Intelligence and Miscellaneous Articles. 175 



radioactive atom on disintegration. Tins problem had been in- 

 vestigated only for the active deposit of radium, and even in 

 this case no high degree of accuracy could be claimed for the 

 result of previous investigators. Moseley succeeded in im- 

 proving the method and in obtaining much more accurate results. 

 He also extended the investigation so as to include most of 

 the radioactive products emitting /3-rays*. His results have 

 since gained additional importance on account of their bearing 

 on theories of the origin of /3- and y-rays. The knowledge 

 and experience which he gained in these experiments Moseley 

 subsequently used to obtain high potentials in vacuo by means 

 of the charge acquired by a radioactive substance during the 

 emission of /3-rays f. He was thus able to obtain higher steady 

 potentials than had previously been reached in this or any other 

 way. Whilst engaged in these difficult researches Moseley still 

 found time to devote attention to other problems. In collaboration 

 with Eajans he developed a most interesting method of deter- 

 mining the life of very rapidly decaying radioactive products J; 

 with Makower he discovered that radium B emitted y-rays which 

 were so easily absorbed that they had not been previously 

 detected § ; and with Robinson he measured the total ionization 

 produced by the {3 and y radiation from radium B and 

 radium C ||. 



In 1912 Moseley resigned his lectureship, and having obtained 

 the John Harling Fellowship at Manchester University, he was 

 able to devote all his time to scientific investigation. In the same 

 year a new field of Physical research was created by Laue's dis- 

 covery of the interference of X-rays in crystals ; and interest was 

 soon intensified by the brilliant work of W. H. and W. L. Bragg 

 on the constitution of X-rays and the structure of crystals. Very 

 soon after Laue's discovery Moseley, working with Darwin, started 

 a thorough investigation of the properties of X-rays by means of 

 the new method. Their results were published in June 1 913 %; 

 and although many of the results were discovered and published 

 earlier by the Braggs, this paper contained a great number of most 

 interesting experimental details and theoretical considerations, and 

 constituted an important step in the rapidly increasing knowledge 

 about the nature of X-rays. Immediately after the completion of 

 this work Moseley undertook a systematic investigation of the 

 characteristic X-radiation from as many different elements as 

 possible. This investigation involved great experimental difficulties, 

 partly on account of the fact that the chemical nature of many 



* Moseley, Proc. Roy. Soc. A. lxxxvii. p. 230 (1912). 

 t Moselev, Proc. Roy. 8oc. A. lxxxviii. p. 471 (191-3). 

 % Moseley and Fajans, Phil. Maor. xxii. p. 629 (1911). 

 § Moseley and Makower, Phil. Mag. xxiii. p. 812 (1912). 

 II Moselev and Robinson, Phil. Maaf. xxviii. p. 327 (1914). 

 % Moseley and Darwin, Phil. Mag. xxvi. p. 210 (1913). 



