the Motion of Electrons in Gases. 883 



10. The experimental results for the three gases may be 

 shown by means o£ curves representing W and k in terms 

 of Z/p. The values of W in the three gases corresponding 

 to the smaller values of Z/p are given by curves fig. 3, and 



Fie:. 3. 



60 



































50 



WxlO" 5 

























J/ 









40 

 30 



















































20 































i 1 



10 















i 































# 







10 



12 



for the larger values of Z/p by the curves fig. 4. The values 

 of h are similarly represented by the curves figs. 5 and 6. 

 Since the results obtained with oxygen are not as accurate 

 as those obtained with nitrogen and hydrogen, the values of 

 W and Jc for that gas are represented by dotted curves. 



11. The results of the experiments may be used to find 

 the mean free path I of an electron between collisions with 

 molecules, and the distance a between the centre of the 

 molecule and the centre of the electron when a collision 



occurs is found from the relation 1= — 2i v being the number 



1TVO" 



of molecules per cubic centimetre of the gas. 



