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PRINCIPLES OF VETERINARY SCIENCE 



results the ventilating flues should be installed as illustrated in 

 Figs. 37 and 38. 



It has been shown that farm animals, under ordinary stable 

 conditions, cannot decrease the oxygen or increase the carbon 

 dioxid content of the air to an extent dangerous to life. Even 

 when the oxygen content of the air was reduced from about 21 per 

 cent, to as low as 5 per cent., and the carbon dioxid raised to 

 2.67 per cent., no appreciable detrimental effect was noticeable. 



Fia. 37. — Ventilating flues when cows 

 face out. 



Fig. 38. — Ventilating flues when 

 cows face in. 



Similar results have been obtained when human beings were con- 

 fined in an unventilated room. The reason why persons and 

 animals get on so well in houses and stables with apparently no 

 ventilation is that air is constantly entering and leaving through 

 the cracks, crevices, and pores in the walls. ■> 



The qualities that determine whether air is good or bad are: 

 temperature, humidity, odor, and motion. The oxygen and 

 carbonic acid gas content are of minor consideration; therefore, 



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