Analysis of some Indian Ores of Manganese. 279 



per cent., and the total quantity of oxygen combined there- 

 with to 22*219 per cent., which corresponds very closely to 

 the constitution of sesquioxide, or of a mixture of nearly equal 

 quantities of protoxide and peroxide, as shewn by the an- 

 nexed calculation. 



ii lo 9flK at 81TJ00O $1 



Mn 53-428) _ Mn O 39050 i.e. Mn 30-2686 + 8-7814 

 Q 22-219] "Mn0 2 36*597 i.e. Mn 23'1594 + 13-4376 



75-647 [te9t 75-647 53-428 22-219 



On comparing the composition of this mineral with those 

 containing manganese, of which analyses have been already 

 published, it is found to agree most nearly with a man- 

 ganese ore called Marcellin from St Marcel in Piedmont, 

 and which has been investigated by Damour. This observer 

 considers the mineral he analysed to be a mixture of Braunite 

 and silicate of the protoxide of manganese ; but Rammelsberg 

 very properly remarks, that if it possess a distinct crystalline 

 form, which it appears to do, it cannot be a mixture, and 

 suggests, as more probable, that the crystals may be Braunite, 

 and that the analysis has been made with a specimen con- 

 taining" impurities. 



The manganese ore from Bimlapatam, a station not far 

 distant from Vizianagram, is very similar, if not identical to 

 the foregoing in its external and chemical characters^ It 

 differs from it, however, to some slight degree, and was 

 found to contain lime, which the other does not. Its quan- 

 titative analysis gave the following results : — Silicic acid, 

 9-09; peroxide of iron, 11*72; lime, 1*244; magnesia, 0*668; 

 water, 0*432 ; reel oxide of manganese, 76-177 ; oxygen, 

 0*655 ; total, 99*986. The quantity of metallic manganese 

 indicated in the above quantity of red oxide would be 54*929, 

 that of the oxygen of the same, together with the free oxygen 

 added, to 22*558, whereas, in order to constitute sesquioxide^ 

 23*904 of oxygen would be required for the same quantity of 

 metallic manganese. It would thus appear that the metal 

 in this case must be in a lower state of oxidation than in the 

 Vizianagram specimen. 



