294 



Hon. E. J. Strutt on the Discharge of 



yet been found connecting it with other properties of the gas. 

 Indeed the data hitherto available are scarcely sufficient for 

 generalization. 



The arrangement I have used for determining the cathode- 

 fall is represented in fig. 1. A is a battery of 400 Plants 

 cells. D is the tube 3 cm. in diameter containing the rarefied 



Fig. 1. 



A — 



gas. The details of this tube are as follows: — q is a long 

 platinum wire used as cathode, r is a platinum wire which 

 extends to a point 4 or 5 mm. from the end of q : r is covered 

 with blue enamel-glass except just at the tip. When the 

 current was passing, r was outside the negative glow, in the 

 Faraday dark space. The cathode-fall was therefore the 

 difference of potential between q and r. The exact position 



