136 Remarks on Priestley’s Analysis 
Saussure, that a cubic foot of atmospherical air can 
contain only 12 grains of water in solution: and 
supposing that it is only the respirable part of it that 
can dissolve water (which is however too great a 
concession) the 12 ounce measures of oxygenous 
gas consumed could not contain one half grain of 
water, even if they had been purposely impregnated 
with as much water as they could take up; though 
the reverse was the case here. 
I ought, in this place also, to refer the Society to 
Dr. Priestley’s experiments in his 3d vol. p. 210. 
He suspended pieces of lead and tin in atmospheri- 
cal air, and heated them by means of a burning mir- 
ror or Jens. The air was diminished 25 per cent. 
And, in p. 212, he informs us, that, by throwing the 
focus of a burning lens on iron, the air was dimi- 
nished and made noxious to as great a degree as in 
the calcination of lead or tin. And when he heat- 
ed iron in atmospherical air, till his lens could make 
no farther impression on it, he always found that 
the iron gained weight upwards of go per cent. 
(Ibid, p. 483). 
The degree of heat, on which Dr. Priestley seems 
to lay some stress, makes no difference in the result 
of the experiment. Every one may convince him- 
self of this by the following simple process. Take 
100 grains of fine harpsichord-wire cut in small 
pieces, or clean iron filings; put them into a tobacco- 
pipe; and expose it to a red heat in a common fire- 
