1908-9.] Dissymmetrical Separations in the Zeeman Effect. 75 
V. — Dissymmetrical Separations in the Zeeman Effect in 
Tungsten and Molybdenum. By Robert Jack, M.A., B.Sc., 
Ph.D., 1851 Exhibition Research Scholar. Communicated by 
Professor A. Gray, LL.D., F.R.S. 
(MS. received October 12, 1908. Read November 2, 1908.) 
It has been mentioned by Professor Voigt of Gottingen in his newly pub- 
lished book * and by Professor Zeeman of Amsterdam in the Physikalische 
Zeitschrift ,f that I have found examples of strongly marked dissymmetry 
in studying the Zeeman Effect in tungsten and molybdenum. Professor 
Zeeman has also discovered and published such cases of dissymmetry in 
other elements. Not only have many examples of normal dissymmetry 
been found, but almost as many cases of abnormal dissymmetry. To explain 
those terms, normal and abnormal , let us consider that the single spectrum 
line is broken up, when the light is in the magnetic field, into the three com- 
ponents, 1, 2, 3, where the numbers begin from the component which has 
the shortest wave-length. In the normal dissymmetrical triplet the middle 
component is nearer the component on the red side than that on the violet one, 
i.e. for the normal type the interval 1-2 is greater than the interval 2-3, but 
in the abnormal dissymmetrical triplet 2 is nearer to 1 than to 3. These 
observations of Professor Zeeman and myself, which were made at the same 
time in the Universities of Amsterdam and Gottingen, having been com- 
municated to Professor Voigt, he wrote and published in the above-mentioned 
book an extension to his and Professor H. A. Lorentz’s theories of the Zeeman 
Effect. In his original theory Professor Voigt had shown that, considering 
the electrons as uncoupled, cases of normal dissymmetry might arise among 
the Zeeman triplets, this dissymmetry being accompanied by a greater 
intensity of the red component than the violet one. J He pointed out also 
that the “ absolute ” dissymmetry or the difference between the absolute 
displacements of the red and violet components should be independent of the 
magnetic field strength used to produce the Zeeman Effect. To explain the 
large numbers of complicated types of Zeeman Effect which have been found 
— in the study of the Zeeman Effect in tungsten I discovered lines with no 
* W. Voigt, Magneto- und Elektrooptih. 
+ P. Zeeman, Phys. Zeit., x. 340, 1908 ; W. Voigt, Phys. Zeit., xi. 353, 1908. 
| Thus normal dissymmetry is the more simply explained and first discovered type, 
whereas abnormal dissymmetry requires a more complicated theory, and when first 
observed was contradictory to any existing theory. 
