IN GASES: HYDROGEN, CARBONIC OXIDE, AND OXYGEN. 
G5 7 
Table XXIV. 
Volume of nitrogen 
added to 100 volumes 
of carbonic oxide 
and hydrogen. 
Volume of burnt gas< s 
in 100 volumes of 
carbonic oxide, 
hydrogen and nitrogen. 
Coefficient 
Found. 
of affinity. 
Calculated. 
60 
20 
37 
4'0 
1 TT 
75 
23 
4-3 
4-4 
> —-96 
113 
28 
5-1 
53 
J cu J0 
70 
22 
4'4 
43 
1 IT 
90 
25 
52 
47 
>—4=3-03 
115 
28 
5'8 
5-2 
J CO 
59 
20 
37 
3-9 
d 
80 
23 
4-7 
4-5 
| IT 
99 
26 
4’8 
4-9 
X *=1-041 
114 
28 
6-2 
5-2 
[ CO ‘ 
125 
30 
53 
53 
J 
These coincidences, Horstmann considers, prove that the presence of the nitrogen 
affects the coefficient in the same way as the presence of an equal quantity of 
carbonic oxide or hydrogen, and point to the conclusion that the constancy of the co¬ 
efficient of affinity in the different experiments depends upon a similarity of physical 
conditions. 
In two later papers Horstmann* has shown that when carbonic acid is added to 
the mixture previous to explosion, more hydrogen and less carbonic oxide is burnt 
than when the mixture is fired without carbonic acid. When a mixture of carbonic 
acid and hydrogen is exploded with insufficient oxygen to burn all the hydrogen some 
of the carbonic acid is reduced to carbonic oxide. 
The influence of carbonic acid, he says, is not the same as that of nitrogen, 
but resembles it; direct experiments show that it is impossible to replace the excess 
of combustible gases in part by carbonic acid, without altering the coefficient of 
affinity. Carbonic acid, which has a higher specific heat than the simpler gases, pro¬ 
duces a greater effect than an equal volume of nitrogen, hydrogen, or carbonic oxide. 
This fact confirms the earlier conclusion that the coefficient not only depends upon the 
percentage of oxygen, but also on the temperature of combustion. Steam acts in 
a manner analogous to carbonic acid. Such are Horstmann’s conclusions as to the 
function of inert gases in the explosive mixture. But in one paragraph he views the 
reaction in a different light 
“The burning appears as a preliminary of secondary importance, through which are 
established the conditions antecedent to the reactions coming particularly into con¬ 
sideration. The chemical equilibrium is brought about by the two reciprocal trans¬ 
formations between carbonic acid and hydrogen on the one hand, and carbonic oxide 
* Ber. Deut. Ch. Ges., x., 1628; xii., 64. 
4 P 
MDCCCLXXXIV. 
