very llowly ; 

 whereas the agent which hurls the burning 

 matters into the air from the volcanic 

 mouths mull a6t with the utmoft rapidity 

 and violence. 



To explain thefe ejections, therefore, 

 we muft have recourfe to other principles. 



Modern 



