Constants of Metallic Oxides at Low Temperatures. 379 



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DIELECT 



TEMPERATURE IN F 



'LATINUM DEGREES 







-200° -I50 : -100° -50' O" 



Fig. 2. — Curves showing the variation in Dielectric Constant with Temperature of 

 various Oxides and Hydrates. 



The only general conclusion that can as yet be drawn from the 

 experiments described is that the presence of certain oxides or 

 hydrates of metals in ice, even to the extent of not many per cent., 

 has an immense influence in raising the dielectric power of the ice 

 when taken at the temperature of liquid air, whereas the presence 

 of other oxides or hydrates chemically analogous has hardly any 

 influence at all. 



In the above described experiments, Mr. J. E. Petavel has given us 

 considerable assistance, 



