670 
MR. H. E. DIXON ON CONDITIONS OF CHEMICAL CHANGE 
Table XLI.—Temperature of Eudiometer = 90° C. 
Reference 
No. 
X 
Before the explosion. 
After the explosion. 
Pressure. 
n. 
Oxygen. 
Carbonic 
oxide. 
Hydrogen. 
Carbonic 
oxide. 
Carbonic 
acid. 
Hydrogen. 
Steam. 
millims. 
130 
11-5 
4G7 
53-3 
41-1 
.5-6 
35'7 
17*5 
400 
3-6 
131 
4D3 
5-4 
35-6 
177 
600 
3-8 
132 
41-4 
5-3 
35-5 
17-8 
800 
3-9 
133 
>5 
n 
41-4 
5-3 
35'4 
17-8 
1000 
39 
The “ critical pressure ” of this mixture is near 1000 millims. 
From these series of experiments at a high temperature it appears that when the 
proportion of oxygen is low, the division of the oxygen varies with changes of pressure 
even beyond 2 metres of mercury. As the proportion of oxygen is raised, the point is 
sooner reached at which no further increase of pressure affects the result. In these 
experiments no condensation of steam was possible during the reaction. 
These experiments also show that a variation in the quantity of oxygen from 11*5 
to 15 4 (for every hundred of the combustible gases) has no effect on the coefficient a. 
According to Horstmann this coefficient varies from 3'8 to 5‘6 when the proportion of 
oxygen is increased from 10 to 15 parts for every 100 of combustible gases. In the 
following experiments larger proportions of oxygen, increasing from 17'5 to 38’6 parts, 
were exploded with a mixture containing three of carbonic oxide to one of hydrogen. 
In each case the explosion was made under a pressure of 1000 millims. of mercury. 
Table XLII. 
.Reference 
No. 
Before the expl 
Dsion. 
After the explosion. 
Oxygen. 
Carbonic 
oxide. 
Hydrogen. 
Caibonic 
oxide. 
Carbonic 
acid. 
Hydrogen. 
Steam. 
Temperature. 
a. 
97 
17-5 
733 
267 
53-6 
197 
11-4 
153 
0 C 
80 
37 
134 
26-3 
75-3 
247 
4D3 
34-0 
67 
18'6 
37 
135 
27-2 
757 
24-4 
39-8 
35-9 
5-8 
18'6 
36 
136 
30-5 
75-3 
247 
34-5 
40‘8 
47 
20-0 
36 
137 
38-6 
75-3 
247 
20-6 
547 
23 
22‘4 
r> 
3-6 
The increase in oxygen from 17*5 to 38 - 6 for 100 of the combustible gases produces 
only the slight change in the coefficient from 37 to 3'6. 
According to Horstmann, this change in the quantity of oxygen should be 
accompanied by a fall in the coefficient from about 6 to 4'5. 
With a mixture containing three times as much hydrogen as carbonic oxide a 
