tO2 NATURE STUDY 



Why does ice float ? Of course former work lias shown 

 It is because that, bulk for bulk, it is lighter than water, that is, when 

 water freezes, it expands. Fill a small bottle with water and place 

 it in a freezing mixture, keeping it there until its contents are 

 frozen hard. The bottle will be broken by the expanding ice. 

 This also illustrates the action of freezing water in breaking up 

 rocks, a very active disintegrating agent in cold countries, also in 

 high mountains, as in the Sierra of California, etc. 



An experiment showing that a solution of salt and water 

 requires a lower freezing temperature can be performed. Have 

 the pupils show that when the solution of salt freezes, the ice 

 separates the salt out from itself, the ice being fresh. 



These experiments may be much varied; their application to 

 geographical phenomena are obvious. For other freezing mix- 

 tures see some work on Physics. How is artificial ice manufactured? 



