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Hygiene
This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1884 edition. ...22. Now, out of 100 volumes of gas, there disappeared under experiment in 2 hours, 47 of hydrogen, and in 10 hours, 47 of CO,. This proportion of I-to 5 is nearly equal to the square roots of their densities, I. to 22. When several different gases are admitted into the same space, each of them diffuses itself equally through the whole space as if the others were not there. 107. Its Principle.--All true methods of ventilation must proceed on one principle--an incast of fresh air, and an outcast of impure air. In a coal-mine we should speak of these as a downcast shaft and an upcast shaft. Few places are better ventilated than coal-pits, for a fresh supply of air is secured by burning a fire in the workings between the two shafts, thus causing the warmed light air to force its way out up one shaft, and the fresh cooler air to rush down the other to supply its place. The same principle may be illustrated in another way. If a piece of candle be placed in a flask and lighted, it will soon die out, from having consumed all the oxygen present; but if a piece of zinc be inserted in the neck so as to hang down a little distance into the body of the flask, the candle will continue to burn, because an incast shaft and an outcast shaft have been formed, and the candle receives from the one a constant supply of fresh air, while the vitiated air passes away by the other. Unless these two points be secured, namely, an incast of fresh air and an outcast of impure air, there can be no true ventilation. Rooms of public assembly can often be seen supplied with numerous openings in the ceiling for the escape of heated foul air, and yet there is no real movement of the atmosphere, which becomes unhealthy and oppressive. It may be that crooked passages or...
50 pages, Paperback
Published September 13, 2013
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