8 7 o Dr. watson’s Experiments and 
fire, the ftopple of the quilled receiver had a ftrong fmell 
refembling that of the inflammable air feparable from 
fome metals by folution in acids; foon after a fm all por- 
tion of a liquid came over into the receiver; the fire was 
then raifed till the retort was of a white heat, when a 
black matter began to be fublimed into the neck of the 
retort; the operation was then difcontinued. This expe- 
riment was undertaken with a view of feeing whether 
fulphur could be feparated from lead ore, as it may be 
from fome fpecies of the pyrites, by diftillation, and it 
appears from the iffue of the experiment that it cannot. 
What might have been the event of the experiment if it 
had been conducted with a very gentle heat for along 
time, I cannot pretend to fay. Upon breaking the retort 
I found, that the ore had been melted during the opera- 
tion, for there was a confiftent cake of ore of the figure 
of the bottom of the retort ; the weight of this cake was 
fifteen ounces and an half, the weight of the liquid in 
the receiver, and of the black matter which had been 
fublimed, did not together amount to one quarter of an 
ounce, fo that a quarter of an ounce or more had been 
difperfed, probably in the form of air, or fome elaftic 
fluid. The ore by this procefs had loft one thirty-fecond 
part of its weight ; but I am of opinion, that if the ope- 
ration had been conducted with a lefs degree of heat and 
continued 
