OBSERVATIONS. 
47 
pletely faturated with fixed vegetable al¬ 
kali, whereby I obtained the remaining 
portion of copper in a precipitate of a 
pure green colour. Being edulcorated 
and dried, it was with thofe iy grains 
of metallic particles which were left after 
deflagration of the fulphur, and with the 
copper which remained by depurating the 
tin (in the former experiment) ftrongly 
heated and then digefted in nitrous acid. 
After a ftrong digeftion, the blue folu- 
tion of copper was feparated by the filtre 
from the infoluble refiduum, and the cop¬ 
per was precipitated by a poliihed iron, 
and weighed 53 grains. 
(d) The infoluble refiduum which was 
© 
of a white grey colour, and weighed 
twenty-three grains, was heated in a cru¬ 
cible with a little wax : the magnet at¬ 
tracted three grains. The other 20 grains 
appeared to be calx of tin, which are 
nearly equivalent to 16 grains of tin in 
its metallic form. 
The 
