[ 391 ] 
exiftence of fo much fixed air in the atmofphere. I believe 
this experiment is the firfl inftance of the proper gene- 
ration of fixed air from other principles. What we have 
got of it hitherto has been by diflodging it from fub- 
fiances, that were fuppofed to contain it. Notwith- 
fianding red lead yields fo pure an air, paint made with 
it diminifhes common air, and makes it noxious, as much 
as white paint ; which feems to prove, that it is the oil, 
that yields the phlogi/ioriy which injures the air to which 
it is expofed. 
LETTER III. 
TO SIR JOHN PRINGLE, BART. P. R. S. 
S I am defirous to prefent to the Royal Society a ge#- 
neral review of my late obfervations on air, with*- 
out troubling them with a detail of my experiments, J[ 
beg you would lay before them the following particu>- 
lars, in addition to thofe contained in the letter whiohvl 
took the liberty. to write to you, dated March 15, and in 
the extrad from that to Dr. price,' dated April i, 1775^; 
fubmitting the whole to the difpofal of the Society. 
London, May i^S, 177,^, 
DEAR SIR, 
VoL. LXY. 
Ggg 
I have 
