The Origin of Radium

Abstract

I CANNOT let Prof. Rutherford's letter in NATURE of June 6 pass without directing attention to one striking consequence, in which I personally am interested. During 1904 and 1905 I published (NATURE, May 12, 1904, January 26, 1905, and Phil. Mag., June, 1905, p. 768) the result of an experiment which went to show that a kilogram of uranyl nitrate, purified initially from radium by precipitating barium as sulphate in its solution, and kept 550 days, generated a quantity of radium which, although only one-thousandth part of what is theoretically to be expected on the view that a direct change of uranium X into radium takes place, was still one hundred times the amount initially present. Boltwood (Am. Journ. Sci., September, 1905, xx., 239), working with one hundred grams of uranyl nitrate purified from radium initially by repeated crystallisations from water, was unable to observe any detectable increase after a period of 390 days, and concluded that “the results obtained by Mr. Soddy are without significance,” and averred that my results were due to the introduction of radium salts during the tests.