The rate of solution of hydrogen by palladium

In two recent communications* the view has been advanced that in hydrogen-palladium the dissolved gas cannot be regarded as homogeneously distributed, and that solution takes place through the medium of an amorphous metallic phase which acts as a vehicle for the transference of gas to the crystalline metal. Experiments have been described from which it is concluded that in hydrogen-palladium one is dealing with a case of simultaneous adsorption and solution (or sorption), since as soon as any gas is adsorbed solution begins through diffusion from the adsorbed layer. The adsorption equilibrium would be rapidly established, too quickly, perhaps, for any record of its rate to be measured, but could such observations be made it might be expected that the following relation would hold:—Dc /dt =k Cn , Where C is the concentration in the adsorbed layer and k and n constants depending on the nature of the adsorbent and the substance adsorbed, the rate of adsorption of a gas at constant pressure varying with the concentration of the gas in the adsorbed layer. If, therefore the adsorbed layer is maintained at constant concentration by surrounding it with an unlimited supply of gas at constant pressure, the rate of inward diffusion from it could be measured. Thus a complete rate of solution curve should consist of two portions, the first representing adsorption and the second inward diffusion, the two coinciding when the rate of adsorption equals the rate of diffusion.