The Evolution of the Sciences 



experimentally, viz., one milligramme of emana- 

 tion produced per gramme of radium per year, 

 is permanent the transformation would be com- 

 plete at the end of a few thousand years. 



We have not come to the end of the complica- 

 tions. Ramsay kept a few cubic millimetres of 

 his precious emanation on mercury in a tiny test- 

 tube, where it formed a glowing column. A few 

 days later he noticed that the volume of the gas 

 had decreased; the decrease continued regularly 

 until at the end of three weeks nothing was left 

 in the test-tribe but a glowing point ; at the end 

 of a month the last trace of the emanation had 

 disappeared; however, when the mercury was 

 lowered, forming a vacuum in the apparatus, and 

 the tube was slightly warmed, an amount of gas 

 was produced equal to about four times the initial 

 volume of the emanation ; this gas was helium. 



So unexpected a result can only be accepted 

 by science after serious verification ; in addition 

 to Ramsay seven observers, including Curie, 

 have pursued the question in France and Ger- 

 many, and ascertained that not only radium, but 

 also thorium and actinium are transformed, first 



into the emanation and finally into helium. 



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