VENTILATION. 



Ill 



Diffusion of gases. — Carbonic gas is considerably heavier 

 than air and the lower levels usually contain a slightly higher 

 percentage than the higher ones in a stable, but the difference 

 is not so great as one would suppose, on account of the diffu- 

 sion which takes place in response to the law of diffusion of 

 gases — which operates independently of relative weights. This 

 force is so strong in its action that considerable diffusion takes 

 place through nnpainted lumber and through ordinary brick, but 

 to a very slight extent if at all through painted surfaces or pa- 

 per. 



AIR CURRENTS. 



An entering current of air has the effect of inducing other 

 currents within the stable the induced current setting in at right 

 angles to the inlet current. 



FIG. 42. VENTILATION. 



Air currents. 



iPAlGK.) 

 Manger front inlet. 



With windows wide open to windward, openings on the 

 other side of the stable being closed, and with ridge ventilation — 

 it is found that the current of air rushes in, strikes the floor 

 at a variable distance after spreading- out somewhat, then rises 

 and most of it passes out at the ridge. A current decreases, 

 very rapidly in velocity after the first five or six feet from the 

 inlet. The atmosphere immediately under the inlet is but mod- 

 erately disturbed. 



When opposite windows are fully open the air comes in 

 from the windward side, strikes the ground, rises again and a 

 considerable portion passes directly out at the opposite side. 



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