July 14, 1916] 



SCIENCE 



43 



with greater compactness. Likewise the 

 existence of powerful chemical affinity be- 

 tween elements forming a compound is 

 usually associated with great decrease in 

 volume during the act of combination, and 

 consequent increase in the density of the 

 product in relation to the average density 

 of the constituents. Thus we can hardly 

 escape the inference that both cohesion and 

 affinity, by pulling the atoms together with 

 enormous pressure, actually exert a com- 

 pressing effect upon the atoms, or at least 

 upon the space which they demand for their 

 occupation. The result of each of these 

 compressing agencies is found to be greater 

 the greater the compressibility of the sub- 

 stances concerned — a new evidence of the 

 reasonableness of the inference. Not al- 

 ways are these effects easily traced, because 

 the situation is often complicated, and the 

 several effects are superposed. Neverthe- 

 less, enough evidence has been obtained to 

 leave but little doubt, at least in my mind, 

 as to the manner of working of the essential 

 agencies concerned. 



But we need not dwell upon this tentative 

 hypothesis. Many more data and much 

 more thought are necessary to establish it 

 in an impregnable position, although no 

 important inconsistency has thus far been 

 pointed out in it. At present it may be 

 looked upon as valuable because it, like 

 other hypotheses of this type, has stimu- 

 lated thought and experiment concerning 

 the fundamental facts with which it deals. 



As the years go on, the recent contribu- 

 tions to the study of atomic weights and 

 volumes and other properties will be sifted 

 and tested; and such contributions as may 

 stand the test of time will take their places 

 among the multifarious array of accepted 

 chemical facts, laws and interpretations 

 accumulated by many workers all over the 

 world. 



But we may well ask: What use, in the 



years to come, will mankind make of this 

 knowledge gained step by step through the 

 eager study of many investigators? 



Chemistry has, indeed, a many-sided 

 destiny. A mere catalogue of the countless 

 applications of the science, which underlies 

 many other sciences and arts, would de- 

 mand time far exceeding the limits of this 

 brief discourse. Some of the more obvious 

 uses of chemistry have become daily topics 

 in the public press. America is gradually 

 awakening to the consciousness that, because 

 every material object is composed of chem- 

 ical elements and possesses its properties by 

 virtue of the nature of these elements, chem- 

 istry enters more or less into everything. 

 We perceive that chemical manufactures 

 must be fostered, and also that chemical 

 knowledge must be applied in many other 

 industries not primarily of a chemical na- 

 ture. Although chemistry plays so promi- 

 nent and ghastly a role in war, her greatest 

 and most significant contributions are to- 

 wards the arts of peace. Even explosives 

 may be highly beneficent; they may open 

 tunnels and destroy reefs, furthering 

 friendly communication between men; dig 

 ditches for irrigation; help the farmer in 

 his planting; and in many other ways ad- 

 vance the constructive activities of man- 

 kind. Again, poisonous gases, confined and 

 harnessed within safe limits, may render 

 valuable aid to humanity in preparing 

 precious substances otherwise unattainable. 



Such obvious and well recognized offices 

 of chemistry need no further presentation 

 to this intelligent company. Neither is it 

 necessary for me to call your attention to 

 the services which science may render to 

 agriculture through the chemical study and 

 enrichment of the soil in preparing it for 

 the development of those subtle chemical 

 mechanisms called plants, upon which we 

 depend for our very existence. 



There is a further beneficent possibility 



