﻿Motion of Electrons in Argon and in Hydrogen. 1051 



measurements o£ W and u in pure argon is larger than the 

 true value corresponding to the mean velocity u. 



The free path of an electron in argon at a millimetre 

 pressure has a maximum value of 1*0 cm. for the velocity 

 3*75 xlO 7 cm. per second, which corresponds to a potential 

 fall of "39 volt. As the value of I is an average for a 

 number of different velocities having a mean value u, it is 

 probable that the mean free path for electrons all moving 

 with the velocity 3*75 XlO 7 cm. per sec. is greater than 

 1"6 centimetres. 



The free paths in hydrogen at a millimetre pressure are 

 indicated by the lower curve in fig. 8 for purposes of 

 comparison. 



Fig. 8. 



ZlfQ 



















150 



































100 







\ -c 



I 



























so 









\ ° 

































■iijdro 



)tn (l 



m. m.) 







f 



10 



4jL %IQ 



-7 



Ik- 



In hydrogen at a millimetre pressure the mean free path / 

 of an electron has a minimum value of '0195 cm. when the 

 velocity u is 7 x 10 7 cm. per sec. As u diminishes I increases, 

 and when w=r3xl0 7 , l = '0U. In nitrogen a minimum 

 value of / equal to '02G occurs when w=9 X 10 7 , and I increases 

 to -057 when ,/ = 2-5xl0 7 . 



It appears from the curves showing I in terms otu that 

 the free paths in hydrogen and nitrogen would continue to 

 increase with further reduction in the velocity, and it is 

 probable that in these gases I attains a maximum value 



3 Y2 



