20 PROPERTIES OF ELECTRICALLY CONDUCTING SYSTEMS 



whose average composition corresponds to the reaction which occurs at 

 the electrode on electrolysis of these solutions. The precipitation at the 

 anode in these solutions corresponds to the average composition of the 

 complex. 



The solutions of the alkali metals and the metals of the alkaline 

 earths in liquid ammonia constitute another apparent exception to Fara- 

 day's Law, and in order to reconcile the results obtained in the case of 

 these solutions with Faraday's Law it is necessary to extend it. 8 When, 

 for example, a current is passed through a solution of sodium in liquid 

 ammonia, only a fraction of the current appears to be accompanied by 

 an observable material process. These solutions, therefore, behave as 

 though the current were in part carried by an electrolytic and in part 

 by a metallic process. In order to reconcile these results with Faraday's 

 Law, it is necessary to assume that the process of metallic conduction is 

 likewise an ionic one, the current in this case being carried by the nega- 

 tive electrons. If this hypothesis is made, then Faraday's Laws hold in 

 these cases also. 



Faraday's Laws lead to important conclusions, not only with regard 

 to the mechanism of the conduction process in electrolytes, but also with 

 regard to the relation between electricity and matter. Interpreted from 

 a molecular kinetic point of view, Faraday's Laws state that definite fixed 

 quantities of electricity are associated with definite amounts of matter. 

 As Helmholtz 9 pointed out, if matter consists of discrete particles, then 

 electricity likewise is discrete in character. Corresponding to the atom, 

 the smallest subdivision of matter, we have a fundamental electric 

 charge, namely, the charge on a univalent ion. The charge, therefore, 

 on any given particle of matter, whether it be of molecular or atomic 

 dimensions or whether it be of larger dimensions as, for example, a drop 

 of oil, may not be varied continuously but only in multiples of the unit 

 charge. The discontinuous nature of the electric charge is one of the 

 fundamental facts underlying electrochemical phenomena and must be 

 taken into account in the interpretation of these phenomena. 



The reactions accompanying the passage of the current through an 

 electrode surface indicate clearly that an intimate relation exists between 

 chemical and electrical phenomena. Berzelius 10 attempted to account 

 for the structure of chemical compounds by means of an electrical 

 hypothesis. In this, however, he was unsuccessful, largely because he 

 assumed a false mechanism as representing the association between 

 electricity and matter. Instead of associating the charge with the atoms 



Kraus, J. Am. Chem. Soc. 30, 1323 (1908) ; 36, 864 (1914). 



Helmholtz, J. Chem. Soc. 39, 277 (1881) ; Wiss. Abh. 3, p. 52. 



10 Berzelius, Lehrbuch, Ed. 3, Vol. 5 (1835) ; Ostwald, Electrochemie, p. 335. 



