156 
flattish and angular, and others finely granulated. Mena- 
chanite is easily pulverized, is rather brittle, and slightly 
attractable by the magnet. Its surface is opaque, some- 
what shining, grayish black, retaining its colour when 
pounded, in which it differs from the Tron Sand of ¢al. 197. 
By analysis, Mr. Gregor found it to contain 
Oxide of Titanium . . 45 
Oxide'of Iron) <=.) 47 AG 
se Noe ec ce ee 
Among the loss a little Silica and Oxide of Manganese 
are included. A trifle of Oxide of Manganese, Silica, and 
Alumina have been found since:in some specimens by 
othet persons ; but as these may be reckoned rather adven- 
titious, Mr. Gregor’s seems most to be depended upon. 
Klaproth, Hecht, and Vauquelin have clearly proved Mr. 
Gregor’s accuracy by their analyses, 
Spec. Grav. 4°497. 
The Oxide of Titanium, when separate from the other 
ingredients of the Menachanite, has these peculiar pro- 
perties. It may be reduced by exposing it with charcoal to 
a violent heat, when it assumes a deep copper colour, with 
much lustre and brittleness, but is elastic when in thin 
plates. It is extremely difficult of fusion. It is easily 
tarnished by air, or oxidized by heat, becoming blue, and 
detonates when thrown on hot Nitre. It is said to form 
three Oxides, viz. the blue or purple, the red, and the white. 
We, as well as Haiiy, consider the Nigrine of Karsten as 
a variety of Menachanite, but generally much freer from 
Tron. 
