( 3Si ) 



that It infinuated itfelf into the body of the 

 lava ; and ifTued out upv>rards, caufmg the 

 Inflations, ejedions, and detonations. As 

 to the poflibility of its entrance to the moft 

 internal recefTeSj containing the melted lava ; 

 it feemed to admit of eafy proof from the 

 cavernous ftrudlure of volcanic mountains. 

 But how this air could be fufficiently pow- 

 erful to infmuate itfelf into the great mafs 

 of lava, traverfe it to the top, and there oc- 

 cafion the explofions, I could not conceive, 

 from the two following, in my opinion, in- 

 fuperable obftacles. Firft, it is undeniable 

 that the atmofpheric air which might pene- 

 trate through the cavities of the mountain, 

 till it approached the immenfe mafs of 

 melted and burning lava, would be ex- 

 tremely dilated, and make its way where it 

 found the eafieft paflage, which v/ould be 

 by the caverns that had admitted it ; but it 

 could never penetrate the lava, from its too 

 great refiftance. Secondly, even granting 

 for a moment that it might penetrate the 

 lava, from the dilatation it mufl fuffer, it 

 would penetrate it extremely rarefied, and 



be 



