Nature of Chemical Forces

Abstract

PROF. FAJANS' Cornell lectures from a very small volume in comparison with those provided by former holders of the Baker lectureship, since they cover only 113 pages of text. The reason for this is a wish to avoid republication of material which is already in print. Thus a course of lectures on radioactivity and isotopy has been omitted, because these subjects are dealt with in existing books by the author and others; but one of the most interesting of current problems is discussed fully in a chapter on the origin of actinium. The conclusion is drawn that this element has an atomic weight of 227 and must, therefore, be entirely distinct from the radium and thorium series, where all the atomic weights are even, thus giving rise to radium lead, Pb²⁰⁶, and thorium lead, Pb²⁰⁸, which have both been separated in an almost pure state from minerals rich in uranium and thorium respectively. Strong confirmation of this conclusion is supplied by Aston's observation that lead actually contains the third isotope, Pb²⁰⁷, and we may, therefore, now accept also the further deduction that actinium has its origin through protactinium in an odd-numbered isotope of U²³⁸.

Radioelements and Isotopes: Chemical Forces and Optical Properties of Substances.

By Kasimir Fajans. (The George Fisher Baker Non-resident Lectureship in Chemistry at Cornell University, Vol. 9.) Pp. x + 125. (New York: McGraw-Hill Book Co., Inc.; London: McGraw-Hill Publishing Co., Ltd., 1931.) 12s. net.