200 



BENJ. PIKE S, JR., DESCRIPTIVPJ CATALOGUE. 



stop-cock attached to the side of the chamber, having pre- 

 viously condensed sufficient air therein, place a bullet, pea, 

 or cork ball within the barrel, and quickly open the stop- 

 cock ; the ball will be thrown violently out of the barrel. 



Price, of the whole apparatus, $12.00. 

 Fig. is/. " condenser only, $5.00. 



smaller size, $4.00. 



Lever Condenser on Frame. 

 In this instrument (Fig. 387), 

 the barrel of the condenser is 

 sunk into the air chamber, 

 which is supported on the un- 

 der side of the frame by four 

 stout rods passing through the 

 frame ; and also .a round board 

 {it the bottom of the air cham- 

 ber clamping them firmly to- 

 gether by means of screw 

 m;ts. The piston is worked 

 by a lever and arm fastened to 

 the frame ; on one side of the 

 air chamber is a stop-cock. 

 Price, $20.00. 



Fig. 188. 



Swelled Receivers for the Air Pump. (Fig. 188, as above.) 

 The receivers of the air pump are large glass vessels 

 placed on the pump plate and over an orifice, in order to be 

 exhausted of air ; being thus called from their being the re- 

 cipients of those things on which the experiments are made. 



