XXXII. <i>On the magnetic properties and electrical resistance of iron as dependent upon temperature</i>

Abstract

T HE changes brought about by heating in the various physical properties of iron have been, since the firs~ investigations into the nature of the phenomenon of recalescence by Gore and by Barrett, the subject of much experimental work, which, during the last ten years, has been largely upon the relation of the magnetic properties of iron to temperature.As long ago as 1879, however, Baur of Ziirich ~ described experiments on an iron bar inserted while hot into a long magnetizing helix, which served to determine its permeability at any instant, the temperature being estimated from a knowledge of the law of cooling.This method, although rough, enabled him to show that in weak magnetic fields the permeability of iron rises, and that in strong ones it falls, with rise of temperature ; and that as the critical poin~ is reached the magnetic qualities of iron in fields of all strengths very rapidly disappear, These resalts have been confirmed and extended by the * Communicated by the Physical