Electricity by Radium and Thorium Emanations. 463 



emanation was able to diffuse into the testing-vessel. The 

 effect on the leak is shown by the following observations, the 

 zero o£ time being taken as the moment at which the radium 

 tube was broken. 



I. Leaf charged +200 volts. II. Leaf charged —200 volts. 



Time in minutes. 



Position of Leaf 

 on Scale. 





Time in minutes. 



Scale -readings. 



3 



5 



7 



9 



11 



13 



15 



95-0 

 93-6 

 92-7 

 91-0 

 89-6 

 87-9 

 86-5 



19 82-9 

 24 82-7 

 29 82-5 

 34 82-2 

 39 82-8 

 44 82-1 



Leak per hour, 42*5 scale-div. 



Leak per hour, 1*9 div. 



III. Leaf charged 4-200 volts. 



Time in minutes. 



Scale-readings. 



48 

 52 

 56 

 60 

 65 



84-1 

 81-2 

 76-9 

 74-7 

 710 



Leak per hour, 46 div. 



At 1-J hours after the breaking of the bulb, the positive 

 leak reached its maximum value of 52 divisions per hour, and 

 then fell off, the leak after 4-|- hours being 39. This was 

 evidently due to the gradual diffusion of the emanation into 

 the branch tubes, and away from the gold-leaf. 



The charcoal tube H was now put into liquid air, and 

 an immediate reduction of the positive leak was observed. 

 Measuring time from the moment at which the tube was 

 placed in the liquid air, the readings obtained were as 

 follows : — 



