276 Count de Bournon’s Description of 
i 
IMPERFECT CORUNDUM. 
From the 
From 
From 
From 
Carnatic. 
Malabar. 
China. 
Ava. 
Silica 
5,o 
- 7,0 - 
5.25 - 
6,5 
Alumina - 
- 9L o 
- 8b, 5 - 
8b, 50 - 
00 
*.# 
0 
Iron 
- L5 
4>° 
6,50 - 
4.5 
Loss 
2,5 
2,5 
J.7 5 - 
2,0 
100,0 
100,0 
100,00 
100,0. 
PERFECT CORUNDUM. 
Blue, or 
Red, or 
sapphire. 
oriental ruby. 
Silica 
- 
5.25 - 
l 
■<r 
0 
Alumina 
~ - 
92,0 
' - 9°>° 
Iron 
~ 
1,0 
- 1,2 
Loss 
- 
1,75 - 
- i,8 
100,00 
100,0. 
From what has been said it appears, that the analogy 
existing between the stones hitherto known by the names of 
corundum, sapphire, oriental ruby, oriental hyacinth, &c. is 
so strong and complete, as no longer to permit us to doubt 
that they ought all to be considered merely as varieties of the 
same substance, to which I have therefore given the general 
name of corundum. 
In the learned work on mineralogy which the Abb4 Hauy 
has just published, this celebrated naturalist says, that near- 
ly at the same time I communicated to the Royal Society 
my first observations on this substance, he had himself ob- 
served the existence of corundum, among the crystals of 
