1913] on Active Nitrogen 661 



active nitrogen stream, we do not get very brilliant effects of 

 luminosity — nothing striking enough to be worth showing you — but 

 none the less interesting chemical actions are going on. The tube in 

 which the action occurs gets covered with the dark blue transparent 

 deposit, which I show by projection on the screen. This substance 

 is a known compound of nitrogen and sulphur, originally investigated 

 by i\Ir. Burt in 1910. If the gases are condensed farther on in the 

 tube by liquid air, we get a second deposit of brown colour, which 

 can be identified as the brown polymeric carbon monosulphide studied 

 ])y Sir James Dewar and the late Dr. H. 0. Jones. You see, then, 

 that the chemical action is completely traced. Active nitrogen takes 

 part of the sulphur from carbon disulphide, leaving carbon mono- 

 sulphide. 



The behaviour of active nitrogen with metallic vapours is of 

 interest, though it has not yet been very completely studied. I select 

 the case of mercury to show you. We pass the stream of glowing 

 gas through this tube, which contains a small pool of mercury. 

 While the mercury is cold, the yellow glow passes on unaffected. I 

 apply heat, and green mercury light, of the colour familiar in the 

 mercury vapour lamps used in electric lighting, is apparent, when 

 active nitrogen mingles with mercury vapour. Soon the tube gets 

 obscured, except when I am actually heating it, by a dirty looking 

 solid deposit containing much metallic mercury. 



I wish to convince you that an explosive compound of nitrogen 

 and mercury has been formed. For this purpose, to save the trouble 

 of dismounting the tube already used, we will take a similar one pre- 

 pared beforehand. I heat the mercurial deposit moderately over a 

 Bunsen burner, and, if you will kindly be quite still for a moment, 

 we shall hear a distinct crackling sound, as the explosive compound 

 decomposes. At close quarters it is easy to see flashes of light 

 accompanying the minute explosions, but these can scarcely be shown 

 to an audience, as the opaque deposit over the greater part of the 

 tube obscures them. 



It has only been possible this evening to bring forward a selection 

 of the results of two years' work on this subject at the Imperial 

 College, with generous help from colleagues, and facihties provided 

 by the Governors. 



Let me conclude by reading to you a prophetic passage from one 

 of Faraday's letters to Schonbein : — " What of nitrogen ? Is not its 

 apparent quiet simplicity of action all a sham ? Not a sham, indeed, 

 but still not the only state in which it can exist. If the compounds 

 which a body can form, show something of the state and powers it 

 may have when isolated, then what should nitrogen be in its separate 

 state ? You see I do not work ; I cannot. But I fancy, and stuff 

 my letters with such fancies (not a fit return) to you," 



[R. J. S.] 



