Societies and Academies

Abstract

LONDON Royal Society, March 23.—Sir Charles Sherrington, president, in the chair.—Sir Richard Glazebrook: Specific heats of air, steam, and carbon dioxide. The values for the specific heats of these gases below 1000° C. given recently by Womersley are higher by 5-10 per cent, than those which follow from the results given by Holborn and Henning.—A. E. H. Tutton: (1) Monoclinic double selenates of the manganese group. The manganese group of double selenates of the isomorphous series R2Mn(SeO4)2.6H2O includes only three salts, those in which R is rubidium, cassium, and ammonium. Optically these salts are precisely in line with those for analogous salts of other groups, so that if the potassium salt could be obtained, it would be the first member of a progressive series, and the general law of progression of the crystallographic properties with the atomic number of the alkali metal would be obeyed rigidly. The volume and edge-dimensions of the space-lattice cells of the crystal structures of ammonium manganous selenate hexa-hydrate and rubidium manganous selenate are nearly identical. Similar facts obtain for all analogous ammonium and rubidium salts throughout the whole isomorphous series, as well as for the rhombic simple sulphates themselves. (2) Monoclinic double selenates of the cadmium group. Crystals of the ammonium salt, (NH4)2Cd (SeO4)2 6H2O, which were sufficiently transparent in parts for optical use were obtained on very keen frosty nights. The potassium salt appears to be incapable of existence, its limit being probably below o° C. Crystals of the rubidium or caesium salt were obtained during the coldest nights of January, but they were quite opaque, so that only goniometrical measurements were possible. The results are in complete accord with those from other, complete groups.—F. A. Freeth: The system: Na2O—CO2—NaCl—H2O. The system is arbitrarily considered as composed of two four-component systems, namely:—Na2CO3—NaHCO3—NaCl—H2O, and Na2CO2—NaOH—NaCl—H2O. Determinations have been made at 0°, 15°, 20°, 25°, 30°, 35°, 45°, and 60° C. A general treatment is given showing how the composition and quantities of the stable phases from any mixtures of the components may be deduced.- M. A. Catalán: Series and other regularities in the spectrum of manganese. Flame-arc, arc and spark spectra of manganese have been observed and new series lines traced. Series belonging to the spectrum of the neutral atom are (a) a system of triplet series; (b) a system consisting of narrow triplets; and (c) a system of narrower triplet series running parallel to the preceding system. Intercombination lines between the two first systems appear as two lines very prominent at low temperatures. The calculated ionisation and resonance potentials of manganese are 7.4 volts and 2.3 volts. Diffuse triplets in the spectrum of the ionised atom are composed of nine lines. At different temperatures, groups of lines of the same character and related by very exact numerical separations (“multiplets”) have been identified. The neutral atom of manganese probably has two electrons in the outermost ring, and when it loses one electron and becomes ionised, another electron comes out to the ring. Thus, the spectra of neutral and ionised atoms would be similarly constituted in accordance with observations.—D. W. Dye: Calculation of a standard of mutual inductance and comparison of it with the similar laboratory standard. The windings of the primary helices and the secondary overwound coil of a Campbell type of mutual inductance standard were measured in terms of the length standards of the N.P.L. and the value in absolute millihenries has been calculated. Comparisons with the similar laboratory standard at a frequency of ten cycles per second showed that the ratio of the calculated values of the two standards was in agreement with the ratio of the experimentally compared values to an accuracy of 5 in 106.—P. E. Shaw and N. Davy: The effect of temperature on gravita-tive attraction. Results with a torsion balance of the Boys-Cavendish type indicated a temperature effect of gravitation of about 1 × 10-5 per 1° C. With similar apparatus modified to eliminate small mechanical movements caused possibly by the raising of the large gravitative masses to a high temperature, the effect was shown to be due to such movements reversible with temperature. The temperature effect, if any, must be less than 2 × 10-6 per 1° C. The mean effect observed is a very small diminution in attraction as temperature rises.