lines of neon, helium and sodium in a magnetic field. 51 



Also, in agreement with Lohmann's observations, and opposed 

 to Baly's, no neon line at 6328"38 was observed on any of the 

 plates; but, as in Lohmann's neon, there was a well marked one 

 at 6835. 



Sodium. When the discharge through the neon was going 

 on, the influence of the magnetic iield was to force it against 

 the side of the glass capillary, so that small particles of the glass 

 were illuminated, and the A and D,^ lines of the sodium in the 

 glass were seen quite clearly. The divided constituents of these 

 two lines were sharp and well defined, and they could be seen more 

 easily than when a sodium flame was placed between the magnet 

 poles. Lohmann used the same method in examining these lines, 

 and the following table contains the results of the values obtained 

 from my measurements compared with his, and also with those of 

 Runge and Paschen, who used a Rowland grating and a field 

 strength of 31,000 units*. 



Z>i. 5896-2 



A. 5890-2 



Lohmann 



X'xH 



X 1013. 



- 5,89 s 

 -2,92p 







+ 2,92p 

 + 5,89 s 



-7,35 s 



- 4,43 s 



- 1,46^ 





 + 1,46^ 

 + 4,43 s 

 + 7,35 s 



Runge & Paschen 

 - /\xlO". 



-6,00 

 -2,97 





 + 3,02 

 + 5,95 



-7,18 

 -4,53 

 -1,48 





 + 1,48 

 + 4,32 

 + 7,39 



Purvis 



X^ X 24,000 



X 1013. 



-6,40 

 -3,16 





 + 3,16 

 + 6,30 



-7,42 

 -4,75 

 -1,44 





 + 1,44 

 + 4,75 

 + 7,42 



The agreement between these numbers is only moderately 

 good. It is difficult to explain the variations, for the ratio of 

 2 : 1 of the constituents of A is fairly well maintained. The 

 values are the close mean of 12 separate measurements on three 

 separate plates ; and no changes in the strength of the field were 

 observed during any of the experiments. 



Helium. One of the neon tubes contained some helium, for 

 the triplet from the line 5875-618 was well marked in the photo- 



* Sitz. der Berl. Akad. 1902, p. 722. 



4—2 



