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



Resistance of Condenser with Pure Ice as Dielectric. 



Temperature 



Resistance of the 



in platinum 



condenser in 



degrees. 



megohms. 



-206-0 



25,000 



-1521 



2,500 



-138-2 



2,000 



-92-0 



1,200 



-68-2 



1,200 



-47-0 



410 



-421 



260 



-33-2 



250 



-27-6 



40 



-26-1 



15 



-19-2 



3 



-10-2 



1 



It is seen from the above figures that our former observations on 

 the resistance of ice from ordinary distilled water are confirmed. 

 Above a certain temperature there is a relatively rapid increase 

 in the conductivity of the ice, as it rises in temperature. 



It was considered desirable to ascertain the difference made in 

 these values by using the ordinary distilled water of the laboratory 

 instead of this carefully purified distilled water, and therefore the 

 same experiments were repeated, using ordinary water, with the 

 following results : — 



Dielectric Constant of Ice from ordinary Distilled Water. 



Frequency of contact maker 120. Corrected galvanometer deflection 

 with condenser having air at 15° C. as dielectric = 5*63 cm. for 

 100 volts. 





Mean 







Temperature 



galvanometer 







in platinum 

 degrees. 



deflection in 



Dielectric 





centimetres. 



constant. 



Observations. 



-205-8 



17-30 



2-88 



Charging volts 104'0. 



-205-8 



3-59 



2-90 



Charging volts 20*2. 



-199-9 



17-22 



2-88 



Charging volts 103" 7. 



-195-0 



17-24 



2-91 





-154-0 



24-7 



4-16 





-146-3 



6-2 



5-37 



Charging volts 20*3. 



-143-2 



715 



6-18 





-137-2 



915 



7-97 





-132-2 



13-9 



12-1 





-128-6 



162 



14] 



Changing resistance in 



from 91,500 to 1,500 ohms 

 only altered deflection 1 mm. 



