330 ILLINOIS STATE ACADEMY OF SCIENCE 



A METHOD OF DETERMINATION OF DIELEC- 

 TRIC CONSTANTS 



A. P. Carman and G. T. Lorance, University of Illinois 



Use has been made of the arrangement of oscillating 

 currents described by J. J. DoAvling in his article on ' ' The 

 Recording Ultra-Micrometer" in London ** Engineering" 

 for September 30, 1921. In this method the variation of 

 the anode current of an oscillating electric valve is meas- 

 ured by a sensitive galvanometer and a curve is drawn 

 showing the relation between the variation of this current 

 and the change in the capacity in the circuit. A part of 

 this curve is practically a straight line, so that a small 

 change of capacity due to a change of dielectric in a 

 condenser can be read off directly from the curve. We 

 have been able to show the difference in capacity in an 

 air condenser produced by exhausting the air ; that is, the 

 method is capable of measuring the dielectric constants of 

 gases. It is proposed to measure the effect of pressure 

 on the dielectric constants of gases, the constants of va- 

 rious solid and liquid dielectrics, and the effects of va- 

 rious changes in the dielectrics. 

 Laboratory of Physics 



University of Illinois 

 March 30, 1922 



