234 
IOWA ACADEMY OP SCIENCE Vol. XXIV, 1917 
experimental results by Dr. F. C. Brown 3 , and the writer (loc. 
cit.) such atmospheres of any appreciable depth must have very 
low density values. At present the writer favors the view that 
the conduction currents are due to ions of some kind between the 
plates. 
TABLE ii. 
Curve 
D. 
Curve 
E. 
Curve 
C. 
t (mins.) 
D 
t 
D 
t . 
D 
0.00 
40 
0.0 
72 
0.0 
76.5 
0.25 
36 
0.5 
63 
0.5 
68 
0.50 
33 
1.0 
56 
1.0 
61 
0.75 
30.5 
1.5 
49 
1.5 
55 
1.00 
28 
2.0 
43 
2.0 
49 
1.25 
25.5 
2.5 
38 
2.5 
44.5 
1.50 
24.5 
3.0 
40 
1.75 
23 
3.5 
36.5 
2.00 
21.5 
Department of Physics, 
The State University. 
3 Physical Review, Vol. II, No. 4, p. 314, Oct., 1913. 
