at Loiu Pressures. 
393 
Table IV. 
The Electric Intensity in the Uniform Positive Column 
in Oxygen. 
Pressure. 
Electric Intensity. 
X 
(P) 
(X) 
Jp 
0*139 
10-3 
27-6 
0-31 
15-5 
27-9 
0-37 
16-3 
27-0 
0-40 
17-2 
27-1 
0-44 
17-7 
26-6 
0-64 
20-7 
25-9 
0-85 
24-3 
26-4 
Mean 26*9 
The Hall Effect and Electric Intensity in oxygen are therefore 
H — 
given by the equations Z = 3’79 x 10~ 3 — , and X = 26 - 9 Vp. 
In the previous paper it is shown that in a uniform part of 
the discharge 
Z=\HX(k 2 -k x ), 
k 2 and k x being the velocities of the negative and positive ions 
respectively due to one volt per cm. Consequently for hydrogen 
we have 
, _ 2Z 
kl ~HX 
2 x 2-05 x 10- 2 
28 
p- 1 - 5 = 1 *47 x 10 -3 j9 -1 ’ 5 
This must be multiplied by 10 8 to get k 2 — k x in cms. per 
second, so that 
h-h = 1-47 x 10 5 p- 1 - 5 — . 
1 sec. 
The value of k 2 — k x found in air was T42 x 10 5 p -1 ' 5 . For 
oxygen in the same way 
k 2 k x — 
2 x 3 79 x lO" 3 x 10 8 
~W9” 
p-i-5— 2S2 x 10 4 p -1 * 5 . 
It thus appears that k 2 — k x in the uniform positive column in 
oxygen is only about one-fifth of k 2 — k x in hydrogen or air. 
