S°4? Count de Bournon’s Description of 
it contained nearly equal quantities of corundum and of oxide 
of iron. 
If, to what has been already said, I add, that there are some- 
times found in this matrix, small pieces of green pulverulent 
talc, (chlorite,) and small masses of thallite, in thin elongated 
crystals, of a beautiful yellowish green colour, in the form of 
diverging rays, I shall have mentioned all the substances I 
have been able to observe, in the matrix of imperfect corundum 
from China. 
Of the matrix of imperfect corundum from the kingdom of 
Ava, a small quantity only was sent; but that quantity was 
sufficient to demonstrate, that its nature is exactly the same as 
that of the matrix of imperfect corundum from China. 
MATRIX OF PERFECT CORUNDUM FROM THE ISLAND OF CEYLON, 
AND SUBSTANCES WITH WHICH IT IS ACCOMPANIED. 
I cannot help regretting, that it is not in my power to give 
much information respecting the matrix of perfect corundum 
from Ceylon. The precious stones comprised under that deno- 
mination, which are selected from the sands washed down by 
the rivers of the island, and sold under the name of sand of Ceylon , 
have never been brought to Europe in any kind of matrix, nor 
has any account of their matrix ever been transmitted to us. 
Perhaps, indeed, no more information on this head could be pro- 
cured on the spot, than was obtained by those naturalists who 
sought for the origin of the sapphires, &c. found in the sands of 
the small rivulet at Expailly, already spoken of. I may also 
observe, that the great care taken to free the sand of Ceylon 
from every substance, except such as, on account of their 
