BETWEEN THE VISCOSITY OF LIQUIDS AND THEIR CHEMICAL NATURE. 687 
hydrogen be taken to be normal, and to be H = — 64, the value of oxygen in water 
is 105 + 128 = 233. 
In the normal alcohols, siuce H . . , OH = 156, using the normal value for 
hydrogen, 
0 = 156 + 128 = 284. 
The values which may thus be ascribed to oxygen, when linking hydrogen to tb.e 
various groups in these compounds, are given below. 
(CO)—0—(H). Linking hydrogen to carboxyl in an acid = 180. 
(H)—0—(H) „ ,, hydrogen in water = 233. 
(L)—0—(H) ,, ,, a saturated rest in a normal alcohol = 284. 
The value which, by the above method of calculation, may be ascribed to 0, is seen 
from the table to be larger for water than for an acid, and largest of all for an alcohol. 
The preceding discussion has also shown how the behaviour of tlie alcohols is probably 
related to the effect which the (HO) group exerts ujoon the rest of the molecule, and 
it is now indicated that this effect is greater in the case of an alcohol than in that of 
any other of the liquids examined. 
The values for CH^ given by the viscosity coefficients of the acids, it will be 
remembered, varied irregularly as the series was ascended. The same is true for the 
values given by molecular viscosity and molecular viscosity work. 
Although in these latter cases the mean effect of CH^ is not far removed from that 
of simply-constituted liquids, coupled with the peculiar behaviour of isobutyric acid 
as compared with other iso compounds, the irregularities observed point to the 
peculiar behaviour of the acids which is so obvious in glancing at their viscosity- 
curves and which is no doubt to be ascribed to molecular complexity. 
The normal alcohols appear to give a constant value for CH^, which is decidedly 
different from that given by simply-constituted liquids. Moreover, the variation in 
the numbers for isomeric alcohols is enormous when compared with that given by the 
other liquids, the acids included. 
All the above facts point to the molecular complexity of the hydroxy liquids 
which we have examined, and also to the conclusion that if complexity, as dis¬ 
tinguished from the purely chemical constitution of simple molecules, is the sole 
cause of the irregularities, it exerts a much more profound effect in the case of the 
alcohols than in any of the other liquids. This last conclusion is further supported 
by the comparisons made at different slopes. 
It will be remembered that, on passing from one slope to another, the viscosity 
magnitudes of water and the acids alter to the same extent as those of the 
other liquids. The alcohols, however, do not follow the same rule, for, as 
will be seen later (p. 692), on passing to a new slope, the extent to which the 
