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PARIS. Academy of Sciences, October I.—M. Lœwy in the chair.—The mass of Mercury and the acceleration of the mean movement of Encke's comet, according to the recent work of M. O. Backlund. A note by M. O. Callandreau.—On the automatic transmitter of steering directions, by Lieut. H. Bersier. The alternating current from a Ruhmkorff's coil passes from the pivot of a compass through the aluminium pointer, and leaps from the extremity of this needle to one of six vertical plates placed at intervals round the inside of the compass-box. This alternating current has no effect on the magnet, but serves to work six corresponding relays, and hence to cause the illumination of corresponding signal lamps placed in various parts of a vessel, and to set in motion the steering apparatus. The least deviation from the set course is automatically and immediately corrected in this way. The course is altered by simply rotating the drum carrying the plates.—A description of a bundle of descending cerebral fibres disappearing in the olivary bodies (cerebro-olivary bundle), by M. Y. Luys.—Influence of low temperatures on the laws of crystallisation, by M. Raoul Pictet. The author shows the essential difference in the manner in which the crystallising body loses heat at the moment of solidification in the two cases where the substance is (1) adiathermanous and (2) diaihermanous. All substances become diathermanous below —70°, and hence the true temperature of crystallisation is only obtained when the surrounding medium is maintained at a temperature very slightly below the solidifying point. Hence an explanation of the anomalies occurring in determinations of the crystallisation point of such substances as chloroform.—On the development of the latent image in photography by alkaline peroxides, by M. G. A. Le Roy. Aqueous solutions of alkaline peroxides or alkaline solutions of hydroxyl can be used as developers, but are inferior to the ordinary reagents.—Action of hydrogen phosphide on potassammonium and sodammonium, by M. A. Joannis. When hydrogen phosphide is passed into a solution of potassammonium or sodammonium in liquefied ammonia, it is absorbed with the production of the solid white substances PH2K and PH2Na. Heat destroys these compounds in accordance with the equation 3PH2K = 2PH3 + PK3. Water decomposes them with liberation of hydrogen phosphide. Nitrous oxide does not yield any substance corresponding with the salts of hydrazoic acid.—Researches on mercuric picrate, by M. Raoul Varet. The preparation and properties of mercuric picrate are described. Thermal data are given in detail, and from them it is seen that the picrate ranges itself along with the acetate rather than with the other soluble salts, the chloride and cyanide. Picric acid displaces hydrocyanic acid from its potassium combination with disengagement of + 10˙7 Cal., whereas hydrocyanic acid completely replaces picric acid in the mercuric salt with liberation of + I2˙2 Cal.—Action of picric acid and picrates on metallic cyanides. The isopurpurates. A note by M. Raoul Varet. When picric acid can replace hydrocyanic acid in its compounds with evolution of heat, isopurpurates are formed; when, as with the mercuric salt, the hydrocyanic acid replaces picric acid with evolution of heat, isopurpurates are not formed.—The antiseptic properties of the vapours of formaldehyde, by M. A. Trillat. The vapours of formaldehyde, produced by the incomplete combuuion of methyl alcohol, have proved very efficacious in destroying germs in sick rooms, and have no action on metals or instruments, and but little action on dyed fabrics.—Observations on flours, by M. Balland. —On the anterior extremity of the dorsal cord in the superior vertebrates, by M. G. Saint-Remy.—Evolution of the sexual elements in the composite Ascidians, by M. Antoine Pizon.—On one of the Cbytridineœ parasitic on the vine, by M. A. Prunet.—On the calcareous tuffs of the col de Lautaret (Hautes-Alpes), by M. W. Kilian. From this preliminary study of the Lautaret tuffs, it may be concluded: (1) That these tuffs are relatively recent, their disposition indicating that the present aspect of the surface is much the same as that obtaining at the time of their formation. They are more or less mixed with moraine deposits. (2) The vegetable débris contained in these tuffs, notably the cones and branches of Pinus sylveslris, indicate the existence at the epoch of their formation of a forest vegetation which has since abandoned these altitudes.—On the presence of carboniferous earth in the Sahara, by M. F. Foureau.—Thermometric observations on the summit of Ararat, by M. Venukoff. M. Gimmer visited the summit of Ararat on August 16, 1894, and found two thermometers left by M. Pastoukoff the preceding year in a tin-plate box. The maximum registered + I7˙25°C., the minimum –4O°C. Another minimum instrument, attached in the open air to a vertical object, indicated – 38° C. At the time of the visit, the temperature of the air in the shade was + 3°C.—;On an aerostatic ascension effected in Russia, by M. Venukoff.
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Societies and Academies. Nature 50, 587–588 (1894). https://doi.org/10.1038/050587a0
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DOI: https://doi.org/10.1038/050587a0