OF THE AIR-PUMP. 223 



and film from its smallest end, then put the egg under LECT. 

 a receiver, and pump out the air ; upon which all the s^-\-^ 

 contents in the egg will be forced out into the receiver, 

 by the expansion of a small bubble of air contained in 

 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 close receiver, and then 

 exhaust the air. Whilst this is doing, and thereby the 

 pressure more and more taken off from the beer in the 

 glass, the air therein will expand itself, and rise up in 

 innumerable bubbles to the surface of the beer ; and 

 from thence it will be taken away witli the other air in 

 the receiver. When the receiver is nearly exhausted, 

 the air in the beer, which could not disentangle itself 

 quick enough to get oft* with the rest, will now expand 

 itself so as to cause the beer to have all the appearance 

 of boiling ; and the greatest part of it will go over the 

 glass. 



25. Put some warm water in a glass, and put a bit of 

 dry wainscot or other wood into the water. Then, co- 

 ver the glass with a close receiver, and exhaust the air ; 

 upon which, the air in the wood, having liberty to expand 

 itself, will come out plentifully, and make all the water 

 to bubble about the wood, especially about the ends, 

 because the pores lie lengthwise. A cubic inch of dry 

 wainscot has so much air in it, that it will continue 

 bubling for near half an hour together. 



Miscellaneous Experiments. 



26. Screw the syringe H (page 214) to a piece of 

 lead that weighs one pound at least ; and, holding the 

 lead in one hand, pull up the piston in the syringe with 

 the other ; then, quitting hold of the lead, the air will 

 push it upward, and drive back the syringe upon the 

 piston. The reason of this is, that the drawing up of 

 the piston makes a vacuum in the syringe, and the air, 

 which, presses every way equally, having nothing to 



