Abstract
PARIS. Academy of Sciences, July 24.-M. Ed. Perrier in the ochair.-The president announced the death of Sir William Ramsay, foreign associate.-G. Bigourdan: The propagation of sound to a great distance. The distance at which the sound of firing at the,front can be heard, given in a recent note as 250 .kilometres, must be extended to 300 kilometres.-C. Richet: The time minimum in the psycho-physiological reaction to visual and aural stimulations. Remarking on a note by MM. J. Camus and Nepper (see below), the author agrees that the figures put forward byM. Lahy appear to be too low, arid are probably affected by a systematic error.-M. Petrovitch: The relations of inequality between arithmetical and geometrical o means.--M. Mesnager: The displacement of the point's of a rectangular plate.-M. de BrogUe: The K absorption band of the elements for the X-rays, from bromine to bismuth, and the emission of a Coolidge tube for very short wave-lengths. Measurements of the absorption band of elements-that is, indirectly the shortest line of the K group of their spectra-are given for twenty-four elements, ranging in atomic weight from bromine to thorium. A tungsten antikathode was used and the wave-lengths measured, decreasing regularly with the increase in the atomic weight, the only exception being the relative positions of iodine and tellurium.- Mile. P. Collet: The working of galena employed as detectors in wireless telegraphy.-MM. Massol and Faucon: The absorption of ultra-violet radiations by the bromo-derivatives of methane. Experiments were made on bromine, carbon tetrabromide, tribromo-methane, and dibromomethane. The characteristic band of bromine in solution was not found in any of the bromo-derivatives of methane. These compounds increase in transparency for ultra-violet light as the proportion of bromine they contain diminishes, and each bromine derivative is less transparent than the corresponding chlorine derivative, examined under the same conditions of concentration and thickness.- E. Moles: The density of hydrogen bromide. Contribution to the revision of the atomic weight of bromine. The mean of thirty-two determinations of the density of hydrobromic acid is 3-64442 grams per normal litre. This leads to the value 79-926 for the atomic weight of bromine.-J. Eriksson: The reappearance of mildew (Phytophtora infestans) in the potato. -M. Repelin: The age of the Oligocene deposits of the basins of Aix and Marseilles, and, in particular, of the clays of Milles and the lignites of Saint-Zacharie. -Mmes. M. Lapicque and C. Veil: Muscular velocities measured by chronaxy in the different cavities of the heart.-J. Camus and M. Nepper; The reaction times of the candidates for aviation. A criticism of a recent communication by M. Lahy. The authors find it difficult to explain the reaction times measured by M. Lahy, which appear to be much too small.-L. Vialleton: Ontogenic development and the analogous organs.-H. Bierry: The detection of tuberculous bacilli in sputa. Details of a method based on the liquefaction and subsequent centrifugation of the sputa, which has given good results in practice.
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Societies and Academies . Nature 97, 496 (1916). https://doi.org/10.1038/097496a0
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DOI: https://doi.org/10.1038/097496a0