2 Rutherford, Decay of the Radimn Emanation. 



was found to decay exponentially from the beginning 

 with a period of 4*4 days. Similar differences have been 

 observed in a number (^f experiments. These variations 

 in period of decay must be ascribed to differences of 

 quality of the emanation in the various cases. 



z^s a result of a series of experiments, it has been 

 found that samples of emanation which decay most 

 rapidly are more easily absorbed in water and more easily 

 condensed by liquid air than the more slowly decaying 

 fractions. For example, if the radium emanation is 

 allowed to stand over water for some hours, the part 

 absorbed in the' water decays more rapidly than the part 

 unabsorbed. In a similar way on condensing the emana- 

 tion, the part removed by pumping has a longer period 

 than the part condensed. 



We have been unable to find any evidence that 

 radium produces two emanations, or that the products of 

 transformation of the emanation of slow period are in 

 any way different from those of the emanation of quick 

 period. 



Tiie results indicate that the emanation is a non- 

 homogeneous chemical substance. So far as our observa- 

 tions have gone, it appears probable that the physical 

 and chemical properties of the emanation atoms vary 

 to some extent with their life, i.e., on the length of time 

 after production before disintegration. It seems probable 

 that the atoms of emanation undergo a progressive change 

 in properties before disintegration. Further experiments 

 are in progress to test the correctness of this point of 

 view. 



