t. 





^^l 



'^en k 



Icanic, ; 

 )rigin, 



i> 



ne. ..> . 



) 



[lie, 



^' 



^ 



4: 



HUTTONIAN THEORY. 261 



in his account of the Euganean Hills, in Lom- 

 bardy, defcribes fome of the rocks as a' ound- 

 ing at their furface, and even in th.ir interior, 

 with air-bubbles of various fizes, from uch as 

 are hardly perceptible, to fome that are half an 

 inch in diameter ; and which, he fays, are all of 

 an oval figure, with their longeft diameters in - 

 the fame diredion. This he confiders as a proof 

 that the rock is a genuine lava ; for the air- 

 [.. J ,' bubbles prove the ftone to have had its fluidity 



from fire ; and by their elongation in the fame 

 diredion they prove, that the mafs when fluid 

 was alfo in motion. Spallanzani adds, that 7na- 

 ny of thefe cavities are f died with cryjlals of the 

 carbojiat of lime, an effect of the infiltration 



'^\ water *. 



; froi I 



235. Though the argument here advanced 

 for the igneous origin of the rock may be admit- 



llaiicet- tied as conclufive. the introdudion of 



\M fpar into it by infiltration mufl; ft ill be que 



■ flioned. Lava, except in a fl:ate of decay or de 



;lTiir£'' compofition, is not readily penetrated by wate 

 [he £3'' and, if it were, the filling of cavities with fp 



/ 



^^itlifif #y means of the water percolating through them, 



[j^e,l? would ftill be fubject to many difficulties, (§ 12.). 



Befides, whinftone rocks are frequently found 



.^^ R3 fb 



J * Voyages dans les deux Siciles, tom.iii. p. 157 



Edit, de Faujas ds St Fond. 



% 



