. A manual of veterinary hygiene. Veterinary hygiene. VENTILATION 63 the most favourable circumstances, viz., where the air is obtained through cracks and crannies in doors and windows, diffusion is a slow process, and by itself can never be trusted for the purpose of renovating vitiated air. Diffusion merely causes the various gases present in a building to mix. Eoscoe showed that carbonic acid experi- mentally evolved in a room was reduced to one-half in ninety minutes by this process. This is not sufficiently rapid for the purpose of ventilation, and further, it leaves the solid particles o
. A manual of veterinary hygiene. Veterinary hygiene. VENTILATION 63 the most favourable circumstances, viz., where the air is obtained through cracks and crannies in doors and windows, diffusion is a slow process, and by itself can never be trusted for the purpose of renovating vitiated air. Diffusion merely causes the various gases present in a building to mix. Eoscoe showed that carbonic acid experi- mentally evolved in a room was reduced to one-half in ninety minutes by this process. This is not sufficiently rapid for the purpose of ventilation, and further, it leaves the solid particles of the air quite unaffected. Winds are the great power in natural ventilation; they mainly act by perflation, viz., setting masses of air in motion, and as a means of flushing and renewing the Fig. 1.—Transverse section of stable. Two horses are placed between opposite windows, heads to outer walls. The arrows indicate the direction of the wind. there is no natural force comparable with them; for example, blowing at the rate of three miles an hour (which is little more than perceptible) through a ventilator one square foot in size, 15,840 cubic feet of air will pass per hour, the amount, in fact, demanded for the larger herbivora. Analyses of stable air show how rapidly by free perflation organic impurities may be removed; in half an hour the COg of respiration may be reduced from '6 to "1 per 1,000. The chief difficulty in dealing with the wind as a ventila- ting agent is in regulating its velocity. With high velocities it causes a draught so that regulation of windows and ventilators becomes necessary. The opposite extreme may Digitized by Microsoft®. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Smith, Frederick 1857-1929. New York : W. R. Jenkins
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