606 PROCEEDINGS OF THE AMERICAN ACADEMY. 



the analysis at the temperature necessary for the setting free of the in- 

 cluded substances. There are, however, a number of points in previous 

 researches which fall within our general knowledge of chemical equilib- 

 rium, and it is the purpose of the present paper to discuss these and to 

 add some new experimental evidence in the matter. 



The Equilibrium C0 2 + H 2 ^± CO + H 2 0. 



The fundamental conclusion which Hiittner draws from his results is 

 that the carbon monoxide which he finds is formed at the temperature 

 of the experiment by the action of hydrogen on carbon dioxide. Now 

 the results of all the investigations on the water-gas equilibrium show 

 that the equilibrium constant 



T7- CO, H, 



^co ' ^H,0 



is about unity at 800° ; that is to say, at this temperature carbon monox- 

 ide and hydrogen are equally strong reducing agents and carbon dioxide 

 and water vapor are equally strong oxidizing agents. At lower temper- 

 atures carbon monoxide is the stronger reducing agent, while at higher 

 temperatures hydrogen is stronger. 41 



The results of experiments on this equilibrium have shown that under 

 ordinary conditions, where the gases are simply mixed together in a 

 vessel, the reaction 



CO, -f H 2 -> CO + H 2 



has not a measurable velocity at 900°. Hoitsema 42 used the most 

 sensitive tests for carbon monoxide, but could find no trace of this gas 

 even after hours of heating of the reacting mixture at 900°. Hahn 43 

 found the presence of a great surface of platinum necessary to cause 

 the reaction to reach equilibrium even in the space of many hours. It 

 is of course possible that the minerals themselves act as catalyzers for 

 the reaction, but even if equilibrium were completely reached during the 

 progress of the experiment the relative amounts of hydrogen, carbon 

 dioxide, carbon monoxide, and water vapor found in my experiments 

 cannot possibly be represented by the reaction which Hiittner assumes 

 to be fundamental. 



41 Hahn, Ztsch. phys. Chem., 44, 541 (1903). 



42 Ztsch. phys. Chem., 25, 686 (1898). 



43 Ibid., 44, 541 (1903). 



