216 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1916. 



concerning the nature of things which echoes down the ages from 

 the time of the ancient philosophers. To the feehng of curiosity, as 

 time went on, was added the perception that only through a knowl- 

 edge of the fundamental laws of chemistry can men use the re- 

 sources of the world to the best advantage. Any further gain in 

 this knowledge must, sooner or later, directly or indirectly, give 

 mankind more power. Even an abstract chemical generalization 

 must ultimately be of priceless service to humanity, because of the 

 extraordinarily intimate relation between theory and practice. 



The field is wide and it is traversed by many paths. Among these 

 one must be chosen and persistently followed if progress is to be 

 made; and in my case that one was the study of the fundamental 

 attributes or properties of the chemical elements and the relation of 

 these properties to one another. The work was undertaken with the 

 hope of helping a little to lay a solid foundation for our under- 

 standing of the human environment. 



What, now, are the fundamental attributes of the elements? First 

 and foremost among these stands weight — the manifestation of the 

 all-pervading and mysterious force of gravitation possessed by all 

 forms of matter. Hand in hand with this attribute of weight goes 

 the equally inscrutable property of inertia — that tendency which 

 causes a body once in motion to keep on moving forever in the same 

 straight line, if not acted upon by some new force. The idea of 

 inertia, conceived by Galileo and amplified by Newton, was one of 

 the starting points of both modern philosophy and modern physics. 

 So far as we know weight and inertia run parallel to each other. Of 

 any two adjacent bodies, that having greater weight has also greater 

 inertia. Hence they may be determined at one and the same time, 

 and this Siamese- twinlike conjunction of properties establishes 

 itself at once as perhaps the most fundamental of all the attributes 

 of matter. Next perhaps comes volume, the attribute which enables 

 matter to occupy space, with the corollaries dealing with the changes 

 of volume caused by changes of temperature and pressure. Other 

 fundamental properties are the tendency to cohere (which has to 

 do with the freezing and boiling points of the liquids) and the 

 mutual tendency of the elements to combine, almost infinite in its 

 diversity, which may be measured by the energy changes manifest- 

 ing themselves during the reaction of one substance with another. 



These are only a few of the important properties of the elements, 

 but they present an endless prospect of further investigation, in spite 

 of all that has been done during the past hundred years. For as 

 yet we know only the surface of these things, and comprehend but 

 little as to the underlying connections between them and the reasons 

 for their several magnitudes. Why, for example, should oxygen be 

 a gas, having an atomic weight just four times as great as that of 



