Abstract
Annalen der Physik und Chemie, No. 9.—Questions in molecular physics figure largely in this number. Herr v. Wroblewski inquires into the nature of absorption of gases, by a kinematical method, inferring from the phenomena of motion of gases diffusing in absorbent substances, the condition in which they exist in these. The phenomena in caoutchouc are studied, and the author concludes, inter alia, that the absorption of protoxide of nitrogen, carbonic acid, and hydrogen by caoutchouc is a purely physical process, and the gases retain, after absorption, their gaseous state and all characteristic properties. The constant of diffusion of a gas depends only on physical properties, and chiefly its specific gravity, being approximately inversely proportional to the square root of this; but the specifically lighter gases show greater constants than this relation expresses. The constant for protoxide of nitrogen and carbonic acid increases with increase of temperature, and at 10°C. is fifty times smaller than that for carbonic acid in water. A caoutchouc membrane is to be conceived as a porous plate endowed with gas-condensing and rarefying powers (the gas moving through the pores).—M. Chappuis investigates the condensation of gases on a glass surface by a similar method to Magnus's, viz., measuring the expansion between two exactly known temperatures, of a certain volume of gas at constant pressure in contact with a large glass surface, and inferring the original volume of the gas. The numerical results for hydrogen, air, carbonic acid, sulphurous acid, and ammonia, from 0° to 100° and 180°, are given, and utilised in determining the absolute coefficient of expansion at constant pressure (a slight correction of the former determinations being necessitated by the phenomenon in question). Magnus's statement that at 100° there is no condensed gas layer on a glass surface is shown to be incorrect in the case of ammonia.—A paper by Herr Schleiermacher treats of the quantity of liquid condensed on a moistened body. The author rejects Wilhelmy's numerical values for the condensation, and considers that, in determining the specific gravity of a liquid, if one be content with an accuracy of 0.002 per cent., the influence of condensation may be neglected; in general the coefficients of condensation would be, at the most, of the order of 0.00001 g. —The specific heat of water is anew determined by Sq.ctm.
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Scientific Serials . Nature 21, 27–28 (1879). https://doi.org/10.1038/021027a0
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DOI: https://doi.org/10.1038/021027a0