688 Prof. J. S. Townsend and Mr. V. A. Bailey on 

 Table VI. — Oxygen. 



1-81 x 10" 



z 













» 



p 



Jc. 



wxio- 5 . 



«xl0~ 6 . 



Jxioo. 



<7X10 S . 



/. 



50 



136 



201 



134 



3 74 



1-57 



0-9775 



20 



70 



86 



96 



2-89 



1-78 



0-9919 



14 



55-5 



61 



855 



2-57 



1-89 



0-9949 



10 



50 



46 



81-2 



2-58 



1-88 



0-9968 



6 



45 



36 



77-1 



3-22 



1-69 



0-9978 



2 



22\5 



30 



54-5 



5-6 



1-27 



0-9969 



Table VII.— Air. 

 o - 1 = l-85xl0- 8 . 



z 



V 



k. 



wxio- 5 . 



wxio- 6 . 



/xioo. 



<rxl0 8 . 



/■ 



100 



J 60 



270 



145 



| 2-72 



1-84 



0-9654 



60 



102 



173 



116 



I 2-78 



1-82 



0-9778 



20 



57 



90 



87 



! 271 



1-84 



09893 



10 



46 



52 



78 



2-82 



1-80 



09956 



5 



38 



30 



71 



2-96 



1-76 



99823 



2 



22 



175 



54 



3-28 



1-67 



099897 



1 



11 



12-5 



38 



I 3-30 



1-67 



099894 



0-5 



5-7 



9 



27 



! 3-37 



i 



1-65 



099891 



The values of a depend on the velocity u with which the 

 electron collides with a molecule, and attain a maximum 

 value within the range of the velocities that have heen 

 measured. 



It will be noticed that for velocities u less than 1*2 X 10 8 

 cr is greater for hydrogen than for nitrogen, so that the field 

 of force round a molecule as measured by a charged particle 

 of small mass is wider for a molecule of hydrogen than for 

 a molecule of nitrogen. 



13. The determination of the velocities may be used to 

 find what proportion of the total energy of an electron is 

 lost by a collision with a molecule. An approximate esti- 

 mate of the average loss of energy at each collision to the 

 average energy (mu 2 /2) of an electron is easily obtained. 

 In passing through a distance of one centimetre in the 

 direction of the electric force in the time 1/W, the electron 

 acquires the amount of energy Ze, and in the steady state 

 when the motion has attained the final value corresponding 

 to the force Z this energy is transferred to the molecules of 

 the gas. The total path traversed by the electron in the time 



