50 ILLINOIS ACADEMY OF SCIENCE. 



therefore to avoid the inference that inertia is a function of the 

 speed of the charge. 



One of the possibiHties of the future — one that must be impar- 

 tially faced — is that of establishing a science of mechanics purely 

 upon the dynamics of a system of positive charges surrounded 

 by disembodied negative charges in rapid motion. 



HEAT EMISSION OF RADIUM. 



Time remains to mention only one other phenomenon connected 

 with this bewildering element. The imagination is at once stimu- 

 lated and baffled in trying to picture a mechanism capable of 

 ejecting a material particle with a speed which, if maintained for 

 a single second, would carry it more than half way around the 

 world. And yet, I believe it will be generally conceded that of 

 all the facts connected with radium and radio-active substances 

 the most striking and the most fundamental — the most marvelous 

 and the most interesting — is that discovered by Curie and 

 Laborde® in 1903, namely, that a radium compound has the ability 

 to maintain itself permanently at a temperature several degrees 

 higher than that of the surrounding neighborhood. Experiments, 

 carefully verified by German and English investigators, show 

 that this spontaneous heat generation goes on at the rate of about 

 100 gram-calories per hour for each gram of radium. 



At first, it appeared as if a coach-and-four had been driven 

 through the law of the Conservation of Energy. But men were not 

 long in recovering faith in that great generalization; and at once 

 began asking whether the radium atom was a mere transformer 

 for energy, or whether it was really a magazine of energy. The 

 discovery of radium emanation and its brief existence, the emis- 

 sion of a-particles of enormous energy, not only by radium but 

 by its products, and the absence of any other plausible source of 

 energy soon led nearly everyone to view the atom as a storehouse 

 of energy, a view which lies at the very bottom of Rutherford's 

 theory of disintegration. 



The upshot of the whole matter is then to leave the Energy 

 Principle unimpeached as one of the postulates of all the physical 

 sciences; while, on the positive side of the account, a new item 

 has been added to the list of our energy sources, viz., the internal 

 energy which the radio-active atom possesses independently of 

 its motion or position. Rutherford has shown that the excess of 



•Curie & Laborde C. R. 136, 673 (1903). 



