Rochester Paper - Some Electrical Properties of Nickel and Monel Wires

This paper gives the results of an investigation of the specific resistance and temperature coefficient of the electrical resistance of nickel and its important alloy, monel metal. For most of the pure metals, the temperature coefficient of resistance is approximately 0.004 per degree centigrade at 20" C. Nickel and iron, however, are exceptions. This property is important as it gives us good material for the construction of thermometers and other instruments involving electrical control. A summary of information on this subject has been publishcd by the Bureau of Standards.l The present experiments antedate this publication by several years and as the information obtained is not contained in it, the results of the experiments arc published as additional information. Electrical Properties of Pure Nickel It is generally conceded that the lowest values for electrical resistance are obtained in the purest metal. In the case of nickel, the best material obtainable is electrolytic nickel, which contains approximately 99.80 per cent. nickel, 0.15 per cent. iron, and 0.05 per cent. copper. Any cobalt that may be present is included in the nickel figure. If the elcctrolStic sheet has been deposited without intermission, it is possible to cut a section from the sheet and roll it into wire without melting. By this means a nickel wire may be obtained that is uncontaminated by any of the impurities always taken up by nickel during melting. Two samples of nickel wire obtained from different electrolytic nickels had the follolving electrical resistance and temperature coefficient of electrical resistance: Specific Temp. CofEE. Sample MateRial ReSISTance peR Deg. C. NO. 1 Electrolytic nickel.................... 7.55 0.00550 NO. 2 Electrolytic nickcl ................... 7.60 0.00553 * Rensselacr Polytechnic Institute. Director of Research, Driver-Harris Co. Russell Sage Laboratory, Rensselaer Polyt,ecllnic Institute. 1 U. S. Bureau of Standards, Circular 100 (March, 1921).