The Periodic Law

THE Mendeleeff Centenary Lecture was delivered before the Chemical Society at the Royal Institution on April 19 by Lord Rutherford, and is printed in the Journal of the Society for May. Lord Rutherford gave an account of the researches on atomic structure which have led to a realisation of the true meaning of the Periodic Law (see NATUBB, 133, 161, 656; 1934), with so many of which he has himself been associated. He dealt with the question of the order of the elements, as defined by the atomic number, with the discovery of isotopes, with the arrangement of electrons outside the atom, and with a number of related topics. The lecture sets out very clearly the course of investigation which has provided an explanation of the remarkable generalisation pro posed by Mendeleeff in 1869, and also the elucidation of some points of difficulty associated with the Periodic Table before the work of Moseley in 1912-13, which Lord Rutherford described as “an outstanding landmark in the history of our knowledge of the elements”.