Jack — Magnetic Resolution oj the Spectrum Lines of Niobium. 45 



limits of error, tlie separations might be tabulated as multiples of some 

 otiier aliquot part. 



Eitz* has written a theory, and claims that according to it separations 

 of the components of the complicated types aie represented by much smaller 

 numbers, though in some cases the same numbers are required as for the 

 Runge rule. The Ritz law states that if Vo = the frequency of the spectral 

 line, H = field strength, m and n = whole numbers, and w, w' are two 

 numbers pertaining to the special spectrum line, then the frequencies of the 

 components are given by the following : — 



Parallel to H : i-,, ± mw m = 0, 1, 2 . . . 



Perpendicular to H : >'„ ± w' ± nw n = 0,1,2 .. . 



lie has given examples illustrating the advantage of his rule over that of 

 Runge. Further examples of the application of the Ritz rule have been 

 published lately.f In my Dissertation (I.e.) I have given other examples ; 

 but have also pointed out cases where the Ritz rule does not hold. 



Both of those rules will again be applied, where possible, in considering 

 the separations found for this substance. The results obtained by the Range 

 rule will be found in the columns marked A. For the field-strength to 

 which the observations have been reduced the normal interval a = 1'07 (6), 

 and the separations are represented as multiples of rational fractions of a. 



The intensities of the components in the second order are given under i. 



By - '*' is denoted the alteration in the number of vibrations per cm. 

 A 



Hence the positive and negative values denote respectively components on 



the blue and red sides of the original position of the line. If the separation 



is given in square brackets, then the reading, owing to the want of sharpness 



of the line, its intensity, or some other cause, is not very accurate. The 



letters jp and s denote respectively that the vibrations are parallel and 



perpendicular to the magnetic lines of force. Where both letters appear 



after a value, then the component contains both kinds of vibrations. When 



two intensities are given opposite an interval representing components at 



equal distances on the blue and red sides, then the iirst value always refers 



to the compoiient having the smaller wave-length. If only one intensity be 



given to correspond to two components, then both components have the 



same intensity. 



* W. Kitz, Ann. d. I'ilys., x\y, 660, 1908. 

 t W. Ritz, Phys. Zeit., ix, 1909. 



X Here A. is expressed in cms., tliougli when \ denotes a wave-length at other phices the unit is 

 tlic angstrom. 



