IN GASES: HYDROGEN, CARBONIC OXIDE, AND OXYGEN. 
675 
(1) CO +H 3 0=C0 3 +H 3 
(2) C0 3 +H 3 = CO +h 3 o 
So that at the end of the reaction the product of the carbonic oxide and steam 
molecules is equal to the product of the carbonic acid and hydrogen molecules multi¬ 
plied by a “coefficient of affinity.” This result agrees with Horstmann’s conclusion ; 
but Horstmann considers the coefficient to vary with the relative mass of oxygen 
taken. 
5. A small difference in the initial temperature at which tire gases are fired makes 
a considerable difference in the products of the reaction. This difference is due to 
the condensation of steam by the sides of the vessel during the explosion, and its 
consequent removal from the sphere of action during the chemical change. When the 
gases are exploded at a temperature sufficiently high to prevent any condensation of 
steam during the progress of the reaction, the coefficient is found to be constant 
whatever the quantity of oxygen used, provided that the hydrogen is more than 
double the oxygen. 
6. The presence of an inert gas, such as nitrogen, by diminishing the intensity of 
the reaction fa vours the formation of carbonic acid in preference to steam. When the 
hydrogen is less than double the oxygen the excess of oxygen cannot react with any 
of the three other gases present—carbonic oxide, carbonic acid, and steam—but has 
to wait until an equal volume of steam is reduced to hydrogen by the carbonic oxide. 
The excess of inert oxygen has the same effect as the inert nitrogen in favouring the 
formation of carbonic acid. 
The variations in the coefficient of affinity found by Horstmann with different 
quantities of oxygen are due partly to this cause, but chiefly to the varying amounts 
of steam condensed by the cold eudiometer during the reaction in different experi¬ 
ments. 
7. As the general result of these experiments, it has been shown that when a 
mixture of carbonic oxide and hydrogen is exploded with insufficient oxygen for 
complete combustion, at a temperature at which no condensation of steam can take 
place during the reaction, and at a pressure greater than the critical pressure, an 
equilibrium between two opposite changes is established, which is independent of the 
quantity of oxygen taken, so long as this quantity is less than half the hydrogen. 
Within the limits marked out above, the law of mass is completely verified for the 
gaseous system composed of carbonic oxide, carbonic acid, hydrogen, and steam at a 
high temperature. 
The experiments described in this paper were made partly in the laboratory of 
Christ Church, and partly in the laboratory of Balliol College, Oxford. I desire to 
express my sincere thanks to Mr. A. G. Vernon Harcourt and to Mr. W. Esson for 
their constant help and advice in all stages of the inquiry, and to the Government 
Grant Committee of the Royal Society for giving me the leisure and the appliances to 
complete this research. 
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