290 



THE SUCTION-PUMP 



the experiment, but good tubing will nearly resume 



its original dimensions after the air is allowed to escape 



It is not advisable to condense the air under the re 



ceiver (which would be done by drawing out the pistoi 



FIG. 193 (^ real size}. 



FIG. 194 (\real sise). 



while the stop-cock is in position III., and pushing it 

 while the stop-cock is in position II.), because glass : 

 ceivers are liable to burst by the increasing pressure, r 

 to be thrown upwards if they are not well fixed up i 

 the plate; in any case serious accidents may happen. 



