﻿THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FOURTH SERIES.] 



JUNE 1869. 



LVIII. On the Spectra of certain Gases in Geissler's Tubes. 

 By A. Wqllner*. 



I. Hydrogen, 



THE spectrum which hydrogen enclosed in Geissler's tubes, 

 under very small pressure, exhibits when the current from 

 a small RuhmkorfPs coil passes through it consists, as Plucker 

 first showed j% essentially of three bright lines, which he has de- 

 signated as H a, H /3, H <y. H a is a brilliant red line which takes 

 the place of Fraunhofer's line C ; H /3 is a bright bluish-green 

 line exactly corresponding to the dark line F ; and H 7 a bluish- 

 violet line which corresponds to a delicate dark line just in front 

 of G; this M. Angstrom J also designated as belonging to hy- 

 drogen. Besides these there is a further violet line H S, the posi- 

 tion of which, owing to its feeble light, cannot be accurately de- 

 termined. 



Besides these bright sharp lines there is seen in many tubes a 

 feebly bright field traversed by dark lines, in the neighbourhood 

 of the sodium-line in the place corresponding to the dark line 

 D of the spectrum. This bright field begins about 0'8 of the 

 space between a and D in front of D, and extends beyond D so 

 far that the part on that side is about half as broad as that on 

 the other side of D. Looked at with a flint-glass prism of 60° 



* Translated from Poggendorff's Annalen, "December 1868. 

 t Pogg. Ann. vol. cvii. pp. 506 & 518. 

 'I Pogg. Ann. vol. exxiii. 



Phil. Mag. S. 4. Vol. 37. No. 251. June 1869. 2 E 



