428 Report of the Progress of the Sciences in France. 
The difference between the quantities of carbonic acid formed 
at different temperatures is still less considerable. 
In all cases there is less carbonic acid produced than oxygen 
absorbed. I concluded, he says, with M. Berthollet, that there 
was a production of azote. 
In an experiment made upon a hare, the manometre con- 
tained 0:7900 azote, 0 2100 oxygen. 
After the experiment, the azote was 0°7991, the oxygen 
0°1516, and the carbonic acid 0-0416. 
There was therefore a production of 0:0091 of azote, and 
0-054 of oxygen absorbed. I had remarked the same pheno- 
mena, and I have observed in my Essay upon pure Air, that in 
the air expired there was always a production of a portion of 
impure aur, the azote of the new nomenclature. 
Spallanzani has proved that a contrary effect takes place in 
the cold-blooded animals. My experiments, says M. Delaroche, 
prove also that heat augments in a most remarkable manner the 
activity of respiration in these animals. The quantity of oxy- 
gen absorbed by frogs exposed to a heat of 27° has been in one 
experiment doulle, and in the other quadruple, to what it was 
when the external temperature did not exceed six or seven de- 
grees. 
ANIMAL HEAT. 
Respiration being regarded as a kind of combustion, it has 
been considered as the principal cause of the heat of animals; 
but I have shown that too much stress has been laid on this 
cause. 
1. a. We find that a man of middling stature only takes in 
at every inspiration a few cubic inches of atmospheric air. Now 
atmospheric air contains but little more than one-fifth of oxy- 
gen, or 0-21. 
b. There is but a small quantity of this oxygen combined in 
respiration, certainly less than a cubic inch. 
2. a. Aman who sleeps tranquilly takes cold, although he 
breathes quite at his ease. 
Lb. If he takes exercise, he acquires heat, and even perspires. 
¢. An animal exposed to a severe cold may perish if it does 
not take exercise. If, on the contrary, it moves or carries bur- 
dens, it preserves its life. 
d. Consequently the muscular motion has the greatest in- 
fluence on animal heat. 
3. Oxygen gas contains very little heat ; therefore the small 
portion which is combined in the act of respiration has produced 
very little heat. 
I have concluded from these facts, that animal heat pro 
ceedec 
