III. 4] 
ATOMICITY IN ELECTRICITY 
35 
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played the part of the Weber elements, so as to correspond to 
the electron theory of the molecular magnet. 
It is convenient to have a definite name for these Weber 
elements, and we may call them “ magnetons,” defining the 
word in the following way. The structure within the atom 
which behaves as the Weber element and may be regarded as 
the origin of tubes of magnetic induction, will be called a 
“ magneton,” using that term in its widest sense. This word 
seems to have been employed first by Dr. L. A. Bauer * in a 
paper read at a meeting of the Philosophical Society of Washing 
ton on 7th May, 1910. “ The corpuscles in magnetism might be 
atomic systems in which the electron is revolving about an inner 
nucleus consisting, for example, of a positive ion. . . . Since 
the system creates an atomic magnetic field, the axis of which 
passes through the centre of rotation of the electron and per 
pendicular to the plane of rotation, the speaker suggests calling 
such systems ‘ magnetons.’ ” f The word was suggested and 
used independently about the same time by Professor Gans and 
by Professor Weiss, and is now well established in the subject. 
Although the name “ magneton ” is of comparatively recent 
date the idea of a magneton has existed from at least the time 
of Weber’s Works. In 1902 Voigt discussed magnetic elements 
consisting of homogeneous uniformly charged solids in rotation. 
In 1903 Abraham discussed a spherical electron in rotation and 
uniformly charged either over the surface or throughout the 
volume. 
4. The Magneton of Weiss 
Weiss gave the name “ magneton ” to the fundamental 
unit of magnetic moment which he believed he had discovered 
in the molecule of ferromagnetic substances. In the theory of 
magnetism it is often convenient to deal not with the magnetic 
moment per unit volume but with the magnetic moment per 
unit mass, and we may, if we choose, take as the unit of mass 
the gram atom. In this case the magnetic moment estimated 
for a single atom may be calculated if we divide the magnetic 
moment of the gram atom by Avogadro’s constant, 6-062 x io 23 , 
the number of atoms in the gram atom. 
Weiss carried out experiments first of all on the molecular 
susceptibility of magnetite. When this quantity was plotted 
against the reciprocal of the absolute temperature he obtained 
a series of straight lines, the slopes of these linear portions being 
in the ratio 4 : 5 : 6 : 8 :10. This result Weiss attributed to a 
ft 449, w