Abstract
PARIS Academy of Sciences, October 4.— M. Wurtz in the chair. M. Perrier presented a Compte rendu of the determinations of longitudes, latitudes, and azimuths in Africa under his direction, at Géryville, Laghouat, Biskra, and Carthage in 1877 and 1878, with a description of instruments and methods. In the exchange of signals it was possible to calculate the mean retardatipn of transmission of a signal along an aerial conductor, from chronograph to chronograph, for distances comprised between 414 km. and 1,236 km. The mean velocity of propagation was found about 40,000 km. At this rate an electric signal would go round the earth in a second.—Military and geographical exploration of the region comprised between the Upper Senegal and the Niger, by M. Perrier. A Government expedition under Commandant Desbordes was to start on the 5th, Commandant Derrien having charge of the topographical department. They go to St. Louis, and make their way to Bafoulabé, at the confluence of the Bating and the Bakhoy. Here they construct their first fort, and organise escorts and convoy, with a view to a general triangulation of the region between Bafoulabé on the Senegal, and Dina and Bamakou on the Niger. The railway contemplated would run from Medina, by Bafoulabé and Fangalla, to the Niger.—Order of appearance of the first vessels in the spike of Lepturus subulatus, by M. Trécul.—M. de Lesseps presented the “Bimensual bulletin of the Inter-oceanic Canal” for September.—On utilisation of the crystals of lead-chambers, by MM. Girard and Pabst. The crystals offer an abundant and economical source of nitrous acid, and the authors have been able to prepare .on a large scale, the dinitric bodies, amidoazo-benzol and nitroalizarine, by making the nitroso-sulphuric acid act on the corresponding amidised derivatives, or aniline and alizarine. But the crystals can only be employed in presence of a quantity of sulphuric or nitric acid (preferably the former) sufficient to prevent their decomposition by water.— Observations of Faye's comet made at the Observatory of Florence - Arcetri, by M. Tempel.—On some thermoinetric questions, by M. Crafts. It is very probable that the least change of volume of a thermometer is accompanied by a change of the coefficient of dilatation.—On the decomposition of salts by liquids, by M. Ditte. The laws of dissociation by heat which apply to decomposition of salts by pure water and. by saline or acid solutions, apply also to decomposition by alcohols, and probably in general to decompositions of salts by the wet way, whatever the solvent.—On the physiological action of Conium maculatum, by M. Bochefontaine. Conine diminishes or abolishes the physiological properties of the nervous centres before acting like curare on the “nervo-muscular junctive substance” (Vulpian). In the dog and frog it at length abolishes the nervous excito-motricity if given in sufficient quantity, and it is fatal for batrachians as well as for mammalia. Hemlock then may act like curare, but it has additional physiological effects.— Floral dimorphism and staminal petalody observed in Convolvulus arvensis, L.; artificial production of this latter monstrosity, by M. Heckel, Petalody is the effect of direct fertilisation long continued. The autogamic process in plants as in animals (but in a longer period with the former) has the result of altering the organs of reproduction and leading to absolute infertility.
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Societies and Academies . Nature 22, 576 (1880). https://doi.org/10.1038/022576a0
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DOI: https://doi.org/10.1038/022576a0