392 Mr Wilson, The Hall Effect in Gases 



Table II. 



The Electric Intensity in the Uniform Positive Column 

 in Hydrogen. 



Pressure. Electric Intensity. ±_ 



(P) (*) Jp 



0-25 mms. 13*9 volts per cm. 27*8 



0-48 18-8 27-2 



0-56 21-6 28-9 



0-60 21-9 28-3 



1-05 28-5 27-8 



1-2*7 31-9 28-4 



1-36 32-3 27-7 



Mean 28 -0 



The pressures are expressed in millimetres of mercury and the 

 Hall Effects and Electric Intensities in Volts per centimetre. 

 Above one millimetre pressure satisfactory measurements of the 

 Hall Effect were not obtained. 



The above results show that the Hall Effect and Electric 

 Intensity in hydrogen at pressures below one millimetre follow the 

 same laws as in air. The Hall Effect is given by the equation 



TT 



Z=2'0bxl0~ 2 — , and the electric intensity by the equation 



_ P 

 X = 28 \/p. The corresponding equations found for air in the 



TT 



previous paper were Z= 2*48 x 10~ 2 — , and X = 34'9 \fp. 



P 



Tables III. and IV. give the results obtained in oxygen. 



Table III. 



The Hall Effect in the Uniform Positive Column in Oxygen. 



Pressure. Hall Effect. Magnetic Field. Zp 



(P) W (H) h 



0-21 0-802 42-6 3-95 x 10~ 3 



0-32 0-463 43-1 3-43 „ 



0-40 0-399 42-6 3-74 „ 



0-48 0-348 43-1 3-83 „ 



0-83 0-207 43-1 3-98 „ 



Mean 3-79 x 10" 3 



