OXIDE OF COBALT AND MAGNESIAN OPAL. 



Oxide of Cobalt from Silver Bluff, S. 0. 



The existence of this oxide was first brought to my notice 

 by Prof. Ellet. It is accompanied by the oxide of manganese, 

 and with it stains a coarse gravel found in the primitive region 

 of this state. These stains are in the form of streaks, varying 

 in length and breadth. The sand has the appearance of coarse 

 gunpowder, and arises from the disintegration of mica granite. 

 Hydrochloric acid readily dissolves this black matter with an 

 evolution of chlorine. The solution is of a pinkish color, and 

 affords a green salt when evaporated to dryness, from which it 

 is evident that it must contain both the oxides of manganese 

 and cobalt. It is perfectly free from iron, arsenic, and nickel; 

 but at the same time it is impossible to obtain a solution of it 

 free from iron, owing to the presence of ferruginous matter in 

 the sand from which it is derived. This black matter has 

 evidently originated from the disintegration of cobaltiferous 

 oxide of manganese, minute particles of which are still to be 

 traced, mixed with the sand. The relative proportions of the 

 oxides are not always the same. One analysis gave 



Oxide of cobalt 24.00 



Oxide of manganese 76.00 



100.00 



The method by which these oxides are separated is that 

 recommended by Prof. Liebig, and one that deserves the notice 

 of all analytical chemists engaged in the separation of the oxide 

 of cobalt from other oxides. I allude to the method with the 

 cyanide of potassium. The locality where this is found is one 

 of the two or three in this country where cobalt is found under 



