OBSERVATIONS. 51 
fum, there remained 40 grains; to which 
muft be added 1 grain of tin feparated 
from the folution of copper. The pro¬ 
duct of pure tin in this experiment is 
confequently 41 grains. 
The refults of this procefs are 
Pure Sulphur —- 30 grainy 
—— Tin — 41 
—— Copper — 43 
—— Iron — 2 
Earth of the ftony matrix 3 
11 9 
Of the two drams therefore ufed for 
this analyfis only one Angle grain was 
loft. 
The reafon why I firft precipitated 
from the folution in aqua-regia with al¬ 
kali, and diffolved the precipitate again 
in marine acid, was in confequence of 
knowing, that, when tin is precipitated 
from aqua regia by zinc, the whole quan¬ 
tity is feldom precipitated in a metallic 
form ; but a confiderable part of it is 
E z corroded 
