﻿Quantum- Orbit Theory of Spectra. 34',) 



readers who may not be familiar with spectral data, it may 

 be well to consider them here. 



(s, p.) For the s, p the lowest order are : 



s. p. 



TT [ Alkaline earths ... 2 1 



"'iZn, Cd, Eu, Hg... 2 1 



p. 



Rare gases 1 1 



T [The alkalies I 2 



L - \Cu, Ag, Au 1 J 



Group III 2 1 



I£ it were not for the cases of the rare gases and the 

 Cu subgroup, the assumption might be explained by an 

 interchange of the nature of the sequences which produce 

 P, S series (for which in Groups I. and IJ. indeed there is 

 also direct evidence). But that two groups make s, p both 

 have unity for their first order is fatal. 



(r/.) The assumption of 3 as the first order for d(in) 

 no doubt is based on the fact that Pitz made it in dealing 

 with the D series in the alkalies. The denominators of the 

 first orders in this group are comparable with 2*9, which 

 Ritz wrote as 3 — '1 and called the first order 3. But this 

 procedure is inadmissible either on the side of the formula or 

 from what Ave know of the constitution of the d sequence. 

 In Sommerfeld's formula /jl is positive, and it is only by 

 treating the fraction as positive that we find a detinite 

 dependence of it on certain spectral constants. But even so, 

 the first order is not 2 for all groups. The law of the first 

 order of the d sequence is a quite simple and definite one, 

 and is given on p. 18S of my recently published 'Analysis of 

 Spectra.' It is that in each group of the periodic series, 

 the subgroup of elements whose melting-points increase with 

 atomic weight take as their first order m = l, whilst the sub- 

 group with decreasing melting-points take m = 2. 



(/.) In the case of / the 3 + fraction has again clearly 

 been written 4 — /, and the assumption lias been made that 

 the lowest orders of the / type take m = 4. But here also, 

 for the same reasons as in d, the fraction must be taken as 

 positive. In the alkalies certainly the lowest order observed 

 is F(3), but F(2) would lie far up in the ultra-red, beyond 

 even Paschen's longest lines. In the Cu subgroup there is 

 evidence for m = 2 and indications for m = l. The alkaline 

 earths have m — 2 both in triplets and doublets. In the 

 Zn subgroup only F(3) has been observed, but F('2) would 

 lie in the extreme ultra-red. In Group III. there is no 

 evidence, whilst in the rare gases there are examples of* F(l) 

 and F(2). 



It would thus appear that the theoretical deduction that 

 different types depend on successive changes of azimuthal 

 quanta by unity is not tenable. 



