Dielectric Constants of certain Frozen Electrolytes. 315 



hydrochloric acids at the temperature of liquid air all have values 

 not far removed from 3. The dielectric constants of the caustic 

 potash solutions thus preserve a high value until a very low tem- 

 perature is reached. It is, however, clear from the diagrams that 

 the curves representing these last constants are in each case bending 

 downwards, and a very moderate further reduction of temperature 

 would probably reduce the constant in these cases also to a low 

 value. 



We were desirous of seeing what effect the solvent had in the case 

 of the caustic potash, and accordingly prepared a 5 per cent, solution 

 of caustic potash in ethylic alcohol and examined this with, the 

 following result: — 



Dielectric Constant of Alcoholic Solution of Caustic Potash. 



(5 per cent, solution.) 



Frequency of fork 120. Galvanometer deflection with air as dielectric 

 of condenser = 3*44 cm. for 100 volts. 



Temperature 



Galvanometer 







in platinum 



deflection 



Dielectric 





degrees. 



in centimetres. 



Constant. 



Observations. 



-199-2 



10-15 



2-86 



Charging voltage 99'8. 



-200-6 



10-05 



2-83 



1000 ohms in series with 



-197-8 



10-40 



2-93 



galvanometer. 



-197-0 



12-45 



3-53? 









cooled again 



-196-3 



9-77 



2-75 



Charging voltage 99'8. 



-194;8 



1-97 



2-81 



Charging voltage 19*8. 



-191-0 



2-05 



2-92 



1000 ohms in series with 



-184-8 



2-45 



3-50 



galvanometer. 



-181-8 



3-02 



4-35 





The above observations are plotted in the short curve marked K in 

 fig. 5. 



It is thus seen that the 5 per cent, alcoholic solution of caustic 

 potash behaves quite differently to the 5 per cent, aqueous solution 

 and has a much lower dielectric constant at —185° C. The conduc- 

 tivity of the alcoholic solution rises so rapidly just above —185° C. 

 that the dielectric measurements cannot be carried up very far, 

 but as far as they go they show that the solution in water has 

 an immensely greater dielectric value than the solution in alcohol 

 at —200° and upwards. 



The observations we have so far made lead us to the following 

 conclusions : — 



z 2 



