Trans. N. V. Ac. Set. 



30 



Nov. ly 



Mechanical separation ) Franklinite — 48.2 



gave \ Zincite 2.7 



Silicates and ) 



Carbonates ) '^"' 



48.2 per cent. Franklinite= 9.99 per cent. ZnO. 

 2.7 per cent. Zincite= 2.57 " " 



12.56 



Total ZnO in sample= 34-13 



12.56 



(mite. 



21.57 per cent. ZnO due toWille- 



8.27 SiOa. 



30.84 per cent. Silicate of Zinc* 



Total Si02 in sample= 11.85 



8.27 



(donite. 



3.58 per cent. SiOo due to Rho- 

 4.22 per cent. MnO. 



7.80 per cent. Rhodonite. 



By analysis 10. 1 1 per cent. Limestone. 



Carb. Manganese for excess CO2 1.27 



Franklinite 48.2 



Zincite .... 2.7 



Willemite 30.84) =,38.64 Silicates. 



Rhodonite 7.80^ -^ ^ 



Lii^^ir' '°''l\ =11.38 Carbonates. 



Carb. Manganese 1.27 ^ '^ 



(Carbonates. 



100.92 50.02 per cent. Silicates and 



Other methods of calculation were employed, such as applying the 

 various standard analyses of Franklinite to the complete analysis given, 

 considering that all the iron found came from the Franklinite, and us- 

 ing that as a starting point. For instance, taking an analysis of 

 Franklinite as given by Cook, and applying it to complete analysis 

 marked " D," we should obtain the following calculation and results : 



The analysis of Franklinite gives sesqui-oxide of iron, 62.36 — equi- 

 valent to proto-sesqui-oxide, 60.28 ; oxide of zinc, 22.95 ; protoxide of 

 manganese, 17.20. Taking the proto-sesqui-oxide of iron in the 

 sample at 31.05, and comparing with the proto-sesqui-oxide of iron in 

 100 parts, as found in the Franklinite, the amount of Franklinite 

 corresponding to 31.05 is easily obtained. Calculating the silicate of 

 manganese as rhodonite, taking all the oxide of zinc necessary for 



