G64 
MESSRS. T. E. THORPE AND J. W. RODGER ON THE RELATIONS 
Probably the first three hydrocarbons are alone strictly comparable, as the others 
contain two side chains. The mean of all the differences is, however, exactly the 
same as that deduced from the first three. The average difference from the mean, which 
in tlie case of the xylenes is mainly due to constitutive influences, is only some 3 units. 
It is thus evident that the ring-gTouping of atoms exerts a definite and profound 
Influence on the magnitude of the molecular viscosity work. 
If it is assumed that three double linkages occur in benzene, the differences would 
be reduced to 
369 — 3 X 95 = 84 units, 
so that the original difference is in the same sense as tliat which would be produced 
by double linkage, but evidently it can not be explained on the assumption that 
double linkages alone produce it. 
As in the case of aromatic hydrocarbons the calculated value for thiophen is 
hii'gely in excess of that observed : 
Thiophen I • ^^^iDifference, 294. 
L Observed . 305 J 
The value of the effect of two double linkages is 190, so that here also it is 
impossible to attribute the observed difference to the double linkage of carbon atoms 
alone. 
4T\e values thus obtained for the fundamental constants are summarized in the 
following table :— 
Fundamental Viscosity Constants (Molecular Viscosity Work at Slope ’0^323). 
Hytlrogen. 
H 
- 34 
Cai'bon. 
. 
C 
\ /• 
148 
Hydroxyl-oxygea .... 
. C—O-H 
o 
100 
Etlier-oxygeii. 
. C- ()—C 
0< 
43 
Carbonyl-oxygen .... 
C--=0 
II 
\/ 
1 
- 19 
Snl])hnr. 
. C—8—C 
s 
144 
Clilorine (in monochlorides) 
Cl 
89 
„ (in dicblorides) 
Cl' 
82 
1 
Rroinine (in monobroinides) 
Br 
151 
,, (in dibromides) 
Br' 
148 
Iodine. 
1 
218 
Iso grouping. 
< 
- 8 
1 
Double linkage. 
(=) 
- 95 
Ring-grouping. 
® 
- 369 
