Abstract
PARIS.
Academy of Sciences, October 12.—M. Duchartre in the chair.—On the theory of the antagonism of visual fields, by M. A. Chauveau.—An apparatus for carrying out various experiments connected with the study of binocular contrast, by the same author. The instrument described is that used by M. Chauveau in the experiments the results of which were communicated to the Academy on September 7 and 21. In the main it consists of a stereoscope having arrangements by means of which exact equality of luminous impressions may be realized, and the colours of the two fields altered independently.—New réscau of isotherms for carbonic acid, by M. E. H. Amagat. The author has determined the isotherms of carbonic acid for every 10° from 0° to 100°, and also those corresponding to 32°, 35°, 137°, 198°, and 258°; the pressures having been taken up to 1000 atmospheres, The results obtained are graphically shown in the accompanying figure, in which the abscissæ represent pressures, and products of P x V furnish the ordinates.—Variation of the composition of Jerusalem artichokes at different periods of their growth; rôle of the leaves, by M. G. Lechartier. Analyses of the dried black leaves which appear on Jerusalem artichokes in the autumn have been made, and the results compared with analyses of green and yellow leaves. The effect of different fertilizers on their composition has also been studied. It appears that the black leaves must have had the same composition as the green leaves, and the substances which they lose are utilized for the nutrition of the higher leaves of the plants. They preserve their vitality as long as the soil furnishes the plant with sufficient phosphoric acid and potash. But if either of these fertilizers be absent, the leaves begin to dry up.—Observations of Tempel-Swift's periodic comet, made at Paris Observatory with the West Tower equatorial, by M. G. Bigourdan. Observations for position were made on October 8 and 9. It is remarked:
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Societies and Academies. Nature 44, 608 (1891). https://doi.org/10.1038/044608a0
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DOI: https://doi.org/10.1038/044608a0