CHAPTER VI 



THE COMPOSITION OF THE AIR AND THE PREPARA- 

 TION OF CARBONIC ACID GAS 



WE have now learnt two facts about the plant. We 

 know that it obtains charcoal from the air, and we 

 also know that it can restore air, which has been 

 vitiated by burning substances or by passing through 

 the lungs, to its former state. 



There is surely some connection between these 

 facts which we should be able to find out. 



And first, take note that the substances burnt, 

 whether they be the spirits of wine prepared from 

 fermented corn, or the candle prepared from animal 

 or vegetable fat, were all of animal or vegetable origin, 

 and would probably contain charcoal as one of their 

 parts. 



Let us then burn some charcoal and see whether 

 that also produces vitiated air, which can be restored 

 to its pure state by the plant. But before doing so, 

 let us try another test for the presence of vitiated 

 air. 



