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XL Obfervations on Refpiration . 
By the Rev . Jofeph Prieftley, LL.D . F. i?. £ 
Read February 25, 1790. 
W HEN I wrote the Obfervations on the Subject of Re- 
fpiration , publiffied in the Philofophical Tran factions, 
VoL LXVI. p. 226, I fuppofed, that in this animal proceis 
there was limply an emiffion of phlogifton from the lungs. 
But the refult of my late experiments on the mutual tranfmif- 
fion of dephlogifticated air and of inflammable and nitrous air, 
through a moift bladder interpofed between them, and likewife 
the opinions and obfervations of others, foon convinced me, 
that, befides the emiffion of phlogifton from the blood, de- 
phlogifticated air, or the acidifying principle of it, is at the fame 
time received into the blood. Still, however, there remained 
a doubt how much of the dephlogifticated air which we inhale 
enters the blood, becaufe part of it is employed in forming the 
fixed air, which is the produce of refpiration, by its uniting 
with the phlogifton difcharged from the blood : for fuch I take 
it for granted is the origin of that fixed air, fince it is formed 
by the combination of the fame principles in other, but exactly 
fimilar, circumftances. 
Dr. Goodwyn’s very ingenious obfervations prove, that de- 
phlogifticated air is confumed , as he properly terms it, in refpira- 
tion ; but, for any thing that he has noted, it may be wholly 
employed 
