The magnetic properties of binary thallium alloys before and after heat treatment in a vacuum

Abstract

The science of Magnetism has developed from the observation, many centuries ago, that loadstone attracted iron, and until 1778 when Brugmans noticed that Bismuth was repelled by a magnet, the metals of the Iron group were considered to be the only ones possessing magnetic2properties. Becquerel, in 1827, observed a similar action with Antimony, and in 1845, Faraday showed that a sufficiently strong magnetic field has an action on practically every substance. He divided substances into two classes, according to the position they took up when suspended in a magnetic field.(1) Paramagnetic - Those which tend to come to rest with their axes parallel to the field.(2) Diamagnetic - Those which come to rest with their axes at right angles to the direction of the lines of force in field. Later, this division was modified according to the manner in which the substances affect the lines of force of the magnetic field.1. (a) Lines of force concentrated to a large extent -ferromagnetic.(b) Lines of force concentrated to a very small extent -paramagnetic.2. Lines of force slightly dispersed - diamagnetic. Members of class 1. are Fe, Co, Ni, and certain of their alloys and compounds. All other substances belong to either class 2. or class 3.When a body is placed in a magnetic field it either concentrates or disperses the lines of magnetic force. The Intensity of Magnetisation is proportional to the strength of the field. I = KH where I is the Intensity of magnetisation per cc.H is the field strength or force per unit pole. K is the magnetic susceptibility or coefficient of magnetisation. i.e. the ratio of the magnetic moment per cc. at any point within the body to the field H (provided that the body is of such dimensions that the intensity may be regarded as uniform. The fundamental characteristics of dia and paramagnetism were later established by P. Curie.