i882. 



29 



Trans. N. V. Ac. Set. 



Willemite= 28.107 



Rhodonites 8.482 



Silicate of Alumina, etc.= 0.920 



Total Silicate 37-509 



Carb. of CaO & MgO lo.i 10 (by analysis.) 



Total Silicates and Carbonates. . . . 47.619 

 Found by Wendt 49.100 



Differences 1.481 



Carb. of Manganese, calculated from 

 excess of Carbonic Acid 1.270 



.2ii=Cu, etc. 



Statement. 



To check this calculation, the average composition of Franklinite, 

 Willemite and Zincite, as given by Dana, were used in connection with 

 the mechanical separation already referred to, and the following calcu- 

 lation made as to the composition of Sample " A." 



Zincite. 



ZnO 9S-20 



MnO 3.19 



Franklinite. 



ZnO 20.72 



MnO...' 12.72 



Fe304 63-90 



Willemite. 



ZnO 69.97 



MnO 1. 14 



Fe304 trace 



SiOa 26.81 



