656 Professor The Hon. R. J. Strutt [Feb. 28, 



WEEKLY EVENING MEETING, 

 Friday, February 28, 1913, 



The Right Hon. Lord Rayleigh, O.M. M.A. D.C.L. LL.D. 

 D.Sc. F.R.S., in the Chair. 



Professor The Hon. R. J. Strutt, M.A. P.R.S. 



Active Nitrogen. 



Everyone has heard of ozone, the active modification of oxygen, 

 whicli is produced when this gas is subjected to electric discharge. 

 I hope to show you to-night that nitrogen can also be made to assume 

 an active state under suitable experimental conditions. We will begin 

 with an experiment (Fig. 1) which will serve to introduce the subject. 

 A rapid stream of rarefied nitrogen gas passes through the tube a 

 at a pressure of a few mm. of mercury, and on its way the gas 

 is sparked through l.)y a series of high tension electric discliarges 

 from a Leyden jar. It then issues as a jet into the large vessel Z*, 



Fig. 1. 



where it is seen to be brilliantly luminous, the stream of gas bein 

 visible as a whirling cloud of brilliant yellow light. Notice that 

 this light is of a different colour from that of the electric discharge 

 in the former vessel. 



Why does the gas remain luminous in this way for an appreciable 

 time after the electric discharge has passed through it ? The view 

 which I shall develop this evening is that the discharge has split the 

 nitrogen molecules into single atoms. Nitrogen atoms in this condi- 

 tion are uneasy, and are anxious to find partners again. But to do 

 this takes time. The reunion of the nitrogen atoms is attended with 



