194 CHEMISTRY 



The simplest statement of facts is sufficiently wonderful and mys- 

 terious. Although not more than two or three grams of radium have 

 been gathered from the earth's crust, its natural history is already 

 well developed, and at latest news we are told that one gram of 

 radium bromide will evolve 0.0022 milligrams of helium in one year; 

 that the life of a radium atom is 1050 years, or, in another experiment, 

 1250 years. 



It may be said that within this decade the knowledge of the struc- 

 ture of carbon compounds has become so complete that the way to the 

 production of the most useful bodies has become evident in theory, 

 and I need not remind you of the consequent achievements by that 

 happy combination of pure and industrial science in Germany. 



Also within this decade, the somewhat neglected study of mineral 

 chemistry has acquired unexpected interest by the discovery in 

 France of metallic carbides and nitrides, formed at temperatures 

 comparable with those of the sun, and these discoveries, besides giving 

 rise to most unexpected industrial applications, show entirely new 

 possibilities for the geology of the primitive rocks. 



The active pursuit of physical chemistry has extended over some 

 thirty years. Great dates are the publication, just two decades ago, 

 of van 't Hoff 's Etudes de dynamique chimique, and one year after- 

 wards of Ostwald's Allgemeine Chemie; and, again, ten years ago Dix 

 Annees d'une Theorie. 



Suffice it to say that the title, General Chemistry, has been amply 

 justified. The attractive presentation of bold theories, their rapid 

 confirmation by experiment, and the completeness of treatment by 

 the founders of the new science have led to the immediate acceptance 

 of their views, until the mathematical analysis of chemical pheno- 

 mena has become the dominating feature of our science, and has 

 transformed our methods of thought, as Kepler and Newton's 

 theories transformed the study of astronomy. 



