NON-LIVING THINGS 2O3 



directions. In quiet weather the column of smoke from a 

 large fire will often have a cloud-tipped top. Explain. 



It is a fact not very generally known that water vapor 

 will diffuse through a vacuum as quickly as it will through 

 air. In other words, the presence of air is in no way essen- 

 tial to the process of evaporation, which is even prevented 

 if the air is already saturated with water vapor. Why then 

 does not the earth lose some of its water supply by evapora- 

 tion into space? Why should high ranges of mountains 

 prove barriers for moisture in winds? 



Experiments in magnetism are full of interest for the 

 younger pupils. These should include a study of both the 



bar and the horseshoe magnet. Show the 

 Magnetism 



lines of magnetic force by covering the 



magnet with a sheet of paper upon which iron filings are 

 gently sifted. If blue print paper is used and exposed to 

 sunshine for two or three minutes, a permanent print may 

 be secured showing the lines of force. Suspend magnetized 

 needles by fine silk threads, noting their direction when the 

 motion stops. Show the practical application of the mag- 

 net in the mariner's compass. What other uses might it 

 have? With older pupils take up in an elementary way 

 the electro-magnet in some of its simpler applications, such 

 as the electric bell, a part of telephone receivers, telegraph 

 instruments. 



Provide a florence flask fitted with a rubber stopper 

 which has been bored to fit small glass tubing. Secure a 



piece of glass tubing five or six feet long; 

 Expansion 

 By Heat P ut xt mto "* e P enm ' m the stopper so 



that all connections are air tight. The re- 

 sulting piece of apparatus is of course full of air, and the 



