io 



"?6 



NATURE 



[January 2. 1919 



auspices of the Society oi Dyers and Colourists, and 

 a further investigation cm the nitration 

 been I >< -^iin , and under the research scheme oi the 

 Institution of Electrical Engineers work is nov i ng 



done concerning insulating oils. The stud 



chlorination products of rubber, one of which, known 

 as "duroprene," is remarkable for its resistani and 



lei properties, has been taken up. Research on 

 fuels has included: heating In gas, the stripping of 

 coal-gas, the distillation of cannel .md othei coals, as 

 well as exhaustive examinations on certain products 

 obtained from coal-mines, and il o upon a series <>f 

 seams of Lancashire coal, ["he conditions of car- 

 bonisation of iron, especially in case-hardening; the 

 influence of impurities on the strength and >>n the 

 resistance to corrosion of cast-iron; the influence "I 

 sulphur in the processes for making malleable iron 

 castings, and on the toughening of copper and in- 

 creasing the strength of copper alloys, have all been 

 the subjeel of investigation and experiment with 

 valuable results which have found industrial 

 applications, whilsl research on cellulose subsidised bj 

 the Department of Scientific and Industrial Research 

 has also bei n in progress. 



In the department of printing and photo 

 technology investigations were carried out, and are 

 still proceeding, on the development of machine- 

 printed photogravure, and much attention has been 

 paid to new methods for the production of lithographic 

 printing surfaces in monochrome and colour. 



Much other research has been carried out or is in 

 progress on the economic use of fuel, on air pollution, 

 on gas flames, on the economic use of electricity for 

 heating purposes, on fibre testing, and on the use of 

 ramie waste for gas-mantles. 



\ll the departments of the college have throughout 

 the period of the war been busily engaged on investi- 

 gations in M'd of the requirements of the several 

 departments of the Government. The results of some 

 of the researches engaged in are shown in the space 

 allotted to the college at the exhibition. It is to he 

 d that the exhibition s,, happily inaugurated in 

 London will serve to convince the public that British 

 science intelligent!} applied can, if we so will it, con- 

 tend successfully with the best efforts of the most 

 highly educated of foreign nations. 



THE CONCEPTION OF THE CHEMICAL 

 ELEMENT AS ENLARGED BY THE 

 STl D] OF RADIO-ACTUVE CHANGE. 1 



IF a chemist were to purify lead from silver, and 

 found on re-examining the lead that silver were; 

 11, and if, again and again, silver, initial!} absent, 

 reappeared the doctrine of the unchangeability of the 

 its would he at an end. The conclusion in 1902 

 by Sir Ernest Rutherford and myself with regard to 

 the element thorium was of this direct and simple 

 characl Vs often as the constituents responsible for 



the radio-activitj are separated by physical or chemical 

 ' . the} reform. One of the constituents, the 

 thorium emanation, is a gas which was shown to 

 possess tin- complete absence of chemical character 

 characteristic of the argon family of gases. It is 

 ed front thorium through the intermediary of 

 another constitue nt, th irium-X, which is left in the fil- 

 trate, when a solution of thorium is pi. - ipitated by am- 

 monia, but not l>\ other chemical reagents. In turn the 

 emanation changes into non-volatile products causing 

 the active d po it. The cleat 1 onception of the nature 

 mical change, the distinction between atoms and 

 ule s, which we owe to the Founders of chemistry, 



1 1 



1 . It Soddjt, F R.5. 



made it possible to n cognise 1 adio-ai tivi eh 

 almost instantlj as a ca transmuta- 



tion. Novel as the explanation was, the phenomei 

 explained are so novel as to transcend what to a 

 ition ago would have appeared as the limits oi 

 the pi;, sit all} possible. But even to-da} it is only in 

 radio-active phenomena that the limits reached long 

 ago in the chemical analysis ol mattei have been over- 

 stepped, and the rubicon, which many have -vaulted over 

 so lightly in imagination, has actual!} been crossed 



|.\ SC 1. Ill 1 . 



I In iii ,1 phase oi the stud} ol radio-active change 

 was mainl} concerned with the disentanglement of tin- 

 long and in\ol\'d sequence of transformations which, 

 starting From uranium and thorium, were ultimatel} 

 found to include all the known radio-elements. Beyond 

 the fact that the radio-elements were in present coursi 

 oi evolution, it added little to thi conceptions of chemis- 

 try. Bui in the second and more recent phase — con- 

 cerned with the chemical character of the succi 

 products, tin- law connecting this with the type of iav 

 expelled in the change, the discovery of elements with 

 unique radio-active l/ul identical chemical and spe 

 scopic character, the identification of these as ism 

 or elements occupying the same place in the periodic 

 table, the interpretation of the latter and the- recogni- 

 tion that the- so-called chemical elements are in reality 

 heterotopes or substances occupying different pi 

 in the periodic table, and are not necessaril} even 

 homogeneous — conclusions, not merely novel, but up- 

 setting, have been reached. 



The criterion at first relied upon in the analysis oi 

 matter into its elements, the possession of a unique 

 chemical character, was added to by Daltpn's atomic 

 theory, which gave to each element a unique atomic 

 weight. The periodic law apparentl} connected 

 two criteria, fitted the individual elements into familii 3, 

 and showed that, whatever the elements were, they 

 were all of a class, the limits of chemical analysis, 

 and, if complex, then all of the same kind of com- 

 plcxitv. The periodic law introduced a third criterion 

 of the element, that it occupied a place to itself in 

 this scheme, and the discovery of spectrum anal} sis, 

 a fourth, that it possessed a unique spectrum. The 

 discovery of radio-activitv introduced a fifth, the pos- 

 session of a unique radio-active character, in the case 

 of the radio-elements. Of the first three new elements 

 discovered by the aid of the fifth criterion, polonium, 

 actinium, and radium, the claim of the last to the 

 title of element was brilliantly substantiated by the 

 successive determination of its unique spectrum, 

 unique chemical character, unique place in the periodic 

 table, and unique atomic weight. The production of 

 this element from uranium through the intermediary of 

 ionium, and the production of helium from radium, 

 and, in due course, from the other radio-elements, 

 furnished conclusive proofs of the correctness of the 

 first interpretation of the transmutational chara 

 of radio-active change. 



I hen came a totally new departure. The possession 

 of unique radio-active character does not always, as in 

 the case of radium, connote unique chemical and 

 scopic character. As, one after another, the 

 various members of the disintegration s, rie s were dis- 

 tinguished, by their breaking up in characteristic ways 

 at definite rates, no further chemically new elements 



were found. All resembled known elements so closely 

 that they could not be separated by chemical analysis, 

 and those actually a1 work on these substances 

 to the conclusion lhat the chemical resemhl 

 amount to identity. Radio-thorium is. for example, 



d chemically with thorium. It v. 

 from thorium and individually recognised b} Sir 

 William Ramsay and O. Hahn onl; I se i.t is 



XO. 2566, VOL. I02] 



