Magnetism and atomic structure.—I

Abstract

The present communication aims at an interpretation of the electron structure of matter which is compatible with the results of recent magnetic investigations. While acknowledging in full the success of the Rutherford-Bohr-Sommerfeld theory, in so far as it applies to radiation problems, it must at the same time be admitted that this success is confined to the simplest types of atoms, the hydrogen atom and the positively charged helium atom, each with a single electron, such atoms being very probably in an abnormal state as compared with that which prevails in unexcited matter, and upon which the magnetic determinations have been conducted. As a consequence, we are led to somewhat different interpretations of atomic structure, according to which viewpoint is adopted; but a fuller recognition of the possible differences of atomic structure between radiating and non-radiating matter may, in the near future, enable us to bridge the gap which at the moment unmistakably divides them. This paper is a continuation of previous memoirs on “The Influence of Molecular Constitution and Temperature on Magnetic Susceptibility” (‘Phil. Trans.,’ A, vol. 214, p. 109, 1914, Parts I and II ; vol. 215, p. 79, 1915, Part III ; vol. 220, p. 247, 1920, Part IV ; ‘ Proc. Roy. Soc.,’ A, vol. 95, p. 58, 1918). In Part III, p. 92, and Part IV, pp. 270-276, I have called attention to the classical experiments of Tyndall on the deportment of crystalline bodies in the magnetic field. From observations on about 100 different crystals suspended in a uniform magnetic field, Tyndall showed that, in general, “if the arrangement of the component particles of any body be such as to present different degrees of proximity in different directions, then the line of closest proximity, other circumstances being equal, will be that chosen by the respective forces for the exhibition of their greatest energy. If the mass be magnetic, this line will stand axial; if diamagnetic, equatorial.” Tyndall propounded the “ theory of reciprocal induction” to account for the augmented diamagnetic or paramagnetic property in the direction of closest packing of the particles. At that time (1870) the diamagnetic forces were known to be so minute that the theory of reciprocal induction, as applied to minute diamagnets, appeared incredible, and, as a correspondence between Lord Kelvin and Tyndall shows, the former expressed emphatically his opinion that this theory was quite incapable of accounting quantitatively for the effects observed. Regarding a diamagnetic molecule as a simple diamagnet, the mutual actions between such systems would certainly be inadequate. It has, however, been shown (Part II, p. 143; Part III, pp. 83-92) that a diamagnetic molecule is not a simple but a complex diamagnet, formed of at least two components, each of which is strongly magnetic locally.