33 f> Mr. Gregor’s Experiments on a mineral Substance 
of the substance, except a small portion, was effected. I added 
a few drops of muriatic acid, and continued the digestion. 
(3.) The acid was now diluted with distilled water, and 
poured off from the residuum, which consisted partly of a fine 
spongy earth, and partly of fragments of quartz. It was caught 
on a filter and sufficiently edulcorated. The last portion of 
edulcorating water dropped through the filter of an opalish 
hue. 
The residuum, dried and exposed to a red heat, for ten 
minutes, = -Jg- of a grain, yg- of which consisted of fragments 
of quartz, ~ was found to be silica, and alumina. 
C. 
{ 1 . ) The clear solution and the edulcorating water were 
poured into a large matrass and boiled, and whilst boiling, the 
contents were precipitated, in white flakes, by ammonia. 
( 2. ) When the ammonia had ceased to produce any further 
precipitate, the clear fluid was decanted, and assayed with 
carbonate of ammonia. But its transparency was not in the 
least disturbed. 
(3. ) This clear fluid, together with the edulcorating water, 
with which the subsided precipitate had been washed, wa 3 
gradually evaporated. When its volume was considerably di- 
minished, a separation of a spongy earth took place, more 
copiously than I had reason to expect, and the quantity of it 
was still further increased by a few drops of ammonia. This 
earth, thus separated, was sufficiently edulcorated, and added 
.to the former precipitate. 
( 4. ) The fluid was again evaporated, and at last transferred 
to a crucible of platina, and the salt reduced to a dry state : on 
