Abstract
LONDON. Royal Society, May 20.—Sir J. J. Thomson, president, in the chair.—Prof. J. N. Collie: Some notes on krypton and xenon. In the paper the measurements of a considerable number of new spectroscopic lines at the red end of the spectrum are given; also a curious property of xenon has been noted. In tubes containing xenon, when a strong current from an induction coil is passed, much splashing of the electrodes occurs, and the xenon disappears as a gas. What becomes of the xenon is not clear, as it does not seem to be liberated again, either by strongly heating the metallic splash or by dissolving up the splash in suitable solvents.—Sih Ling Ting: Experiments on electron emission from hot bodies. Experiments on the electron currents from: a platinum disc in a uniform field made by Prof, Richardson in 1907–9 showed that under the conditions of these experiments the distribution of velocity among the emitted electrons was very close to the requirements of Maxwell's law for a gas of equal molecufar weight and temperature, but it was noted at the time that rough tests made on the liquid alloy of sodium and potassium, on platinum coated with lime, and on platinum saturated with hydrogen indicated an exceptional behaviour. The further investigation of these substances was postponed owing to technical difficulties and to the pressure of other problems. In 1914 Schottky investigated the electrons emitted from tungsten and carbon, and found a distribution of energy in close accordance with Maxwell's law, except that the mean energy varied between 2 per cent. and 25 per cent. in excess of that calculated from the filament temperatures. Errors in the estimation of these temperatures and in other directions might, however, have accounted for these discrepancies. The present experiments show that deviations from Maxwell's law, if not general, are at any rate quite common. With tungsten and platinum in a well-exhausted enclosure a common distribution is one which satisfies the requirements of Maxwell's law, except that the average electron energy is in excess of (frequently about twice as great as) that corresponding to the temperature of the source. Other cases have been recorded in which the velocity distribution has a different functional form.—L. Silberstein: The aspherical nucleus theory applied to the Balmer series of hydrogen. The general formulae for spectrum emission by atomic systems containing an aspherical nucleus, given by the author in a previous paper (Phil. Mag., vol. xxxix., p. 76), are now applied to hydrogen atoms the nuclei of which are treated as axially symmetrical charged distributions. The asphericity and the value of the Rydberg factor are determined from Mr. Curtis's observations of Hα up to Hγ. The.series formula thus resulting (and containing but two constants) is shown to agree well with the six observations. The value of the asphericity coefficient is then used to determine the fine structure of the members or groups of the Balmer series, more especially of the groups Hα and Hβ, which are discussed in some detail.—T. E. Stanton, Miss D. Marshall, and Mrs. C. N. Bryant: The conditions at the boundary of a fluid in turbulent motion. Observations were made on air flowing through long pipes of circular cross-section at mean rates of flow covering as wide a range as possible below and above the critical speed. Dimensions of pipes used were 0.269, 0.714, and 12.7 cm. in diameter. Range in experimental conditions varied from νd/v = 460 to νd/v = 325,000, where ν is mean speed of flow, d diameter of pipe, and v kinematic viscosity of air. Estimation of velocity of fluid in neighbourhood of boundary was made from observations of difference in pressure existing in a small Pitot tube facing the direction of flow, and that in a hole in the wall of the pipe. The Pitot was of rectangular section, external dimensions at orifice being 0.1 × 0.8 mm. and internal dimensions 0.05 × 0.75 mm. By this means observations could be made up to a distance of 0.05 mm. from the wall. For distances less than this, by a special device the wall of the Pitot nearest the wall of the pipe was cut away and its place taken by the wall of the pipe. By this means observations could be taken at a distance of 0.01 mm. from the walls. From a comparison of the curves of velocity distribution near the boundary, obtained from observations with the Pitot and the composite tube, it was found that in the case of the former the interference with the flow near the orifice by side of tube adjacent to boundary was considerable. Velocity curves obtained from the composite tube, when further corrected for interference, were found to tend to a definite slope at boundary, which was identical with that which would exist in a layer of fluid in laminar motion and having the same surface friction as that actually measured.
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Societies and Academies. Nature 105, 441–443 (1920). https://doi.org/10.1038/105441a0
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DOI: https://doi.org/10.1038/105441a0