The theory of absolute reaction rates is developed for condensed phases. The equation for the rate of a reaction of any order in any phase where the slow process is the passage over an energy barrier consists of the product of a transmission coefficient κ, a frequency kT/h, an equilibrium constant between an activated complex and the reactants and an activity coefficient factor. Previous theories of reaction rates such as Brönsted's, the collision theory of Mc C. Lewis, etc., are seen to be special cases of the general theory. A variety of examples are considered.

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Newcas tle-upon-Tyne 1A study has been made of the anodic behaviour of lead and silver in N KOH with a view to determining the nature of the oxide layers formed and their influence upon measurements of oxygen overvoltage. Measurements of the variation of oxygen overvoltage with current density under constant surface conditions are reported for the two systems and the probable nature of the oxides deduced from voltage and, when possible, X-ray diffraction measurements. Comparison is made with earlier work.A recent study1 of the behaviour of lead in sulphuric acid during anodic polarization under conditions of constant apparent current density, has shown that the electrode reaction may be regarded as occurring in three stages.(i) A stage in which a lead sulphate layer is formed on the electrode surface, and which occurs at potentials near to the reversible PbjPbS04 potential. This layer eventually becomes complete, at least in the sense that the formation of lead sulphate cannot continue, and the electrode potential rises very rapidly to a sharp peak. The quantity of lead sulphate formed in this stage increases markedly with decreasing current density.(ii) The electrode potential falls rapidly from the peak, passes successively through a minimum and a maximum, and is at all times positive with respect to the reversible Pb02/PbS04/H2S04 potential. This stage is a complex one in which the formation of lead dioxide from the lead sulphate and the evolution of oxygen both contribute to the total electrode reaction, to extents which are dependent both on current density and time.