PHYSICAL PARADOXES. 



They are, therefore, not things to be played 

 with. If highly heated, or opened in an im- 

 proper manner, they explode with great violence. 

 They should not be experimented with in any 

 irregular manner by those who do not well 

 understand such matters. If, however, they are 

 kept at ordinary temperatures and opened in 

 the proper way, they are as safe as they are 

 convenient. 



We will, therefore, use the proper apparatus 

 for opening them, the ordinary Aerators' siphon- 

 head, as shown reduced to about half-size in 

 Fig. 39, simply removed from the siphon and 

 without the glass tube and connections. 



Put the sparklet bulb A into the open- 

 sided holder B, and screw it loosely into posi- 

 tion, with its small end just entering the 

 rubber washer. Press the base C against a 

 roll of flannel or other porous cloth, in such a 

 position (for the best possible effect) that the 

 sparklet bulb A shall be vertical. Now screw 

 down the holder by its ear-pieces D D, so as to 

 force the small end of the bulb against the 

 point of a pricker, which pierces it. Screw 

 it down well to make a good hole. 



The liquid carbonic acid rushes violently 

 out of the hole, through a slot in the pricker, 

 and into the chamber C, in which it expands 

 and vaporises. The sudden expansion and 

 conversion into vapour require much heat, 

 which is supplied largely by the liquid itself. 



170 



