of Atmospherical Arr, &c. | 133 
Dr. Priestley introduced into a glass vessel, con- 
taining seven ounce-measures of pretty pure dephlo- 
gisticated air, a quantity of iron turnings ; having pre- 
viously made them, the air, and the mercury by which 
it was confined, as dry as possible. Also, to pre- 
vent the air from imbibing any moisture, he receiv- 
edit immediately in the vessel in which the expe- 
riment was made, by the process for obtaining it 
from red precipitate, so that it had never been in 
contact with any water. “ I then,” says he, ‘ fired 
the iron by means of a burning lens, and presently 
reduced the 7 ounce-measures of air to 0.65 of a 
measure. Examining the residuum of the air, I 
found one fifth of it to be fixed air; and when I 
tried the purity of that which remained, by the test 
of nitrous air, it did not appear that any phlogisticated 
air had been produced in the process: for, though it 
was more impure than I suppose the air with which 
I began the experiment must have been, it was not 
more so than the phlogisticated air of the 7 ounce- 
measures, which had not been affected by the pro- 
cess, and which must have been contained in the re- 
siduum, would necessarily make it. In this case, 
one ounce-measure of the residuum and two of 
nitrous air occupied the space of 0.32 of a mea- 
sure. In another experiment of this kind, ten 
ounce-measures of dephlogisticated air were reduc- 
ed to 0.8 of a measure; and, by washing in lime- 
water, to 0.38.” Sensible that such a quantity of 
air must have been imbibed by something, to which 
