272 POPULAR SCIENCE MONTHLY. 



able to find any radioactivity in any of the heavy spars examined by 

 him, and even if he did not specially examine heavy spar from 

 Joaehimsthal, the above result would be strange, since all other ex- 

 perience of the co-occurrence and mutual replacement of the elements 

 would preclude that radium, in contradistinction to calcium and 

 strontium, would be prevented from association with natural barium 

 compounds, if it really were an element closely resembling barium. 

 But if radioactive heavy spar occurs, its radium contents would pass 

 into the barium chloride manufactured therefrom, and in that case it 

 would not be difficult to separate it by fractional crystallizations on a 

 large scale, however minute the radium contents might be. The ex- 

 periment made by S. Curie with 50 kilos of commercial barium chloride 

 has, however, given a negative result. 



But even if radium for reasons at present unknown should ex- 

 clusively follow the occurrence of uranium, it ought to occur in 

 relatively wide diffusion at least in the Erzgebirge. For even outside 

 of the deposits of pitchblende, such as those of Joaehimsthal or of 

 Johanngeorgenstadt, Schneeberg, Annaberg and Freiberg, one finds 

 in the region specified frequently uranium-carrying rocks, especially 

 granites, the uranium contents of which are indicated by an incrustation 

 of calcium uranite acting on the sensitive plate and often visible in the 

 crushed rocks used in the streets. It therefore appears not impossible 

 to find in that region, where also bismuth is widely diffused, a new 

 material which might successfully be worked for the extraction of 

 radioactive substances. By producing radium in the pure state in 

 larger quantities and by the thorough study of its chemical behavior we 

 might possibly not only attain knowledge of the essence of radio- 

 activity, but also place the existence of radioactive elements of individual 

 character and definite chemical behavior beyond doubt. 



