Societies and Academies

Abstract

LONDON Royal Society, February 15. J. C. STIMSON: The electrical condition of hot surfaces (5). The rates at which the steady equilibrium potentials are built up on gold, nickel, platinum, carbon, and copper surfaces after earthing have been studied under varying experimental conditions. The rate of charging up of a surface is a linear function of its instantaneous potential, and its logarithm is directly proportional to the reciprocal of its absolute temperature. It is extremely probable that the hot surfaces emit positive electricity over the temperature range investigated (up to 850° C.). When heated in a vacuum, the emission probably consists of positively charged metal ions; while in contact with gases, the ions are positively charged atoms or molecules of the gas. With oxygen at low temperatures, however 7 the ions appear to be negatively charged. G. I. FINCH and B. W. BBADFOBD: The electrical condition of hot surfaces (6): A series of experiments with a gold gauze surface was carried out in such a manner that the catalytic and electrical activities of the metal could be simultaneously observed and followed. The reaction selected was the heterogeneous combination of carbon monoxide and oxygen in both moist and dry systems. The electrical condition of the metallic surface was expressed in terms of the magnitude and sign of the equilibrium potential which it acquired in given conditions, and its electrical activity was measured by the specific rate at which that potential was approached on insulation at zero or other standard potential. In general, throughout the experiments, changes in the rate of electrical charging of the metal followed closely the corresponding changes in the catalytic activity, increasing with rising temperature or with the introduction of water, and undergoing similar variations to the rate of reaction when the surface was maintained at constant temperature. G. I. FINCH and A. W. IKIN: The catalytic properties and structure of metal films (2), The surface potentials and rates of charging-up of cathodically sputtered platinum films in contact with electrolytic gas at room temperature have been determined, and the film structure examined by the method of electron diffraction. It is concluded that (1) catalytic action is determined by a prior interaction between the surface and one or both constituents of the combining mixture, whereby the catalyst becomes electrically charged, (2) activity is not determined by either crystal size or orientation, (3) catalytic activity appears to be centred round isolated atoms or molecules of platinum not forming part of any ordered array or structure. S. F. BOYS: Optical rotatory power. (1) A theoretical calculation for a molecule containing only isotropic refractive centres. (2) The calculation of the rotatory power of a molecule containing four refractive radicals at the corners of an irregular tetrahedron. A theoretical formula connecting rotatory power and chemical constitution has been obtained on the basis of the electronic theory of dispersion. The rotatory power of any molecule is expressed in terms of the ordinary refractive properties and the linear dimensions by means of certain determinants. The expression for the rotatory power is applied to the special case of the molecule containing four radicals attached to one atom, when it becomes quite simple, and theoretical predictions of rotations are compared with experimental data. The formula explains the variation of rotatory power with chemical substitution and also the effects of temperature and solvent. The rotatory dispersion is expressed in terms of the refractive dispersions of the radicals in the molecule. The formula also connects the sense of the rotation with the absolute configuration of the compound, and this should be of vital importance in the study of Walden inversion reactions.