The Activation of Gases by Adsorption.

In his theory of the catalytic surfaces Taylor3 suggested that the surfaces of metallic catalysts are composed of atoms in different states of lattice saturation. In many catalytic reactions, notably those sensitive to poisons, only a part of the surface atoms produce in adsorbed molecules such changes as will facilitate a possible reaction, although almost the whole surface is capable of adsorbing gas. It seemed to be very probable that the change in adsorbed molecules is an energy-consuming activation and in the limit with diatomic molecules, a dissociation into atoms, produced by the most unsaturated surface atoms. Several attempts were made to prove the existence of these activated molecules by studying the critical potentials of adsorbed gases.' There is, however, another way of testing the presence of activated molecules on catalytic surfaces, namely, by measurements of the heat of adsorption. Although no full mathematical theory of adsorption on catalytic surfaces can be given at present, it seems to be possible to draw certain qualitative conclusions from the measured heats of adsorption on the state of adsorbed molecules, using the adsorption theory of Langmuir. In his paper5 Langmuir derived for a surface composed of n kinds of atoms, each adsorbing one gas molecule, an equation, which can be written in the following way: