MANY of the radio-elements have been shown, after close examination, t o resemble other elements, and to be non-separable from them by chemical processes ; thus the impossibility of separating radiolead (radium-D) from lead, mesothorium-1 and thorium-X from radium, ionium and radio-thorium from thorium is well known (Soddy, " Chemistry of the Radio-elements The chemistry of the best known disintegration products is summed up by Baying that they are identical with such elements as lead in the

more »

... e of radium-D, or as radium in the case of mesothorium-1. Other such resemblances no doubt exist, and in the present paper a systematic investigation has been made of all the radio-elements of period sufficiently long for chemical examination, in the course of which it has been shown that many of the radio-elements known to resemble other elements, either radio-active or inactive, are, in fact, non-separable from them, and several new CM of the same kind have been discovered. The work detailed in this paper increases the number of disintegration products the chemistry of which can be referred tu the chemistry of ordinary non-radio-active elements. Uranium-X. One of the methods used by Sir W. Crookes (Yroc. Roy. Soc., 1900, 66, 409) when he discovered uranium-X was to dissolve uranyl nitrate containing a small quantity of an iron salt in excess of dilute ammonium carbonate solution, when most of the iron remained undissolved, and this contained the &activity due to uranium-X. Other methQds of aepairating this substance are known, but until recently thme methods have been quite empirical. Among such methods are: (1) Shaking uranyl nitrate, crystallised from water, with ether. The uranyl nitrate dissolves mainly in thO ether, wh:lst the aqueous layer from the water of crystallisation contains the uranium-X. (2) Precipitating barium sulphate in a solution of uranyl nitrate. The uranium-X is adsorbed by barium sulphate and can b s collected with it.