298 



PRESSURE IN THE AIU, 



of the receiv- 

 er itself; the 

 volume of air 

 amounting to 2 

 feet, the weight 

 of which might 

 amount to 30 

 grains. The 

 whole appara- 

 tus, therefore^ 

 consisted <H 

 a Torricellia 

 tube filled withV <^ 

 quicksilver in v 

 the usual way, 

 placed under the 

 receiver. On 

 exhausting the 

 air out of the 

 receiver, the 

 mercury in the 

 tube immedi- 

 ately sunk to 

 the. same lev el 



as the mercury in the basin. By turning the 

 stop-cocks, the air which the bladder contained 

 immediately passed into the receiver; the ef- 

 fects of which were rendered evident, by the 

 alteration which the mercury in the basin un- 

 derwent ; the mercury which before was at the 



