Rural Architecture. 



VENTILATION" OF FAKM BUILDINGS. 



In the physiological sense air is as indispensable to the 

 cow and horse as is water, grain, hay or grass j so, too, is it 

 as essential to the development of power in the steam 

 engine as is the water and the fuel. It is so abundant about 

 us and we procure it usually so unconsciously that its 

 necessity does not occur to us. But when large numbers 

 of animals are housed together in close stables ample pro- 

 vision must be made for the ingress and egress of air. 



431. Necessity for Ventilation The need of ventilating 

 dwellings and stables grows out of several conditions: (1) 

 The consumption of the oxygen which is 'the essential in- 

 gredient; (2) the exhalation from the lungs of carbon 

 dioxide, moisture, ammonia, marsh gas (0 H 4 ) and organic 

 matter ; (3) the accumulation in the air of occupied stables 

 and dwellings of bacteria and other micro-organisms as 

 well as solid dust particles. 



432. Carbon Dioxide in the Air, This gas is given off 

 from the lungs with each respiration in nearly the same 

 ratio that the oxygen is removed, hence air once breathed 

 is not only deprived of a portion of its oxygen but it is di- 

 luted with an equal volume of carbon dioxide and is there- 

 fore rendered doubly unfit for use again. 



That air once breathed from the lungs is not suited to 

 further use can be clearly and forcibly proved by filling 

 a quart Mason jar with air from the lungs, by blowing 

 through a rubber tube, and then quickly lowering a lighted 

 taper into it, which is quickly extinguished, showing that 

 the air has lost so much oxygen and gained so much carbon 

 dioxide that the taper cannot burn in it. 



433. Moisture from the Lungs and Skin. The moisture 

 taken with the food and as drink must be again removed 



