JULY 19, 1923 KIESS AND KIESS: SPECTRUM OF TITANIUM 271 
lished up to the year 1912. Since that time have appeared measure- 
ments by Kiess and Meggers® describing the spectrum from 5500 A 
to 9700 A in international units, and interferometer measurements by 
Brown” of 118 lines between the limits 4263 A and 6261 A. The char- 
acter of the spectrum as a function of the temperature of the source 
has been studied by King" who has given the temperature classifica- 
tion of all the arc lines from 3888 A to 7364 A. King” also studied 
the Zeeman effect for the titanium spark in approximately the same 
spectral regions. 
It is the purpose of this note to describe regularities of complex type 
that have been found to occur among the arc lines of titanium. In 
describing similar complex groups which he found in the spectrum of 
manganese, Catalin’ coined the name multiplet for them. The 
multiplets of titanium are characterized by two different sets of 
recurring constant frequency differences. The differences 170.1 and > 
216.7 link together groups of six and seven lines similar to those found 
by Popow, Gitze, Lorenser and others" in the spectra of the alkaline 
earths and of some of the elements of column III. The differences 
42.0, 62.3, 81.7 and 100.2 occur in more complex groups of 11 and of 
13 lines similar to the multiplets of manganese, or those of chromium"* 
and molybdenum.!” 
The majority of the lines so far classified belong to King’s tempera- 
ture classes I and II, although some of classes III and IV have been 
assigned to multiplets. It is worth while to remark here that the 
temperature classification of spectrum lines is an invaluable aid in 
unravelling complex spectra, furnishing clues which lead readily to the 
sought-for regularities. In each of the following groups the wave- 
lengths of the lines are followed by parentheses in which the arabic 
numeral gives the arc intensity of the line as taken from published data, 
and the Roman numeral gives the temperature class of the line. 
Beneath the wave-length is printed the wave-number of the line cor- 
rected to vacuum. The italicized numbers give the frequency differ 
* ences occurring between the connected pairs of lines. 
9 B.S. Sci. Papers, 16: 51. 1920. 
10 Astroph. Journ. 56: 53. 1922. 
1 Astroph. Journ. 39: 139. 1914. 
12 Astroph. Journ. 29: 76. 1909; also 30: 1. 1909. 
13 Proc. Roy. Soc. London, A 223: 146. 1922. 
144 Paschen-Gotze, Seriengestze, Berlin, 1922. 
16 Loc. cit. 
16 Ann. der Physik, IV 69: 147. 1922, Anales Espafi. de Fis. y Quim. 21: 84. 1923. 
17 B.S. Sci. Papers, In press. 
