Trans. N. Y. Ac. Set. 



28 



Nov. 13, 



The Franklinite, after deducting foreign constituents, such as silica, 

 magnesia, lime, etc., would have the following composition : oxide of 

 zinc, 22.90, protoxide of manganese, 18.08, and proto-sesqui-oxide of 

 iron, 59.15. The Zincite, allowing for the impurities which even careful 

 picking could not separate, would have the following constitution : 

 oxide of zinc, 96.44, protoxide of manganese, 3.55, proto-sesqui-oxide 

 of iron, a trace. 



The Willemite analyzed evidently contained considerable limestone 

 and impurities, and although the analysis is stated, it was thought safer 

 to take the composition of Willemite as given by Dana, in calculating 

 the mineralogical constituents of the ore. 



Taking the analysis of sample marked " A," considering the constitu- 

 tion of the Franklinite and Zincite as determined, and using the mechan- 

 ical separation marked " A," we would have the following as the min- 

 eralogical composition of the sample : 



f Franklinite . . 48,2 

 Mechanical separation of 1,700 ton sample gave: giijcatesand 



[ Carbonates 49.1 



48.2 per cent Franklinite = 11.04 per cent. ZnO. 

 2.7 " Zincite . . = 2.60 



13-64 



Analysis of Sample " A " gives : 



ZnO 34.13 



ZnO for F, and Z 1 3.64 



20.49 per cent, for Willemite : 



which will require 7.617 per cent, of SiOa and correspond to 28.107 of 



Willemite. 



SiOa in 1,700 ton sample= 11.850 

 " for ZnO = 7.617 



" MnO andAUOa 4.233 

 SiOa for AlaOs, etc 0.340 per cent. 



3.893=Balance SiOj. 

 Which would require 4.589 per cent, of MnO. 



8.482 per cent, of Rhodonite. 



