ON GASEOUS COMBUSTION. 469 



Report on Gaseous Combustion. 

 By William Arthur Bone, D.Sc, Ph.D., F.R.S. 



[Ordered by the General Committee to be printed in extenso.] 



[Plate VII.] 



[This Report aims at summarising the results of the principal researches upon the 

 chemical aspects of gaseous combustion during the past thirty years.] 



Synopsis. 



Introduction. — The earlier work of Davy and Bunsen. The latter's erroneous 

 assumption of ' discontinuity ' in gaseous combustion. The new era inaugurated 

 by the investigations of Mallard and Le Chatelier, Berthelot and Vieille, and of 

 H. B. Dixon and H. B. Baker. 



Section I. Ignition Temperatures and the Initial Phases of Gaseous Explo- 

 sions. — Slow combustion below the ignition-point. Recent determinations of igni- 

 tion temperatures by H. B. Dixon and H. F. Coward. Rates of ignition. Photo- 

 graphic researches of Mallard and Le Chatelier and of H. B. Dixon and his pupils 

 upon the initial phases of gaseous explosions and the influence of reflected 

 compression waves in accelerating combustion and determining detonation. Dis- 

 covery of ' retonation ' and its bearing upon the question of residual or continued 

 combustion in gaseous explosions. 



Section II. The Explosion Wave. — Discovery by Berthelot and Vieille of 

 ' detonation ' {I'onde explosive) in gaseous explosions. Theories advanced by 

 Berthelot, H. B. Dixon, and D. L. Chapman respecting rates of explosion. 

 Influence of inert gases upon rates of explosion. Inferences to be drawn from 

 observed rates of explosion respecting the combustion of gaseous carbon and 

 of hydrocarbons. 



Section III. The Pressures produced in Gaseous Explosions. Experiments 

 by Bunsen in 1867, by Mallard and Le Chatelier in 1883, and by Berthelot and 

 Vieille in 1885. Discussion of the reasons why the maximum pressures ordinarily 

 observed in gaseous explosions are always considerably less than those calculated 

 on the supposition of adiabatic conditions and the constancy of the specific heats 

 of the products. Evidences that (1) increases in the specific heats of steam 

 and carbon dioxide with temperature, (2) continued combustion, and (3) loss of 

 heat by direct radiation from explosion flames, affect the maximum pressures 

 observed. Possible influence of dissociation. 



Section IV. The Influence of Moisture upon Combustion. — Discovery by 

 H. B. Dixon of the non-inflammability of a thoroughly dried mixture of carbon 

 monoxide and oxygen. H. B. Baker's researches. Instances in which gaseous 

 combustion is apparently independent of the presence of water vapour. Theories 

 respecting the function of steam in combustion. 



Section V. The. Combustion of Hydrocarbons. — Disproof of the older ideas 

 of preferential combustion, whether of hydrogen or of carbon. Theory of the 

 intermediate formation of 'oxygenated' or ' hydroxylated ' molecules in hydro- 

 carbon combustion as suggested by the author's researches. Schemes representing 

 the combustion of typical hydrocarbons. Presence of water vapour not essential 

 in hydrocarbon combustion. Outward differences between the partial combustion 

 of defines and paraffins. The much greater affinities of hydrocarbons as com- 

 pared with hydrogen or carbonic oxide for oxygen at high temperatures. 



Section VI. The Influence of Hot Surfaces upon Combustion. — The earlier 

 researches and theories of Davy, Dulong and Thenard, William Henry, Thomas 

 Graham, Dobereiner, Fusinieri, Faraday, and De la Rive. Surfaces as accelerators 

 of gaseous combustion. The factors operative in ' surface combustion ' as revealed 

 by recent investigations. The ' activation ' of hydrogen by heated surfaces. The 

 electrical condition of surfaces during surface combustion. 



