324 Profs. J. A. Fleming and J. Dewar. On the Dielectric 



These last two sets of observations are delineated in the short 

 curves marked water 250-*~ and water 120-*" given in Fig. 1. 



The following observations were then taken with a mixture of 

 water and ethyl alcohol. 



Dielectric Gonstant of Alcohol and Water. 



(39 per cent, alcohol.) 



Frequency of contact maker 120. Deflection of galvanometer with 

 air as dielectric of condenser = 3*44 cm. for 100 volts. 



Temperature 



Gralvanometer 







in platinum 



deflection 



Dielectric 





degrees. 



in centimetres. 



constant. 



Observations. 



-198-5 



10-82 



3-06 



Charging voltage 100. 



-145-0 



25-00 



36-6 





-140-2 



2-07 



41-8 



Charging voltage 19*8. 



-133-7 



2-27 



46-0 



1000 ohms in series with 



-128-2 



2-35 



47-7 



the galvanometer. 



-125-2 



2-52 



51-2 





-122-0 



2-67 



541 





-117-3 



2-80 



56-7 





The dielectric constant is seen to rise with great rapidity very soon 

 above the temperature of —190°. This is clearly connected with 

 the temperature at which the alcoholic mixture becomes plastic 

 previous to fusion. 



We attempted to obtain the dielectric curve of pure ethylic 

 alcohol, to compare it with that of water, but were stopped by the 

 fact that at a temperature very little above —200° the ethylic alcohol, 

 although still apparently in a solid condition, becomes possessed of 

 such an amount of conductivity that our method is no longer able to 

 give us the true dielectric constant. 



In contrast to this we have taken the dielectric constant of 

 pure glycerine (a triatomic alcohol), with the following results : — 



Dielectric Constant of Glycerine. 



Frequency of contact maker 120. Gralvanometer deflection with air 

 as dielectric in the condenser = 2'43 cm. for 100 volts. 



Temperature 

 in platinum 

 degrees. 



-198-2 

 -138-2 

 -122-0 

 -100-8 



Gralvanometer 



deflection 

 in centimetres. 



8-4 



8- 84 



9- 27 

 11-80 



Dielectric 

 constant. 



321 

 3-40 



3- 56 



4- 62 



Observations. 

 Charging voltage 100'8 



