A HISTORY OF SCIENCE 



vin, Beattie, Smolan, and Rutherford confirmed the 

 fact that, like the Roentgen rays, the uranium rays not 

 only acted upon the photographic plate but discharged 

 electrified bodies. And what seemed the more won- 

 derful was the fact that these " Becquerel rays," as 

 they were now called, emanated spontaneously from 

 the pitch-blende. But although this action is analogous 

 to the Roentgen rays, at least as regards its action upon 

 the photographic plate and its influence on the electric 

 field, its action is extremely feeble in comparison, the 

 Roentgen rays producing effects in minutes, or even sec- 

 onds, which require days of exposure to uranium rays. 

 The discovery of the radio - active properties of 

 uranium was followed about two years later by the dis- 

 covery that thorium, and the minerals containing 

 thorium, possess properties similar to those of uranium. 

 This discovery was made independently and at about 

 the same time by Schmidt and Madame Skaldowska 

 Curie. But the importance of this discovery was soon 

 completely overshadowed by the discovery of radium 

 by Madame Curie, working with her husband, Pro- 

 fessor Pierre Curie, at the Ecole Polytechnique in 

 Paris. Madame Curie, stimulated by her own discov- 

 eries and those of the other scientists just referred to, 

 began a series of examinations upon various substances 

 by numerous complicated methods to try and find a 

 possible new element, as certain peculiarities of the 

 substances found in the pitch-blende seemed to indicate 

 the presence of some hitherto unknown body. The 

 search proved a most difficult one on account of the 

 peculiar nature of the object in question, but the tire- 

 less enthusiasm of Madame Curie knew nothing of in- 



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