76 PHYSICAL PROPERTIES AND COMPOSITION 



At 



2-T6 

 2-l6 

 2-17 

 2OI 



1-52 



i-34 



1-22 



It seems then that this quantity is constant up to tem- 

 peratures about 50 below the critical point. 



In a comparison between 36 substances the change of 

 molecular surface energy was found to vary between 2-31 

 and 1-92, as shown by the following table : 



It is striking to note how hydroxylic liquids that, on 

 other grounds are thought to be associated, here too are 

 abnormal. 



Methyl alcohol 0*93 



Formic acid 0-9 



Water 0.87 



C. Theoretical Relations. 



On account of the ease and accessibility of Ramsay and 

 Shields' method, it is of importance to discuss its theoretical 

 basis, to see how far the conclusions must be regarded as 

 binding. 



For this reason we may consider what relations exist 

 between the Eotvos-Ramsay rule, and that of Mathias on 

 the rectilinear diameter. 



