the Electrical Conduction produced by it. 



131 



in diameter and moved parallel to the uranium surface. 

 The base-plate was connected to one pole of a battery of 

 100 volts, the other pole of which was connected to earth. 

 The rate of movement of the electrometer-needle was taken 

 as a measure of the current between the plates. In some 

 cases the uranium compound was covered with a thin layer of 

 aluminium foil, but although this diminished the rate of leak 

 the general relations obtained were unaltered. 



The following tables give the results obtained for air, 

 hydrogen, and carbonic acid at different pressures with a 

 potential-difference of 100 volts between the plates — an 

 amount sufficient to approximately " saturate " the gases air 

 and hydrogen. Much larger voltages are required to produce 

 approximate saturation for carbonic acid. 



Air : Uranium oxide on base-plate. Plates about 3*5 mm. 

 apart. 



Air. 



Pressure. 



Current. 



mm. 

 760 



1 



600 



•86 



480 



•74 



365 



•56 



210 



•32 



150 



•23 



100 



•17 



50 



•088 



35 



•062 



For hydrogen and carbonic acid. Plates about 3*5 mm. 

 apart. 



Hydrogen. Carbonic Acid. 



Pressure. 



Current. 



mm. 

 760 



1 



540 



•73 



335 



•46 



220 



•29 



135 



•18 



Pressure. 



Current. 



mm. 

 760 



1 



410 



•92 



220 



•69 



125 



•38 



55 



•175 



K2 



