DR. W. M. HICKS: A CRITICAL STUDY OF SPECTRAL SRKIKS. 



377 



denominators of the extreme satellites of the first line are multiples of A, or A, and 

 that explanations should be sought for apparent exceptions. 



The S and P Series. 



The relationships between the doublet and triplet sets of the P series and between 

 the S and P series were discussed in [II., p. 51] by comparing the differences between 

 the corresponding denominators. It is now possible to see how, if at all, these 

 differences are related to the oun. 



The P Series. In the alkalies the differences between the corresponding 

 denominators of the two sets were found to be constant within error limits and 

 of course equal to A. In the other elements in which the P series have been 

 allocated, there was always a drop in the difference, which in several cases then 

 remained constant for the succeeding orders. The values were given on [II., pp. 51-53]. 

 They are reproduced here, and it is seen at once how they proceed on quite analogous 

 lines with successive satellite differences of the D series considered above. The 

 possible eiTors of the single lines from which they are deduced are given in brackets. 

 Thus ZnP(l) are 1'599352 (2), F592143 (3), 1'5886G9 (4), and the differences are 

 given as 7209 (2, 3), 3474 (3, 4). The higher orders, in which the possible errors are 

 so large as to be themselves multiples of S lt are not included. The value of <$, is 

 given with the symbol for the element. 



It will be noticed that the more accurate the observations the closer are the 

 differences to the multiples of the oun. But the observed variations from true 

 multiples in the case of the large separations would seem to point to a difference 

 in the a as well as in the M- Iu any case it would seem that n must alter 

 per saltum from order to order, unless the sequence formula is a complicated 

 function of m. 



Zn (S 1 = 3875). 



, = 113-8). 



7209 (2, 3) 



128-5 

 5355 (19, 28) 



8 + 9 

 5191 (9, 9) 



8,-! 

 5154 (30, 30) 



3474 (3, 4) 



68 + 20 

 2525 (28, 36) 



38! -5 

 2414(9,9) 



i 

 2375 (30, 30) 



87815 (?) 

 118-118 



71967(?) 

 28, -122 



71364(1) 



23109(4,5) 

 508, -5 

 17423(25,25) 



18269 (922) 

 17109(26, 28) J 



38, + 27 



10368 (5, 5) 

 308, -26 

 6980 (25, 25) 



6461 (1837) 



6407 (28,25) t 



58, +4 



VOL. CCXIII. A. 



Hg (*, = 362-87). 



30002 (1) 



148, + 143 

 24779 (1) 



38, 126 or 28, + 237 

 23817 (t) 



3 c 



