Conducting Gases on the Direction of the Electric Field. 211 



plate is considerably gi*eater when the upper plate is positive 

 than when it is negative. 



Tier. 2 a. 



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The results given in the table for 107 volts show that the 

 rate of change of potential per centim. from about 6 centims. 

 upwards from the lower plate is numerically very nearly the 

 same for both directions of the electric field. 



If this holds accurately, it can be readily shown that the 

 currents through the gas in the two directions for the same 

 P.D. are directly proportional to the ratio of the velocities of 

 the positive and negative ions. 



For let V be the P.D. between the plates. Let us suppose 

 that the lower plate is positively charged, and that positive 

 ions only are present near the upper plate. 



