CHEMICAL IXVESTIGATTONS RICHARDS. 219 



fascinating subject of radioactivity bids fair to give us in many 

 ways an entirely new insight into the innermost structure of the 

 atom. 



During the progress of the study of the combining proportions of 

 the elements, it became more and more evident to me that the atomic 

 weights should be considered not only in relation to one another 

 but also in relation to many other essential distinguishing properties 

 of the elements. This wider problem involved a great extension of 

 the experimental field. 



Among other attributes of the various forms of matter, compressi- 

 bilities, surface tensions, densities, dielectric constants, heats of re- 

 action, and electromotive forces have begun to receive attention, and 

 already many new data have been accumulated. The explanation 

 of the nature of these researches would take us far beyond the scope 

 of this present address, but their object deserves attention. This 

 object is the correlation of the various properties into a consistent 

 whole, in the hope of tracing the unknown physical influences which 

 determine the nature of the elements. 



The rigorous science of thermodynamics enable^s us to predict in 

 logical and precise fashion some of the relations between physical 

 properties. My hope is not only to aid in providing accurate experi- 

 mental basis for calculations of this kind, but also to achieve the 

 correlation of different properties, apparently independent of one 

 another from a thermodynamic point of view, thus, perhaps, enabling 

 one by inductive reasoning to penetrate further into the causes 

 which lie back of all the attributes of matter. 



In attempting to follow this inductive path comparisons of the 

 properties of the elements have been made in two different ways. 



On the one hand, a given property of one element has been com- 

 pared with the same property of another. For example, the ques- 

 tion, " WTiich of the two elements, cobalt or nickel, has the heavier 

 atom?" was answered by parallel determinations, using the same 

 methods, conducted side by side in the laboratory. Cobalt was 

 found to possess the higher atomic weight. 



On the other hand, the attempt has been made to discover a rela- 

 tion between the different, apparently quite distinct, properties of a 

 single element. For example, one may ask : " Have the low melting 

 and boiling points of phosphorus any connection with its small 

 density and its large compressibility?" Here one compares various 

 properties of the same element, and one seeks to discover if all are 

 based upon some common, ultimate characteristic of phosphorus, of 

 which the properties are merely symptoms. 



The inductive methods used in comparisons of this sort can not 

 be explained here. They are partly statistical, partly mathematical. 



