﻿294 Mr. E. D. Kleeman on the Recombination 



Curve A in fig. 5 was obtained with a film of polonium 

 about eighteen months after it had been prepared. 



Ficr. 5. 





k 1- L S 



^-^ ^N ^- ^ "■■ 





~^% ~*"S% ""5"% V^3 



J it-/ +4 l zr £_r 



_ _t ttl ±1 / J 7 



7 -U-t Xt t _ If 



-t ill tl tl 



1 itt t tl 



t tt h -it tf~ 



-4 til 1-1 -a- 



/ ° 7" E W G /» 



fl 3ft 3t 



iii it 



The tubes used were *5 cm. high and '04 cm. in diameter. 

 The gauze was kept at a potential of 160 volts, and the leak 

 allowed to run into the electrometer for one minute. 



The readings were taken without the protecting gauze k, 

 since it appeared from some experiments, which will be 

 described further on, that no drift of ions into the chamber 

 took place, even with low voltages. 



The curve shows that the a particle from polonium, like 

 the a particle from radium, is a more efficient ionizer towards 

 the end of its course. 



It was also found that the greater the velocity of the 

 a particle, the better the ions are able to get away from their 

 parent molecules. 



For example, when the distance of the polonium film from 

 gauze was about *7 cm., the leaks for 8 and 160 volts per cm. 

 were respectively 475 and 628 scale-divisions per minute, 

 each leak being the mean of two readings. The lack of 

 saturation when 8 volts are applied is therefore 24 per cent., 

 the current being practically saturated with 160 volts. When 

 the distance of polonium from gauze was about 2'7 cms., the 

 leaks for 8 and 160 volts were respectively 629 and 967 scale- 

 divisions, each leak being, as before, the mean of two readings. 

 This gives a lack of saturation of 35 per cent, for 8 volts, or 

 a lack of saturation about 1*5 times that obtained when the 

 distance was *7 cm. 



This is brought out very nicely by the curves B, C, D, 

 which correspond to a difference of potential of 320, 24, and 



