﻿Motion of Electrons in Argon and in Hyd/rogen. 4049 



the number of collisions of an electron with molecules of 

 argon at 24 millimetres pressure is less than the number with 

 molecules of hydrogen at one millimetre pressure. 



At the. higher forces the difference between the two gases 

 is less marked. 



The effect of adding 4 per cent, of hydrogen to pure 

 argon may also be seen from the curves. Taking the case 

 where Z is It) and the pressure of argon 24 millimetres, the 

 velocity YV in pure argon is 4'6 x 10 5 cm. per second (as 

 shown by the point on the curve for argon corresponding to 

 Z/p = "666). When hydrogen at one millimetre pressure is 

 added, the velocity is 24 x 40' cm. per second (corresponding 

 to Z/p = 16 on the curve for the mixture). The addition of 

 the hydrogen causes the velocity of agitation to be reduced 

 from 47'4x 40 7 to 822 x 40 7 cm. per second, and this change 

 in v would not be sufficient to account for the increase in W 

 if the mean free path in the argon were unaltered by the 

 change in the velocity of agitation. 



43. The following table gives the mean velocity of 

 agitation u, and the velocity W in the direction of the 

 electric force in a mixture containing 96 per cent, of argon 

 and 4 per cent, of hydrogen by pressure, for different values 

 of the ratio Z//?, Z being the electric force in volts per 

 centimetre and p the partial pressure of the hydrogen. 



Table IV. 



*. 



Z/p. 



wxio- 5 . 



ux\.0~ 7 . 



ImXlO*. 



lh X 10 2 . 



JaXlO 2 . 



4 



•5 



635 



2-3 



2-05 



362 



113 



G 



75 



7-95 



2-82 



2-09 



3-30 



138 



8 



10 



91 



3-26 



2-08 



306 



154 



10 



1-28 



10-0 



364 



1-99 



3-88 



161 



13 



1-72 



11-1 



4-15 



T87 



2-66 



154 



16 



225 



12-2 



4-6 



1-75 



249 



138 



20 



3-25 



136 



5-15 



1-51 



2-29 



110 



, 30 



6 "55 



167 



6-3 



1-12 



1-99 



61'5 



40 



108 



19-0 



7-28 



•89 



1-95 



395 



50 



156 



20-8 



8-14 



•76 



200 



295 



70 



26-0 



235 



9-62 



•61 



2-30 



200 



100 



42-4 



25-4 



11-5 



•48 



2-98 



136 



140 



64-8 



26-5 



136 



•39 



40U 



104 



The mean free paths corresponding to the velocity u given 

 in the last three columns of the table are : l m for a mixture 

 containing hydrogen at one millimetre pressure'and argon at 

 Phil. May. S. 6. Vol. 44. No. 263. Nov. 4922. 3 Y 



