226 Dr. P. Zeeman on the Influence of Magnetism 



8. Finally, it should be carefully noted that the essence of 

 the whole matter lies in the fact that when the specified con- 

 ditions hold, the given determinant is transformable into an 

 axi-symmetric determinant in which x is involved in the same 

 way as before. 



Mowbray Hall, Capetown, S.A., 

 November 30, 1896. 



XXXII. On the Influence of Magnetism on the Nature of the 

 Light emitted by a Substance. By Dr. P. Zeeman*. 



1. OlEVERAL years ago. in the course of my measurements 

 k3 concerning the Kerr phenomenon, it occurred to me 

 whether the light of a flame if submitted to the action of mag- 

 netism would perhaps undergo any change. The train of 

 reasoning by which I attempted to illustrate to myself the 

 possibility of this is of minor importance at present!, at any 

 rate I was induced thereby to try the experiment. With an 

 extemporized apparatus the spectrum of a flame, coloured 

 with sodinm, placed between the poles of a Ruhmkorff elec- 

 tromagnet, was looked at. The result was negative. Probably 

 I should not have tried this experiment again so soon had not 

 my attention been drawn some two years ago to the following 

 quotation from Maxwell's sketch of Faraday's life. Here 

 (Maxwell, ' Collected Works,' ii. p. 790) we read :— " Before 

 we describe this result we may mention that in 18()2 he made 

 the relation between magnetism and light the subject of his 

 very last experimental work. He endeavoured, but in vain, 

 to detect any change in the lines of the spectrum of a flame 

 when the flame was acted on by a powerful magnet/' If a 

 Faraday £ thought of the possibility of the above-mentioned 

 relation, perhaps it might be yet worth while to try the experi- 

 ment again with the excellent auxiliaries of spectroscopy of 

 the present time, as 1 am not aware that it has been done by 

 others§. I will take the liberty of stating briefly to the 

 readers of the Philosophical Magazine the results I have 

 obtained up till now. 



2. The electromagnet used was one made by Ruhmkorff 

 and of medium size. The magnetizing current furnished by 

 accumulators was in most of the cases 27 amperes, and could 



* Communicated by Prof. Oliver Lodge, F,RS., with the remark that 

 he had verified the author's resul ts so far as related to emission spectra 

 and their polarization. 



t Cf. § 15 and § 16. 



% See Appendix for Faraday's own description of the experiment. 



§ See Appendix. 



