348 



Mr. J. B. B. Burke on the 



which shows that it is possible for the glowing molecules to 

 diffuse through very narrow brass tubing put to earth. The 

 diffusion is allowed to take place from the bulb in which the 

 ring-discharge has been sent, into another in which no dis- 

 charge has passed. 



Thus fig. 3 represents two such bulbs A and B ; con- 

 nected by a brass tube a b about 10 cms. in length and 1 mm. 

 in diameter, having a tap t in the middle. 



When a number of ring-discharges are sent through the- 

 bulb A, and the tap t is open, the glow diffuses slowly through 

 the tube ab into the bulb B ; and though ultimately it does 

 not acquire the same intensity in the latter as in A whilst 

 the discharges are passing, yet, when they cease, the glow in 

 A rapidlv dies out, whilst that in B remains bright for a 

 length of time fully four or five times as long as the duration 

 of the glow in A. 



"When t is closed, however, the glow does not appear in the 

 second bulb ; thus showing that the glow does actually diffuse 

 through the tube a b, and it is not, as might otherwise have 

 been thought possible, the result of induced discharges in B, 

 caused by the powerful ring-discharge in A. Thus it is 

 quite clear that a diffusion of particles or molecules does 

 actually take place, and that it cannot be a diffusion of particles 

 or molecules carrying an electric charge. 



The fact that the phosphorescence in B is much more per- 

 sistent than that in A is very singular indeed, and suggests 

 at once that the ring-discharge, whilst on the one hand it 

 oives rise to the phosphorescent after-glow, on the other also 

 produces something in the gas which to some extent is de- 

 structive to the existence of the glow ; and that this is largely 

 if not altogether removed by allowing the gas through which 



