Chemistry and Physics. 65 



under some conditions gave a barely perceptible glow, too faint 

 to be studied, though attended by a notable rise of temperature. 

 On one occasion, when the glow was not observable, a white 

 solid was deposited on the glass. This solid exploded spontane- 

 ously, with a loud report, breaking the apparatus, and leaving a 

 deposit of carbon. The explosive compound was probably the 

 " ozobenzene " of Houzeau and Renard. Napthalene and camphor 

 failed to give a glow but were energetically acted on. The 

 former substance was carbonized, and the latter converted into a 

 dull, opaque white solid. Cyanogen gave a white glow with a 

 purple tinge in the vicinity of the nozzle. The spectrum con- 

 sisted of the characteristic cyanogen bands together with the 

 hydrocarbon band at A4315. An unidentified band at X415 was 

 also observed. Strutt suggests that this band " may eventually 

 prove of interest in connection with the spectra of comets." — Pro- 

 ceedings Phys. Soe. London, xxiii, Feb. 1911. h. s. u. 



6. A Chemically Active Modification of Nitrogen, produced 

 by the Mlectric Discharge. — It is known that vacuum tubes fre- 

 quently show luminosity of the contained gas after the discharge 

 is over. In a previous paper Strutt showed that this effect, as it 

 occurs in air, is of the nature of a phosphorescent combustion, 

 and is due to the mutual reaction of nitric oxide and ozone, each 

 formed in the discharge. In a second paper, reviewed above, it 

 was shown that other phosphorescent combustions can be observed 

 in ozone. Also, it was stated in the first paper that pure nitro- 

 gen gives no afterglow whatever when a simple induction coil 

 discharge is used. This fact has been frequently verified by sub- 

 sequent experiments of Strutt. On the other hand, E. P. Lewis 

 has described an afterglow obtained in nitrogen when a Leyden- 

 jar discharge with auxiliary spark-gap is employed. By using a 

 jar discharge, in conjunction with apparatus of the type described 

 in the preceding review, Strutt has obtained the remarkable and 

 important results given in his " Bakerian Lecture." The most 

 interesting features of this paper will now be set forth. 



As Lewis observed, the glow for nitrogen has a characteristic 

 band spectrum not known in any other connection. In the visual 

 region there are three bands, one in the green, another in the 

 yellow, and a third in the red. The glow as a whole appears 

 yellow. By using Devvar's continuous flow method, Strutt has 

 " obtained the nitrogen afterglow intense enough to be conspicu- 

 ous to an observer 30 feet off, when it was 18 inches below a 32- 

 candle electric light." Contrary to Lewis, Strutt found that the 

 effect could be obtained with nitrogen from natural and artificial 

 sources, the purer the nitrogen the better the results. " In short, 

 all the evidence obtained points to the conclusion that the glow 

 is connected with nitrogen, and nothing but nitrogen." 



The effect of temperature on the glow is important. If a 

 long tube, through which a stream of glowing nitrogen passes, is 

 moderately heated, the glow is locally extinguished. As the gas 

 passes on to a cooler part of the tube its luminosity is recovered. 



Am. Jour. Sci. — Fourth Series, Vol. XXXII, No. 187. — July, 1911. 

 5 



