EXPANSION. 103 



sets fire to the tinder at the bottom of 

 the tube. 



CHAPTER IX. 



EFFECTS OF HEAT. 



1. EXPANSION. 



Q. What are the principal EFFECTS of HEAT ? 



A. 1. Expansion. 2. Liquefac- 

 tion. 3. Vaporization. 4. Evapora- 

 tion ; and 5. Ignition. 



Q. Does HEAT EXPAND the AIB ? 



A. Yes ; if a bladder (partially filled 

 with air) be tied up at the neck, and laid 

 before the fire, the air will swell till the 

 bladder bursts. 



Q. Why will the AIR SWELL, if the bladder 

 be laid before thejire ? 



A. Because the heat of the fire (jets 

 between the particles of air, and drives 

 them Jurther apart from each other; 

 which causes the bladder to expand. 



