[ 22 9 3 
The air, which I had thus diminifhed by calcina- 
tion of lead, I transferred into another clean phial, 
but found that the calcination of more lead in it had 
no farther effect upon it. This air alfo, like that 
which had been infected with the fumes of charcoal, 
was in the higheft degree noxious, made no effer- 
vefcence with nitrous air, was no farther diminiflied 
by the mixture of iron filings and brimftone, and was 
not only rendered innoxious, but alfo recovered, 
in a great meafure, the other properties of common 
air, by wafhing in water. 
It might be fufpedted that the noxious quality of 
the air in which lead was calcined, might be owing 
to fome fumes peculiar to that metal; but I found no 
fenlible difference between the properties of this air, 
and that in which tin was calcined. 
The water over which metals are calcined acquires 
a yellowifh tinge, and an exceedingly pungent lmell 
and tafte, pretty much, as near as I can recollect, for 
1 did not compare them together, like that over 
which brimftone has been frequently burned. Alfo 
a thin and whitifli pellicle covered both the furface 
of the water, and likewife the Tides of the phial in 
which the calcination was made, infomuch that, 
without frequently agitating the water, it grew fo 
opaque by this conftantly accumulating ineruftation, 
that the fun beams could not be tranfmitted through 
it in a quantity fufhcient to produce the calcination. 
I imagined, however, that, even when this air was 
transferred into a clean phial, the-metals were not fo 
eafily melted or calcined as they were in frefh air > 
for the air being once fully faturated with phlogifton, 
may not fo readily admit any more, though it be only 
to 
