Wafer R ad i octet iviij/. 505 



valuos of 1/A, woiohts proportional to the corresponding 

 intervals, wo get for the mean value 



1/A = 425,000. 

 For raLliuni emanation Rutherford gets 



l/\= 463,000, 

 while Curie gets for the same 



1/X,= 49 7,000. 



The value of \ obtained thus for tap-water is in sufficiently 

 good agreement with that obtained for radium emanation to 

 make it very probable that the former is actually due to 

 radium emanation. 



Similar results have been obtained for air which has been 

 thoroughly bubbled through tap-water, so that it seems that 

 the conductivity produced in air by bubbling it through tap- 

 water is due to the same cause as the conductivity of the 

 dissolved gases in water. 



Absorption of Radium Emanation hy Water, 



According to Rutherford radium emanation passes un- 

 changed through water. But experiments were made to see 

 whether some of the emanation, if only a very small pro- 

 portion of it, was not absorbed by the water. This was done 

 as follows : — 



A weak solution of a radium compound was prepared, 

 using distilled water which had been thoroughly boiled to 

 expel all air. Air was then bubbled through the radium 

 solution, having first passed through a tight plug of glass- 

 wool. From the radium solution the air passed through 

 another tight plug of glass-wool, and then through a large 

 bottle of thoroughly boiled distilled water. This was allowed 

 to go on for three hours. At the end of this time air was 

 blown into the bottle to sweep out thoroughly all of the 

 radium emanation which remained above the surface of the 

 water. Some of the water was then poured into a flask of 

 about a litre capacity, provided with a rubber stopper with 

 two holes, through one of which a glass tube passed to the 

 bottom of the fiask, while through the other a glass tube 

 passed just through the stopper. The water was then boiled, 

 and at the same time air from the room bubbled through it 

 into a gas-holder. In this way all the dissolved gas and 

 emanation, if any, was collected in the gas-holder. From 

 the gas-holder the air was introduced into the electroscope . 

 Before this air was put in, when the electroscope was filled 



Phil Mag. S. 6. Vol. G. No. 35. Aor. 1903. 2 P 



