On Radiant Matter. 27 



completely away from the metal, and leave it non-luminous. 

 I withdraw the magnet, and let the molecules have full 



FIG 21. 



play again ; the metal is now white-hot. I increase the 

 intensity of the spark. The iridio-platinum glows withal- 

 most insupportable brilliancy, and at last melts. 



The Chemistry of Radiant Matter. 



As might be expected, the chemical distinctions between 

 one kind of Radiant Matter and another at these high ex- 

 haustions are difficult to recognise. The physical pro- 

 perties I have been elucidating seem to be common to all 

 matter at this low density. Whether the gas originally 

 under experiment be hydrogen, carbonic acid, or atmospheric 

 air, the phenomena of phosphorescence, shadows, magnetic 

 deflection, &c., are identical, only they commence at 

 different pressures. Other facts however, show that at this 

 low density the molecules retain their chemical character- 

 istics. Thus by introducing into the tubes appropriate ab- 

 sorbents of residual gas, I can see that chemical attraction 

 goes on long after the attenuation has reached the best stage 



