

DR. \V. M. HICKS: A CRITICAL STUDY OF SPECTRAL SERIES. 9ft 



The F Series. 



In Part I. the symbol F was used to denote the series whose limit depends on the 

 values of VD (2) in a similar way to that in which the limits of the S and I) series 

 depend on VP(l). Where the D writ's show satellites tin- F series in ronsei|ueii(v 

 consist of doublet or triplet series with constant separations. They comprise some of 

 the strongest lines in the respective spectra, but as in general they occur in the 

 ultra-red region they have not received the same attention as the other better known 

 ones. In the alkaline earths, however, they come well within the visible regions, and 

 show strong sharply defined lines. They are related also to other strong lines by 

 collateral and other displacements depending on considerable multiples of A, and so 

 naturally come under discussion in the present communication. As will be seen later, 

 the discussion gives the means of obtaining very accurate determinations of the A 

 and consequently of the oun as well as of settling other questions. I propose, 

 however, not to attempt an exhaustive discussion in the present communication, 

 partly because the main object now is only to illustrate the influence of the oun, and 

 partly because it would seem that a large number of lines which clearly belong to the 

 F cycle are related in a manner neither ordinal nor collateral, nor according to Rm's 

 combining theory.* 



For convenience of reference the wave-lengths of these lines are given in the 

 Appendix, together with short historical notes. 



The Alkalies. The table below gives the denominators for the two first lines in 

 each as calculated from PASCHEN'S and from RANDALL'S results. BERGMANN'S measure- 

 ments for other lines are too much in error for the present objects. The limits used 

 are the calculated values of VD, using the limits D(oo) given in Table II. above and 

 the values of D (2) in the Appendix. 



Na. K. Bb. Cs. 



3-997919 (169) - 219& 3 -992817 (252) -290& 3 987849 (433) - 289, 3-977334(146)- 

 4 -997267 (2845) - 569, 4 -989237 (696) -566$, 4 983697 (846) -564, 4-9698 



5-9710 

 6-9642 



The question that first arises is, tlo these refer to actually the first lines of the 

 series? If, like I), the lowest value of m were 2, the wave number* of 

 would be somewhat above, Na, ; K, 1200; Bb, 2060; Cs, 4450. 

 be outside, but the others come within regions observed by PASCHEN.! 



He gave for K lines at wave numbers 1346'3 and 118: 



* The relation is extremely common in certain type, of spectra, e.g., the rare gase. other than Ho. I 

 hope to return to this in a future communication. 



t "Zur Kenntnis ultraroter Linien-spektra III.," ' Ann. d. Phys.,' 33 (1910), p. 1 



3 o 2 



