electro -magnetic fields on the spark spectra of gold, etc. 91 



With regard to the lines divided into triplets, of those which 

 arise from the lines 4524, 3800-3, 30331, 3007-9, 2862-1, 2849'3, 

 2838*9, the two outside components vibrate perpendicular to the 

 lines of force and the inner one parallel thereto. Whilst of the 

 triplets which arise from 3261 '6 and 3174-3, the two outer 

 members vibrate parallel, and the inner one perpendicular, to the 

 lines of force. 



There is a weak line at 3032-2 which appears to belong to 

 arsenic, and it seems to be widened in the magnetic field. 



The general results, therefore, of the effect of very strong 

 electro-magnetic fields on the spark spectra of the above-mentioned 

 elements are : — 



(1) That there is a division of some lines into triplets, the 

 components of which vary in the directions of their vibrations. 



(2)- That other lines are widened, even when they do not 

 seem to be divided. 



(3) That there is an increase in the number of lines which 

 are reversed, if these, or some of them, are not real doublets. 

 It may be mentioned that some of these reversals or doublets 

 seem to be as persistent as those which have been noticed when 

 the reversed line has its origin in the arc. 



With regard to the doublets or reversals, it does not seem 

 easy to distinguish them from each other when they are observed 

 with the magnet broadside on. But there may be a difference 

 in that when a line is really doubled, the two components seem 

 to be much wider apart than is observed usually in reversals ; and 

 they are also sharp, well defined and persistent. However, this is 

 a question which will be investigated later. 



The investigation is still in progress, together with other 

 elements and alloys, and some of the photographs will be pub- 

 lished later. 



Finally, I desire to express my best thanks to Professor Liveing 

 for allowing me the use of his spectroscope ; to Mr G. F. C Searle 

 for measuring the magnet after it was constructed ; and to Mr C. T. 

 Heycock for the gift of the electrodes of pure gold. 



