PEOrESSOE BUNSEN AND DE. H. E. EOSCOE’S PHOTO-CHEMICAL EESEAECHES. 393 
The first column, as before, contains the times of the observations in minutes, the 
following ones the volumes of hydrochloric acid formed by insolation in one minute. 
The mean action of the normal gas before and after the experiment amounted to 48‘8. 
On addition of of oxygen the mean action diminished to 4' 7, and by addition 
of of oxygen it sank to 1’3. These experiments show, — 
(1) That the combining power of the chlorine and hydrogen mixture undergoes a 
much greater diminution in the presence of oxygen than of hydrogen ; so much so, that 
the maximum induction of the normal gas in presence of xi^o of oxygen diminished 
from 100 to 9*7, and in presence of iwo from 100 to 2-7. 
(2) That the diminished maximum of induction efiected by the catalytic action of the 
oxygen is attained by exposure to light in a much less time than the larger maximum 
of the normal gas. 
The following experiments show the catalytic action which an excess of chlorine exerts 
upon the normal mixture. The somewhat considerable irregularities seen in a few of 
the determinations arise from capillary resistances in the observation-tube, and therefore 
disappear when the mean of a number of observations is taken. 
Series of Experiments VIII. 
Time of 
observation. 
Normal gas, 
before 
experiment. 
Ditto, after 
experiment. 
Ditto, with 
i'o'oo 
of chlorine. 
Ditto, with 
7 a 
1000 
of chlorine. 
Ditto, with 
18 0 
1000 
of chlorine. 
0 
1 
8*3 
3-1 
2*1 
2-1 
0-0 
2 
20-8 
14-6 
6*7 
2-6 
0-0 
3 
26-1 
55*9 
14-8 
10-9 
0-0 
4 
35*3 
56*0 
26-0 
21-9 
13-6 
5 
43*5 
57-3* 
34-0 
25-9 
13-5 
6 
50-2 
32*9 
30-2 
18-8 
7 
60-0* 
37-4* 
26-0 
19*8 
8 
61-0 
36-0 
27-6 
23-4* 
9 
? 
39-5 
29*1* 
25-3 
10 
60-0 
35-0 
31-5 
? 
11 
35-0 
30-5 
25-9 
12 
35-0 
30-5 
24-0 
13 
26-5 
23'0 
14 
29-5 
24*0 
The results, obtained from the experiment before us, show — 
(1) That the catalytic action which chlorine exerts on the photo-chemical induction is 
very much less than that effected by oxygen or hydrogen, and that the mean maximum 
action diminishes when y^g p chlorine is present from 100 to 60-2, and when y op -Q chlo- 
rine is present from 100 to 50'3, and when y^^ chlorine is present from 100 to 41-3. 
It appeared to us of great interest to determine the action which the presence of 
hydrochloric acid exerts on the normal chlorine mixture. If the action were as con- 
siderable as was found with the gases just mentioned, the indications of the instrument 
would not be constant when (as is often required) various-sized insolation-vessels are 
MDCCCLVII. 3 F 
