126 EFFECTS OF HEAT. 



Q. Why does the BOTTOM COME OFF, if a GLASS 

 BEAKER be set on a warm HOB ? 



A. Glass is a non-conductor,; and, 

 as the bottom of the glass (from the 

 warmth of the hot stove) expands, before 

 the sides are heated, the two parts separate 

 the one from the other. 



CHAPTER XL 



2. LIQUEFACTION. 

 3. VAPORIZATION. 



Q. What is meant by LIQUEFACTION ? 

 A. The state of being melted ; as ice 

 is melted by the heat of the sun. 



Q. Why is ICE MELTED by the HEAT of the 



SUN? 



A. The heat of the sun (entering the 

 solid ice) forces its particles asunder, till 

 their attraction of cohesion is sufficiently 

 overcome, to convert the solid ice into 

 liquid. (See p. 112.) 



