CONTENTS ix 



CHAPTER VI 



THE COMPOSITION OF THE AIR AND THE PREPARATION 

 OF CARBONIC ACID GAS 



PAGE 



The Action of Vitiated Air on Lime Water . . 48 



Vitiated Air is Produced by burning Charcoal . . 48 



The Charcoal combines with the Air to form a Gas . 50 



The Action of burning Phosphorus on Air . . .51 



The Phosphorus removes Part of the Air . . .52 



The Air contains two Gases, Oxygen and Nitrogen . 55 



Oxygen set Free by Plants in Sunlight . . .56 



CHAPTER VII 



THE NITROGEN REQUIRED BY PLANTS 



Ammonia contains Nitrogen . . . .58 



Plants cannot absorb Nitrogen directly . . .59 



The Natural Order, Leguminosse, and the Absorption of 



Nitrogen . . . . . .59 



Nitrogen Compounds obtained from the Decay of Plants . 60 



Nitrogen Manures . . . . . .60 



CONCLUSION . 61 



APPENDICES 



I. NOTES ON THE EXPERIMENTS 



II. ON THE USE OF THE BALANCE 



List of Apparatus and Chemicals required . . .74 



