CHAPTER III 



VENTILATION 



The object of ventilation is to supply pure air to the lungs, 

 to dilute and remove from the stable the products of 

 respiration, and the effluvia arising from the fluid and 

 solid excreta which have been evacuated. 



To fulfil the conditions of ventilation it is necessary that 

 pure air be supplied, it would not be ventilation if the 

 incoming air were derived from a contaminated source. 



It is usual to consider the subject of ventilation under 

 three heads : — 



i. The amount of fresh air required. 



ii. The methods by which fresh air can be supplied. 



iii. The methods of examining whether ventilation be 

 sufficient or not. 



AMOUNT OF FEESH AIE REQUIRED. 



The large herbivora take into their lungs during a condi- 

 tion of repose something less than 100 cubic feet of air per 

 hour. At first sight it might appear that if this amount be 

 known, the quantity of air required to be delivered for the 

 purpose of ventilation could easily be ascertained. 



The amount of air breathed by an animal is no guide to 

 its requirements in the stable, for the reason that if only 

 this quantity were supplied per hour, the proportion of 

 impurity present in the air would be enormous. 



The larger herbivora are capable of rendering 25 cubic 

 feet of air absolutely irrespirable every hour ; that is to 

 say, if such a sample of air were collected experimentally, 



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