Theory of the Magneton.

(Gans. Statistische Theorie des Dia-, Para-und Metamagnetismus. Ann. d. Ph. 1916, 49, p. 147 and Gans Über Paramagnetismus. Ann. der Ph. 1916, 50, p. 163).

As Gans indicates, the theory of magnetism is undergoing a peculiar crisis. On the one hand, Einstein and de Haas have shown that the magnetism of iron has its basis not in elementary little magnets, but in Ampère molecular currents. On the other hand, according to the work of Kroo, the electron theory of magnetism encounters difficulties in the phenomena of paramagnetism and ferromagnetism. Gans, striving to eliminate these contradictions, proceeds from the conception of the magneton as an invariable system built up of electrons, i.e. of negatively charged bodies. Such an electron system is situated inside a positively charged sphere of constant density, so that the center of gravity of the magneton coincides with the center of the sphere. Gans first of all proves that such an electrically charged body, when rotating about its own axis, does not radiate. If the magneton does not possess a definite axis, then the body is diamagnetic in a magnetic field; in the opposite case it is paramagnetic. Pure paramagnetism does not exist at all, since, as a consequence of thermal motion, a diamagnetic effect is always superposed upon the paramagnetic excitation; at high temperatures this may predominate (the phenomenon of metamagnetism, Weber and Overbeck). But at ordinary temperatures the superposed diamagnetism may be neglected. At the present time the theory of the magneton, thanks to the work of Gans and Weiss, has attained considerable development. The magnitude of the magneton has been determined as \(16.5 \times 10^{-22}\).

B. V. Ilyin.