Mr. Brodie's Experiments and Observations, &c. 379 
pletely restored, that heat is produced in sufficient quantity to 
counteract the cold of the surrounding atmosphere.* 
In the experiments formerly detailed, as well as in those 
just mentioned, I observed that the blood underwent the usual 
alteration of colour in the two systems of capillary vessels, 
while carbonic acid was evolved from the lungs at each expi- 
ration ; and hence I was led to believe, that the respiratory 
function was performed nearly as under ordinary circum- 
stances, and that the usual chemical changes were produced 
on the blood. It appeared, however, desirable to obtain some 
more accurate knowledge on this point, and I have therefore 
instituted a series of experiments, for the purpose of ascertain- 
ing the relative quantities of air consumed in breathing, by 
animals in a natural state, and by animals in which the brain 
has ceased to perform its office, and I now have the honour of 
communicating an account of these experiments to this Society. 
It has been shewn, by Messrs. Allen and Pepys, first, -f that 
every cubic inch of carbonic acid requires exactly a cubic inch 
of oxygen gas for its formation ; secondly, J that when respi- 
ration is performed by a warm-blooded animal in atmospheric 
air, the azote remains unaltered, and the carbonic acid exactly 
equals, volume for volume, the oxygen gas, which disappears. 
There is therefore reason to believe, that the watery vapour, 
which escapes with the air in expiration, is not formed from 
* The poison employed in this experiment should be the essential oil of almonds, 
or some other, the effects of which speedily subside. If the woorara is employed, so 
long a time elapses before the poison ceases to exert its influence, that it becomes 
necessary that the experiment should be made in a high temperature, otherwise the 
great loss of heat which takes place, is sufficient to prevent recovery, 
f Phil. Trans. 1807, Part II. 
| Phil. Trans. 1808, Part II. Ibid. 1809, Part II. 
