72 CARBONIC ACID. 



and the carbonic acid gas will be disengaged, and 

 maybe collected in the pneumatic apparatus. In this 

 process the sulphuric acid severs the lime, leaving 

 the carbonic acid free, which escapes in the gase- 

 ous form. 



Carbonic acid gas cannot support flame, as may 

 be seen by plunging a lighted taper into a vessel 

 of it : it will be instantly extinguished. 



It is fatal to animal life : a small animal confined 

 in it would die in a few minutes. 



Its taste is sour: and it is capable of being ab- 

 sorbed by water. Water so impregnated has an 

 acidulous taste, and reddens vegetable blues. 

 Many mineral waters owe their qualities to this gas, 

 which is contained in them, and they may be imi- 

 tated by impregnating water with carbonic acid gas. 

 Agitation and pressure promotes the absorption ; 

 and in this manner the artificial soda water is 

 made. 



During the process of fermentation, this gas 

 is disengaged, and yeast is carbonic acid enveloped 

 in a viscous substance. If a lighted candle be 

 plunged into the upper part of a cask containing 

 fermenting liquor, it will be extinguished, the 

 apparently empty part of the vessel being filled 

 with carbonic acid gas. 



This gas is heavier than common air ; hence, 

 when disengaged, it occupies the lowest situation. 

 It may be poured from one vessel into another, 

 which makes a pretty experiment. Fill a vessel 

 with this gas, and then, having placed a bit of 

 lighted paper in the bottom of an empty tumbler, 

 pour the gas into the tumbler upon the taper: the 

 flame will be extinguished : here the gas will be 

 invisible, but its presence is thus manifested. 



