380 



TRANSACTIONS OP SECTION B. 



between methane and liydiogen in the two sets of experiments were as 

 follows : 



Distribution of Oxygen ivhen Mixtures CHj + On+xH, are cxiiloded. 



It is at once evident from the results with the mixture CH^+O^+SH^ 

 that the affinity of methane is at least twenty to thirty times greater than 

 that of hydrogen for oxygen in explosion flames. The actual distribution of 

 oxygen when a particular mixture is exploded is undoubtedly influenced to some 

 extent by the walls of the containing vessel, but not, so lar as I have been 

 able to ascertain, by the absolute initial pressure. Moreover, it is evident that 

 the influences of successive increases in x, the volume ratio of H^ to CH^ in the 

 mixture exploded, upon the actual oxygen distribution for a given explosion 

 is proportionate to x", which can hardly mean other than that in explosion 

 flames hydrogen is kllrectly burnt to steam, and not, as many have supposed, 

 ■via the intermediate formation of hydrogen peroxide. 



A similar series of experiments with mixtures GYi^ + O^+xCO show that 

 whilst it is impossible, owing to circumstances which I need not here detail, 

 to deduce, even approximately, any numerical relation between the affinities 

 of methane and carbon monoxide for oxygen in flames, yet we can confidently 

 say that the affinity of the hydrocarbon is again vastly the superior, although 

 carbon monoxide is apparently more effective than hydrogen in pulling away 

 oxygen from the predominating attraction of methane. 



Having thus satisfactorily disposed of the question of relative affinities of 

 the three gases for oxygen in explosion flames, it remained to jirove whether or 

 not such chemical factors determine the ratio of attainment of maximum 

 pressure in explosions, by exploding mixtures of each of the three combustible 

 gases with air, in such proportions as correspond with the primary oxidation, 

 namely: (1) CH, + 02+4N,, (2) 2H, + 0„+4N„ and (3) _2CO + 0„+4N„ 

 at initial pressure of from 45 to 50 atmospheres in the spherical Bomb B to 

 which was attached a Petavel recording manometer with its optical accessories. 



The pressure records which are reproduced in the following diagrams (figs. 

 5, 6, and 7), in which pressures in atmospheres are plotted against time in 

 seconds, prove conclusively the absence of any direct relation between the 



2 4 6 8 10 15 20 25 30 



TIME INy^SECONOS 



' After Firing 



Fig. 5. 



actual rate at which the potential energy of an explosive mixture is transferred 

 on explosion as sensible heat to its products and the magnitude of the chemical 

 affinity between its combining constituents. This is hardly to be wondered at, 



