34 



mum. Since the loss due to recombination depends 

 upon the square of the density, the experiment described 

 indicates the existence (in addition to general) of a process 

 of initial recombination, which is completed within a very 

 short period after the act of ionization. 



Summary. 



Experiments upon ionized gas blown through gauzes are 

 in agreement with the theory of Bragg and Kleeman, that 

 there exists an initial recombination between a molecule 

 ionized by a rays and the ejected electron or electrons. 



Two methods of experiments described show no trace of 

 such effect when the gas is examined 1-lOth — l-20th of a 

 second after the act of ionization. 



Initial recombination is thus to be considered initial in 

 respect to time. 



The aetion of gauzes, electrified or unelectrified, 

 upon ionized gases blown through them is to be explained 

 by the aid of the theory of diffusion. 



An arrangement of gauzes as herein described allows of 

 the removal by an electric field of all the ions of one sign 

 from a very defined region in a tube along which the ions are 

 carried by a current of gas. 



The ionization produced in air by Rontgen rays or 

 by a wire made active by exposure to thorium emanation 

 is the same in air which has just previously passed under 

 the influence of uranium radiation as in air not so treated. 



In conclusion, I wish to express my indebtedness and 

 sincere thanks to Professor Bragg for suggesting these ex- 

 periments, and for much advice and help during their 

 progress. 



University of Adelaide, 1907. 



