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dilatation ; or when it infmuates kfelf late- 

 rally among the liquefied matters ; of which 

 we have a fatlsfadory proof in the explo. 

 fion of the lava, violently forced from the 

 containing vefl'el, on the introduction of 

 water inro a cavity made in it. 



Though, from the faCls now adduced, 

 there is the utmoft reafon to believe, that 

 water changed to vapour, by the incredible 

 power it acquires, is extremely well adapted 

 to produce the great volcanic eruptions ; 

 and, by the ludden fmkings of the fea, 

 which frequently happen on fuch occafions, 

 it is nearly certain that they are to be 

 afcribed to this moft powerful agent ; it is 

 not neceflary to recur to it for the caufe of 

 the more moderate and fmaller ejed:Ions ; 

 as, to produce thefe, the different perma* 

 nent gafes mentioned above are fufficient ; 

 and it is, in fad:, beyond doubt, that they 

 are the caufes of fuch eruptions in fome 

 volcanos, as, for inftance, that of Stromboli* 

 In Chap. X. v/e have feen that the fymp- 

 toms of that volcano confift In an ebullition 

 B b A of 



