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Societies and Academies

Nature volume 85, pages 360362 (12 January 1911) | Download Citation



LONDON. Faraday Society, December 13, 1010.—Mr. F. W. Harbord in the chair.—J. Swinburne: Separation of oxygen by cold. The problem of separating oxygen from the air is not the same as making liquid air. To separate oxygen from nitrogen involves doing mechanical work, which is converted into heat. A rectifying plant may be considered as an apparatus, which takes in heat substantially at the boiling point of the liquid with highest boiling point, and gives it out at a lower temperature near the boiling point of the most volatile liquid. An air separator thus takes in heat at 90° A, gives out heat at about 82° A, and at the temperature of the works, say, 273° A. The Linde process may be regarded as a rectifying plant of this sort, and a thermodynamic engine, in which a gas is compressed so as to liquefy at 90° A under pressure, and to evaporate at 82°, thus supplying the heat at the boiling point of oxygen and absorbing it at the boiling point of the air. Such a process is generally considered irreversible, but is, in fact, nearly reversible, and therefore economical. Assuming an efficiency of 40 per cent., the cost of oxygen comes out approximately is. a ton on a large scale. This ought to lead to its use in blast furnaces and other cases where an extra high temperature may be important.—Dr. H. J. S. Sand and W. M. Smalley: A new apparatus for the rapid electro-analytical determination of metals. A glass-frame anode for use with silver and nickel kathodes. In order to reduce the amount of platinum employed, a pair of electrodes has been designed which, while retaining as much as possible the essential features of those previously described, contains as little platinum as possible. The anode has been made largely of glass, so that the total weight of platinum has been reduced to about 5 grams. Special care has been taken in the design to render it as little fragile as possible. For copper determinations a kathode of silver is employed, which has been designed so that it can be made without much difficulty with the facilities usually available in a chemical laboratory. For zinc determinations a kathode of nickel was employed. The results of copper and zinc depositions are substantiallv as good as those obtained with platinum electrodes. The time required for determining 0.3 gram of copper is about seven minutes. A stand for holding the auxiliary apparatus required in electro-analysis is also described.

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