93 Mr. W. Crookes. [June 11, 



pole being kept negative, so as to drive off a certain portion of the 

 silver electrode. On subsequent examination it was found that the 

 silver had all been deposited in the immediate neighbourhood of the 

 pole, whilst at the far end of the tube the spot D, that had been 

 continuously glowing with phosphorescent light, was practically free 

 from silver. 



A tube was next made as shown in fig. 10. It had two negative poles 

 connected together, A, A', so placed as to project two luminous spots 

 on the phosphorescent glass of the tube. One of the electrodes, A', 

 was of silver, a volatile metal ; the other, A, was of aluminium, prac- 

 tically non-volatile. On connecting the two negative poles. A, A', 

 with one terminal of the coil, and the positive pole, B, with the other 

 terminal, it was seen in the course of half an hour that a considerable 

 quantity of metal had been projected from the silver negative pole, 

 blackening the tube in its neighbourhood, while no projection of 

 metallic particles took place from the aluminium positive pole. 

 During the whole time of the experiment, however, the two patches 

 of phosphorescent light, C and C', had been glowing with exactly the 

 same intensity, showing that the active agent in effecting phosphor- 

 escence was not the molecules of the solid projected from the poles, 

 but the residual gaseous particles, or "radiant matter." 



In the tubes hitherto made containing silver, it had not been easy 

 to observe the spectrum of the negative pole, owing to the rapid 

 manner in which the deposit obscured the glass. A special tube 

 (fig. 11) was therefore devised, of the following character. The silver 

 pole, A, was attached to the platinum pole at one end of the tube, and 

 the aluminium positive pole, B, was at the side. The end of the tube 

 opposite the silver pole was rounded, and the spectroscope was 



