( 100 ) 



doublet along the lines of force. On the negative the component at 

 the red side of the spectrum was darker, independently of a commu- 

 tation of the current. Of course the difference of intensity is depen- 

 dant upon the time of exposition. Upon some of the negatives the 

 difference was for a special line perhaps 50 or 100 percent. 



However it was plain enough, that the outer components of the 

 triplets and also the two components of the doublets were, in the 

 case of the strong iron lines, of equal intensity. Now in the case 

 of feebler lines, let L be one of them, perturbations will be possible 

 due to the overlapping of one of the components of a „normal" 

 triplet or doublet and a feeble line, say but slightly affected by 

 magnetism. The latter line can 1" be present near L in the same 

 spectrum; or 2^* belong to a spectrum of another order as the line 

 -L ; or 3" by the very presence of the field a special line may become 

 relatively to other lines more intense or a new line may be ori- 

 ginated. By taking negatives with different fields it will of course 

 be possible to evade difficulties from these three causes, at any rate, 

 if the supposed line is thin. We can however by taking also negatives 

 in absence of the field exclude 1, and by taking negatives in spectra 

 of different order or by cutting off any interfering spectrum in using 

 absorbents 2. Having done this, it appeared that also case 3 some- 

 times occurs; the intensity of the iron lines relatively to the air 

 lines varies considerably and the mutual intensity of the iron Hues 

 appreciably. New lines appear, at least lines absent on negatives 

 taken with the field off, became distinctly visible, while yet the 

 intensity of the field was insufficient to resolve the lines in 

 triplets etc. 



The last mentioned perturbation is of course most treacherous. 

 Using however fields of varying intensities, I could avoid perturbation 

 3. Excluding however 1, 2, 3, only triplets, doublets etc. remained, 

 which, I think, can only be called quite symmetrical. Hence till now 

 there is no evidence for a directing influence of the magnetic field 

 on the orbits of the light-ions. ^) 



') cf. Preston, Phil. Mag. Vol. 45, p. 333. 1898. 



(August 9th 1898). 



