1 .Vj Prof. T. E. Thorpe and Mr. J. W. Rodger. [Feb. 25 



in the case of the alcohols the coefficients vary irregularly with ascent 

 f the series. 



2. Of corresponding compounds, the one having the highest mo1< 

 cular weight has in general the highest coefficient (the aliphatic acidt 

 and to a much greater extent the alcohols, do not conform with tin 



rale). 



3. Normal propyl compounds have, as a rule, slightly higher value 

 than allyl compounds ; in the case of the alcohols, propyl compounc 

 hare much the higher value. 



4. The effect of molecular weight in some cases may be more tl 

 counterbalanced by that of constitution, or of complexity. 



5. The lowest members of homologous series frequently exhil 

 deviations from the regularity shown by higher members. 



6. An iso-compound has in general a larger coefficient than 

 normal componnd, and the differences reach their maximum in the 

 case of the alcohols. 



7. In the case of other metameric substances, branching in tl 

 atomic chain and the symmetry of the molecule influence the 

 tndes of the coefficients ; the ortho-position, in the case of aromatic 

 compounds, appears to have a more marked effect on the coefficit 

 than either the meta- or para- position. Acetone and ether hai 

 coefficients that are less than half the values given by the isomer 

 alcohols. 



8. One of the most striking points thus brought to light is tl 

 peculiar behaviour of the alcohols, and to some extent of the acic 

 as contrasted with that of other liquids. 



Comparisons of molecular viscosity at the boiling point show 



1. That, with the exception of the alcohols, dibromides, and t' 

 lowest members of homologous series, an increment of CH 2 in che 

 composition corresponds with an increase in molecular viscosity. 



2. With the above exceptions, it is also apparent that the co 

 sponding compound having the highest molecular weight has t 

 highest molecular viscosity : the difference in molecular viscosity 

 tween the corresponding members of two correlated series is 

 constant. 



3. The relationships shown in the other tables are substantially 

 the same nature as those given by the viscosity coefficients. 



The comparisons which give the largest deviation from regnlari 

 contain those substances which, as already shown, exhibit a pecu- 

 liar behaviour, namely, the alcohols, acids, propylene dibromide, 

 ethylene dichloride, <tc. 



In order to indicate how molecular viscosity at the boiling point is 

 quantitatively connected with chemical nature, attempts were made 

 to calculate the probable partial effects of the atoms on the molecul 





