Combustion preferential theory

Although, as has already been mentioned (see p. 59), preferential combustion may take place in the presence of certain catalysts, the theory as applied promiscuously to all cases of combustion leads to many difficulties. For example, when methane is exploded with its own volume of oxygen—that is, a volume insufficient for complete combustion—hydrogen and carbon monoxide are produced as well as water-vapour, m accordance with the equation... 

Cause of Luminosity.—In 1815 Davy 1 suggested that the luminosity of a candle flame is due to the presence of minute particles of carbon at white heat. These particles were believed to be produced by incomplete combustion of the hydrocarbon vapours in the restricted supplies of air available within the flame, the hydrogen of the vapours being preferentially oxidised (see p. 64), leaving the carbon to shift for itself. This theory was generally accepted for many years, and it was not until 1867 that a rival theory wras projected by Frankland,2 according to which the luminosity of the flame is due to radiations from dense but transparent hydrocarbon vapours. ... 

The early theory of methane oxidation assumed that carbon and water ware tile initial products of reaction or that hydrogen burned preferentially to carbon. However, in 1861 Kersten0 declared that carbon monoxide and hydrogen were the primary products, and that although some free carbon may form at times, the carbon is normally oxidized to carbon monoxide before the hydrogeu is reacted upon. This idea, later revived by Misterli,7 involves the preferential combustion of carbon and is thus directly opposed to the hydroxylation theory. Tins theory might possibly apply to the case of acetylene combustion, since this hydrocarbou is sufficiently unstable as to explode alone under certain conditions, but cannot hold for the more saturated hydrocarbons which do not explode alone. 

Armstrong at first inclined to the view that hydrogen burns preferentially to carbon, whilst Stokes thought it more likely that carbon burns preferentially to hydrogen. Armstrong does not seem to have advanced the hydroxylation theory to explain the combustion of hydrocarbons until 1902. ... 

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