i 
50 MINERALOGICAt 
folution was of a blue colour, and one 
grain of tin in a white calciform ftate, 
was left undiffolved. It contained there¬ 
fore 43 grains of copper. 
fdj The cylinder of tin ufed for preci¬ 
pitating the copper weighed now 128 
grains, and 89 grains had been of courfe 
diffolved. By a cylinder made of zinc I 
now precipitated all the tin, which was 
connected loofely to the zinc in tender 
leaves and arborefcent forms. Being fa- 
tisfied that all the tin was precipitated, I 
collected it carefully, wafhed and dried 
it. It weighed 130 grains. I then melt¬ 
ed it, mixed with tallow and powdered 
charcoal, and when it was cold, feparated 
the charcoal by wafhing. With the 
wafhed tin globules I found fome black 
flocculi of iron, attractable by the mag¬ 
net, which weighed 1 grain. This being 
deducted from the weight of tin, there re¬ 
mained 129 grains. The above 89 grains 
of the cylinder of tin, ufed for precipi¬ 
tating the copper, taken then from this 
fum, 
/• 
