LECTURE XXVII. 

 VENTILATION. 



Purposes. — There are two purposes in ventilation, viz.: get- 

 ting fresh air with its oxygen into a stable, and getting impuri- 

 ties out, and these are equally important. 



Impurities. — Disease germs and their products, carbonic di- 

 oxide gas, various volatile matters from the lungs, together with 

 the various excretions and the products which result from their 

 chemical decompositions. 



Necessity of ventilation. — To illustrate the effect of poor san- 

 itary conditions, particularly lack of ventilation, it is only necessary 

 to call attention to the common experience of moving an animal 

 affected with a chronic type of glanders or tuberculosis from a well 

 lijrhted and well ventilated stable to one where the conditions are 

 the opposite. Under the latter conditions there is rapid develop- 

 ment of a disease which had hitherto been mild. It is a com- 

 mon experience that accidental and surgical wounds do badly 

 in poorly lighted and poorly ventilated stables. 



Sick animals especially need free ventilation. This is par- 

 ticularly true in certain diseases, e. g., tetanus and diseases of 

 the lungs. 



A warm barn in a cold climate is not objectionable, pro- 

 viding sanitary conditions such as abundant air, sunlight, good 

 food and water are provided. But making a barn warm and 

 tight may very easily establish an ideal place for the propaga- 

 tion of germs and the spread of disease. 



Degree of impurity. — When one goes into a close room or 

 stable and does not notice anything of the condition which we 

 call closeness, the carbonic dioxide gas will usually be about .3 

 per thousand. If the atmosphere seems rather close there is 

 ordinarily somewhere near .4 per thousand. If the atmosphere 

 seems very close and is offensive, then according to Dr. D'Chau- 

 mont, there must be about .9 per thousand. This gas is some- 



