Energy and Heat 



127 



consists of a metal ball, which just passes through a 

 circular hole in a flat metal plate mounted upon a 

 stand. After testing the ball as to its ability to pass 

 through the hole when cold, heat it in a Bunsen flame 

 for about a minute. Again try to pass it through the 

 hole while still hot. It will no longer go through, 

 showing that its volume has been increased, with con- 

 sequent extension of its circumference. 



83. To show that liquids occupy a larger volume 

 when heated, perform 



EXPERIMENT 41. Completely 

 similar flasks, one with water, and 

 the other with another liquid, say 

 alcohol. Insert into the mouth of 

 each flask a rubber stopper, fitted 

 with a long straight piece of glass 

 tubing passing through a hole in 

 the middle of the stopper. As 

 the stoppers are pushed in, the 

 liquids should rise in the glass 

 tubes for a short distance. Should 

 this not be the case, the fitting 

 of the stopper is not good enough, 

 or the glass tube does not pro- 

 perly fill the hole in the stopper. 

 Remedy this and arrange the 

 heights of the liquids so that the 

 upper surface is an inch above 

 the top of the stopper. To see 

 the movement of the liquids better, 

 they may be coloured with a little 

 indigo or other colouring- matter, 

 and the glass tubes may be pushed 



fill each of two 



Fig. 36. 



