FLAMELESS COMBUSTION ELLIS. 641 



conversely, may be diminished by previous contact with oxygen. 

 Again, there is abundant evidence that the actual surface combustion 

 is dependent upon a prior "absorption" (or condensation) of the 

 combustible gas, and possibly also of the oxygen, by the surface. To 

 what extent oxygen is involved, is not as yet perfectly clear. The 

 "absorbed" (or condensed) gas becomes "activated" (probably 

 "ionized," as the physicists would call it) by association with the 

 surface. Finally, certain important differences have been established 

 between ordinary homogeneous combustion and heterogeneous sur- 

 face or flameless combustion. Thus, for example, whereas the 

 presence of water vapor certainly accelerates, if it is not essential 

 to, the homogeneous combustion of carbon monoxide, it greatly re- 

 tards the heterogeneous combustion of the same gas in contact with 

 a surface such as fire-clay. Again, whereas methane has, in ordinary 

 flames, a much greater affinity for oxygen than either hydrogen or 

 carbon monoxide, a hot surface, by virtue of some " selective " action, 

 will completely reverse this usual order of things — a remarkable 

 circumstance, than which no better proof could be afforded of the 

 reality of surface combustion. 



In a discussion before the British Association in 1910, Sir J. J. 

 Thompson insisted that combustion is concerned not only with atoms 

 and molecules, but also with electrons — i. e., bodies of much smaller 

 dimensions and moving with very high velocities — and suggested that 

 " in reference to the influences of hot surfaces in promoting com- 

 bustion, to which Professor Bone has drawn attention, it was not 

 improbable that the emission of charged particles from the surface 

 was a factor of primary importance." Those who have followed 

 recent developments of the corpuscular theories of electrical action 

 will recall the experimental proof that incandescent surfaces emit 

 enormous streams of electrons, traveling with high velocities; and 

 the action of such surfaces in promoting combustion may ultimately 

 be found to depend on the fact that they bring about the formation 

 of layers of electrified gas, in which chemical changes proceed with 

 extraordinary rapidity. 



A distinguishing feature of the new processes employing flameless 

 combustion is, that a homogeneous explosive mixture of gas and air, 

 in the proper proportions for complete combustion (or with air in 

 slight excess), is caused to burn without flame in contact with a 

 granular incandescent solid, whereby a large proportion of the poten- 

 tial energy of the gas is immediately converted into radiant form. 

 The advantages claimed for the new system, are: (1) The combus- 

 tion is greatly accelerated by the incandescent surface, and may be 

 concentrated just where the heat is required; (2) the combustion is 

 perfect with a minimum excess of air; (3) the attainment of very 



44S63°— SM 1913 41 



