of the Oxides of Manganese. 171 



after the muriates have been removed by distilled water, the neu- 

 tral solution in muriatic acid gives traces of lime with oxalate of 

 potash. It contains silica and baryta nearly in the same propor- 

 tion as the first variety. 



The following is the result of my analysis : 



Red oxide 85-617 



Oxygen ..... 11 -599 



Water .,,. , . . 1-566 



Silica v,V'. . . . . 0-553 



Baryta ; / . 0-665 



Lime a trace 



100.000 



Subtracting 2'784 as impurities, there remain 97'214 parts, which 

 lose 11*599, or 11 "931 per cent, of oxygen in being converted in- 

 to the red oxide. It is therefore an anhydrous peroxide, most 

 probably containing an admixture of some other oxide. 



Analysis of Psilomelane, or the Unckavable Manganese-ore. 



This mineral when reduced to powder has a brownish-black 

 colour. With sulphuric acid it does not emit any odour of chlo- 

 rine. It dissolves completely in muriatic acid, excepting a small 

 quantity of silica which amounts to 0'26 per cent ; and the only 

 substances which 1 could detect in the solution are baryta and 

 the oxide of manganese. Though this ore has been placed by 

 mineralogists among the oxides of iron, under the names of Black 

 Hematite and Black Iron-ore, pure fragments of it do not con- 

 tain a trace of that metal. 



Y 2 



