[ 323 J 



VIII. A Critical Study of Spectral Series. Part HI. The Atomic Weight Term 

 and its Import in the Constitution of Spectra. 



By W. M. HICKS, F.R.S. 



Received June 7, Read June 26, 1913. 



CONTENTS. 



Page 



Abbreviations 323 



The " oun " 324 



Collaterals 336 



The diffuse series 



General 338 



Table of denominator and satellite differences 341 



Satellite separations 352 



Order differences 353 



The D (2) term 372 



The S and P series 377 



The F series 379 



Closer approximation to the value of the oun 400 



Ag and Au 403 



Summary 407 



Appendix I. Sc 408 



II. Wave-lengths and notes 411 



ABBREVIATIONS. 



[I.] and [II.] denote the two previous parts of this discussion published respectively in the 'Phil. 



Trans.,' A, voL 210 (1910), and vol. 212 (1912). 

 The formula for a line is = N/D^ - N/D m *. 

 N/Di 2 is the limit or value when m = o>. 



denotes the correction to be added to any limit adopted to give the true value. 

 N/D, Z is referred to as the V part (variable). 

 D m is referred to as the denominator of the line. 

 "Separation " of two lines is the difference of their wave numbers. 

 " Difference " of two lines is the difference of their denominators. 

 "Mantissa" is the decimal part of the denominator. 

 v denotes the separation of two lines of a doublet. 



A is used for the denominator difference of the two lines which produces v. 

 v \* "fc Aj, A 2 are similar quantities for triplets. 

 VOL. C'CX I II. A 504. 2 T 2 Publithed ep.raUly, October 22, 1913. 



