GASEOUS COMBUSTION AT HIGH PRESSUEES. 



293 



air.* Prof. THORNTON'S experiments on the ignition by the continuous current of such 

 hydrocarbon-air mixtures have proved that if I is the least igniting current and p the 

 percentage of gas in the mixture, the ratio I/p is nearly proportional to the number 

 of hydrogen atoms in the molecule, a fact which suggests that the initial attack of 

 the oxygen is directed upon the hydrogen atoms in the hydrocarbon molecule ; and 

 inasmuch as any supposition of a preferential burning, in the old sense, of hydrogen 

 is clearly inadmissible on chemical grounds, the " hydroxylation " theory seems to 

 be the only satisfactory substitute. 



With regard to the thermal decomposition of methyl alcohol, CH 3 .OH, it now is 

 definitely established that at high temperatures it is resolved ultimately into carbon 

 monoxide and hydrogen, without any deposition of carbon or steam formation, in 



accordance with the following scheme : t 



H 



CO + H 2 . 



And with regard to dihydroxymethane, CH 2 (OH) 2 , there is little doubt but that 

 at high temperatures it is ultimately resolved into carbon monoxide, hydrogen, and 



steam, as follows : 



H H 



OH 



CO + H 2 . 



If now, the above facts be combined with the corresponding thermal changes, 

 expressed in kilogram-centigrade units per gram-molecule, the scheme for the primary 

 oxidation of methane may be represented as follows : 



A. B. 



oxidation 



wSH a :C:(OH) a 

 H 3 : C OH > H 2 



C. 



oxidation 



CH 4 



+ 30 



I 



+ 59 



-22'8 



a 

 o 



a 



a 

 8 



Pi 



CO + 2H 2 

 B' 



-13'4 



CO + H 2 



C'. 



* 'Roy. Soc. Proc.,' 1914, A, vol. 90, pp. 272-280. 



t BONE and DA VIES, 'Trans. Chem. Soc.,' 1914, vol. 106, pp. 1691-1696. 



2 Q 2 



