78 Professor William Arthur Bone [Feb. 28, 



under these conditions than is ethane itself : it is, however, formed in 

 quantity when ethane is oxidised by means of ozone at 100° C. The 

 second stage involves the rapid oxidation of the alcohol to the un- 

 stable CHg . CH(0H)2, which at once decomposes into steam and 

 acetaldehyde. The acetaldehyde is in turn burnt to carbonic oxide, 



steam, smd formaldehyde /possibly through the unstable ho.c.h\ ^nd 



\ ho. 0:0/ 



finally the formaldehyde is burnt to steam and oxides of carbon, 

 probably through formic acid and carbonic acid. 



As the temperature rises, the intermediate products become 

 more and more unstable, and to an increasing extent decompose 

 into simpler products, which then undergo independent oxida- 

 tion. Thus ethyl alcohol decomposes into ethylene and steam, 

 acetaldehyde either into methane and carbon monoxide, or into carbon, 

 hydrogen, methane, and carbon monoxide, according to the tempera- 

 ture, and formaldehyde is resolved into carbon monoxide'' and 

 hydrogen, as follows : — 



Etlnjl Alcohol Acetaldehyde Formaldehyde 



an^oH. CH3.CH0 H.cHo 



OhT+IU) . J ' CH, + C0~^ ( CO +I12 



\C + 2H2 + CO/ 



With the extension of the research to the conditions existing in 

 hydrocarbon flames and explosions, it became increasingly evident 

 that the mechanism of combustion is essentially the same above as 

 below the ignition point. I do not mean, of course, that the 

 phenomena observed at low temperatures, in slow combustion, are 

 exactly reproduced in flames, but rather that the result of the initial 

 molecular encounter between the hydrocarbon and oxygen is probably 

 much the same in the two cases, namely, the formation of an 

 " oxygenated " molecule. At the higher temperatures of flames, 

 secondary thermal decompositions undoubtedly come into operation 

 at an earlier stage, and play a more important role than in slow 

 combustion, but they do not precede the onslaught of the oxygen 

 upon the hydrocarbon, but arise in consequence of it. I am aware 

 that there are eminent critics who, whilst admitting the validity of 

 these views as applied to slow comlmstion, hesitate to accept entirely 

 their extension to explosive combustion. They find it difiicult to 

 believe that such compounds as ethyl alcohol, acetaldehyde, formalde- 

 hyde, and the like, which are undoubtedly very unstable at liigh 

 temperatures, can possibly be formed in flames. But surely this 

 objection involves some confusion of thought as to the factors which 

 govern .the formation and stability of chemical compounds ; the fact 

 that a substance cannot permanently exist at a given temperature 



