14 Prof. Pliicker on the Spectra in Rarefied Gases 



with hydrogen, nitrogen, and carbonic acid, and, after as complete 

 as possible rarefaction, showed characteristic and beautiful spectra 

 entirely distinct in nature from one another. I confine myself 

 here to a mere noting of these and the hitherto observed spectra, 

 reserving a more exact description together with pictorial deli- 

 neation*. 



102. In the spectrum of hydrogen, almost the whole of the 

 light is concentrated into three bands, — namely, a dazzling red 

 at the extremity of the spectrum, a beautiful greenish blue, and 

 finally a violet of inferior brightness, whose distance from the 

 greenish blue is about two-thirds of the distance of the latter 

 from the dazzling red. In the narrow tube the electric hght- 

 stream appears red. 



103. In the spectrum of nitrogen all the colours are fine, none 

 of them being faded, as is the case in the broad spaces lying 

 between the bright bands of the hydrogen spectrum. In the 

 spaces of the red, orange, and yellow, there are about fifteen 

 narrow dark-grey lines at nearly equal distances apart. Six of 

 these belong to the orange and yellow : both of these colours 



*are beautiful. The red, ia the direction away from the orange, 

 is shaded ofi" into brown, but becomes brighter and purer towards 

 the extremity of the spectrum, which stretches beyond the daz- 

 zling red bauds of the hydrogen spectrum. A broad green 

 space is separated from the yellow by a narrow black band. The 

 greater part of this space appears shaded with black in the di- 

 rection away from the black band. On more careful examination, 

 however, this shading is seen to consist of very fine black lines, 

 which are at equal distances apart, but nearer together than the 

 previously mentioned bands in the red, orange, and yellow. The 

 rest of the green space is again subdivided. The green is bor- 

 dered by two beautiful bright-blue bands, which are sharply sepa- 

 rated from one another and from the green by narrow black bands. 

 The blue and red-violet ends of the spectrum form nine sharply- 

 bordered violet bands, alternating with dark ones. The former 

 have various degrees of brightness ; the latter appear partly dark 

 violet, partly black. The fourth and fifth bright-bands, sepa- 

 rated by a black band, possess the most light ; the four following 

 ones are less prominent ; the last one, however, which forms a 

 sharp boundary to the whole spectrum, is the most distinct. The 

 light of the discharge-current in the narrow tube is yelloivish red. 

 10-i. In the spectrum of carbonic acid (see 115), six bright 

 bands sharply separate the bright portion into five spaces, of 

 which the two first are of equal breadth, the third, and especially 

 the two last, somewhat broader. The first of the six bands is 



* I have been assisted in drawing the different spectra by MM. Lick 

 and Dronke. 



