1889.] Wave-length of chief Fluting in Manganese Spectrum. 35 



Selenium Oxy chloride. 



It may be useful here to mention a reaction, hitherto undescribed, 

 by which selenium oxychloride can be obtained. It consists in dis- 

 tilling" a mixture of sodium chloride and selenium dioxide. The 

 reaction is a simple one — 



2Se0 2 + 2NaCl = Na 2 Se0 3 + SeOCl 2 . 



Half the selenium remains as sodium selenite. 



III. " On the Wave-length of the chief Fluting seen in the 

 Spectrum of Manganese." By J. Norman LoGKYER, F.R.S. 

 Received April 6, 1889. 



In a paper communicated to the Royal Society in November, 

 1887, I pointed out that in the spectra of certain classes of heavenly 

 bodies there are several lines and flutings which occur in the low-tem- 

 perature spectra of meteorites. 



In a subsequent paper* I gave tables showing further that lines 

 occupying nearly the same position had also been recorded in the 

 spectra of aurorae. The coincidences were really surprising, and I 

 therefore suggested that the spectrum of the aurora might in part 

 be due to particles of meteoric dust in the upper parts of our 

 atmosphere. 



One of the most constant flutings thus apparently common to the 

 spectra of meteorites, meteor-swarms (nebulge and stars as well as 

 comets), and auroree is one near wave-length 558. I, therefore, 

 suggested that the remnant of this fluting, which is seen in the spec- 

 trum of manganese (whether due to the metal or a compound is 

 unimportant in the present connexion), was the origin of the chief line 

 of the aurora spectrum. I distinctly stated that only small dispersion 

 had been employed of set purpose, and that the wave-lengths given 

 had no claim to great accuracy. 



From a detailed discussion of all the published observations avail- 

 able to me,t the suggestion as to the meteoritic nature of the aurora 

 seemed fully justified, both as regards the general characteristics of 

 the spectra and the positions of the lines and flutings observed, but I 

 was particularly careful to point out that the object of my paper was 

 mainly to direct further inquiries. 



Dr. Huggins has communicated an interesting paper to the Royal 

 Society, J in which he gives the results of some very careful measure- 



* ' Roy. Soc. Proc.,' vol. 43, p. 320. 

 f ' Roy. Soc. Proc.,' vol. 45, p. 217. 

 X ' Roy. Soc. Proc.,' vol. 45, p. 430. 



D 2 



