556 



Professor Svante Arrhenhis 



[June'3, 



Tlie conductivity is then found to be increased, and to have the 

 value /jo. Increasing in the same manner, the volume, by addition of 

 pure water until it is doubled, the level 4 is reached, and the con- 

 ductivity 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, h^. This is best seen in the next diagrams, which 

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



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

 ductivity depends upon the velocity with which the ions (Zn and 

 SO4) of the molecules (ZnS04) are carried through the liquid by 





Fig. 4. 



the electric force, i.e. the potential difference between E and E^. 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 surrounding molecules. As these, at higher dilutions, 

 are only water molecules, it might be expected that the conduc- 

 tivity would remain constant and independent of the dilution if it 

 be supposed that all molecules, ZnS04, '^^^ \)^xi in the electric 

 transport. As experiment now teaches us that the molecular con- 

 ductivity increases with the dilution, even if this is very high (1000 

 or more molecules of water to one molecule of ZnS04), we are led to 

 the hypothesis that not all, but only a part of, the ZnS04 molecules 



