﻿212 Prof. A. Lielegg on the Spectra of the 



The pea-green line, 201 of the group 7, and the last violet 

 band, 101*5-98, which (as is well known) nearly coincide with 

 Fraunhofer's lines C and G, are also those lines which are 

 always visible if we use as a source of light a flame of spirit of 

 wine, or the lowest non-luminous blue part of the flame of a 

 wax-light, or the spherical light of the gas-flame of a Bun- 

 sen's burner; in the two latter there can also usually be di- 

 stinctly observed, under favourable circumstances, the second 

 line (198) of the group y, the first line (233) of the group /3, and, 

 lastly, the whole group 8; only the individual lines of the latter 

 are not to be distinguished, the whole group appearing to stand 

 out from the background as a faint broad band. 



It is moreover to be remarked that, when the combustion of 

 the coal-gas takes place with an insufficient quantity of oxygen, 

 the group of five red lines cannot be even momentarily discerned, 

 and the red and yellow part of the spectrum generally is not 

 perceptible, the space corresponding to it being quite dark up to 

 the first line of the group ft. 



Spectrum of Olefiant Gas. 



If we burn olefiant gas with oxygen in the same manner as 

 we have described for coal-gas, we obtain a spectrum which 

 agrees perfectly with that of coal-gas, and presents only in the 

 development of the extreme violet part (appropriately called by 

 Brucke* lavender-grey) a form quite peculiar, in that it is in- 

 tersected by a great number of strong black lines, which are 

 arranged near each other in the dark violet part fine and narrow, 

 but in this lavender-grey part, immediately following it, become 

 increasingly broader, and also are separated by longer intervals, 

 until, again approaching nearer, they at last terminate in abroad 

 dark streak, succeeded by a lavender-grey one of equal breadth, 

 at which the visible part of the spectrum ends. 



The extent and appearance of this part of the spectrum, which 

 comes immediately after that of the coal-gas, will be at once 

 understood by an inspection of the following results of the mea- 

 sures made of it : — 



951 Blue-violet space intersected by fine black lines, the light 

 71 J constantly decreasing in intensity towards 71. 



701 



p.-. >Dark space, black at 61. 



f Lavender- grey intersected by many black lines, which 

 50 J continually increase in breadth, as well as the inter- 

 7 1 spaces, and in the last third of the whole space again 

 [_ become gradually narrower, but in a less degree f. 



* Poggendorff' s Annalen, vol. Ixxiv. p. 461. 



t The violet potassium line K /3 has the position 49. 



