The High-Frequency Spectra of the Elements

London: Taylor and Francis, 1913. First edition. Original wrappers. Very Good. FIRST EDITION IN ORIGINAL WRAPPERS of both parts of Moseley's groundbreaking work providing the scientific basis for our understanding of atomic numbers and the ordering of the periodic table. PMM 407. "Moseley, working under Rutherford at Manchester, used the method of X-ray spectroscopy devised by the Braggs to calculate variations in the wavelength of the rays emitted by each element. These he was able to arrange in a series according to the nuclear charge of each element. Thus if the nuclear charge of hydrogen is 1, in helium it is 2, in lithium 3, and so on by regular progression to uranium at 92. These figures Moseley called atomic numbers. He pointed out that they also represented a corresponding increase in extra-nuclear electrons and that it is the number and arrangement of these electrons rather than the atomic weight that determines the properties of an element. It was now possible to base the periodic table on a firm foundation, and to state with confidence that the number of elements up to uranium is limited to 92" (Printing and the Mind of Man 407). "Moseley's fundamental discovery was a milestone in our knowledge of the constitution of the atom" (Dictionary of Scientific Biography). IN: The London, Edinburgh, and Dublin Philosophical Magazine. Sixth series, vol.26, no.156 (December 1913), pp.1024-1034; and Sixth series, vol.27, no.160 (April 1914), pp.703-713. London: Taylor and Francis, 1913-1914. Octavo, original wrappers; custom cloth box. Two volumes. December 1913 issue (part I) with light edgewear and chip to bottom outside corner of rear wrapper; April 1914 issue with chip to bottom inner corner of rear wrapper. RARE IN ORIGINAL WRAPPERS.