DOMAIN XII. VOLCANIC. 



as enveloping balls of lava. Fragments 

 are also found partly glass and partly lava, 

 the former appearing in delicate veins. 

 While the lava is decomposed into black 

 ferruginous earth, the obsidian passes into 

 a light ashy substance. The bubbles and 

 cavities are full of calcareous spar, while 

 others, though rarely, present confused 

 crystals of white and semitransparent 

 quartz*. 



In fine, our laborious and intelligent 

 author concludes that " those Neptunists, 

 who deny the volcanic origin of the basaltic 

 columns of Sicily, must never have ob- 

 served them, else they might have seen 

 them surrounded with amorphous lava of 

 the same identic paste, and often continu- 

 ous with them ; and must have seen in the 

 mass fissures which indicate regular divi- 

 sions/'^ Such is this important work of 

 Ferrara, which must be pronounced one of 

 the most solid and judicious that has yet 

 appeared upon the subject. 



* P. 177, 179, &c. f P. 316. 



