Societies and Academies

Abstract

LONDON. Royal Society, January 16.—Sir Archibald Geikie, K.C.B., president, in the chair.—Lord Rayleigh: The effect of junctions on the propagation of electric waves along conductors.—W. B. Hardy: The influence of chemical constitution upon interfacial tension and upon the formation of composite surfaces.—Hon. R. J. Strutt: Duration of luminosity of electric discharge in gases and vapours.—Rev. P. J. Kirkby and J. E. Marsh: Some electrical and chemical effects of the explosion of azoimide. The experiments consisted in exploding azoimide gas (HN3) at low pressures between two insulated coaxial cylinders, of gilded brass, connected to the terminals of a battery of about 105 volts. The quantity of electricity that reached one of the cylinders was measured by a ballistic galvanometer and compared with the quantity of gas exploded. The results show that, in every case, the number of molecules of gas exploded was more than 100,000 times the number of pairs of gaseous ions observed. This disproportion indicates that the atoms of the gas when separated by the explosion do not carry electric charges. The gaseous ions are probably produced by favourable collisions of free atoms in the process of forming the products of the explosion.—Dr. G. J. Burch: Negative after-images with pure spectral colours. The results obtained by Mr. A. W. Porter and Dr. Edridge-Green in their experiments on negative after-images and successive contrast with pure spectral colours (Proceedings B, vol. lxxxv., p. 434) can be explained in accordance with the theory of Thomas Young if the “stray light” referred to by the authors is taken into account. Thus fatigue by red light renders the blue and violet of a spectrum projected on a screen in an imperfectly darkened room darker and bluer along the line of the after-image, because it removes the red constituent of the “stray light” with which they are contaminated. The results of fatigue with other spectral colours may be similarly explained.—H. Hartridge: Factors affecting the measurement of absorption bands.—Dr. G. Barlow: A new method of measuring the torque produced by a beam of light in oblique refraction through a glass plate. According to theory, the torque produced on a erlass plate by the nearly normal passage of a beam of light is directly proportional to the angle of incidence and always tends to turn the plate further from the normal position. The period of small torsional oscillations of a plate suspended by a quartz fibre should therefore be increased when the plate is traversed by the light. An experiment is described in which this change in period, actually an increase of about 1/5 per cent., was measured. The observed change agreed within 3 per cent, with that calculated from theory.—Dr. F. Horton: The positive ionisation-produced by platinum and by certain salts when heated. The emission of positive electricity from platinum and from several samples of aluminium phosphate and of sodium phosphate has been investigated at different temperatures, observations being made of the variation of the emission with time and with the pressure of the surrounding gas.—Clive Cuthbertson and Maude Cuthbertson: The refraction and dispersion of the halogens, halogen acids, ozone, steam, oxides of nitrogen and ammonia, and the causes of the failure of the additive law. The refraction and dispersion of the elements and compounds named in the title have been determined betweer λ = 6708 and λ = 4800.—R. Donald: Liquid measurement by drops. To apply measurement by drops to various serological and bacteriological estimations of liquids and liquid suspensions, the author has worked out a system of using practically uniform easily-made pipettes of any size under any required constant pressure. The pipettes of suitably drawn-out glass tubing are simply gauged in, e.g. the Morse drill and wire gauge. The constant pressure is obtained by a column of mercury flowing as a piston to and fro in a suitable glass tube held at any required angle in a stand, or, for less exact work, in the hand.—Prof. W. H. Young:—The new theory of integration. The present communication is a sketch of a mode whereby the modern theory of generalised, or Lebesgue, integration may be developed without the aid of the theory of sets of points.