MEMOIR II.] SPECTRUM ANALYSIS OF FLAMES. f 3 



by the centre of the yellow space, and the light termi- 

 nates at equal distances in the violet and red. 



Do not these observations lead us to conclude that 

 the cause, whatever it may be, which produces these 

 fixed lines is periodic in its action ? 



What that cause in reality is we have not now facts 

 sufficient to determine. I would not affirm that the 

 disengagement of incombustible matter by a flame will 

 always give rise to dark lines. But this is very clear, 

 that in all those cases, as cyanogen, alcoholic solutions 

 of nitrate of strontia, of boracic acid, etc., in which these 

 lines are developed, incombustible matter is uniformly 

 disengaged. 



UNIVERSITY OF NEW YORK, Dec. 25, 1847. 



