44 Mr Patterson, Note on spontaneous ionization in air. 



Note on spontaneous ionization in air at different temperatures 

 and pressures. By J. Patterson, B. A., Professor of Physics, Muir 

 Central College, Allahabad. 



[Read 24 November 1902.] 



The object of the experiment was to find if possible the cause 

 of the so-called spontaneous ionization in air. 



To measure the spontaneous ionization at different tempera- 

 tures, the air was contained in an insulated iron cylinder containing 

 about 13 litres, and the rate of leak was measured between the 

 walls of the vessel and an insulated electrode. This electrode was 

 connected to one pair of quadrants of a very delicate electrometer 

 and the rate of leak observed. 



The experiments shewed that from the temperature of the room 

 (20° C.) to about 500° C. the current through the gas was constant, 

 the air in the cylinder being at atmospheric pressure throughout 

 the investigation. 



To measure the ionization at different pressures the same 

 cylinder and electrode were used. The joints were made air-tight 

 with sealing-wax and the air filtered through glass wool. 



The results shewed that down to a pressure of about ^ atmos. 

 the current through the gas was independent of the pressure and 

 that for pressures below 90 mm. of mercury the ionization was 

 proportional to the pressure. 



Using the value 6 x 10 -10 for e, the charge on an ion, the 

 number of ions produced per c.c. per sec. was about 30. 



The results of the experiments indicate that the " spontaneous 

 ionization" is really due to easily absorbed radiation from the 

 walls of the vessel. 



