London: Edward Arnold & Co. 1922. First Edition. viii,152 pages. 8vo. Publisher's blue cloth gilt. Previous owner name penciled on front flyleaf. Several previous bookseller markings on pastedown endpapers (codes, prices, inventory numbers). Endpapers lightly offset (toned) as normal. A few penciled notations in the text. Boards lightly bowed, top page edges dusty. A sound copy. Very Good. Cloth. 
Aston was awarded the Nobel Prize in Chemistry in 1922 "for his discovery, by means of his mass spectrograph, of isotopes, in a large number of non-radioactive elements, and for his enunciation of the whole-number rule."
Aston was an assistant to JJ Thomson (PMM 386 - cathode rays) who in 1913 entrusted him with "the task of ascertaining the difference in atomic weights of [two forms] of neon." Interrupted by WWI, Aston after the war worked to improve Thomson's parabola experiments, devising "the mass spectrograph by which the gas traces were induced to focus themselves within a much smaller area" [than Thomson's apparatus] giving greater clarity of identification. Where "previous investigators had assumed a mystique of the atomic table by which the atomic weights of the elements would prove to be exact multiples of hydrogen," Aston disproved this showing that "the true atomic weight of an element is arrived at by averaging the mass of it's constituent parts."
See PMM (2nd), #412 for a more detailed discussion. A significant work.