30 



29 



Z-7 



2-e 



2-3 



22 



524 Saturation Constants and van der Waals's Equation. 



(fig. 2) is more marked than that given by experimental 

 results. 



Fig. 2. 





































































\ 



































+ 









\ 



















































































d 











S. Young [loc. cit.) finds as a more correct formula 



For all substances a. is negative ; j3 is zero only when 

 the ratio of the actual to the theoretical density at the 

 critical point has the normal value 3 77. When this ratio 

 <3*77, ft is positive and the curve is convex to the tem- 

 perature-axis. This is quite in accordance with fig. 2, where 

 the ratio has the value 2 67. 



University College, Dundee, 

 February, 1907. 



