A text-book on chemistryFor the use of schools and colleges . 2-iG THE AIB-PUMP. of the air in the construction of the air-pomp, an instru-ment intended for the removal of air from closed ves-sels. It consists of two cylinders, Fig. 214, the pistons. of which may be alternately raised and depressed by arack and pinion. They communicate by a tube with theinterior of a bell-jar or receiver, which stands on theair-pump plate*and makes a tight joint with it becausethe two are ground flat. On working the handle theair in the bell-jar is, little by little, removed, and event-ually only a small fract
A text-book on chemistryFor the use of schools and colleges . 2-iG THE AIB-PUMP. of the air in the construction of the air-pomp, an instru-ment intended for the removal of air from closed ves-sels. It consists of two cylinders, Fig. 214, the pistons. of which may be alternately raised and depressed by arack and pinion. They communicate by a tube with theinterior of a bell-jar or receiver, which stands on theair-pump plate*and makes a tight joint with it becausethe two are ground flat. On working the handle theair in the bell-jar is, little by little, removed, and event-ually only a small fraction of the original amount re-mains. Let the glass globe c/, Fig. 215, be nearly filledFig. -215. with water, and inverted so that its neck. &,dips beneath the water contained in vessel the whole be covered with an air-pumpreceiver, d, and the receiver exhausted, thebubble at a dilates, and after a time, as theaction of the machine continues, fills the en-tire glass, both bulb and tube. As the press-ure is restored by letting air again into thebell-jar, the bubble contracts and eventually regains itsoriginal size. The air-pump enables us to exhibit in a striking man-ner the chief mechanical properties of the air. Thus, ifon the plate
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Keywords: ., bookcentury1800, bookde, booksubjectchemistry, booksubjectphysics
