678 Scientific Proceedings, Royal Dublin Society. 



been confirmed and extended by others. It shows primarily that secondary 

 radiation or scattering of electrons is an atomic property. It is, in fact, 

 additive, as McClelland proved in 1906; the elements carrying unaltered 

 their characteristic effects into their compounds one with another. The 

 elemental scattering follows their periodic classification as based on other 

 physical properties. Very intimate chemical relations are attended with 

 closely similar elemental scattering. 



In 1907 McClelland, working with F. E. Hackett, showed that the periodic 

 lay could also be traced in the absorption of /3 radiations. 



McClelland's work has been attended with that inspiration which is the 

 first attribute of secure and sound advance. His work on ionization has- 

 been used by Sir J. J. Thomson in his work on Conductivity through Gases. 

 His discoveries on secondary radiations have been the starting-point of much 

 similar work done, not only in England, but abroad. Most of his principal 

 papers find a place in the Transactions of this Society, 



Of McClelland's other work for the Eoyal Dublin Society during the 

 many years of sustained interest in its affairs, and more especially in its 

 scientific advancement, it is not easy to speak too highly. As a teacher his- 

 pupils speak gratefully of his devotion to their interests. His beneficial 

 influence has extended itself to the sister Institution, the Eoyal Irish. 

 Academy. More recently he has served with distinction on the Advisory 

 Council for Eesearch instituted by the State. 



PAPEES BY THE LATE PEOFESSOE McCLELLAND, F.E.S. 

 [The names in italics indicate joint authorship.] 



1. Leakage through Dielectrics traversed by Pontgen Eays. Camb. Phil. Soc. 



Proc, ix, p. 126. 1896. With J. J. Thomson. 



2. Selective Absorption of Eontgen Rays. Eoyal Society Proc, lx, pp. 146-148. 



1897. 



3. Cathode and Lenard Eays. Eoyal Society Proc, lxi, pp. 227-235. 1897. 



4. On the Figures Produced on Photographic Plates by Electric Discharges.. 



Camb. Phil. Soc. Proc, ix, pp. 522-525. 1898. 



5. On the Conductivity of Hot Gases from Flames. Phil. Mag., xlvi,. 



pp. 29-42. 1898. 



6. On the Conductivity of Gases from an Arc and from Incandescent Metals. 



Camb. Phil. Soc. Proc, x, pp. 241-257. 1900. 



7. Action of Incandescent Metals in Producing Electric Conductivity in Gases.. 



Camb. Phil. Soc. Proc, xi, pp. 296-805. 1902. 



