1918-19.] 
An Electron-Transference Hypothesis, etc. 
XV. — An Analysis of an Electron - Transference Hypothesis of 
Chemical Valency and Combination. By John Marshall, 
M.A., B.Sc., Scholar of Trinity College, Cambridge ; Lecturer in 
Mathematics, University College, Nottingham. Communicated by 
Professor W. Peddie, D.Sc. 
(MS. received March 6, 1919. Read May 5, 1919.) 
Introduction. 
In this paper it is proposed to analyse in a tentative way the Electron- 
Transference Hypothesis of Chemical Combination which has been put 
forward by Lord Kelvin in his paper entitled “ Aepinus Atomised ” (Phil. 
Mag., 1902), and by Sir J. J. Thomson (Phil. Mag., 1904). 
This hypothesis postulates that on the combination of two or more 
atoms to form a chemical compound electrons are transferred from atoms 
playing an electro-positive part to those playing an electro-negative part 
in the molecule, the number of electrons thus transferred being taken as a 
measure of the valencies of the respective atoms in the molecule. Such an 
hypothesis would not lead to conceptions at variance with the facts of 
electrolytic dissociation. 
The methods employed and the assumptions made are similar to those 
formulated by H. A. Lorentz in his discussion of the Molecular Refractive 
Index of Mixtures and Compounds (vide Theory of Electrons, § 117-130), 
and by Sir J. J. Thomson in his discussion of the Molecular Refractivity of 
a collection of atoms (vide Phil. Mag., 1906). 
H. A. Lorentz’s discussion ignores the contribution given by the 
positive electrification of the atom to its atomic refractive index except 
in so far as the positive electrification may be the origin of the force which 
tends to restore a displaced electron to its position of equilibrium when it 
is disturbed by the periodic changes in the electro-magnetic forces in the 
.aether when light is incident on the atom. 
In Sir J. J. Thomson’s paper in Phil. Mag., 1906, the contribution of 
the positive electrification is not ignored, and the well-known structure 
of the atom as a sphere of positive electrification in which negative electrons 
are situated is assumed. 
It may be noted at once that the additive law for atomic refractive 
indices will follow from any structure assumed for the atom, so long as 
VOL. XXXIX. 14 
