the Motion of Electrons in Gases. 



877 



the diagram fig. 2) is the same for all gases and independent 

 of the pressure, and will be referred to as the normal 

 distribution curve. 



Fig. 2. 



0-7 



0-6 

 0-5 

 0»4 



0-3 l~ 



0-2 



0-1 





| 



1 











^~ 





' 





^1 





: 



R 



\ \ 



i 



^\ 



i 







r 



i 













! 





2 



R 







/ 



/^ 



i 







C>I3 5 



i 



0-1 



0-!6S 







/ 





\ 





0-2 



0-208 



0-5 



0-314 











i 

 1 





1 -0 



0-425 







7] 



!-5 



0-506 



2-0 



0-570 







2-5 



0-61 9 



' 



1 









3-0 



0-56 1 







3-5 



0-696 



4-0 



0-725 













i 



Z 











O 0-5 S 1-5 2-5 3 3-5 



It is to be noticed that when the normal distribution of 

 the stream is determined experimentally, it is necessary that 

 the conditions should be arranged so that the self-repulsion 

 of the ions does not contribute to the divergence of the 

 stream. The currents should therefore be small and the 

 experiments made at low pressures, since the effect of self- 

 repulsion is directly proportional to the intensity of the 

 current and inversely proportional to the velocity of the 

 ions. 



5. Generally when the gases are very dry the elec- 

 trons move freely between the molecules of the gas and they 

 acquire an energy of agitation exceeding the value corre- 

 sponding to thermal equilibrium with the gas, as shown 

 by an abnormal divergence of the stream. If k be the factor 

 by which the energy of agitation of the electrons exceeds 

 that of the molecules of the gas, the ratio R becomes 

 R=/(N*Z/HI), Thus when the ratio R corresponding to a 

 force Z is found experimentally, the value of k is equal to 



