SCIENTIFIC HYPOTHESIS 247 



fied bodies. Days elapsed without any appan-nt dimi- 

 nution of the radiation. On tin- siippo- tlu; 

 rays might resemble light he tried to n-fn 

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

 periments of Kutherford, and of IVrqucrt'l hin 

 ultimately overthrown. In the mean time the K: 

 scientist obtained radiations from metallic uranium 

 and from uranous salts. These, in contrast with 

 the uranic salts, are non-phosphorescent. Becqu< 

 original hypothesis was thus overthrown. Kadi 

 is a property inherent in uranium and independent 

 both of light and of phosphorescence. 



On April 13 and April 23 (1898) respect! 

 Mme. 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 disco 

 naturally led to further investigation, on the assum|>- 

 tion that pitchblende contains more than one in- 

 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 



