494 REPORTS ON THE STATE OF SCIENCE. 



mainly carbon monoxide and hydrogen without any separation of carbon, 

 similar mixtures of paraffins and oxygen — namely, C„Hvn +.2 + ^0., — yie 



carbon, oxides of carbon, methane, hydrogen, and steam all in consider- 

 able quantities. (2) That, even in the case of an define, if the proportion 



of oxygen be reduced below that indicated by the expression C„H._. n + -0.,, 



both carbon and steam are prominently formed. 



In his presidential address to this Section at the Leicester meeting in 

 1907, Smithells criticised the writer's interpretation of explosive combus- 

 tion on the ground that ' the isolation of an intermediate product under 

 one set of circumstances is in itself no proof that this product is tran- 

 sitorily formed when the reaction is proceeding under another set of 

 circumstances.' To this criticism it may be replied (1) that there is 

 direct experimental proof of the formation of intermediate aldehydic 

 products in hydrocarbon flames and explosions; (2) that notwithstand- 

 ing the fact that the combustion of hydrocarbons has now been investi- 

 gated over a range of temperature extending from that of incipient 

 oxidation right up to the extreme conditions prevailing in detonation, 

 no evidence has yet come to hand which warrants the assumption 

 of any discontinuity in the immediate result of the initial encounter 

 between hydrocarbon and oxygen molecules ; and (3) that the theory 

 of the intermediate formation of ' hydroxylated ' or ' oxygenated ' 

 products furnishes a complete and sufficient explanation of the facts 

 of hydrocarbon combustion as at present known, a requirement 

 which no other alternative theory yet put forward is capable of satisfy- 

 ing. In this connection the writer is glad to find support in the recent 

 presidential address of H. B. Dixon to the Chemical Society, where, 

 speaking of the detonation of a mixture of equal volume of ethane and 

 oxygen, he says: ' The ethane is not burnt wholly to carbon monoxide 

 and hydrogen, but appears to form (as Professor Bone has shown at 

 lower temperatures) acetaldehyde and steam, the aceialdehyde yielding 

 methane and carbon monoxide.' * 



But to return to the consideration of facts : One of the most signifi- 

 cant features of the writer's experiments has been the proof afforded of 

 the relatively much greater affinity of hydrocarbons, as compared with that 

 of either hydrogen or carbon monoxide, for oxygen at the high tempera- 

 tures of flames. Thus when a mixture of acetylene and electrolytic gas 

 corresponding to C 2 H 2 + 2H 2 + 2 is exploded, there is absolutely no 

 separation of carbon or formation of steam, and practically the 

 same thing holds good in the case of a mixture of ethylene, 

 hydrogen, and oxygen corresponding to C 2 H 4 + H 2 + 2 . In each 

 case the hydrocarbon is burnt to (ultimately) carbon monoxide 

 and hydrogen, just as would be the case were . no hydrogen 

 originally present in the mixture. Becently the writer in an 

 unpublished research on the division of oxygen between methane and 

 hydrogen, in which mixtures corresponding to CH 4 + 2 + xH 2 (a; = 2, 4, 

 6, or 8) have been exploded at high initial pressures, has proved that 

 with x — '2 upwards of 95 per cent, of the oxygen initially reacts with 



1 Trans. Chem. So',., 1910. 97, 605. 



