Currents to the Study of Ionization by Collision. 473 



(reproduced in fig. 3) the temperature of the air at the 

 pressures actually used in the ionization experiments was 

 obtained, and was used in the way already indicated to 

 deduce the pressure of air at 17° C. which would have the 



Fig. 3. 



120 



no 



51 too 



§. 90 

 I 



SO 





n: m^^H 







^** 



.^r j 



~^ 



! | 



^•^ 



! 



! 1 



i /^ 



i 



| / 





f~V~ 



i 



12 3 4 



Pressure in mm. 



10 



same density as that experimented on. In the following- 

 table the values of a, p, and X are collected. The tem- 

 perature of the gas experimented on, as deduced from the 

 subsidiary experiments, and the "corrected pressures" are 



also given. 



Electric Intensity, X = 410 volts per cm. 



Temperature 

 of gas. 



Observed 

 pressures. 



P 

 mm. of mercury. 



Corresponding 



pressure if gas 



were cooled with 



constant density 



to 17° O. 



P 



mm. of mercury. 



a. 



117 

 113 

 107 

 103 

 95 



9-86 

 8-12 

 5-32 

 4-00 

 1-81 



7-33 

 610 

 4-06 

 309 

 1-43 



•97 

 1-63 

 2-68 

 409 

 622 



