S 3 9 . Mr - Chenevix's Analysis of Corundum and of 
The chief difference between these proportions and those 
established by Mr. Klaproth, is in the silica. That chemist 
did not find any notable portion of it in the specimens he exa- 
mined. This naturally induced me to make a very strict research, 
into every possible means by which any silica might have been 
introduced into the results ; whether by the borax, the alkali, 
or any of the other re-agents I had used. But, finding very 
clearly, that none of these substances did contain any, I could 
no longer hesitate to believe, that the proportion I have here 
stated, was actually contained in the sapphire. I analyzed. I am 
likewise convinced, that no more than the quantity I have 
mentioned was worn from the agate mortar and pestle ; for my 
constant practice was, to weigh them, both before and after I 
had used them, in scales which, when charged with four pounds 
on each end, turn easily with the tenth part of a grain. 
The general results, from all the different kinds of corundum, 
were as follows. 
Blue perfect Corundum , or 
Sapphire. 
Silica - - 5,25 
Alumina - -92 
Iron - - 1 
Loss - - 1,75 
100,00. 
Imperfect Corundum from the 
Carnatic. 
Silica - -5 
Alumina - - 91 
Iron - - 1,5 
Loss - - 2,5 
100,0. 
Red perfect Corundum , or 
Ruby. 
Silica 7 
Alumina - -90 
Iron - - 1,2 
Loss - - 1,8 
ioo,o„ 
Imperfect Corundum from 
Malabar . 
Silica 
Alumina 
Iron 
Loss 
7 
4 
2,5 
100,0. 
