2 Rutherford, Production of Helium by Radium. 



gases were completely removed by heating and exposed 

 to charcoal cooled in liquid air. The unabsorbed gases 

 were pumped out and repeatedly exposed to fresh cooled 

 charcoal. The residual gas consisting of essentially pure 

 helium was found to have a volume corresponding to the 

 production of helium at the rate of 163 cubic mms. per 

 gram of radium per year. 



With the experience gained in these preliminary 

 experiments, it is hoped ultimately to determine the 

 value of this constant with considerable precision. 



Other experiments which have been made to test 

 whether helium is produced by polonium have shown 

 conclusively that such is the case. 



