DISCHARGE FROM xMETALLIC SURFACES IN DIFFERENT GASES. 
445 
Table I. 
Potential to wLicli 
zinc is charged 
Current from zinc 
surface in liydrogen in electrometer scale divisions 
pressure being— 
in 10 seconds, the 
^ in cells. 
(1 cell = 21 volts.) 
760 3.51 
101 
49 -5 
20 
8 
3 -3 
0-70 
0-27 
0 -13 
0-003 
760 
millims. millims. 
millims. 
millims. 
millims. 
millims. 
millims. 
millim. 
millim. 
millim. 
millim. 
millims. 
4 
21 
29 
48 
71 
108 
118 
92 
89 
67 
20 
16 26 
40 
51 
80 
111 
158 
213 
149 
131 
16 
40 
- - 
— 
— 
— 
— 
280 
412 
240 
_ 
_ 
60 
- - 
64 
77 
116 
204 
— 
— 
_ 
140 
- ■ 
__ 
SO 
- - 
— 
— 
— 
338 
— 
_ 
_ 
_ 
- 
_ 
100 
34 44 
76 
100 
167 
— 
_ 
_ 
142 
_ 
33 
140 
- - 
— 
— 
303 
— 
— 
_ 
_ 
144 
- 
180 
43 61 
98 
145 
— 
— 
— 
— 
158 
67 
45 
J liese results cau be seen more clearly from fig. 4, where the curves comiectiiig the 
currents and jioteiitial difierence at the difierent pi'essures are plotted. The curves 
corresponding to the three lowest pressures are shown hy dotted lines to avoid 
confusion. 
Ihe results of a further set of observations, showing more fully than the above the 
variation of the photo-electric current at very low pressures, are given in Table II. 
The distance between the electrodes was again 3’5 millims., and 1 volt on the electro¬ 
meter corresponded to a deflection of 7G divisions. The illuminated electrode was, as 
