EFFECT OF HEAT OX MATTER 



15 



Effect of heat on liquids. Not only are solids affected 

 by heat and cold, but liquids behave similarly with 

 changes in temperature. Everyone knows that if a 

 tea kettle is filled with cold water and heat applied, the 

 water will soon overflow. 



The expansion of water can easily be shown by heat- 

 ing a test tube filled with water and closed 

 by a rubber stopper through which a piece 

 of glass tubing passes. When the 

 water is heated it expands and rises 

 in the small tube. If the water in 

 the test tube is cooled by 

 running cold water over it, 

 the water in the tube con- 

 tracts, falls, and finally 

 reaches its original level. 

 If mercury is used in place 

 of water, the expansion 

 and contraction will not be 

 so great, for the volume of 

 mercury does not change 

 so rapidly. 



The action of 

 a thermometer de- 

 pends upon the 

 fact that mercury 

 expands when heated and contracts when cooled. In 

 some thermometers alcohol is used in place of mercury, 

 but the principle involved is the same. 



Fig. 8. Experiment to show the effects 

 of a change of temperature on the volume 

 of a liquid. 



