London: Taylor and Francis, 1920. Hardcover. First Edition. viii, , 832 pp. 8vo. 17 Plates . Original brown library bindings with gold embossed titling to spine. Blind embossed library stamp on first free endpaper along with an ink WITHDRAWN stamp, blind embossed library stamp on title page; due date sheet tipped onto last page of volume, very clean within. Fine.
The second part of Aston's description of his early experiments demonstrating the "whole number rule" and Chadwick's confirmation that the atomic number corresponds to the charge of the nucleus.