Part III/) 

 On the spectra of elements of higher atomic number. 



§ I. General structure of series spectra. 



According to Rutherford's theory we shall assume that the atoms of the elements 

 consist of a number of electrons moving round a central nucleus of large mass and 



^) As it will appear from the introduction to tlie first part of this paper, it was the original 

 plan in a treatise consisting of four parts to discuss from a uniform point of view tlie applications of 

 tlie quantum theory to problems of atomic constitution. Already at the appearance of Part 1 a manuscript 

 of the whole treatise existed, wliich to a large extent was ready for printing. For various reasons, how- 

 ever, onh' two parts were puhlishcd at that time; besides the first part wliich appeared in March 1918, 

 a second part wliich appeared in December 1918. This delay of the later parts was due in tlie first place 

 to the nature of the subject. In fact already before the appearance of the second part it was felt 

 necessary to change and to e.\tend the original manuscript materially on account of tlie development 

 of the theory brought about by the elaboration of the general ideas presented in Part I. A corresponding 

 revision of the later parts, which was felt unavoidable, was however never brought to a satisfactory' 

 conclusion. Especially, the problem of the stabilit}' of atoms containing several electrons came more and 

 more in the foreground and gave rise to difficulties which brought the limitation of the direct appli- 

 cability of tlie general Ideas as formulated in the first parts to light. A preliminary account of the 

 results of my worli with this problem in the last years is given in a lecture delivered about a year 

 ago in the Physical Society of Copenhagen and published In Danish in Fysisk Tidsskrift XIX, p. 153, 

 1921, and in German in Zeitschrift für Physik. IX, p. 1, 1922. Together with two other lectures, delivered 

 on previous occasions, In whicli the state of the theory at earlier stages of its development has been ex- 

 posed, the lecture has moreover appeared in German In Sammlung VIeweg (Drei .Aufsätze über Spektren 

 und Atombau) and in English In a volume edited by the Cambridge University Press (Three essays 

 on spectra and atomic constitution). 



Under these circumstances the original plan has been abandoned, and the writer intends in a 

 new series of papers to give a detailed account of the ideas and results exposed in the lecture referred 

 to. On the other hand 1 have been advised on the part of several physicists to bring the treatise com- 

 menced to an end by publishing also the manuscript of the later parts, as far as it was ready for 

 printing at the time when the first part appeared. Following this advice 1 herewitli bring out Part III 

 in the form which it had in the spring of 1918, with no alteration except such changes in the enumer- 

 ation of the formula? and in the references to the previous parts, which were necessitated by the subse- 

 quent extension of the manuscript of Part II before its pulilication in December 1918. 



As will appear from the appendix, added at the end of this paper, several of the problems dis- 

 cussed in it have in the meantime been subject to investigations by various authors. This issue of 

 Part III is therefore not to be considered as a scientific publication in the usual sense, the main In- 

 tention with the publication of the original manuscript being to give the reader of the preceding parts 

 an insight Into some characteristic applications whicli the writer had in mind when exposing the general 

 considerations In Part 1, and therewith to bring the treatise to a natural conclusion. At the same time, 

 however, the appendix referred to will give the reader a brief survey of the development of the theory 

 since the redaction of the manuscript of this treatise. 



D. K. D. Vidensli. SelsU. Skr., niilunidensk og malhem. Afd., 8. Kække. IV. 1 14 



