Refpiration, and the Vfe of the Blood. 24 ± 
inflammable air might have recovered it by means of this 
more powerful menftruum. 
Since however, blood, after becoming black in phlo- 
gifticated air, is always capable of refuming its red co- 
lour on being again expofed to pure air, it lay be con- 
cluded, that the preceding blacknefs, difcharged in the 
pure air, and producing the conftant effedt of phloa ift on 
in depraving the air, was owing to the phlogifto/it had 
imbibed in the former fituation, and which it parted with 
in the latter. And this is remarkably the cafe when 
blood is transferred from phlogiflicated into dephlogifti- 
cated air Even the circumftance of the deeper colour is 
fufficient to give a chemift a fufpicion that it contains 
more phlogifton than blood of a lighter colour 
• Whenlhad found how readily pieces of blood changed 
en colour, according to the quality of the air to which 
they were expofed, I proceeded to examine the flate of 
that air, in order to obferve what change had taken place 
m it; and as dephlogifticated air admits of a more l'enfi- 
ble change ot quality than common air, I gave it the pre- 
ference in this experiment; putting a piece of crafTa- 
mentum, about the bignefs of a walnut, into the quantity 
ot about five ounce meafures of this air. 
This procefs I continued for the fpace of twenty-four 
hours, changing the blood about ten or twelve times • 
alter which I found the air fo far depraved, that whereas’ 
at the beginning of the experiment, one meafure of it -nd 
two ot nitrous air occupied the fpace of no more than 
hall a meafure, the lame mixtures afterwards occir^d 
Vo l. LX VI. Ii 
x the 
