MOLECULAR VOLUME 



665 



If, as Traube assumes, the constitution of liquids, and even 

 solids, resembles in some respects that of vapours, it is logical 

 to suppose that the co-volume would be the same for all sub- 

 stances under similar physical conditions. Facts are, however, 

 against this supposition. The following diagram, which gives 

 the volumes of the normal Paraffins at the different temperatures, 

 shows this. 



The Volumes of the n-Paraffins at the Different Temperatures 



(Data due to Young) 



Temperature in degrees absolute. 



An inspection of the curve shows that the molecular critical 

 volumes lie on a curve represented by the dotted line c 5 c 6 c 7 . 

 The molecular volumes at the B.P. lie along another dotted 

 line a/3. 



The volumes at the reduced pressure P/P^o'011796 are 



