ARC SPECTRUM OF ELECTROLYTIC IRON. 
995 
Lines lyrohabhj due to iron which occur in McClean’s Photographs, hut not in 
the Kensington Arc Photographs. 
Wave¬ 
length. 
Intensity. 
Wave¬ 
length. 
Intensity. 
Wave¬ 
length. 
Intensity. | 
Wave¬ 
length. 
Intensity. 
3914-1 
6 
4205-3 
6 
4418-5 
6 
5428-2 
6 
1 3925-2 
6 
4208-1 
6 
4421-8 
6 
5443-5 
6 
i 3939-2 
6 
42.33-4 
3 
4541-7 
6 
5464-5 
6 
3940-1 
6 
4253-4 
6 
4875-2 
6 
5583-0 
6 
3963-8 
6 
4257-0 
6 
4913-6 
6 
5600-3 
6 
3972-2 
6 
4283-7 
6 
5197-8 
6 
5607-9 
6 
4105-1 
6 
4314-1 
5 
5250-9 
5 
56-23-6 
6 
4129-3 
6 
4371-5 
6 
5375-6 
6 
5650-9 
G 
4141-1 
6 
4377-6 
6 
5409-3 
6 
5707-2 
6 
4146-7 
6 
i 
4381-0 
5 
5426-2 
6 
5714-3 
6 
In general, the intensities of corresponding lines in the arc and spark spectra 
closely agree. The more remarkable differences in the intensity of the lines are 
given in the following table. It will be seen that in the great majority of cases the 
spark lines are attributable to the air between the iron poles being raised to a state 
of incandescence, and producing lines in the spectrum due to oxygen and nitrogen. 
In the others the difference is apparently due to a closely adjacent impurity line 
which appears in one spectrum and not in the other. Tliese impurities are indicted 
in the last column of the table. 
In comparatively few cases does there apj^ear to be a genuine difference of intensity. 
G i: 2 
