G86 
MESSES. T. E. THORPE AND J. W. RODGER ON THE RELATIONS 
molecular aggregates in the alcohols at the temperature of comparison. The values 
used for the molecular viscosity work in the case of the alcohols are therefore not the 
actual values of this cjuantity, since they involve the theoretical molecular weights 
instead of the actual liquid molecular weights of the substances. They can, therefore, 
not be taken to represent the same magnitude as is dealt with in the case of simply 
constituted liquids, but serve only to indicate how the simple relationships which hold 
for such substances are complicated by the presence of molecular complexes. 
It would be interesting, no doubt, to ascertain with such data as are to hand, the 
actual value of the viscosity magnitudes, calculated from liquid molecular weights. 
But until the theoretical basis of Eotvos’s method of estimating molecular complexity 
has been definitely established we do not see that much will be gained by instituting 
such a comparison. 
We are indeed inclined to believe that the question of the actual extent of the com¬ 
plexity will not be settled by the study of one single property but by a comparison of 
as many properties as are more or less immediately related to the acting molecule of 
a liquid substance. 
Results Obtained from Associated Liquids. 
The most satisfactory method of showing the presence of complexes in the hydroxy 
liquids which we have examined would be to compare the observed values with those 
calculated by means of the effect produced by hydroxyl oxygen in simply constituted 
liquids. The general conclusion which seems to flow from the physico-chemical 
evidence at present accumulated is, however, that a simply constituted hydroxy 
compound does not exist; all hydroxy compounds seem to contain molecular aggre¬ 
gates, Hence, the most that can be done is to show that the value of hydroxyl 
oxygen which applies to one series of substances, does not apply to another, and 
that, in the case of the same series, owing to variations in the complexity of indi¬ 
vidual members, the differences between the observed and calculated values are 
larger than in similar comparisons involving simply constituted liquids. Evidence 
may also be obtained on comparing the effects produced by a definite change in 
chemical composition on the viscosity magnitudes of the hydroxy liquids with those 
produced by the same change in the case of simply constituted liquids. 
The varying values which, by the preceding mode of treatment, may be ascribed to 
hydroxyl oxygen in the acids, water, and the alcohols, and which may be affected to 
some extent by chemical constitution as well as molecular complexity are as follows. 
The value of hydroxyl oxygen originally used was derived from the numbers given by 
the acids wherein the “ rest ” contained the unsaturated carbox 3 d group, so that the 
value of O = 184 refers only to the acids. In the case of water, it has been shown 
that here the value of O derived from the acids no longer applies. If the value of 
