122 Journal of the Mitchell Society [Mai'ch 



recently drawn attention to the inadequacy of the designation ' ' atomic 

 number." He suggests as a substitute "element number" but this 

 seems equally inadequate. The truth is, it is merely a position number 

 and no longer represents either single atoms or simple elements. 



In his address as president before the recent meeting of the British 

 Association, Thorpe says : 



The term atomic weight has thus acquired for the chemist an altogether new 

 and much wider significance. It has long been recognized that it has a much 

 deeper import than as a constant useful in chemical arithmetic. For the ordinary 

 purposes of quantitative analysis, of technology, and of trade these constants 

 may be said to be now kuowai with sufficient accuracy. But in view of their 

 bearing on the great problem of the essential nature of matter and on the super- 

 latively grand question, ' ' What is the inner mechanism of the atom ? ' ' they 

 become of supreme importance. Their determination and study must now be 

 approached from entirely new standpoints and by the conjoint action of chemists 

 and i^hysicists. 



In conclusion, I ask you and myself the question : How shall we 

 now detine the element in the light of these new and wonderful reve- 

 lations? Years ago in an address before the American Association I 

 pointed out how often in the history of science we had been forced 

 to change the definition because of new developments and how shifting 

 were the sands upon which it was based. The homogeneity so fer- 

 vently relied upon in our textbooks must be abandoned as the hetero- 

 geneity of their component particles has been made manifest. One 

 stand is left to us and it has the appearance of permanence. However 

 heterogeneous physically, these component particles are homogeneous 

 chemically. In fact, the sole difference seems to be that of mass. For 

 the present, then, the defiuition may safely run : The masses of all 

 elements are composed of chemically similar particles. So long as this 

 is true the chemist at least need not disturb himself. Of course, there 

 alwaj^s looms before us the fact of atomic disintegration. 



Chapel Hill, N. C. 



