. The London, Edinburgh and Dublin philosophical magazine and journal of science . n alloys areexamined by the aid of the induction-balance does not cor-respond with Matthiessens determinations of the electric con-ductivities of the same alloys. The nature of the induction-curve remained therefore more or less obscure ; but I haverecently observed a remarkable resemblance between my ownresults t and those given by Calvert and Johnson J for theconductivity of heat, which had hitherto escaped me, as theauthors did not plot their figures. The following diagramshows the relation of the curve publi
. The London, Edinburgh and Dublin philosophical magazine and journal of science . n alloys areexamined by the aid of the induction-balance does not cor-respond with Matthiessens determinations of the electric con-ductivities of the same alloys. The nature of the induction-curve remained therefore more or less obscure ; but I haverecently observed a remarkable resemblance between my ownresults t and those given by Calvert and Johnson J for theconductivity of heat, which had hitherto escaped me, as theauthors did not plot their figures. The following diagramshows the relation of the curve published by me in July lastwith those of Calvert and Johnson and Matthiessen respec-tively, which I find for the first time placed in juxtapositionin a valuable report on the copper-tin alloys recently issuedby the United-States Government^ * Communicated by the Physical Society, having been read onNovember 8th. t Phil. Mag. (5) vol. viii. p. 57, 1879. % Phil. Trans, vol. cxlviii. 1858, p. 349. § Report made under the Direction of the Committee on MetallicAlloys. Washington, Note.—The curves for the conductivity of heat and electricity are takenfrom Plate xiv. of the Report on Copper-Tin Alloys, above referred latter curve should, however, be moved slightly to the left, as Mat-thiessens numbers represent volumes, and not weights, per cent, of copper. The earlier results, which were obtained by observations onblocks of alloy 18 millims. square and 7 millims. thick, havesince been verified (except in the case of pure copper,which as originally given is too low) by a series of disks24 millims. in diameter and 3 millims. thick, formed in thelathe, or, in the case of the very brittle ones, by filing. The close agreement between the conductivity for heat andelectricity has, as is well known, been pointed out by Wiede-mann and Franz *; but as the similarity has hitherto, I believe,only been observed in isolated cases, the above results on anextended series of alloys may b
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