804- Dr. J. W. Nicholson on a Structural 



The results of the present experiments indicate that that 

 part of Bragg's argument applies with equal force to the case 

 of the radiations which produce the photo-electric effect. 

 Since the photo-electric effect can be produced with visible 

 light in the case of sufficiently electro-positive metals, and 

 since there is a continuous gradation between such cases and 

 the effects here investigated, there seems to be no valid reason 

 for supposing that the difference between the emergent and 

 incident effect is not characteristic of both ordinary and 

 ultra-violet light as well as the more penetrating radiations 

 examined by Bragg. If it stood alone this investigation 

 would be a strong argument in favour of the unitary theory of 

 light. The objections to such theories on other and ap- 

 parently more fundamental grounds are very serious, as 

 Lorentz has recently shown. Under the circumstances it 

 seems desirable to postpone further discussion pending the 

 accumulation of more experimental evidence. 



This subject and its method of investigation was suggested 

 by Prof. O. W. Richardson and carried to its present stage 

 under his direction. I wish to thank him here for his 

 valuable assistance, advice, and encouragement throughout 

 the course of this work. 



Palmer Physical Laboratory, 



Princeton University, 



Princeton, N.J., U.S.A. - 



— n 



LXXXIV. A Structural Theory of the Chemical Elements. 

 By J. W. Nicholson, M.A., I).Sc* 



rj^HIS paper gives a preliminary account of a structural 

 JL theory of the chemical elements, which derives them as 

 compounds, in a certain sense, of primary forms of matter. 

 Tt is possible, on certain views, to accomplish this for the 

 simpler elements, and to a greater degree, of course, for 

 those which are more complex, the degree of complexity 

 being measured by the atomic weight. 



Calculations of the atomic weights of these hypothetical 

 constructions, even in the simplest cases, can give results 

 in sufficient and indeed unexpected accord with the best 

 chemical determinations. The groupings of primary forms 

 for the elements as arranged in the Periodic Table show 

 curious systems which appear to shed light on the mutual 

 relations of the elements. This is more especially the case 



* Communicated by the Author, having" been read at the meetiDg of 

 the British Association at Portsmouth, 1911. 



