THE ALUMNI JOURNAL 



169 



SECTION OF THE CHEMICAL LABORATORY 

 iPROF. VORISEK ON PLATFORM' 



THE EVOLUTION OF ELEMENTS.- 



Bv W. W. Strong, Ph. D. 



Mellon Institute of Industrial Research, University of Pittsburgh. 



The Heating of the Earth by Radio-active Matter and the 

 Age of the Rocks. — Geologists have usually claimed that the earth 

 has been cooling during the past and that at one time it was a molten 

 mass. These conclusions were inevitable as long as there was no 

 source of heat in the earth. Since radio-active matter is evolving 

 heat continually, it follows that its existence in the rocks furnishes a 

 source of heat and if it generates heat more rapidly than the rocks 

 conduct it to the surface, the temperature must rise. Assuming that 

 the rocks of the earth possess the radio-active contents as determined 

 by Strutt, Eve and others, it follows that a thickness of about 30 miles 

 of the radio-active bearing rock would generate the heat which is 

 being lost by conduction and radiation. If radio-active matter is dis- 

 tributed in the same wav throughout the earth, two conclusions follow 



* From "Rarlium." 



