HYDROGEN AND OXYGEN IN CONTACT WITH HOT SURFACES. 
7 
power of many metallic surfaces (and especially nickel) of rendering hydrogen 
“ active ” at comparatively low temperatures. In illustration of their results we need 
only give the following typical instances of direct “ hydrogenations ” effected by 
passing a mixture of the substance in question with hydrogen over finely divided and 
freshly reduced nickel. In this way hydrocarbons of the olefine series were quanti¬ 
tatively converted into the corresponding paraffins at 160°, and benzene yielded 
cyclo-hexane. Nitrobenzene was directly reduced to aniline, whilst nitromethane 
was converted into methylamine at 150° to 180°, and into methane and ammonia at 
350°. The most remarkable results of all, however, were obtained with a mixture of 
carbon monoxide (1 volume) and hydrogen (3 volumes), which the authors state was 
completely transformed into methane and steam when passed over finely divided 
nickel at 250°. 
Whilst there can be no gainsaying the facts relative to the extraordinary 
“ activity of hydrogen when it is condensed or occluded by many surfaces, metallic 
and otherwise, opinions will probably differ as to the cause of the “ activity.” Many 
will attribute it to the dissociation of the hydrogen molecule at the moment of 
occlusion, whilst others will possibly connect it with some influence of hydrogen 
upon the rate of emission of ions by the surfaces involved. The experiments of 
Dr. H. A. Wilson on “ The Discharge of Electricity from Hot Platinum”* are very 
suggestive in this connection. He found that hydrogen has an enormous influence on 
the negative leakage from a clean platinum wire at high temperatures. Thus at 
1350°, for a given potential difference, the leakage in hydrogen, at 0‘014 millim. 
pressure, was 25,000 times greater than the corresponding leakage in air. The 
leakage was, moreover, proportional to the pressure and depended on the hydrogen 
actually occluded by the metal. These experiments were made at much higher 
temperatures than any employed in our research, but Professor J. J. Thomson has 
recently found that the rate of emission of negative corpuscles by alkali metals at the 
ordinary temperatures is greatly increased whilst they are absorbing hydrogen, f It 
should also be mentioned that the Reverend P. J. Kirkby, who has qualitatively 
examined the effects of electrically heating a platinum wire (to circa 275°) in 
electrolytic gas at low pressures (40 millims. and under), concludes that the catalytic 
combination is “ probably connected with the corpuscular discharge which is known 
to be emitted by platinum.It therefore seems possible that the results obtained 
by the above investigators and those recorded in this paper may have a common 
explanation. Whether or not the emission of negative corpuscles by a metal under 
the influence of hydrogen would induce,the combination of the gases immediately in 
contact with the surface is a question for further investigation. 
Our experiments with reducible oxides, and particularly those with copper oxide, 
* ‘Phil. Trans.,’ A, vol. 202, (1903), p. 243. 
t ‘Phil. Mag.,’ 6th series, vol. X. (1905), p. 584. 
J ‘ Phil. Mag.,’ 6th series, vol. X, (1905), p. 467, 
