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Of the Air' Pump.

'will break the phial outwards by the force of its spring, because tbereis no air lest on the outside of the phial to act against the air within it.

22. Put a shrivelled apple under a dose receiver, and exhaust theair; then the spring of the air within the apple will plump it out, soas to Laufe all the wrinkles disappear; hüt upon letting the air intothe receiver again, to press upon the apple, it will instantly return toits former decayed and shrivelled state.

23. Take a fresh egg, and cut off a little of the (hell and filmfrom its knallest end, then put the egg under a receiver, and pumpout the air; upon which, all the Contents in the egg will be forced outinto the receiver, by the expansion of a small bubble of air containedin the great end, between the shell and film.

24. Put some warm beer in a glass, and having set it on the pump,cover it with a dose receiver, and then exhaust the air. Whilst thisis doing, and thereby the pressure more and more taken off from thebeer in the glass, the air therein will expand itself, and rise up in in-numerable bubbles to the surface of the beer; and from thence it willbe taken away with the other air in the receiver. When the receiveris near exhausted, the air in the beer, which could not disentangle it-self quick enough to get off with the reff, will now expand itself so,as to cause the beer to have all the appearance of boiling; and thegreatest part of it will go over the glass.

25. Put some warm water in a glass, and put a bit of dry wainfcot orother wood into the water. Then, cover the glass with a dose receiver,and exhaust the air; upon which, the air in the wood having libertyto expand itself, will come out plentifully, and make all the water tobubble about the wood, especially about the ends, because the poreslie lengthwise. A cubic inch of dry wainfcot has so much air in it,that it will continue bubbling for near half an hour together.

Miscellaneous exferiments.

26. Screw the syringe H (Fig. 8.) to a piece of lead that weighs onepound at least; and, holding the lead in one band, pull up the pistonin the syringe with the other; then, quitting hold of the lead, theair will pufh it upward, and drive back the syringe upon the piston.The reason of this is, that the drawing up of the piston made a va-cuum in the syringe, and the air, which presses every way equally,having nothing to resist its pressure upward, the lead is therebypressest upward, contrary to its natural tendency by gravity. If thesyringe, so loaded, be hung in a receiver, and the air be exhausted, the

R syringe

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