48 BUNSEN ON THE FORMATION OF 



in the mixed rocks. A compact black basalt from the source of 

 the Euphrates, which was analysed by M. Jackel in my labora- 

 tory, represents a mixture of 1 trachytic and 0'7332 pyroxenic 

 substance. 



51. 



Found. Calculated. 



Silica 64-76 6474 



Alumina and protoxide of iron . 22*31 20*99 



Lime 5*13 5*84 



Magnesia 1*91 3*07 



Potash 2-51 2-12 



Soda 3-38 3*24 



100-00 100-00 



All the other analyses which Abich gives in his paper likewise 

 correspond in a surprising manner with the law : — 



Rock at the summit of the Greater Ararat, 



52. 



Found. Calculated. 



Silica 70-14 70-14 



Alumina and protoxide of iron . 18*17 17'92 



Lime 4-72 3*85 



Magnesia . l-OO 1-81 



Potash 1-47 2-61 



Soda 4*50 3*67 



100-00 100*00 



1 trachyte and 0'3013 pyroxenic mass. 



Dark Gray Rock from the summit of the Kasbeck. 



53. 



Found. Calculated. 



Silica 69-77 69*77 



Alumina and protoxide of iron . 18*27 18-13 



Lime 5-13 3*99 



Magnesia 1*65 1-89 



Potash and Soda 5*18 6*22 



100-00 100-00 



V , 



1 trachyte and 0*3239 pyroxenic mass. 



