104 Dr. J. L. Smith on Oxide of Cobalt from Silver Bluff. 



this state; these stains are in the form of streaks, varying in 

 length and breadth ; the sand has the appearance of coarse gun- 

 powder and arises from the disintegration of mica granite. Hy- 

 drochloric acid readily dissolves this black matter with an evolu- 

 tion 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, ow- 

 ing 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 



10000 

 The method by which these oxides were 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 

 any form whatsoever, and the only one where it exists in the 

 form of an oxide free from arsenic* 



* The llaclt earthy colalt from Missouri (mine La Motte) had of course not 

 been seen by Dr. Smith when the above was written. We have analyzed it, and 

 found it to consist of the oxides of cobalt, manganese, iron, copper; and traces of 

 silica, lead, magnesia, &c., with about 17 per cent, of water. It generally contains 

 about 40 per cent, of oxide of cobalt. A full notice of this interesting mineral will 

 soon be published. — Eds. 



