50 
Mr. Hatchett's Analysis of 
mineral substance in question came from one of them, although 
it may not now be easy to identify the particular mine. 
§ I. DESCRIPTION OF THE ORE. 
The external colour is dark brownish gray. 
The internal colour is the same, inclining to iron gray. 
The longitudinal fracture is imperfectly lamellated ; and the 
cross fracture shews a fine grain. 
The lustre is vitreous, slightly inclining in some parts to 
metallic lustre. 
It is moderately hard, and is very brittle. 
The colour of the streak or powder is dark chocolate brown. 
The particles are not attracted by the magnet. 
The specific gravity, at temp. 65 0 , is 5918.* 
Experiment 1. 
Some of the ore, reduced to fine powder, was digested in 
boiling muriatic acid for about one hour. 
The acid appeared to have acted but slightly upon the powder; 
as the former remained colourless, and the latter did not seem 
to be diminished. A portion, however, chiefly of iron, was found 
to be dissolved ; for ammonia formed a yellow flocculent pre- 
cipitate; prussiate of potash produced one which was blue; 
; * The following results of some experiments which I have purposely made, will 
shew how much the specific gravity of this ore is different from that of Wolfram, and 
Siberian chromate of ii-on. 
Pure Wolfram, free from extraneous substances, at temp. 65° - - 69 55. 
Siberian chromate of iron, containing some of the green oxide - 37 2 ^- 
Pure Siberian chromate of iron - 435 5 * 
The Siberian chromate of iron, like all other mineral substances which are not 
crystallized, and which consequently are not always homogeneous, must evidently be 
liable to considerable variations in specific gravity. 
