Abstract
LONDON. Royal Society, June 14.— C. Chree: Magnetic phenomena in the region of the south magnetic pole. Magnetographs were in simultaneous operation from April to October 1912, at the base stations of the British and Australasian Antarctic expeditions on opposite sides of the south magnetic pole. A comparison is made of the regular diurnal inequalities and the amplitudes of the absolute daily ranges of the magnetic elements at the two stations. The data show the remarkable sensitiveness of the regular diurnal variations in high latitudes to the presence of magnetic disturbance. The results are also applied to the question of a suitable criterion for the daily activity of magnetic disturbance.—O. R. Howell: The catalytic decomposition of sodium hypochlorite by cobalt peroxide. The rate of decomposition of sodium hypochlorite solution by cobalt peroxide is directly proportional to the amount oi peroxide present. It is accelerated by sodium salts and (in the case of sodium chloride) is directly proportional to the square root of the concentration of sodium ions present. The mechanism of the reaction probably consists in the linkage of hypochlorite ions to the positive oxygen, and sodium ions to the negative oxygen of the peroxide, with immediate decomposition of the quadrivalent oxygen compound. With a fixed amount of hypochlorite the rate is then proportional to the degree of adsorption of the sodium ions. The rate is retarded by alkali and the retardation is proportional to the adsorption of hydroxyl ions. The average temperature coefficient of the reaction between 25° and 50° is 2.37 and the Arrhenius activation coefficient E is 16,574. The catalyst is not affected by any of the common catalytic poisons.—N. M. Hosali: On seismic waves in a visco-elastic earth. Seismic waves are subject to damping and dispersion dependent on the period. For each type of wave—dilatational, distortional, or surface—there exists a minimum period below which a wave cannot be transmitted, and for any period above the minimum two distinct waves can be propagated, one heavily damped and slow travelling and one lightly damped and quick travelling. Observations indicate that if the material in the outer layers of the earth obey the theory here developed it should have a viscosity of order 108 or 109 C.G.S. units. This would have no appreciable effect on the velocity of propagation of earthquake waves.—J. W. Landon and H. Quinney: Experiments with the Hopkinson pressure bar. With a bar of uniform diameter the pressure wave produced by detonation of gun-cotton is considerably distorted as it is propagated, but the rate of distortion decreases as the wave travels along the bar. Pressure falls away rapidly as distance from the axis of the bar increases. To determine the maximum pressure produced in the detonation of gun-cotton the bars were submitted to special heat treatment in the hope that overstrain might be reduced. A substantial improvement was observed except in so far as the life of the bars was increased. The highest maximum pressures recorded weie 117 tons per square inch for a 1-ounce gun-cotton primer in contact with the end of the bar, and 82 tons per square inch with the primer ¾ inch away from the end. These results were obtained with a short bar of ¾-inch diameter. With concrete bars the phenomena exhibited are the same in general as with steel bars, except that the front of the wave appears to be entirely obliterated, and only the part in which pressure is less than the crushing stress of the concrete is propagated along the bar.—S. F. Grace: - Free motion of a sphere in a rotating liquid at right angles to the axis of rotation. The density of the sphere is equal to that of the liquid, and the motion a small disturbance from one of uniform rotation like a rigid body. The motion of the centre of the sphere is wholly in a plane perpendicular to the axis of rotation, and the disturbed motion of the liquid is symmetrical with respect to this plane. The path of the centre of the sphere is a spiral with a definite pole. The sphere winds round the pole in a direction opposite to that of the rotation of the liquid, the motion being such that the time of a complete turn tends to become constant and equal to one-half the time of a revolution of the undisturbed liquid. At points along the prolongation of the polar axis of the sphere the motion is parallel to the equatorial plane and is a maximum at the sphere. Parts of the solution are not applicable for large values of time.—B. F. J. Schonland: The passage of cathode rays through matter. The absorption of cathode rays of velocity 6 × 109–1.2 × 1010 cm./sec. in various metals has been studied with an arrangement designed to eliminate interference from secondary rays and to measure both the fraction of the beam, passed through and that actually absorbed in the foil. The latter fraction varies with thickness and velocity in the same manner for all elements; the nature of the variation of the former depends upon the absorbing material. The results are explained by applying the theory of absorption due to Bohr, with which they are in quantitative agreement.
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Societies and Academies. Nature 111, 866–868 (1923). https://doi.org/10.1038/111866a0
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DOI: https://doi.org/10.1038/111866a0