Abstract
Academy of Sciences, September 12.—M. Faye in the chair.—Meadow land in warm dry summers, by M. Ad. Chatin. A list of those species of plants which have been found to be the most capable of resisting a hot, dry summer. Observation of an aurora borealis, by M. H. Deslandres. An aurora was observed at Meudon on September 9 about 9 p.m., and its general direction was very nearly that of the magnetic meridian, the rays having a greenish colour.—On the crystallisation of the anhydrous sulphides of calcium and strontium, by M. Mourlot. The crystallised sulphides of these metals can be prepared in two ways, either by heating a mixture of the corresponding sulphate with carbon, or by simply fusing the anhydrous sulphide obtained by the method of M. Sabatier, the temperature employed being that of the electric furnace with a current of 1000 amperes at 60 volts. The crystallised sulphides thus produced are more stable than the corresponding amorphous salts, and are attacked with difficulty by reagents; carbon at a very high temperature converts them into carbides. Both crystallise in the cubic system, and are without action upon polarised light.—On a double carbide of iron and tungsten, by M. Percy Williams. This compound, the existence of which was indicated in an earlier paper, is prepared by heating a mixture,of tungstic acid, iron and coke, in the electric furnace with a current of 900 amperes at 45 volts. The ingot formed in the reaction contains the carbide of tungsten WC, probably W2C, and the double carbide 3W2C.2Fe3C.—On the commercial extraction of thorium, by MM. Wyronhoff and A. Verneuil. The mineral is worked up by one of the usual methods as far as the production of the oxalates, these precipitated by sodium carbonate and hydroxide, and the washed precipitate dissolved in hydrochloric acid. This liquid is treated with small portions of barium peroxide, until hydrogen peroxide no longer gives a precipitate. The deposit, which is of a reddish orange colour owing to the presence of cerium, contains the whole of the thoria, with about 20 to 30 per cent. of impurities. Further treatment with hydrogen peroxide after a similar set of operations readily gives a very pure thoria. The method has been applied on the large scale, starting with five tons of monazite, with good results.—On the composition of the humic constituents of the soil, by M. G. André.—On the transformation of luminous variations into mobile relief, by M. Dussaud.—On a new coccus, by M. Louis Leger. The new species is found in the digestive tube of Lithobius hexodus, and belongs to the genus Echinospora. Its microgametes are furnished with vibratile cilia; the name E. ventricosa is suggested.—Influence of light on the form and structure of the branches of the wild grape and ground ivy, by M. Maige. Comparative cultures placed in light of decreasing intensities showed that both from the morphological and anatomical points of view, a feeble light increases the adaptive powers of climbing plants, diffused light favouring the conversion of a flower-bearing bud into a tendril. Direct sunlight produces the opposite effect.—On the adherence of the cupric-solutions used for curing the cryptogamous diseases of the vine, by MM. Guillon and Gouirand.
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Societies and Academies. Nature 58, 516 (1898). https://doi.org/10.1038/058516a0
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DOI: https://doi.org/10.1038/058516a0