Theory of Molecular Volumes. 353 



The Additive Rule in Aromatic Compounds. 



Compound. 



M.V. 



Cinnamene, C G H 5 . CH : CH 2 



Phenyl Acetylene, C 6 H 5 . C j OH 



Anisol, C 6 H 5 . OCH 3 



p Oresyl M. Oxide, C G H 4 (CH 3 )OCH3 



Dimethyl Eesorcin, C 6 H 4 (OCH 3 ) 2 



Benzaldehyde, C 6 H 5 . CHO 



Ethyl Benzoate, C 6 H 5 . CO . OC 2 H 5 



Phenyl Methyl Propionate, C G H 5 . CH 2 . CH 2 . 00 2 Me 

 Cinnamic Methyl Ester, C 6 H 5 . CH : CH . C0 2 CH 3 . . . 



Phenyl Chloride, C G H 5 C1 



Benzylidene Chloride, C 6 H 5 .CH, Cl 2 



2A.V. 



131-2 



1320 



126-2 



124-9 



1255 



125-6 



148-0 



148-0 



1577 



155-4 



118-4 



1187 



174-4 



173-8 



195-7 



196-1 



188-6 



188-7 



114-6 



114-9 



154-7 



155-2 





The above numbers are in fairly good agreement. Many 

 other cases occur, but since they are the subjects of con- 

 stitutive effects they are left til] later. 



The effect of Change of Valency and manner of Linking 

 on Volume. 



A careful examination of the evidence will show that 

 molecular volume is little, if at all, affected by the particular 

 manner in which the linkages are distributed, or by changes 

 in valency. 



Carbon C. 



Hitherto, carbon in combination has been thought to be 

 exclusively quadrivalent. It is now known to be sometimes 

 exceptionally divalent. 



Thus in Carbon Monoxide it is Divalent, for 



< C : forms 



c ;>C:o. 



Also we may compare : — 



C Quadrivalent. 



Ethyl Cyanide, C 2 H 5 -C = N. 

 B.P. 97, tf 0-801, d BJ > -70098, V 78-35 



Ethyl Thiocyanate, C 2 H 5 - S- C = N. 

 B.P. 146, V 1001 



C Divalent. 



Ethyl Isocyanide, C 2 H 5 -N = C. 

 B.P. 82, d Q 0-801, V 77-5 



Ethyl Thiocarbamide, C 2 N 5 ~N = S = C. 

 B.P. 133, V 99-3 





There is certainly a small diminution in volume in the 

 compounds belonging to the second column, and also a 

 depression in the B.P. This corresponds with a displacement 

 of N as well as a different function of C from that in the 



Phil. Mag. S. 6. Vol. 27. No. 158. Feb. 1914. 2 A 



