BETWEEN THE VISCOSITY OP LIQUIDS AND THEIR CHEMICAL NATURE. 639 
Injiuence of the Iso grouping. 
Neglecting, for reasons already given, tlie butyric acids, the six available compari¬ 
sons give 21 as the amount by which the molecular viscosity of a normal compound is 
greater than that of the isomeric iso compound. The mean difference from this value, 
neglecting signs, is about 3. It is therefore assumed that the value of the iso 
grouping is 
Value of Hydrogen. 
On deducting the value of from the observed molecular viscosity of a normal 
paraffin CJl 2 „+ 2 , a value is obtained for the effect of Hg. 
On using the above measure of the effect of the iso mode of linkage, iso paraffins 
may also be included in the comparison. The available data are as under :— 
n. 
CnIIon-i-2* 
uCHa (calc.). 
Ho. 
rjdr. (obs.). 
r 
5 
687 
600 
87 
Normal paraffins . . < 
6 
7 
818 
931 
7-20 
840 
98 
91 
1 
8 
1035 
960 
75 
r 
5 
663 
579 
84 
Iso paraffins . . . . < 
6 
799 
699 
100 
L 
7 
908 
819 
89 
Mean value of Hj = 89. 
Neglecting signs, the average divergence from this value is 7. 
assumed that 
H = 44-5 
It is therefore 
Value of Carbon. 
From the two equations 
CHa = 120, Ha = 89, 
it follows, on the assumption that the effect of CHa is additively composed of those of 
carhon and hydrogen, that the effect on the molecular viscosity of an atom of carbon 
may be taken as 
C = 31. 
