AND CHLORINE UNDER THE INFLUENCE OF LIGHT. 
85 
I. 
IT. ! 
Number 
of illumination. 
Expansion. 
Number 
of illumination. 
Expansion. 
1 
1 
3 
1 
7 
2 
4 
2 
11 
3 
6 
3 
14 
4 
6 
4 
22 
5 
6-5 
5 
20 
6 
8 
6 
23 
7 
7 
7 
33 
8 
12 
8 
30 
9 
11 
9 
25 
10 
11 
10 
33 
11 
12 
11 
30 
HI. 
IV. 
Number 
of illumination. 
Expansion. 
Number 
of illumination. 
Expansion. 
1 
10 
1 
28 
2 
12 
2 
39 
3 
14 
3 
37 
4 
20 
4 
44 
5 
26 
5 
46 
6 
29 
6 
51 
7 
35 
7 
60 
8 
33 
8 
73 
9 
35 
— 
— 
10 
45 
— 
— 
11 
1 
39 
After IV. the same gas was allowed to remain in the dark for three minutes, and 
was then again illuminated for one second. The expansion was 52. The mixture 
was again allowed to remain dark for six minutes, and the expansion for one second 
illumination was 29. Therefore in three minutes the gas has not attained its original 
condition. But six minutes is enough as far as the expansion is concerned to enable 
the gas to return to its initial state. 
These experiments conclusively show that the expansion, for a definite quantity of 
light, depends not only on the amount of light, but also on the condition of the gases. 
In other words, the expansion is dependent on the state of the indnction. 
In every case in the above experiments some hydrochloric acid was formed, and 
the position of the index was such, therefore, that in each series of experiments a 
longer column of water had to be moved in each expansion than in those preceding 
it. The expansion, therefore, in any case is probably a little too small compared 
