L894.] Ihe Viscosity of Liquids and their Chemical Nature. 157 



1. Temperatures of equal slope tend to reveal much more definite 

 slationships between the values of viscosity coefficients and the 

 temical nature of the substances than are obtained at the boiling 

 dnt. 



2. In all homologous series, with the exception of those of the 

 alcohols, acids, and dichlorides, the effect of CH 2 on the value of the 



ioefficient is positive, and tends to diminish as the series is ascended. 



3. Of corresponding compounds the one of highest molecular 

 r eight has the highest coefficient. 



4. Normal propyl compounds have slightly larger coefficients than 

 te corresponding allyl compounds. 



5. An iso-compound has invariably a larger coefficient than a 

 ial compound. 



6. In the case of other isomers the orientation of the molecule and 

 inching of the atomic chain influence the magnitudes of the 



lefficients. Similar effects of constitution are also exhibited on 

 imparing saturated and unsaturated hydrocarbons, and the variable 

 effects produced by successive substitution of halogen for hydrogen. 



7. The alcohols, and to some extent the acids, still give Results 

 hich are peculiar when compared with other substances. 

 As regards molecular viscosity at equal slope the following con- 

 usions may be drawn : 

 1. For the great majority of the substances molecular viscosity at 

 equal slope can be calculated from fundamental constants which 

 :press not only the partial effects of the atoms existing in the 

 lolecule, but also those due to different atomic arrangements. These 

 given in the accompanying table : 



Fundamental Viscosity Constants (molecular viscosity at 

 Slope 0'0 4 323, in dynes x 10 4 ). 



