231 



It is sufficient here to observe, that these causes 

 are concealed at immense depths ; and that we 

 must seek them in the rocks which we call pri- 

 mitive, perhaps even below the earthy and oxided 

 crust of the Globe, in the abysses that contain 

 the metalloidal bases of silex, lime, soda, and 

 potash. 



The phenomena of volcanoes, and those of 

 earthquakes, have been considered of late as the 

 effects of voltaic electricity, developed by a par- 

 ticular disposition of heterogeneous strata. It 

 cannot be denied, that often, when violent shocks 

 succeed each other in the space of a few hours, 

 the electricity of the air * sensibly increases at 

 the instant the ground is most agitated ; but in 

 order to explain this phenomenon, it is unneces- 

 sary to recur to an hypothesis, which is in direct 

 contradiction to every thing that has hitherto 

 been observed respecting the structure of our 

 planet, and the disposition of it's strata. 



* See the electroscopical experiments made in Piedmont, 

 in the valleys of Pelis and Clusson, in 1308. Journal de 

 Phys., t. 67, p. 292. 



