1. Ann. der Physik, 71, 102 (1923).
2. Zeit. für Physik, 20, 170 (1923). Similar but less accurate and complete data have been obtained by Bengtsson, Zeit. für Physik, 20, 229 (1923).
3. Frerichs gives no data on relative intensities of the doublet components, so that this point cannot be checked here.
4. Of the other bands measured by Frerichs, three should show larger isotope effects than 428o and 4328. Of these 4380 was so weak that it could be measured only with a wide slit, while in the case of 465O and 4690 the “lines appear broadened and unsharp due to the continuous background, making measurement difficult"; however, an apparent doubling of the lines from m = 12 on was noted (but not measured) in the case of 465O.
5. Hg, Liese, Zeit. wiss. Phot. 11, 349 (1913). Zn, Hulthén, Compt. rend. 173, 524 (1921). Cd. Hulthén and Bengtsson, Compt. rend., 175, 123 (1922). The results are given to tenths of a wave-number unit.