344 -Mr. Chenevix's Analysis of Corundum , and of 
Mr. Guyton, it is necessary to examine as much of it as may 
be thought objectionable. 
The author says, that he repeated the experiments of Mr. 
Guyton, with an alkaline solution of silica and alumina, and 
that he obtained a precipitate ; which precipitate, though con- 
taining silica, was totally soluble in the acids. “ Here/' he says, 
“ the properties of the silex must be considerably altered. This 
“ must render all analysis with alkalis suspicious ; and shows on 
“ what fallacious grounds the proud dominion of chemistry rests, 
“ which she has exercised so long, in such an arbitrary and over- 
“ bearing manner, in the mineral kingdom/' This opinion is by 
no means likely to overthrow the pretensions of chemistry ; for 
the very circumstance of rendering silica soluble in the acids, is 
one of the discoveries that has most contributed to render certain, 
and to extend, our knowledge of analysis. No earthy substance 
is now thought fit to be submitted to further experiment, till a 
complete solution of it in an acid be first obtained ; and, when 
that solution cannot be effected directly by the acid, it is always 
attempted by previous fusion with an alkali. This mode of 
rendering silica soluble in acids, is no new discovery ; it has 
been long known ; and the analysis of minerals has never been 
brought so near to truth, as since it has become an indispensable 
condition. 
I have no doubt as to the fact of a precipitate being formed, 
by mixing together an alkaline solution of silica and alumina. 
Alumina indeed appears to exercise an attraction, as I before 
stated, for silica, for magnesia, and for lime. All stones in which 
there is but little alumina, and a great quantity of silica, leave, 
after fusion with potash, a light and flocculent substance, which 
