266 ANALYSIS of a COPPER ORE 
§. Tue liquid, thus freed from arfenic acid, was mixed with 
an excefs of ammonia. It affumed a deep blue colour, while a 
brown matter precipitated. It was feparated by the filter, and - 
being dried, drenched in oil, and heated to rednefs, it was to- 
tally attracted by the magnet. It weighed 45.5 grains, and 
was iron. 
6. THE ammoniacal liquid was neutralifed by fulphuric acid, 
and the copper thrown down by means of an iron plate. It 
weighed 17.2 grains. 
4. To afcertain the quantity of fulphur and arfenic, 100 
grains of the purified ore, in the ftate of a fine powder, were 
put into the bottom of a coated glafs-tube, and expofed for two 
hours to a red heat. When the whole was cold, and the bot- 
tom of the tube cut off, the ore was found ina round folid 
mafs, having the metallic luftre, a conchoidal fracture, and the 
colour and appearance of variegated copper-ore. It had loft 16 
grains of its weight. 
8. The upper part of the tube was coated with a yellowith- 
brown fubftance, like melted fulphur. It weighed 12.6 grains. 
Thus, there was a lofs of 3.4 grains. As the tube was long, 
this lofs can fearcely be afcribed to fulphur driven off. I ra- 
ther confider it as water. For towards the beginning of the 
procefs, drops of water were very perceptible in the tube. 
Whether this water was a conftituent of the ore, or derived 
from the previous digeftion in muriatic acid, cannot be deter- 
mined. 
g- WuEN the 12.6 grains of yellowifh brown matter de- 
tached from the tube, were digefted in hot potafh-ley, the 
whole was diffolved, except a fine blackifh powder, which 
weighed 
