OBSERVATIONS OF CHANGE OF TEMPERATURE 51 



of a liquid be found if the coefficient of voluminal expansion for glass is 

 known ? 



18. Describe how the absolute expansion of a liquid may be found 

 by weighing a piece of glass immersed in the liquid at different tempera- 

 tures. What are the probable inaccuracies of the method ? 



19. Mention the advantages and disadvantages of Lavoisier's calori- 

 meter. Mention how some of the inaccuracies may be made relatively 

 small. 



20. How could you demonstrate that changes of temperature are 

 changes which relate to quantity of matter and not to volume ? What 

 hypothesis can you suggest as to the real process which underlies what 

 we call change of temperature ? 



