CHAPTER II 



TH 



E NATURE OF AQUATIC 

 ENVIRONMENT 



PROPERTIES 

 AND USES 



ATER, the one abundant 

 liquid on earth, is, when 

 pure, tasteless, odorless 

 and transparent. Wa- 

 ter is a solvent of a 

 great variety of sub- 

 stances, both solid and 

 gaseous. Not only does 

 it dissolve more sub- 

 stances than any other 

 liquid, but, what is more 

 important, it dissolves 

 those substances which 

 are most needed in solution for the maintenance of 

 life. Water is the greatest medium of exchange in the 

 world. It brings down the gases from the atmosphere; 

 it transfers ammonia from the air into the soil for 

 plant food; it leaches out the soluble constituents 

 of the soil; and it acts of itself as a chemical agent 

 in nutrition, and also in those changes of putrefaction 

 and decay that keep the world's available food supply 

 in circulation. 



Water is nature's great agency for the applica- 

 tion of mechanical energy. It is by means of water 



