Abstract
LONDON. Royal Society, January 29.—Sir William Crookes, O.M., president, in the chair.—Prof. O. W. Richardson: The origin of thermal ionisation from carbon. In a paper recently communicated to the society by Dr. J. N. Pring, experiments bearing on this subject were described. The smallness of the observed currents and the variation of them with the pressure and nature of the gas, led Dr. Pring to the conclusion that considerable doubt was thereby cast on the theory of the emission of electrons from hot solids, and that these effects were to be attributed to chemical action. In the present paper the magnetic field due to the large heating currents employed by Dr. Pring are shown to curl up the paths of the electrons, and so prevent them from reaching the electrode. It is shown that with the larger currents none of the electrons could reach the electrode in these experiments, and owing to the complexity of the apparatus it is impossible to say what proportion would reach it at the lower temperatures. In the opinion of the author of this paper, the conclusions referred to cannot be regarded as established by the experiments under consideration.—Prof. W. H. Bragg: The X-ray spectra given by crystals of sulphur and quartz. A crystal of quartz is found, on examination by the X-ray spectrometer, to contain three interpenetrating hexagonal lattices of silicon atoms and six of oxygen. The angles of reflection in a number of important planes all agree, within 1 or 2 per cent., with the calculated values. Sulphur contains eight interpenetrating lattices, each of the kind formed by placing an atom at each corner of a rectangular parallelopiped and in the centres of two opposite faces. The edges of the parallelopiped are in the known ratios of the crystallographic axes. —Prof. L. N. G. Filon: The temperature variation of the photo-elastic effect in strained glass. The experiments described in this paper were undertaken to see whether the double refraction produced in glass by stress was at all affected by change of temperature. The results show that the refractive indices for rays polarised in and perpendicular to the line of stress are unequally affected, but seem increased-on the whole by rise of temperature. One of these, however, shows a permanent residual change even after cooling. This is important as showing that this property of the glass is affected by previous temperature treatment.—J. H. Shaxby and Dr. E. Emrys Roberts: Studies in Brownian movement. Paper i., The Brownian movement of the spores of bacteria.—Dr. R. Whiddington: The transmission of kathode rays through matter.—Ezer Griffiths: The variation, with temperature, of the specific heat of sodium in the solid and liquid state; also a determination of its latent heat of fusion. The specific heat of sodium (melting point 97.6°) was investigated at various temperatures in the range 0° to 140° by the electrical method. The range of temperature through which the metal was heated was about 1.5°, thus enabling the actual specific heat at each particular temperature to be determined. In the solid state the specific heat is considerably influenced by the nature of the previous heat-treatment, and two distinct specific heat-temperature curves are obtained for the annealed and the quenched state. The increase in the values of the specific heat in the solid state is very marked as the melting point is approached. In the molten state the specific heat decreases with temperature, the relation between specific heat and temperature from 100° to 140° being linear. The latent heat of fusion was found to be 27.52 gram calories.—Dr. G. Green: Natural radiation from a gas. The investigations of Planck have established the result that the total energy emitted from a black body at any temperature consists of discrete quanta, all equal ana similar. If we identify the “energy quantum” as the energy contained in the light pulse emitted each time a molecule undergoes structural change, the determination of the form of this light pulse might lead to useful information regarding the constitution of the molecule. In this paper the form of pulse, in which the energy per wave-length is the same as that required by Planck's law of radiation at any temperature, is first derived. This form accordingly represents the total radiation from any black body at any temperature. The radiating body is now taken to be a gas. By decomposing the above pulse we obtain an infinite succession of wave-trains emitted by the various groups of molecules obtained by arranging the total number according to speed.—Dr. T. E. Stanton and J. R. Pannell: Similarity of motion in relation to the surface friction of fluids. The paper deals with an experimental investigation of the existence of the similarity of motion in fluids, of widely differing viscosities and densities, in motion relative to geometrically similar surfaces, which has been predicted from considerations of dynamical similarity by Stokes, Helmholtz, Osborne Reynolds, and Lord Rayleigh.—A. E. Oxley: The influence of molecular constitution and temperature on magnetic susceptibility.—N. Eumorfopoulos: The boiling point of sulphur on the thermodynamic scale.
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Societies and Academies . Nature 92, 649–651 (1914). https://doi.org/10.1038/092649a0
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DOI: https://doi.org/10.1038/092649a0