220 



BENJ. PIKE 8, JR., DESCRIPTIVE CATALOGUE. 



off the plate and pipe, and if any animal be let down into 

 the receiver it will immediately "be killed. If a candle be 

 let down into the receiver when filled with the air, it will 

 go out, but will purify the air as far as it goes ; for you may 

 let it down the second time lower than the first, and so on 

 till the whole air is purified. The receiver and plate used 

 with the slide rod apparatus before described, answer for 

 this experiment by connecting the tube thereto. 



Price of the whole apparatus, $6.00. 

 " bent tube only, - $1.50. 



Fig. 231. Bursting Squares, or Crushed Bottle. 



(Fig. 231.) These are thin square glass 

 bottles, of about half a pint capacity. To 

 use, take one of the bottles and put in a 

 cork ; then seal it with wax so that no air 

 can escape ; then set it on the pump with 

 a receiver over it : and when you begin to 

 exhaust, the air within the bottle will ex- 

 pand itself so as to break it. 



Or, cement on the neck of the bottle a 

 brass cap, with valve opening outwards ; 

 place under the receiver and exhaust the air, which will 

 escape from the bottle also ; return the air to the receiver, 

 and the valve closes and prevents the air from entering the 

 bottle, which is broken ; the square sides not being strong 

 enough to resist the pressure of the atmosphere. A wire 

 guard is sometimes used to cover the bottle, and prevent 

 the breaking of the receiver. When you have made this 

 experiment, wipe the pump plate so that none of the glass 

 remain, as it may spoil another experiment. 



Price, glass squares, each, $0.16. 

 " cap with valve, each, $0.31. 

 F1 -232. guard of wire gauze, $0.75. 



Transferer.(Yig. 232.) 

 An instrument used with the 

 air pump, as a movable portion 

 or plate, for numerous purposes 

 of experiment. There are sin- 

 gle transferers and double trans- 

 ferers ; the latter of which is 

 shown annexed. It consists of 



