Residual Ionization in Gases. 415 



agreement with some recent experiments of C. Gr. Barkla * 

 on the energy involved in the production of characteristic 

 Rontgen radiation. From these examples it will be seen 

 that even if KosseFs considerations will need modification 

 in order to account in detail for the high frequency spectra, 

 they seem to offer a basis for a further development. 



As in the former section, it is assumed that the spectra 

 considered above are due to the displacement of a single 

 electron. If, however, several electrons should happen to be 

 removed from one of the rings by a violent impact, the con- 

 siderations at the end of the former section would not apply, 

 since the electrons removed in this case can be replaced by 

 electrons in the other rings. We might therefore possibly 

 expect that the rearrangement of the electrons, consequent 

 to the removal of more than one electron from a ring, would 

 give rise to spectra of still higher frequency than those 

 considered in this section. 



University of Manchester, 

 August 1915. 



XLIII. Residual Ionization in (rases. By Professor J. C. 

 McLennan, F.R.S., and 0. L. Treleaven, M.A., 

 University of Toronto^. 



I. Introduction. 



FROM observations made by Simpson k Wright J, 

 McLennan k McLeod §, and others, ir. is now known 

 that the ionization in air confined in air-tight clean zinc 

 vessels is about 8 or 9 ions per c.c. per second when the 

 observations are made on land where the soil contains only 

 such minute traces of radioactive substances as are found in 

 ordinary clays or loams. It is also known that when the 

 observations are made on the Atlantic, the Indian, or the 

 Antarctic Ocean, or on the surface of large bodies of water 

 such as Lake Ontario, the ionization in air confined in the 

 manner indicated above drops to approximately 4 ions 

 per c.c. per second. Moreover, this reduction in the 



* Barkla, Nature, xcv. p. 7 (1915). In this note Barkla proposes 

 an explanation of his experimental results which in some points has 

 great similarity to Kossel's theory. 



t Communicated by the Authors ; read before the Royal Society of 

 Canada, May 26th, 1915. 



X Simpson & Wright, Proc. Roy. Soc, Ser. A, vol. lxxxv. p. 175 

 (1911). 



§ McLennan & McLeod, Phil. Mag., Oct. 1913, p. 740. 



