On Respiration and Animal Heat. 41 
numbers, the area of the earth will be 200 
millions of square milés: calculating the weight 
of the atmosphere at the rate of 15 lbs. upon a 
square inch; for such a number of miles we 
obtain 12 trillions of lbs. avoirdupoise ;—cal- 
culating also the quantity of carbonic acid 
which 1000 millions of men; (the supposed: 
_ population of the earth) would expire in the 
space of 6000 years, at 3 lbs. per day, we 
shall find it to be 6 thousand billions of lbs: 
or just... part of the whole atmosphere : 
now, supposing this doubled, to allow for the 
quantity of acid which may be supposed to be 
generated by combustion, we shall then have 
«cso part of the atmosphere to be carbonic 
acid, which agrees with experiments as to the 
quantity now actually found in it; There is 
not therefore any necessity to believe from the 
phenomena, that means are used by nature for 
the restoration of the purity of the atmo- 
sphere.* 
* Since this paper was sent to press; I have had ati op 
portunity of making a few comparative experiments, the 
results of which deserve notice. Hearing of a young per- 
son living upon simple diets; and taking no fermented 
liquors; who feels cold very sensibly, so as to require 
warmer clothing, and who is obliged to avail himself of 
artificial heat, more than others; I was desirous to learm 
sy 
