Theory of Molecular Volumes. 441 



at 0°, with an additional contraction o£ 3 X 1*7 for three olefin 

 linkings. No reason exists for such a large difference 

 between rings of such similar natures as those of benzene and 

 hexamethylene, 



A very full treatment of the effect of Ring structure on 

 molecular volumes was made by the author in the Phil. Mag. 

 s. 6, vol. xvi. no. 91 (1908), pp. 77-86, and ' Chemical 

 News/ 99. p. 206 (1909). This work seems to have been 

 ignored in recent text-books, although the evidence is very 

 complete and striking. Since then, in a paper read before the 

 British Association, Portsmouth 1911, and reprinted in the 

 * Chemical News/ 104. p. 151 et seg., an extension of the 

 work was indicated. 



Homocyclic Rings. 



Tlie Benzene Nucleus. 

 At the critical point we have the following results : — 



V Benzene, C 6 H 6 256'3 W 30. V/W 8'54 



Hexamethylene, C 6 H ]2 306'7 AV36. V/W 8'52 



6H 50-4 = 6x8-4. 



H in paraffin series has a volume of 9*67. 



The contraction for benzene C 6 H 6 is found to be 32*4, and 

 for hexamethylene C G H 12 40' 1. These values are proportional 

 to their complexity. 



The diminished value of the H atoms in the nucleus of 



benzene at the boiling-point, viz v ~ - - = 3*20, is shown by the 



following fact. If we gradual]}- diminish the H atoms in the 

 nucleus and substitute methyl groups which are paraffin 

 residues, we diminish the contraction by 0*5 for each sub- 

 stitution, that is, the difference between 3*70 and 3*20. 

 CH 3 =25'45. 



Benzene. 



CH M.V. Benzene, C 6 H 6 96'0 



n f \„ Dipropargyl,C 6 H 6 ... 111-0 



|| A for Ring -LfrO 



CH CH 



^ / CH = C-CH 2 -CH 2 -C = CH. 



CH Dipropargyl. 



