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V. 



IONIC MOBILITIES IN AIE AMD HYDEOGEN. 



By PEOFESSOE J. J. NOLAN, M.A., D.Sc, 

 University College, Dublin. 



[Read December U, 1922. Published Januauv 22, 1923.] 



The work described in the present paper consists for the greater part of a 

 careful examination by the Eutherford-Franck method of the ionic mobilities 

 in hydrogen. As certain emendations and additions can be made to the 

 results |for air previously reported,' and as it is necessary to deal with 

 criticism' which some of this work has received, it is convenient to devote 

 the first part of the paper to ionic mobilities in air. 



Ionic Mobilities in Air. 



The conclusions to which the author has been led as a result of his 

 examination of ionization in air may be broadly stated thus : (1) that the 

 ordinary ionization in air is composite, that is to say, that it consists of a 

 mixture of groups of different ions, each of a definite mobility ; and (2) that 

 in the ordinary ionization there are present in small numbers ions of 

 mobility much higher than what is usually regarded as the normal value. 

 The experiments which suggested these conclusions originated in an 

 investigation of the ionization produced by breaking up water. Among 

 these ions were found some of mobility twice the normal value,' and in later 

 work some of four times the normal value* were observed. In these values 

 there was nothing surprising to anyone familiar with the work of Aselmann,* 

 or to anyone accustomed to regard the small ion from the point of view of 

 the cluster theory. In later work, when it was sought to define these ions 



'J. J. Nolan, Proc. Royal Irish Academy, vol xxxv, Sect. A, p. 38, 1920; and 

 J. J. Nolan and Harris, vol. xxxvi, Secc. A, p. 31, 1922. 

 - Blackwood, Physical Review, March, 1922, p. 281. 

 ^ Proc. Royal Society, Sect. A, vol. xc, p. 543, 1914. 



* Proc. Royal Irish Academy, vol. xxxiii, Sect. A, p. 9, 1916. 



* Ann. der Phys., xix, p. 960, 1906, quoted by J. J. Thomson, " Conduction of 

 Electricity through Gases," second edition, p. 429. 



