SCIENTIFIC HYPOTHESIS 247 



fiecl bodies. Days elapsed without any apparent dimi- 

 nution of the radiation. On the supposition that the 

 rays might resemble light he tried to refract, reflect, 

 and polarize them ; but this hypothesis was by the ex- 

 periments of Rutherford, and of Becquerel himself, 

 ultimately overthrown. In the mean time the French 

 scientist obtained radiations from metallic uranium 

 and from uranous salts. These, in contrast with 

 the uranic salts, are non-phosphorescent. Becquerel's 

 original hypothesis was thus overthrown. Radiation 

 is a property inherent in uranium and independent 

 both of light and of phosphorescence. 



On April 13 and April 23 (1898) respectively 

 Mine. Sklodowska Curie and G. C. Schmidt pub- 

 lished the results of their studies of the radiations 

 of the salts of thorium. Each of these studies was 

 based on the work of Becquerel. Mme. Curie ex- 

 amined at the same time the salts of uranium and a 

 number of uranium ores. Among the latter she 

 made use of the composite mineral pitchblende from 

 the mines of Joachimsthal and elsewhere, and found 

 that the radiations from the natural ores are more 

 active than those from pure uranium. This discovery 

 naturally led to further investigation, on the assump- 

 tion that pitchblende contains more than one radio- 

 active substance. Polonium, named by Mme. Curie 

 in honor of her native country, was the third radio- 

 active element to be discovered. In the chemical 

 analysis of pitchblende made by Mme. Curie (as- 

 sisted by M. Curie) polonium was found associated 

 with bismuth. Radium, also discovered in this anal- 

 ysis of 1898, was associated with barium. Mme. 

 Curie succeeded in obtaining the pure chloride of 



