SOME PHYSICAL PROBLEMS 



surmountable obstacles, and soon drew her husband 

 into the search with her. Her first discovery was that 

 of the substance polonium so named by Madame 

 Curie after her native country, Poland. This proved 

 to be another of the radio-active substances, differing 

 from any other yet discovered, but still not the sought- 

 for element. In a short time, however, the two Curies 

 made the great discovery of the element radium a 

 substance which, according to their estimate, is some 

 one million eight hundred thousand times more radio- 

 active than uranium. The name for this element, 

 radium, was proposed by Madame Curie, who had also . 

 suggested the term "radio-activity." 



The bearing of the discovery of radium and radio- 

 activity upon theories of the atom and matter will be 

 considered in a moment ; first the more tangible qual- 

 ities of this wonderful substance may be briefly referred 

 to. The fact that radio-active emanations traverse 

 all forms of matter to greater or less depth that is, 

 pass through wood and iron with something the same 

 ease that light passes through a window-glass makes 

 the subject one of greatest interest; and particularly 

 so as the demonstration of this fact is so tangible. 

 While the rays given out by radium cannot, of course, 

 be seen by the unaided eye, the effects of these rays 

 upon certain substances, which they cause to phos- 

 phoresce, are strikingly shown. One of such sub- 

 stances is the diamond, and a most striking illustra- 

 tion of the power of radium in penetrating opaque sub- 

 stances has been made by Mr. George F. Kunz, of the 

 American Museum of Natural History. Mr. Kunz de- 

 scribes this experiment as follows: 



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