RADIUM. 95 



of the ton or so of material reaches Professor Curie him- 

 self as very impure radium chloride or bromide. It 

 still contains many times its weight of its sister barium 

 and now under Professor Curie's own hands it under- 

 goes the final laborious process of fractional crystallization 

 by means of which the barium is slowly fined away. A 

 slight difference in solubility is practically the only means by 

 which the separation may be accomplished, and its progress 

 is tested by the increased ray-emitting power of the sub- 

 stance which, beginning with 2,000, rises to 10,000, 100,000 

 and, finally, as pure "radium," to 1,300,000 times the ac- 

 tivity of the uranium in which Becquerel first proved the 

 existence of the new property radio-activity. But, alas! 

 out of the ton of material but barely the hundredth of a 

 gram remains. It is like attempting to collect the pollen 

 of a single flower scattered over an acre of ground. 



Considering only the cost of the pitchblende from which 

 it is extracted, the value of radium would be at least $10,000 

 a gram. As a matter of fact, not much more than a gram 

 exists. Of course the amount is slowly increasing and it is 

 now possible to buy a few milligrams of varying degrees of 

 purity in the chemical markets of the world. 



