ACTION OF LIG-HT ON SELENIUM. 
327 
Interval between 
observations. 
Direction of 
current. 
Resistance in 
megobms. 
Number of cells. 
minutes. 
0 
+ 
•03175 "1 
7 
— 
•03155 | 
1 
2 
5 
+ 
•03191 1 
6 
- 
•03182 J 
8 
+ 
•03080 "j 
5 
— 
•03035 j 
o 
6 
+ 
•03080 
>■ 
o 
8 
•03036 J 
35 
— 
•02952 ] 
1 
10 
+ 
•03005 
4 
9 
— 
•02954 
8 
+ 
•03007 J 
8 
+ 
•02932 ] 
7 
— 
•02885 | 
5 
8 
■ + 
•02945 | 
9 
— 
•02900 J 
10 
_ 
•02840 1 
I 
7 
+ 
•02892 
6 
6 
— 
•02852 | 
6 
+ 
•02887 ] 
1 
9 
+ 
*02832 ] 
i 
6 
— 
•02809 
7 
8 
+ 
•02842 | 
A 
7 
— 
•02805 J 
1 
4 
_ 
"•03155 1 
' 
2 
+ 
*03175 J 
\ 
At 
A similar set of observations made with tube No. 14, but only taking two observations 
for each change of battery-power, gave the following results : — 
Interval of the 
observations. 
Direction of 
current. 
Resistance in 
megobms. 
Number of cells. 
minutes. 
0 
+ 
•5000 1 
o 
7 
— 
•4820 J 
At 
6 
— 
•4770 1 
A 
7 
+ 
•4795 J 
TC 
8 
+ 
•4620 1 
5 
*4697 J 
O 
5 
_ 
•4630 \ 
Q 
3 
+ 
•4560 J 
o 
17 
+ 
•4440 1 
10 
6 
— 
•4589 J 
In the second experiment with the battery of 6 cells the current was kept on for more 
than a minute, producing a considerable increase in the resistance ; and the consequence 
of this was that afterwards all the resistances taken with the negative exceeded the 
corresponding ones taken with the positive current. 
