730 



would be the consequence of electrical resolutions of the spectrum 

 lines. It is easy to understand that the greater the density of an 

 (emitting or absorbing) gas, the more frequently it will occur that 

 the vibrating electron systems are in the neighbourhood of electric- 

 ally chai-ged systems, and will therefore perform their vibrations 

 under the influence of the electric field of these charged systems ; 

 hence the spectrum lines brought about by these vibrations will be 

 the more perceptible by the side of those which arise from systems 

 Avhich do not vibrate in an electi-ical field. In this way we shall be 

 al)le to obrain a great number of lines, which all being superposed, 

 can make the imj)ressioii of a broad baud. It is very well 

 possible that definite groups of these vibrations can be predominant 

 which will give rise to the appearance of maxima of absorption 

 (resp. emission). If we wanted to give further particidars about this, 

 it would be necessary to enter into an examination of the mechanism 

 of the phenomena ^). 



As to the order of magnitude of the above described phenomena, 

 it is indeed interesting to compare it with the order of magnitude 

 of the electrical resolutions as Stark has observed them. Wheu we 

 assume that a vibrating system is placed in an electrical field origi- 

 nating from an electrical elementary charge at such a distance as 

 the mean distance of the atoms in saturate sodium vapour of about 

 280° amounts to, the resolution of the Z)-lines, when taken as an 

 electrical resolution, would at this temperature agree — as far as 

 the order of magnitude is concerned — with the resolutions which 

 Stahk found in this part of the spectrum, always ou the supposition 

 of a linear course of the electrical resolution with the intensity of 

 the field. 



Above 260° the observed resolution increases pretty accurately 

 with the power ^/j of the density, the increase being slower at the 

 lower temperatures ; therefore what was observed just now about 

 the order of magnitude of the resolution at 280° cannot possibly 

 be of general \alidity, as this would require an increase not with 

 the power Vs» ^^^^ with the power Vs of t^^e density. 



I also observed the /)-lines in the solar spectrum, which also 

 exhibited two components each. On the whole the phenomenon was 

 in accordance with what is observed for saturate sodium vapour of 



o 



about 270°. The distance of the components was about 0.15 A.U. ; 



1) Even without thinking of electrical resolution^, I pronounced the opinion 

 already before that the ''own period'" of a vibrating system might vary as 

 it was under the influence of neighbouring systems, and that widenings of spectrum 

 Hues might be the consequence of this. Gf. G. J. Elias, Diss. Utrecht; p. 146etseq. 



