*9°4\ 



Mills — Molecular Attraction. 



163 



0° 50° 100° 150° 200° 350° 300* 



Diagram 9. 

 Ordinates give internal heat of vaporization in calories. 



latent heat this variable amount of energy thus externally 

 expended and to plot the internal latent heat of vaporization 

 against the temperature. The values are given in second 

 paper, Tables 2 to 22, under the heading- L — E x . The 

 curves are shown in Diagrams, 8, 9, and 10. The observa- 

 tions are marked with dots, or crosses. The scale needs 

 no explanation except that for water 300 should be added 

 to the ordinates to make the reading- as expressed in calories 

 correct. 



It will be noted: 



i. That the internal latent heat cannot be reg-arded as a 

 linear function of the temperature except at low vapor pres- 

 sures and for a limited rang-e of temperature. Water does 

 show a linear variation to 230°, but this is due to Regnault's 

 linear formula from which the values were obtained. The 

 values obtained from Ramsay and Young's observations above 



