318 JOURNAL OF THE WASHINGTON ACADEMY OF SCIENCES VOL. 13, No. 14 
troscopy section of the Bureau of Standards.* With these more 
accurate and extensive data at hand this laboratory undertook to 
analyze the spectra of one or more elements in each of the higher 
columns of the periodic system, hoping thus to be able to test the 
proposed spectroscopic laws and to shed further light on the structure 
of the atom and on the nature of radiation. The same problem was 
independently attached by Catalin‘ and because of this coincidence 
the goal has been reached somewhat earlier than could otherwise have 
been expected. | 
Attention was first given: to the elements with atomic numbers 
19 to 26 which occupy the fourth row of the periodic system, 
Columns I to VIII. These elements are potassium, calcium, scan- 
dium, titanium, vanadium, chromium, manganese and iron. The are 
spectra of the first two had been fairly completely arranged into 
séries’ for many years, but of the remainder only fragments of series 
were known for manganese. These latter were recently extended by 
Catalin® who also found regularities in the spark spectrum and 
indicated many complex groups of lines for which he coined the word 
“multiplet.” According to Back’ the Zeeman effect in these spectra 
indicates that they are in agreement with the law of alternations as 
outlined by Landé* in a paper on Termstructure and Zeeman effect 
of Multiplets. Regularities in the arc spectrum of chromium were 
discovered quite independently by Kiess’ Gieseler,!? and Catalan." 
Similar investigations on the are spectrum of molybdenum were made 
independently by Kiess” and by Catalin." The results for these two 
elements indicate that the alternation law is valid for column VI. The 
first spectral regularities for any element in column VIII were found 
by Walters“ in the are spectrum of iron. Titanium, of column IV 
has been successfully analysed by Kiess.* I undertook a study of 
scandium and vanadium as representatives of the remaining columns 
III and V respectively. Wave-length data for the scandium" are- 
3 Bur. Standards Scientific Papers, 312, 324, 329, 345, 372, 411, 421, 442, 466. 
4 Anales Soc. Espan. Fis. y Quim. 21: 84, 1923. ° 
5 Fowler, Series in Line Spectra, 1922. 
6 Phil. Trans. Roy. Soc. London A 223: 127. 1922. 
7 Zeit. f. Physik 15: 206. 1923. 
8 Zeit. f. Physik 15:189. 1923. 
9 Science 56: 666. 1922. 
10 Ann. der Physik (IV) 69: 147. 1922. 
11 Anales Soc. Espan. Fis. y Quim. 21:84. 1923, 
12 Bur. Standards Sci. Pap. No. 474. 
13 Anales Soc. Espan. Fis. y Quim. 21:215. 1923. 
144 Journ. Wash. Acad. Sci. 13: 243. 1923. . 
15 Journ. Wash. Acad. Sci. 13:270. 1923. 
16 To be published in Bur. Standards Sci. Pap. 
