Abstract
LONDON. Faraday Society, July 14.—Prof. A. W. Porter, vice-president, in the chair.—L. A. Wild: A method of measuring the magnetic hardness of ferrous metals and its utility for carrying out research work on thermal treatment. The coercive force forms a very convenient criterion for judging the physical condition of steel, as a small change in the heat-treatment con ditions or composition of the steel results in the pro duction of a much larger change in the coercive force. The method has been used for the investigation of many problems relating to the properties of steel.— F. H. Jeffery: The electrolysis of solutions of sodium nitrate, using a silver anode.—W. E. Forsythe: The disappearing-filament type of optical pyrometer. The paper discusses fully the principles that determine the accuracy and use of this type of pyrometer. The instrument is practically a telescope with a lamp fila ment at the focus of the objective, in series with a battery resistance and ammeter. The instrument is lighted in the hot body in such a manner that the image of the filament crosses that of the body. The current is then adjusted until the filament is just as bright as the body sighted. A red glass in,the eyepiece eliminates difficulties due to colour differences.— E. A. Ashcroft: Some chemically reactive alloys. An alloy of 15 per cent, of pure magnesium with 85 per cent, of pure lead has the remarkable property that upon exposure to moist air oxidation of both the magnesium and the lead proceeds so rapidly that a lump of alloy so exposed swells up and falls to a black powder in a single night, or in some instances even in an hour or two. The experiment suggests a ready means of producing nitrogen or nitrogen and hydrogen mixtures from these alloys, or of removing remainders of oxygen from various mixtures in the cold.—nProf. H. Honda and H. Takagi: A theory of invar.—Prof. A. W. Porter: The equation for the chemical equilibrium of homogeneous mixtures. Part 1.: Equilibrium at constant temperature. The general equation for chemical equilibrium is obtained in a way which is so much less abstract than the method depending upon the thermodynamic potential that no dubiety need exist of the meaning of the result and the conditions under which any particular form of it applies. The result is expressed in terms of the pressures of the constituents when isolated and in osmotic equilibrium with the mixture through membranes each permeable to one alone of the con stituents.—Irving Langmuir: The mechanism of the surface phenomena of flotation. The paper directs attention to a theory of adsorption and surface tension which greatly aids in understanding'the phenomena of flotation. The necessity for further researches is urged.
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Societies and Academies . Nature 103, 459–460 (1919). https://doi.org/10.1038/103459a0
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DOI: https://doi.org/10.1038/103459a0