. Annual report of the Agricultural Experiment Station. Cornell University. Agricultural Experiment Station; Agriculture -- New York (State). Buildings and Yards. 543 little noticed except when extremely cold weather causes the incoming air to condense the moisture of the stable into frost where it enters. Every one has noticed the beneficial influence of a heavy snowfall in main- taining the temperature of house or barn, because it fills the cracks and crevices on window sills and about doors. Since the exchange of air is concerned with the subject of ventilation, its eflfect in maintaining t

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. Annual report of the Agricultural Experiment Station. Cornell University. Agricultural Experiment Station; Agriculture -- New York (State). Buildings and Yards. 543 little noticed except when extremely cold weather causes the incoming air to condense the moisture of the stable into frost where it enters. Every one has noticed the beneficial influence of a heavy snowfall in main- taining the temperature of house or barn, because it fills the cracks and crevices on window sills and about doors. Since the exchange of air is concerned with the subject of ventilation, its eflfect in maintaining t
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Image ID: RM8H2R
. Annual report of the Agricultural Experiment Station. Cornell University. Agricultural Experiment Station; Agriculture -- New York (State). Buildings and Yards. 543 little noticed except when extremely cold weather causes the incoming air to condense the moisture of the stable into frost where it enters. Every one has noticed the beneficial influence of a heavy snowfall in main- taining the temperature of house or barn, because it fills the cracks and crevices on window sills and about doors. Since the exchange of air is concerned with the subject of ventilation, its eflfect in maintaining temperature will be discussed in connection with the next topic. ///. To secure pure air, zvith proper degree of humidity While the composition of air is not constant, it may be stated ap- proximately as follows: nitrogen, 78.49 per cent; oxygen, 20.63 per cent; water, 0.84 per cent; carbonic acid gas, 0.04 per cent. Usually there are also present slight traces of ammonia and other substances. If the weight of a given volume of air at freezing point under one atmosphere of press- ure is one pound, an equal volume of nitrogen will weigh 0.9714 lb.; of oxy- gen, 1.1057 lb.; watery vapor, 0.6225 lb.; and carbonic acid gas, 1.5291 lb. It may be asked why these gases do not settle with the heaviest gas at the bottom and the lightest at the top. The reply is that it is the nature of gases when brought together to mix. Fig. 322.—Why has the upper light gone out first in this tight box? In a few moments all will go out. rapidly into a homogeneous mass. It is said that a horse draws into his lungs 45 cubic feet of air per hour and exhales 6.5 cubic feet of carbonic acid. It does not follow from this fact that 45 feet of air per hour is sufficient for a horse, because the large amount of carbonic acid in the exhaled air vitiates a considerable amount of the surrounding air. Air containing an excess of carbonic acid gas, is considered unfit to breathe, not so much because of any injury d