On Radiant Matter. 7 



exhausted, but we must here contemplate the molecules 

 individually. In these highly exhausted vessels the mole- 

 cules of the gaseous residue are able to dart across the tube 

 with comparatively few collisions, and radiating from the pole 

 with enormous velocity, they assume properties so novel and 

 so characteristic as to entirely justify the application of the 

 term borrowed from Faraday, that of Radiant Matter. 



Radiant Matter exerts powerful phosphor o genie action where 



it strikes. 



I have mentioned that the Radiant Matter within the 

 dark space excites luminosity where its velocity is arrested 

 by residual gas outside the dark space. But if no residual 

 gas is left, the molecules will have their velocity ar- 

 rested by the sides of the glass ; and here we come to 

 the first and one of the most noteworthy properties of 

 Radiant Matter discharged from the negative pole its 

 power of exciting phosphorescence when it strikes against 

 solid matter. The number of bodies which respond 

 luminously to this molecular bombardment is very great, 

 and the resulting colours are of every variety. Glass, 

 for instance, is highly phosphorescent when exposed to a 

 stream of Radiant Matter. Here (Fig. 2) are three bulbs 



FIG. 2. 



composed of different glass: one is uranium glass (a), 

 which phosphorescesof adark green colour; anotherisEnglish 

 glass (b), which phosphoresces of a blue colour ; and the third 

 (c) is soft German glass, of which most of the apparatus 

 before you is made, which phosphoresces of a bright apple- 

 green. 



My earlier experiments were almost entirely carried on by 

 the aid of the phosphorescence which glass takes up when it 



