On the Discharge of Electricity through Gases. G85 



was attained, after which it began to diminish rapidly. The 

 differences were more marked at reduced pressures. Hittorf 

 also found that the potential gradient in the positive column 

 was independent of the current, but diminished with the 

 pressure. The " cathode fall " remained practically constant 

 until the cathode was covered with the negative glow, after 

 which it increased with increasing current. It also increased 

 very rapidly with diminishing pressure. 



Apparatus. 



The form of vacuum-tube used in the present series of 

 experiments is shown in the diagram (fig. 1). The electrode 



Ficr. 1. 



To TopteffPt/MP. 



(KK) consisted of a platinum wire bent backwards and for- 

 wards on itself so as to form a plane grating. Four strands 

 of wire of the same thickness fused into each of two side 



