THE DISEASES OF CATTLE. 69 



of enormous proportions, who, in a fit of rage, killed his 

 keeper. The king ordered a charcoal fire to be kindled in the 

 den of the enraged animal, by which means a large quantity 

 of carbonic acid gas was generated, and the monarch of the 

 world soon " bit the dust." This is the mode by which car- 

 bonic acid gas is artificially mixed with air. 



Carbonic acid gas, like many other deleterious v&pors, has, in 

 my opinion, less affinity for pure than impure air, hence, in order 

 to render them wholly innocuous, we have only to secure a 

 uniform current of air w^ithin the barn and stable. 



The atmosphere of a crowded barn or stable, is rendered 

 unfit for respiration in various ways ; 1st, by non-ventilation; 

 2d, by the cutaneous exhalation ; 3d, by re-respiration of air 

 not purified ; 4th, by emanations from the excrements. 



In our crowded cities, where land, comparatively speaking, 

 is w^orth its weight in gold, it is impossible to institute complete 

 sanitary regulations ; yet, we have an " anchor of hope,'' in 

 view of preserving the health of the habitats of these " dis- 

 mal swamps," by a system of thorough ventilation. 



Carbonic acid gas is formed at the expense of the oxygen 

 of a given atmosphere, and under certain circumstances is 

 again decomposed and forms oxygen gas. In view of illus- 

 trating this point, I introduce the record of an experiment 

 made by a French chemist. He mixed twenty cubic feet of car- 

 bonic acid gas with the atmosphere of an air-tight room, and 

 yet, strange to relate, thirty-five minutes afterwards he could 

 not discover the least trace of the same. 



It is evident, therefore, that the intent of nature is to estab- 

 lish an equilibrium between the above processes; that is to 

 say, all the carbonic acid gas formed by combustion in the 

 lungs of animals is decomposed, and results in oxygen. This 

 is in accordance with the economical law of nature, which never 

 suffers any thing to be wasted. 



The process of pulmonary combustion in the lungs is some- 

 what analogous to the consumption of charcoal in a stove. The 

 lungs may be compared to the stove. Carbon, or charcoal, is 

 furnished by venous blood. The oxygen which is necessary to 



