EXPANSION OF LIQUIDS
We have already seen that liquids expand, in connection with our study of liquid-in glass thermometers. The expansion of a liquid may be shown by means of a flask fitted with a rubber bung and a length of glass tubing (Fig. 15.11). The flask is filled with water or other liquid and the bung pushed in until the level of the liquid comes a short distance up the tube. On plunging the flask into a can of hot water it is noticed that the level of the liquid at first falls slightly and then starts to rise steadily.
The initial fall in level is caused by the expansion of the glass which becomes heated
and expands before the heat has had time to be conducted through the glass into the