1"he combustion o] n-heptane-oxygen and propane-oxygen mixtures between 200 ° and 350°C
has been studied using a static system and different reaction vessel surfaces, the oxidation being /ollowed by measuring pressure and temperature changes and by analysis. Using an uncoated vessel cool flames were very readily obtained with n-heptane, the "lower temperature limit" /or a 1 : t mixture being about 230°C compared with 285 ° to 290°C with propane. With the former, packing the vessel or coating it with lead oxide inhibited cool flame formation to some degree, but a potassium chloride coating had little effect. The yield o[ peroxide, particularly of propylhydroperoxide, from the propane combustion was small even at 275°C. With n-heptane at lower temperatures the main peroxidic products were dihydroperoxyheptane and its aldehyde addition compounds, while at high temperatures or after the passage of (i cool flame they were replaced by hydrogen peroxide. Possible elementary reactions occurring in the system, especially those involving the various peroxy radicals, and the role of the surface are discussed. The rate o] internal hydrogen abstraction in alkylperoxy radicals probably governs the relative ease o/ cool flame formation with different hydrocarbons.