40 



CONDUCTIVITY AND VISCOSITY IN MIXED SOLVENTS. 



In mixtures of the alcohols and water the same hydrolysis was found to 

 take place, while in the solutions in absolute alcohol a different change 

 occurred. The solution, originally of a pale straw color, gradually became 

 lighter and lighter when in contact with the platinum black of the electrodes. 

 This was accompanied by a steady rise in the molecular conductivity, which, 

 at the end of 24 hours, was still appreciable. The colorless solution showed 

 only the slightest trace of ferric iron, having apparently been reduced to the 

 ferrous condition. These changes are shown in table 21. 



TABLE 21. Changes in the molecular conductivity of ferric chloride (v = 512), with time. 



SUMMARY. 



The preceding investigation leads to the conclusion that the minimum 

 point, discovered by Zelinsky and Krapiwin, is not an isolated phenomenon 

 restricted to the mixtures of methyl alcohol and water, but is much more 

 general. This minimum point in the conductivity has been found for all the 

 salts studied in mixtures of methyl alcohol and water, with the exception of 

 cadmium iodide. Ethyl alcohol and water yield a minimum in the conduc- 

 tivity of all the salts investigated at 0. At 25 this minimum had disappeared. 

 Mixtures of methyl alcohol and ethyl alcohol do not exhibit this phenomenon, 

 but the conductivity of a salt dissolved in a 50 per cent mixture of methyl and 

 ethyl alcohols is less than the mean of the conductivities of the substance 

 in the pure solvents at the same dilution. 



To explain these facts we advance tentatively the following suggestion : 

 According to the theory of Dutoit and Aston it is only those substances whose 

 molecules are polymerized that can dissociate dissolved electrolytes. If this 



