. The Ontario high school physics. ricke may be repeatedwith a glass flask (Fig. 125) fitted with a stop-cock. If theflask is weighed when filled with air underordinary pressure, then weighed when theair has been compressed into it with abicycle pump, and again when the air hasbeen exhausted from it with an air-pump,it is found that the first weight is less thanthe second but greater than the third. Since the volume of a mass of air varieswith changes in temperature and pressure,the weight of a certain volume will beconstant only at a fixed temperature andpressure. Exact quantitative experimen
. The Ontario high school physics. ricke may be repeatedwith a glass flask (Fig. 125) fitted with a stop-cock. If theflask is weighed when filled with air underordinary pressure, then weighed when theair has been compressed into it with abicycle pump, and again when the air hasbeen exhausted from it with an air-pump,it is found that the first weight is less thanthe second but greater than the third. Since the volume of a mass of air varieswith changes in temperature and pressure,the weight of a certain volume will beconstant only at a fixed temperature andpressure. Exact quantitative experiments have shown thatthe mass of a litre of air at 0 C. and undep normal pressure ofthe air at sea level (760 mm. of mercury) is grams. 116. Pressure of Air. It is evident that since air has weight it nmst, like liquids, exert pressure upon all bodies with which it is in contact. Just as the bed of the ocean sustains enormous pressure from the weight of the water resting on it, so the surface of the earth, the bottom of the 101. Fio. 125, Glolie forweighing air.
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Keywords: ., bookcentury1900, bookdecade1910, bookpublishe, booksubjectphysics
