Mr Wilson, The Hall Effect in Gases at Low Pressures. 391 



The Hall Effect in Gases at Low Pressures. (Second paper.) 

 By Harold A. Wilson, B.A., D.Sc. (Lond.), Clerk-Maxwell 

 Student, Fellow of Trinity College. 



[Read 3 March 1902.] 



The experiments described in this paper are a continuation 

 of those described in the paper entitled " On the Hall Effect in 

 Gases at Low Pressures" (Proc. Camb. Phil. Soc. Vol. XI. Pt. IV.) 

 read to this society last October. 



Measurements have been made of the Hall Effect and electric 

 intensity in uniform positive columns in oxygen and hydrogen, 

 and also of the variation of the Hall Effect along the discharge in 

 air at various pressures. 



I. The Hall Effect in Uniform Positive Columns in Hydrogen 



and Oxygen. 



The apparatus used for the measurements in oxygen and 

 hydrogen was identical with that described in the paper just 

 referred to. The oxygen and hydrogen were obtained by electro- 

 lysis of a strong solution of caustic soda prepared by dissolving 

 metallic sodium in water. They were dried by calcium chloride 

 and then by phosphorus pentoxide. The apparatus was pumped 

 out and refilled until the light from the discharge, when examined 

 with a pocket spectroscope, did not indicate the presence of any 

 impurities in the gas. 



Tables I. and II. contain the results obtained in hydrogen. 







Table 



I. 













The Hall 



Effect 



in the Uniform . 



Positive Goh 



%mn 



in 



Hydrogen. 



Pressure. 

 (P) 





Hall Effect. 





Magnetic Field. 

 (H) 





Zp 

 H 



i 



0'133 mms. 





7 "20 volts per cm 





44-2 







2-16 x 



io- 2 



0-175 





5-24 





44-2 







2-08 



>) 



0-188 





4-82 





45-3 







2-00 



5) 



0-275 





3-50 





45-0 







2-14 



)) 



0-292 





3-17 





44-2 







2-10 



)) 



0-42 





2-02 





40-9 







2-08 



)> 



053 





1-63 





44-7 







1-93 



)) 



0-83 





1-06 





44-2 







1-99 



)) 



1-00 





0-95 





47-9 



Mean 



1-99 



>> 





2-05 x 



io- 2 



