SCHLUNDT — DIELECTRIC CONSTANTS OF PURE SOLVENTS. 



381 



The high dielectric constants of the nitriles and alcohols show 

 a marked contrast to the low dielectric constants of the substi- 

 tuted ammonias, which are of about the same order as the di- 

 electric constant of chloroform [D. C. = 5.0], and ether 

 [D. C. = 4.4], Now the ionizing power of chloroform and 

 ether is exceedingly small, which fact is in perfect accord with 

 the Nernst-Thonison rule. But Prof. Kahlenberg 1 finds that 

 the primary amines, which have values for their dielectric con- 

 stants approximately the same as those of chloroform and 

 ether, still yield solutions that conduct fairly well. Here then 

 we have a number of exceptions to the Nernst-Thomson rule 

 opposite in kind to the case of solutions in hydrocyanic acid ; 

 namely, solvents with relatively very low dielectric constants 

 that still possess moderate ionizing power. 



The electrical conductivity of solutions in nitriles has been 

 studied by Dutoit and Friderich. 2 Their results show that the 

 conductivity of salts dissolved in the homclogues, acetonitrile, 

 propionitrile, and butyronitrile decreases in the order in which 

 the solvents are named. Their dielectric constants also de- 

 crease in the same order ; thus supporting the ISTernst-Thomson 

 rule. This relation between the dielectric constant and electri- 

 cal conductivity is illustrated by the following table, in which 

 U stands for the molecular conductivity at 25° C, and V, the 

 number of liters in which one gram molecule of silver nitratfo 

 is dissolved. 



Propionitrile and benzonitrile have about the same dielectric 

 constant, but the molecular conductivities of silver nitrate dis- 



1 Jonr. phys. Chem. June, 1901. 



4 Bull. Chem. Soc. Paris [3] 19, 321, (1898). 



