AT the general discussion upon explosive reactions in gaseous media, held in London on June 14 under the auspices of the Faraday Society, Prof. R. V. Wheeler and Dr. W. Payman presented a paper on the uniform movement during the propagation of flame, in which they emphasised their supposed ‘Law of Flame Speeds’, claiming it to be applicable to all conditions of flame propagation. They added that “there is a considerable amount of evidence available that the relative speeds of the uniform movement of flame obtained under the specified experimental conditions are directly proportional to the speeds under other conditions, except during the detonation wave”; also, that the law of speeds applies to the rate of development of pressure in complex mixtures of gas with air (Trans. Faraday Soc., 22, pp. 301–306).