VOLATILE LIQUIDS. 



containing a dozen of the aerating bulbs for 

 is. 4d. 



These bulbs, which are sold under the name 

 of sparklets, are strong little steel capsules, 

 containing liquid carbonic acid. This is, in the 

 form of gas, the material which gives their 

 fizzing and vaporising character to soda-water, 



FlQ. 39.-LIQUID CARBONIC ACID FROZEN BY RAPID VAPORISATION 

 THROUGH SPARKLET SIPHON-HEAD. 



lemonade, sparkling wines, and frothy beer. 

 It is so volatile that it tends, when compressed 

 into the liquid state, to re-volatilise with an 

 energy which produces a pressure equal to 

 forty or fifty atmospheres, according to the tem- 

 perature. If the surface area of one of these 

 sparklets be over two square inches, the total 

 pressure inside it tending outwards in all direc- 

 tions is well over half a ton. 



169 



