32 Journal of the Mitchell Society [July 



by its mass but by its electrical content as well. According to 

 Soddy, the system represents the chemical character of mat- 

 ter as the function of two variables instead of one. The 

 electrical content is the essential variable in horizontal col- 

 umns and mass is the essential in vertical columns. 



It is somewhat early to raise the question as to whether 

 all elemental atoms are the result of disintegration pro- 

 cesses, or, conversely, of synthesis, but in any case the old 

 puzzle remains as to their great irregularity in weight re- 

 lations if the most accurate chemical determinations are to be 

 relied upon. If the time should arrive when they could be 

 calculated, chemists would naturally return to hydrogen as 

 the standard. Certainly, at present these weights present no 

 simple synthetic relations. 



An explanation of this is perhaps at hand if the view of 

 Soddy (and of Crookes at an earlier period and from a differ- 

 ent standpoint) is accepted, namely, that in atomic weight 

 determinations it is not a natural constant that is gotten but 

 a mean value of non-homogeneous masses. In other words, 

 the weight may represent the average of various isotopic 

 atoms and not the absolute weight of identical atoms. 



It is very fortunate that the simple expedient of arranging 

 the elements in the order of their atomic weights could give 

 the early workers so nearly correct a view of the periodic 

 system. It would probably have remained hidden for a long 

 time if this had not been so prominent a factor in determining 

 the proper sequence. There is undoubtedly a proper se- 

 quence. This has been settled hitherto chiefly by considera- 

 tion of the atomic weight, but also by examination into the 

 relationship existing between the elements. For instance, the 

 order of atomic weights would be iodine and then tellurium, 

 l)ut chemically tellurium belongs to Group VI and iodine to 

 Group VIT. Therefore, the atomic weight order is reversed. 



The sequence numbers of the elements, or atomic num- 

 bers as they are called, assume a new practical and theoretical 

 importance. Within twenty years after the announcement 

 of the periodic system, some, as Fedaroff, had sought to attach 



