of the Flame and Furnace Spectra of Iron, 223 



which as already explained in § 5 provided better opportunity 

 for observing the less refrangible end of the spectrum, have 

 disclosed the existence of a new outstanding group of five 

 lines having its head at A, 5270. It will hereafter be de- 

 signated as group e. This group is also observed in all the 

 flames, but its less refrangible lines do not show on photo- 

 graphs taken on ordinary plates, and it had therefore escaped 

 my attention. It was further found that group y also consists 

 of five lines and not of only four, as hitherto believed. Groups 

 8 and e overlap partly and some of their lines form close 

 doublets, which it would have been impossible to separate 

 with the low dispersion employed. But since I have now 

 shown that the furnace spectra of iron up to 2400° C. are of 

 identical character with the flame spectra of the same element, 

 it has become possible to take advantage of Dr. King's most 

 carefully prepared table of furnace lines based on observations 

 made with a high-dispersion spectrograph. It was found 

 that nearly all the lines of groups <y and e belong to class I B 

 of Dr. King's classification; those of group 8 all with one 

 exception to class II. I feel now, however, rather doubtful 

 whether the lines of group 8 are genuinely connected, but the 

 decision must be left to further investigation. In any case 

 group 8 is not so prominent as the other tw r o, which indeed 

 seem to belong to the fundamental vibrations of the iron 

 atom. The fifth line of group 8, namely 5341, has not been 

 observed in any of the flames. A list of the revised groups 

 7 and 8, and of the new group e is given below. 





Wave- 



Oscillation 







Dr. King's 



lengths. 



Frequency. 



A i- 



A 2 . 



classification 



^4375-93 

 4427-31 



22852-3 

 22587-1 



265-2 



173-9 



103-1 



37-1 



91-3 



IB. 

 IB. 



y-- 



4461-65 



224132 



70-8 



IB. 





4482-27 



22310-1 



66-0 



IB. 





^ 4489-74 



222730 





IA. 



'5012-07 



19951-8 



600-1 



3776 



207-2 



439 





IB. 



| 516749 



19351-7 



222-5 



II. 



S. <( 5270-35 

 | 5328-54 



18974-1 



1704 



II. 



18766-9 



1633 



II. 



V 534103? 



18723-0 





II. 



f 5269-53 



189770 



208-4 

 151-8 



88-4 

 29-7 





IB 



| 5328-06 



18768-6 



566 



IB. 



€.{ 5371-50 



18616-8 



634 



IB. 



| 5397-12 



18528-4 



58-7 



IB. 





{ 5405-78 



18498-7 





IB. 



