ONE HUNDRED YEARS OF CHEMISTRY 317 



of uranium, which shows the genetic relation between 

 the two. 



In the case of niton, which is produced by radium, and 

 is called also the radium emanation, the rate of decay is 

 rapid, so that if the gas is expelled from radium by heat- 

 ing, equilibrium is reached after a few days, with the 

 accumulation of the largest possible amount of niton. 



The conclusion has been reached by Rutherford and 

 others that the final product besides helium, in the radio- 

 active transformations, is lead, or at least an element 

 or elements resembling lead to such a degree that no 

 separation of them by chemical means is possible. 

 Atomic weight determinations by Richards and others 

 have shown that specimens of lead found in radioactive 

 minerals give distinctly different atomic weights from 

 that of ordinary lead. This fact has led to the view that 

 possibly the atoms of the elements are not all of the same 

 weight, but vary within certain limits a view that is 

 contrary to previous conclusions derived from the uni- 

 formity in atomic weights obtained with material from 

 many different sources. 



The results of the investigations upon radioactivity 

 have led to modified views in regard to the stability of 

 the elements in general. There has been little or no 

 proof obtained that any artificial transmutation of the 

 elements is possible, but the spontaneous transformation 

 of the radioactive elements brings forward the possibility 

 that other elements are changing imperceptibly, and that 

 a state of evolution exists among them. All of the radio- 

 active changes that we know proceed from higher to 

 lower atomic weights, and we are entirely ignorant of the 

 process by which uranium and thorium must have been 

 produced originally. 



Since radioactive changes have been found to be 

 accompanied by the release of vast amounts of energy, 

 compared with which the energy of chemical reactions is 

 trivial, a new aspect in regard to the structure of atoms 

 has arisen, they must be complex in structure, the seats 

 of enormous energy. 



The determination of the amount of radium in the 

 earth 9 a crust has indicated that the heat produced by it is 

 amply sufficient to supply the loss of heat due to radia- 



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