Abstract
PARIS. Academy of Sciences, August 27.—M. A. d'Arsonval in the chair.—Jean Perrin: Observations on fluorescence. The fluorescence of a solution depends on its concentration, thickness of layer, and light-absorbing power of the solvent. An attempt is, made to define specific fluorescence, measurable by a coefficient independent of these factors.—D. Mordouhay-Boltovsky: Certain categories of transcendental numbers.—Jules Baillaud: The astronomical station of the Pic du Midi. This observatory is characterised by the purity of the sky and clear images. The advantage of the height (2870 metres) is not obtained at the price of undue fatigue on the part of the workers. Observations would appear to be possible except during the late winter and spring months.—A. A. Guntz: Phosphorescent sulphide of zinc. The partial substitution of cadmium sulphide in the zinc sulphide gives a more durable phosphorescence and causes changes in the colour of the light. It also renders the phosphorescent sulphides more easy to insolate.—Andre Charriou: The absorption of sodium hyposulphite by photographic papers. The elimination of sodium hyposulphite from photographic papers is much more rapid and complete, if the washing is carried out with solutions of sodium or ammonium bicarbonate instead of with water.—Ch. Kilian and V. Likhite: The development of Hendersonia foliorum.—Maurice Piettre: The chemical relations between humic materials and coal.
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Societies and Academies. Nature 112, 460 (1923). https://doi.org/10.1038/112460a0
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DOI: https://doi.org/10.1038/112460a0