Currents to the Study of Ionization by Collision. 475 



obtained from measurements of the currents at, three dis- 

 tances by means of the equation 



n = n 



(a_/3) 6 ( tt -0><* 



/3e< a - 



fi)d 



The results of these experiments are given in the following 

 tables. From the method of calculation, the values of 

 a and ft when substituted in the above equation give values 

 of n which are equal to those of the observed currents at 

 three distances. It will be seen that the formula expresses 

 the values of the current over the whole range with fair 

 accuracy in the first table. In the experiments where 

 X = 820 volts per cm., observations at three distances only 

 were taken, as the potential differences required for the 

 larger distances were not available. 



Pressure of air, ^ = '820 mm. 



Electric Intensity, X = 410 volts per cm. 



a=5'20. £=-049. 



Distance 



Observed Calculated Ratio of 



, between plates, 

 in cm. 



current. current. < , recessive 



observed currents. 



j 



1 



12-5 117 





1-62 



•2 



20-3 190 





1-68 



•3 



34-1 33-9 





1-72 



•4 



58-5 



58-5 



1-77 



•5 



103-5 103-5 





j 1-85 



•6 



191-5 191-6 



Pressure of! air, p = '810 mm. 



Electric Intensity, X = 820 volts per cm. 



« = 6'50. /3='193. 



■1 



22-2 



22-2 



1-98 



•2 



44-0 



44-0 



210 



•3 



922 



92-2 





