in producing Electric Conductivity in Oases. 



299 



Relation between Current and E.M.F. 



4. As the results at moderate pressures are more or less 

 similar to those at atmospheric pressure, we shall go at once to 

 the effects at low pressures. The numbers below show the relation 

 between the current and the e.m.f. at a pressure of two-thirds of 

 a millimetre, the wire being charged negatively. 



Potential of the 



Current in arbitrary 



wire in volts 



units 



40 



19 



80 



38 



160 



61 



240 



78 



280 



99 



320 



135 



The curve in Fig. 2 is drawn from these numbers. 



zz:±:zzzzzzzzz„: 



/. jz 



20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 



Volts. 

 Fig. 2. 



The current does not reach a maximum as it does when the 



