ELECTROLYTIC DISSOCIATION. 



389 



conductivity is found to be greater than in the previous case — say & 4 . 

 So we may proceed further and further; the conductivity increases, 

 but at the end more slowly than at the beginning. We approach to a 

 final value Jc s . This is best seen in the next diagrams, which represent 

 the newer determinations of Kohlrausch (Figs. 4, 5). 



no 

 KCI 



Molecular Conductivity 



BoC/j 



wo 1000 Dilution 



Fig. 4. 



1000 Dilution. 



Fig. 5. 



I explained this experiment in the following manner: The con- 

 ductivity depends upon the velocity with which the ions (Zn and S0 4 ) 

 of the molecules (ZnSo 4 ) are carried through the liquid by the electric 

 force, i. e., the potential difference between E and E x . If this potential 

 difference remains constant, the velocity depends only on the friction 

 that the ions in their passage through the liquid exert on the surround- 

 ing molecules. As these, at higher dilutions, are only water molecules, 

 it might be expected that the conductivity would remain constant and 

 independent of the dilution if it be supposed that all molecules, ZnS0 4 , 

 take part in the electric transport. As experiment now teaches us that 

 the molecular conductivity increases with the dilution, even if this is 

 very high (1,000 or more molecules of water to one molecule of ZnS0 4 ), 

 we are led to the hypothesis that not all, but only a part of, the ZnS0 4 

 molecules take part in the transport of electricity. This part increases 

 with the dilution in the same proportion as the molecular conductivity 

 Tc. The limiting value Jc s is approached at infinite dilution, and corre- 

 sponds to the limit that all molecules conduct electricity. The con- 

 ducting part of the molecules I called the active part. It may evi- 

 dently be calculated as the quotient h : Tc 8 . 



If now this new conception were only applicable to the explanation 

 of the phenomena of electric conductivity, its value had not been so 



