102 
MANGANESE DJiPOSITS OF INDIA : MINERALOGY. [ ParT It 
Table ld—{contd.). 
Analyses of Indian psilomelanes in terms of manganates. 
Guguldoho. 
iivagudem. 
Tekrasai. 
Tekrasai. 
Tekrasai. 
II57 
A. 372 
A. 380 
A. 381 
J. 917 
Cirried forward 
— 
97 -82 
98-18 
98-99 
97-63 
97-46 
Si02 .... 

0-25 

0-45 
0-05 
0-05 
0-10 
Sulphur .... 
0021 
0-034 
0-039 
0-037 
0025 
P2O5 .... 
0-838 
0-791 
0-737 
0-676 
0-696 
AS2O5 .... 
0-003 
CuO .... 
0-002 
TiOa .... 
0-01 
Moisture at 1 00*^0 . 
0-25 
2-05 
0-45 
0-45 
035 
99- 194 
101-505 
100-260 
98-843 
98-631 
Surplus oxygen 
0-80 
1-24 
1-52 
Oxygen assumed 
1-33 
0 18 
99-994 
100-175 
100-080 
100-083 
100-151 
It will be seen that on tlie assumption that these specimens have the 
respective compositions given above there is a considerable error in the 
oxygen determination. But, as in the analyses of hollandite, these diff- 
erences can be explained on the assumption that in the case of an excess 
of oxygen a corresponding portion of the manganese is in the form, not of 
manganous manganate, Mn2Mn05, as shown above, but of manganic 
manganate, Mn4(Mn05)3 ; whilst in the case of a deficit the difference can 
be explained on the hypothesis that a portion of the iron is in the form of 
ferrous manganate, Fe2Mii05, instead of ferric manganate, Fe4(Mn05)3, 
as represented. To show what difference this would make I wUl take the 
cases of the analyses in columns 2 and 5^ where there is a deficit of 1'33 of 
oxygen in one case and an excess of r52 of oxygen in the other. In the 
former case the oxygen can be obtained from the ferric manganate in 
accordance with the following equation : - 
3Fe4(Mii05)3 = 0Fe2MnO5 •» Mn2Mn05 + 10 O; 
according to this equation the deficit of 1'33 of oxygen could 
be obviated by the conversion of 15-69% Fe4(Mn05)3 into 12-32% 
FeaMnOs + 2-04% MngMnOs + 1-33 % of oxygen. The only difiiculty 
in the way of accepting this interpretation is the fact that there is 
