

DOMAIN XH. VOLCANIC. 



dotted appearance of the lava is such as 

 never occurs in any natural rock. The 

 quantity of potash recently discovered in 

 felspar, sufficiently accounts for its fusibi- 

 lity. Nor, so far as the perusal of most 

 works on the subject can conduct to an 

 opinion, is the power of volcanic heat to 

 be computed from a few examples ; while 

 it is sometimes, on the contrary, demon* 

 strable to be very intense. 

 compact lava It is truly singular that, in the state of a 



dubious. . . 



science so much advanced since the time 

 of Dolomieu, specimens of compact lava 

 do not abound in every cabinet ; and that 

 the subject has not been completely inves- 

 tigated; but attention has been diverted 

 to crystallography, which may be called 

 the entomology of the science, while the 

 grandest objects of nature are neglected. 

 Dolomieu positively allows that what he 

 calls the basaltic columns, chiefly observa- 

 ble on the eastern side of Etna, are com- 

 posed of a lava, " of which the most com- 

 pact morsels are not exempt from some 

 little round pores, easily discoverable with 



