some of the Substances which accompany it, &c. 
Imperfect Corundum from China. 
Silica 
5.25 
Alumina 
86,50 
Iron 
6,5° 
Loss 
1.75 
100,00. 
Imperfect Corundum from Ava.< 
Silica - - 6,5 
Alumina - - 87,0 
Iron - ' - 4,, 5 
Loss - - 2,0 
100 , 0 . 
As I could not discover chrome, or any other colouring sub- 
stance, except iron, in these stones, I can attribute their difference 
of colour only to the different state of oxidizement of the iron ; 
but it is impossible to ascertain what that state may be, from 
so small a quantity. 
The matrices of these stones, and the substances accompa- 
nying them, are more easily fused than the six kinds of corun- 
dum just mentioned. The usual and well known mode of 
treatment by potash, was sufficient to render these substances 
soluble in the acids. Since the many experiments of Klaproth, 
Vauquelin, and others, the mode of analyzing mineral bodies 
is become so familiar to chemists, that I shall mention particu- 
lars with respect to one only of the following substances. 
MATRIX OF CORUNDUM FROM THE PENINSULA OF INDIA. 
1. A certain quantity of this matrix was reduced to powder, 
in the manner already described. 100 grains of it were treated 
with potash, in a silver crucible: they then afforded a limpid 
solution in muriatic acid. The liquor was evaporated ; and, long 
before the mass was entirely dry, it had assumed the appearance 
of a jelly. When the saline matter in the evaporating-dish was 
dissolved in a slight excess of acid, a white powder remained at 
MDCccn. X x 
