216 BENJ. PIKE'S, JR., DESCRIPTIVE CATALOGUE. 



Fig. 222. 



% Fig. -,23. 



Fig. 221. 



Fig. 221. 



Torricellian Experiment with Flexible Tube. (Fig. 223, 

 as above.) This apparatus consists of a stout barometer 

 tube of forty inches in length, bent at one end as represent- 

 ed in the drawing, and having a stop-cock with flexible tube 

 for connecting with the air pump. The barometer tube is 

 graduated to thirty-one inches, marked on the glass. To 

 use, the lower end of the tube is immersed in a cup of mer- 

 cury, and the stop-cock connected with the air pump by a 

 flexible tube ; on exhausting the air the mercury will rise 

 in the tube in proportion to the degree of exhaustion. 



Experiments in the condensation of air, may also be illus- 

 trated by this apparatus ; close the stop-cock, pour mercury 

 in the long end of the tube, to the height of thirty inches 

 above the surface of the mercury in the shorter leg. It 

 will be found that the air in the shorter leg has been com- 



