On the Origin and Composition of Basalt. 151 



granite or any other known rock. With the view of testing in 

 some degree the accuracy of this opinion, Leonhard requested 

 of the celebrated chemist C. G. Gmelin, who has published so 

 interesting an account of the composition of Phonolite or Clink- 

 stone, to examine basalt in the same manner as he had phonolite. 

 Leonhard, in his great work on Trap-rocks, now in the press, tells 

 us that Gmelin readily agreed to undertake the analysis, and 

 had already communicated to him the following examination of 

 basalt. 



Analysis of Basalt, by Professor C. G. Gmelin. 



The analysis was conducted in the same way as that of pho- 

 nolite. 



Basalt from Stetten^ a Conical Basaltic Rock in Hegau. 



Magnesia, 11.47 



Oxidulated Iron, .... 13.35 



Oxide of Manganese, . . . 1.10 



Potash, 0.74 



Soda, 2.01 



Water, 4.01 



96.98 



