OBSERVATIONS. 
79 
I ' ■ . ; 
§ 2 . 
In the folution a precipitate was formed 
of a confiderable quantity of white, Joofe, 
yellow-like earth, which feparated, edul¬ 
corated, dried, and calcined, weighed 
204 grains. It proved to be pure iili- 
ceous earth. 
§ 3 ° 
* 
The folution being filtred and cryftal- 
lized, phlogifticated alkali was added 
to it, when it gave a blue precipitate, 
which collected upon the filtre, was 
edulcorated and dried. After heating it 
to rednefs with fome wax, it weighed 
feven grains, and it was totally attraded 
by the magnet. 
It would be an error to fuppofe thefe 
feven grains the true quantity of iron 
contained in this foap-ftone. For, though 
the 
