IN GASES: HYDROGEN, CARBONIC OXIDE, AND OXYGEN. 
653 
and those made by Bunsen with his chain of sparks given in Table VIL Although 
the path traversed by each flame from the point of ignition is very small in Bunsen’s 
experiments compared with Horstmann’s, yet since the pressures employed by both 
experimenters were near to or above the critical pressures of the mixtures exploded, 
this great difference in the length of column had no effect on the division of the 
oxygen. The same facts also account for the disagreement between my experiments and 
those of Bunsen and Horstmann. For since the first ten experiments in my series 
were made at pressures below the critical pressure of the respective mixtures, both the 
lower pressure and the longer column increase the proportion of carbonic oxide burnt. 
In the four last experiments of this series the increase in the quantity of oxygen 
taken brings the critical pressure below the pressure employed. The results are in 
close accordance with those of Bunsen and Horstmann. 
A third series of pressure experiments was next made with a mixture containing 
only 8 per cent, of oxygen-. 
Composition of Mixture. 
Carbonic oxide.66'28 
Hydrogen.25'66 
Oxygen. 8‘06 
lOO'OO 
This mixture would not explode under 100 millims. pressure. It exploded under 
125 millims. 
Table XX. —Length of column = 400 millims. 
Reference 
Ko. 
Pressure. 
C0 3 
H;0 
Temperature. 
millims. 
° C. 
61 
125 
1-02 
11-3 
62 
150 
1-08 
11-2 
63 
175 
1-09 
11-2 
64 
200 
109 
12-5 
65 
250 
1-09 
7-8 
66 
300 
1-04 
8-6 
67 
400 
1-03 
14-5 
68 
600 
100 
12-4 
69 
1000 
•98 
io-o 
In this series the proportion of carbonic oxide burnt increases at first with increase 
of pressure, reaches a maximum, and then falls continually. No critical pressure 
appeared to be reached as far as the pressure was pushed. If the critical pressure 
for a mixture containing only 8 per cent, of oxygen is above 1000 millims., it follows 
that under this pressure a change in the length of column will affect the division of 
the oxgyen. The following experiments, in which some of the same mixture was 
exploded under 1000 millims. with a short column, prove this to be the case. 
