gqo Mr. Chenevix's Analysis of Corundum, and of 
Darracq has published a paper, intended as a refutation of the 
conclusions drawn by Guyton. I had myself repeated the greater 
part of the experiments of the latter; and the results I ob- 
tained were exactly similar to those of Darraco. In fact, I 
had intended to continue the researches ; but the very satisfac- 
tory paper of Darraco, appeared to me to render a further 
prosecution of them totally useless. However, a paragraph 
inserted in the Annales de Chimie , (Tom. XLI. p. 206.) and 
of which Guyton appears to be the author, shows that he 
has hot derived from the Memoir of Darracq,, that conviction 
which it certainly conveys. The paragraph in question is founded 
upon a letter, written from Frey berg, by Dr, G. M. to Dr. 
Babington, dated December 17, 1800, and inserted in theIVth 
volume of Nicholson’s Journal, page 511. This letter contains 
an opinion which deserves to Jbe canvassed, as it is not perfectly 
just ; and the use Guyton has made of it, has determined me 
to add my observations to those of Darraco. 
I shall follow the order of Guyton’s experiments, in the 
enumeration of those I made. 
Exp. From a mixture of lime-water and barytes-water, 
Guyton obtained a. precipitate. I obtained none. 
Exp. 2. A solution of alumina in potash, mixed with a solu- 
tion of silica in the same, gave a precipitate, after standing some 
time. This had been observed by Darracq, and by Guyton, 
and agrees perfectly with the affinity which, before Guyton 
published his paper, I had asserted to exist between these two 
earthso 
Exp . 3, 4, 5. Lime-water, strontia-water, and barytes-water, 
produce a somewhat similar effect upon a solution of silica in 
potash. 
