III. On effects of retentiveness in the magnetisation of iron and steel. (preliminary notice.)

Abstract

The term Hysteresis was introduced in a paper, recently communicated to the Royal Society, to designate a peculiar action which was observed in the inquiry then recorded, and which had also presented itself in an earlier investigation—of the effects of stress on thermoelectric quality.f It was found that when a stretched iron wire was gradually loaded and unloaded the changes of thermoelectric quality lagged behind the changes of stress, so that curves exhibiting the relation of stress to thermoelectric quality during the putting on and taking off of the load were far from coincident, but inclosed between them a wide area. In prosecuting those experiments it occurred to me that there is much room for investigation of hysteresis § in the changes of magnetisation of iron and other substances produced by (1) change of the magnetic field; (2) change of stress; (3) change of temperature. In (2) and (3) two cases are to be considered :—First, when the substance is exposed to a constant magnetising force; second, when the magnetisation which is changed is wholly residual.