Abstract Metal catalysts have been incorporated into high purity graphites by impregnation with salts in aqueous solutions followed by freeze drying. The catalytic effect has been studied at such temperatures that the rate of the uncatalyzed reaction is negligible. As traces of water vapor cause a large enhancement in the catalytic effect, great care has been taken in purifying the air of combustion. Only metals able to oscillate between two degrees of oxidation, under the given conditions of combustion, do show a catalytic power. Metals showing no effect are those which have an oxide stable under these conditions. The variation of the catalytic effect with the impurity content, as well as the constancy of the activation energy, are in agreement with the assumption of a localised action of impurities. The proposed interpretation is a “chemical” one and renders unlikely an “electronic” mechanism; it also easily accounts for the inhibition caused by some anions.
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