[ 942 ] 
its colour to a deep brown ; but had not that effect 
after the liquor was become tranfparent. 
The black gritty powder, which remained after 
the former procefs, v/as put into a coated retort, and 
diddled by a naked fire ; fo that the whole body of 
the retort continued red-hot for more than two hours. 
This brought over to the receiver near an ounce of a 
watry bituminous liquor, rather dronger than that 
which diddled with a fand heat, and a few drops 
only of a thick bituminous matter, which duck to 
that part of the receiver on which they fell. The 
neck of the retort was thinly incru dated with fome- 
thing that refembled a faline concrete ; but was found 
to be only bituminous matter. In the bottom of the 
retort there remained a very black gritty powder. 
Of this powder, one ounce was put into a crucible, 
fet in a melting furnace, and kept in a pretty drong 
dre for an hour. The powder, after it was grown 
cold, appeared on the furface to be of a pale reddidi 
colour ; but was not in the lead altered underneath. 
It lod, however, in weight, near three drachms. 
Some of the black powder taken out of the crucible, 
and thrown upon a red-hot iron, burnt without 
flame ; but emitted plentifully a heavy black lmoke. 
Two ounces of the black powder, which had been; 
twice diddled, were fet on a clear fire, in an iron 
ladle, and continually dirred from the time that the 
ladle grew red-hot, and the matter began to emit a 
heavy black dinking fmoke, till no more fmoke arofe 
from it. The calcined matter remaining in the ladle 
weighed two fcruples, and feemed to be a kind of 
bole earth. This earth was evaporated in two ounces 
of rain water to one ounce, which, fome days after, 
was poured oft' clean from the fediment. This water 
had: 
