Abstract
LONDON. Royal Society, May 21.—Sir William Crookes, president, in the chair.—Prof. W. M. Hicks: The effect of the magneton in the scattering of a rays. The presence of a magneton in an atom must exert some effect in scattering α or β particles passing through the atom. In order to test the order of magnitude of the effect, the orbits of charged particles moving in the equatorial plane of a magneton are discussed, and it is seen that the scattering produced is very considerable. The nearest approach of an α particle to the centre of the atom is of the same order as in Rutherford's theory. The electrostatic repulsion of an α particle combined with the magnetic field of the atom will therefore be more effective, as the diminished velocity will render the particle, much more susceptible to the magnetic forces.—Hon. R. J. Strntt: Luminous vapours distilled from the arc, with applications to the study of spectrum series and their origin.—I. (1) It is known that mercury vapour distilled away from the arc in vacuo remains luminous for some distance away from the region of discharge. It is now shown how to observe brilliant effects of the same kind from a large number of other metals. (2) As the luminous vapour moves away from the region of discharge, the rate at which different constituents in the spectrum die out is not always the same. Both the subordinate series of lines in the sodium spectrum die out at the same rate, but the principal series dies out more slowly. The lines belonging to any given series always die out at the same rate, but another series may or may not die out at the same rate as the first. (3) In some cases the glowing vapour distilled from the arc shows a band spectrum. The alkali metals show a continuous band beyond the limit of the subordinate series like that seen in absorption in the hydrogen stars.—W. T. Pawlow: The ionisation of gases by collision and the ionising potential for positive ions and negative corpuscles.—C. E. Stromeyer: The determination of elastic limits under alternating stress conditions. The present paper deals exclusively with the question of endurance or fatigue qualities of metals. The apparently incongruous results obtained by previous experimenters, including those by Wöhler, made it appear probable that samples taken from different parts of a bar or plate might differ so much in quality that the law of fatigue would be masked by local variation of quality. The test pieces of the present first series (bending) were therefore shaped in such a manner that consecutive pieces were separated from each other in the original plate toy only one inch. The test results were found to be very consistent and could be expressed by the formula Sn = Fl + C(106: N)¼, where Sn is the nominal alternating stress which will cause fracture after N repetitions, Fl is the fatigue limit found by extrapolation from a series of tests resulting in fracture, and C is a constant. A comparison was made of previous tests with the help of this formula, and it was found to agree well with those of Wöhler, Baker, and Eden, Rose and Cunningham. The torsion fatigue tests were made with the same materials as used in the above tests, and the results also agreed very closely with the above formula, except that new values for FZ and C were found. The inquiry was extended to the measuring of the heat generated during fatigue tests. G. W. C. Kaye and W. F. Higgins The emission of electricity from various substances at high temperatures. Experiments have been conducted at temperatures from. 2000° to 2500° C. within a carbon-tube furnace at atmospheric pressure. Under these conditions the electrical emissions, in the absence of any applied potential, have been measured for a number of substances, (including the alkaline earths and the metals tin, aluminium, iron, and copper) on their introduction into the furnace. During their rapid volatilisation the substances gave out large amounts of electricity which, with one exception, were negative in sign. For example, barium oxide and alumina generated negative currents of the order of 4 amperes per sq. cm., boiling tin about 2 amperes per sq. cm., and boiling iron about 1 ampere per sq. cm. Boiling brass, on the contrary, produced a positive current of about 0.5 ampere per sq. cm. The results have interest in connection with the problems of solar magnetism.
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Societies and Academies . Nature 93, 340–341 (1914). https://doi.org/10.1038/093340a0
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DOI: https://doi.org/10.1038/093340a0