33 6 -Mr. Chenevix’s Analysis of Corundum , and of 
Thallite in Fragments , of a fine transparent Tellow Colour . 
Silica - -42 
Alumina - 25,5 
Lime 16 
Iron - - - 14 
Loss - 2,5, 
100 , 0 . 
Fibrolite accompanying the Matrix of Corundum from China, 
Silica - - - - 38 
Alumina - - 46 
Iron - 13 
Loss » - - 3 
100. 
Felspar from the Sand of Ceylon. 
Silica - - - - 68,5 
Alumina - 20,5 
Lime - 7 
Iron - - - i ,5 
Loss - 2,5 
100,0. 
As the greater part of the above substances were fusible 
without difficulty in potash, I preferred using a silver crucible to 
any other. It may be laid down as a general rule, with respect to 
delicate experiments, that in the treatment of metallic substances, 
we should not use metallic crucibles ; but, in the treatment of 
earthy bodies, they alone are to be depended upon. The easily 
oxidizable metals cannot be employed; but silver and platina 
present advantages which no other metals seem to possess. 
