Societies and Academies

Abstract

LONDON Royal Society, Jan. 19.—C. N. HINSHELWOOD, E. A. MOELWYN-HUGHES and A. C. ROLFE: The combination of hydrogen and oxygen in a silver vessel. The reaction shows the characteristics of a surface reaction up to 700°. There is no sign of the development of reaction chains in the gas. The inhibition of the gas reaction is attributed to the catalytic destruction at the silver-silver oxide surface of the active species which would normally propagate the chains. R. L. Smith-Rose: The electrical properties of soil for alternating currents; with particular reference to radio-frequencies. The first part of this paper comprises a summary of previous investigations of the conductivity and dielectric constant of soil at various frequencies from 50 cycles per second up to 200 million cycles per second. The second part of the paper describes the application of a laboratory method for measuring these constants on samples of soil taken from selected sites at the National Physical Laboratory, Teddington. The conductivity varies from less than 105 E.S.U. for dry soil, up to a value of approximately 108 E.S.U. for normal moisture content. Corresponding values for the dielectric constant range from 2 or 3 for dry soil up to about 20 for moist soil at high radio frequencies. Measurements on a number of samples of soil taken at random from several other sites are included, and show that both the normal moisture content and the conductivity can have values which are appreciably higher than those experienced at Teddington. The paper concludes with a brief discussion of the penetration of radio-frequency currents in the earth, and the effective depth of penetration has been calculated in some instances. C. B. O. MOHR and F. H. NICOLL:—(1) Inelastic electron scattering in gases. The angular distribution of inelastically scattered electrons has been investigated in helium, argon and mercury vapour for the angular range between 20° and 160°. The scattered electrons of different energies were sorted out by a uniform radial electrostatic field. The results suggest that the problem of the scattering of electrons by atoms is not so serious as might be expected from a consideration of the various complicating processes which are involved, and that in the explanation of the observed results for the elastic and inelastic scattering of electrons by the heavier atoms, it is merely the size of the atom which is of fundamental importance. (2) The large angle scattering of electrons in gases (2). With an apparatus described in a previous paper the angular distributions of scattered electrons have been measured to 160° for 30–150-volt electrons. The elastic scattering has been investigated in hydrogen, carbon dioxide, nitrogen, neon, methane, hydrogen sulphide, and phosphine, while the inelastic scattering has also been measured in the first four gases. The diffraction maxima and minima which appear in the inelastic angular distributions are closely similar to those obtained for the elastic scattering. The curves for the elastic scattering show a gradual change in form for successive elements in the periodic table. The general shape of the experimental curves for the elastic and inelastic scattering is qualitatively accounted for, with the aid of a simple picture involving merely the size of the atom.