Influence of Air on Animals. 267 
INFLUENCE OF AIR IN MODIFYING THE HEALTH OF ANIMALS. 
Some idea of the immense consumption of oxygen by animals, 
may be formed by taking the following computation by Boussin- 
gault: An adult man consumes 19.9 oz. carbon, daily, in his food, 
and requires 37 oz. oxygen for its conversion into carbonic acid gas. 
A horse consumes 97| oz. (more than S lbs. Troy) of carbon in 
24 hours, and this requires 13 lbs. 3| oz. oxygen for the same 
purpose; while a cow consumes 69.9 oz. carbon (nearly 6 lbs. 
Troy), which calls for 11 lbs. 10| oz. oxygen. 
From this circumstance alone, we see the necessity of ventila- 
tion in places where animals are kept; and the danger that results 
from crowding them together is heightened by the excretions be- 
ing allowed to accumulate and to throw of! their pestilential gas- 
ses, which are necessarily evolved by decomposing bodies. 
Hence, in ill-ventilated stables we meet with the compounds of 
hydrogen, sulphuretted and carbonated, ammonia and its carbon- 
ate, and the hydro sulphate, besides the carbonic acid and free 
nitrogen given off by respiration ; and, from the inhalation of 
these compound gasses, heated as such an atmosphere necessarily 
is by the congregating of animals, we have frequently inflamma- 
tion and other diseases of those all-important organs, the lungs, 
set up, which, from the debility induced, is followed by farcy and 
glanders, and this more especially, should the predisposing causes 
of hard work and bad food co-exist. Or we have ophthalmia, both 
local and constitutional, engendered; and often that insidious but 
too frequently fatal disease, phthisis pulmonatis. 
The conversion of oxygen into carbonic acid, plain and obvious 
as the fact itself is, and all-important as it also is to the animal 
economy, has, unfortunately, awakened much difference of opin- 
ion among philosophers as to the manner in which it is brought 
about. Doubtless the change is effected through the medium of 
the blood; and the older chemists taught that the venous blood 
being returned to the lungs surcharged with carbon, this united 
in the lungs with the oxygen of the air, and was expelled as car- 
bonic acid gas. This theory, simple and explanatory as it really 
is, unfortunately involved some insurmountable objections ; and it 
at length gave way to that of absorption of oxygen by the blood 
in its transit through the lungs and the gradual conversion of it 
into the compound gas — carbonic acid — during the circulation. 
Yet there was still much that remained inexplicable until Liebig 
advanced the beautiful theory of the iron in the haematisisim be- 
ing the carrier of the oxygen. Thus this metal, it was taught by 
him, in arterial blood existed in the state of peroxide of iron; but 
as it yielded up its oxygen it generally became converted into the 
carbonate or protoxide, and, as such, it was said to be found in 
