DR. W. M. HICKS: A CRITICAL STUDY OF SPECTRAL SERIES. 381 



limit is 3067772 and may be taken as practically correct. That calculated from the 

 series, and used in the preceding discussion is 30678 '93 + / . This, therefore, requires a 

 correction of 1'21. The equations A would be satisfied by p = 1, dn = 2, = 1'21. 

 As however this value of is probably correct within '1 the best value of A 2 is 

 obtainable from f(%), viz., 



A 2 == 4678'098 + '580 (l'21 + 'l) + '086 x 1'002 



= 4678'80-10 

 A' 2 = 4242'IS 06 

 S = 249'536 '005. 



If the difference between S as found from i/,, ^ be real and depend on electronic 

 changes as hinted at in the introduction, the changes calculate to 73 '94 electrons = 74. 

 In other words, the v 2 would refer to mass of nucleus +37 electrons and v l to mass of 

 nucleus 37 electrons. Is it merely a curious coincidence that the atomic number of 

 Kr is 38, that of H being 1 ; all the electrons acting in one way for i/, and in the opposite 

 for i> 2 ? it being remembered that when S lines are emittted one electron at least is 

 absent. 



Xenon. The X diffuse system appears to be a most complicated one. As we shall 

 see later there appears to be a congery of series converging to limits which are 

 collaterals of S (oo) = 51025, and connected with these there are again congeries of F 

 series converging to limits collateral to the various d ln sequents or, say, the normal 

 F(oo). These F series further show the existence of satellites in other words the 

 f sequence is also subject to slight collateral displacements. This renders their 

 disentanglement a very intricate problem not only in itself, but because it renders 

 the region of the spectrum involved very crowded, with lines close together, with the 

 consequence that coincidences occur which may not refer to real relationship. In fact 

 there are cases where the calculated values of supposed lines of different series are the 

 same within observation errors.* This crowding is also increased by the existence of 

 the allied F series referred to above. The complete discussion of all these related 

 series should afford valuable material for arriving at a knowledge of displacement 

 laws. Here it will be sufficient to indicate the nature of the problem and to deal 

 with the material so far as to give confidence in the results as to the assignment of 

 series and especially as to accurate determinations of the oun and the various links. 



As vacuum tube spectra approximate to the spark type, the difficulty of drawing 

 definite conclusion from the existence of a triplet separation is again enormously 

 increased by the presence of the link relations which these spectra show. In arc 

 spectra the appearance of a v l or v 2 separation may always with some certainty be 

 ascribed to the fact that the lines in question are directly connected with series terms. 



* A case in point is P! (5) and P 3 (17) in the series next considered ; also F 3 (13) and F 2 (19). 



