AGE OF THE EARTH

Evening Post, Volume CIV, Issue 7, 8 July 1922, Page 12

AGE OF THE EARTH

WONDERS OF RADIO-ACTIVITY.

Before the discovery of radio-active materials, scientists were content with estimating the age of the earth, at a few hundred million years, more or less. Geologists were wont to claim at least five hundred millions, so as to allow time for the geological changes that have obviously taken place in what is termed the lithosphero, or rOcky crust of the earth. But the stricter theologians, perturbed by this considerable addition to the chronology of the Bible, contested the theories of the scientific men and favoured the cataclysmic hypothesis in' the endeavour to account for the phenomena observed in.'the study of the rocks. WithHhe discovery of raido-actdve matte, there came an altered point of. view. Forthwith'it'became evident that the earth must be vastly older than even the hoary age demanded by the geologists. In a lecture at the Royal Institution on "Radio-activity,! v Professor Sir Eroe_t Rutherford claimed that the "life" of radium was at least five thousand millions of years, and that uranium, the parent of most radio-active substances, must bo no less'than twice that age, otherwise there would be no uranium left on the earth. A thousand million yeate is quite a considerable period,- and somewhat puts out of court the meticulously elaborate calculations of the late Archbishop Usher, by which he fixed the very afternoon on which • the Creation took place, about four thousand years ago. A good many pious people still believe in Dr. Usher's chronology; but, if the deductions which, have been made from the results of the examination of radioactive phenomena are correct, a thousand million years is a moderate estimate of the period' during which the earth has been in existence.

Sir Ernest Rutherford, however, was not chiefly concerned with matters affecting chronology. ' His concern was rather to explain some of the properties and characteristics of ionium, radium, thorium, actinium,, and other radio-active minerals, and the remarkable products or emanations to which these give rise. A noteworthy fact, which he demonstrated by a Series of beautiful experiments; was that these emanations or gases possessed in varying degree the same physical and therapeutic properties a£ the minerals from which they are derived. One important result of this, especially in relation to the treatment of disease, is that radium is .comparatively little used directly in hospital work.' What is done is to collect the emanations in minute tubes and apply these in medical treatment. They are quite as effective as the actual (mineral itself, and there is the advantage that if a tube of radio-active emanation gets broken -or disappears no radium is Tost, arid a fresh supply of the radioactive emanation can be "grown" and collected in a fresh tube in a few days.

■ Thii>re .is" an astonishing- var-iability in the duration of these ' emanations. • A piece of radium itself will, it is estimated, go on pouring out its producits for five thousand million years,_whil_e one of rthe products'rdf iidtinium,' "actiniiihAA," as it is called, disappears in the fivehundredth part of a second. .Yet so marvellous is the refinement of laboratory methods now practised that it has been found possible to determine accurately the physical properties of this rapidly fleeting emanation. Thirty or more elements are produced from radium, ■and in watching the transformations which go on under their eyes scientific investigators'see taking -place that v transmutation of metals so long and vainly sought by the medieval alchemists. It is in this direction that perhaps the most momentous discoveries wjll be made in connection with radio-activity. The disruption of the. atom which is continually going on in radio-active substances may, and probably will, provide the key to the solution of the problem of the constitution of matter, and incidentally place at the disposal of mankind illimitable stores of the energy which is now obtained by the wasteful consumption of coal or the utilisation of water'power.: