PROCEEDINGS 



OF THE 



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The influence of a very strong magnetic field on the spark 

 spectra of palladium, rhodium and ruthenium. By J. E. Purvis, 

 M.A., St John's College, Cambridge. 



The author has previously given an account* of an investiga- 

 tion on the influence of a magnetic field on the spark spectra of 

 vanadium, platinum and iridium. It is there pointed out that 

 there are lines of vanadium which can be grouped together in 

 having the same general appearance of the constituents of the 

 divided lines, and essentially identical values of dX/\ 2 for these 

 constituents ; and also that there are lines of platinum and iridium 

 which can be classified in a similar manner. 



The following account is to describe the results of similar 

 experiments with palladium, rhodium and ruthenium, elements 

 which are usually put in the same group in possessing similar 

 general physical and chemical properties. The same apparatus 

 was used as in the previous experiments. The strength of the 

 magnetic field was 39,980 units ; and only those lines were 

 measured whose constituents left well marked images on the 

 photographic plate in an exposure of 30 minutes. The column 

 X gives the wave length of the undisturbed line ; the distances 

 of the constituents of the divided lines (represented in the 

 column dX in the previous paper) are omitted ; but the values 

 of dX/'X 2 calculated from them are given, a + sign signifying 

 constituents of greater wave length, and a — sign those of 

 shorter wave length. As before, the letter s means that the 

 line vibrates so that its electric-vector is perpendicular to the 

 lines of force, and p that it is parallel thereto. The remark, 

 " the middle constituent removed by calcite " means that the 

 constituents were so close, or so intense, or so diffuse that they 

 could only be seen separated by cutting out those parallel to 

 the lines of force by introducing a calcite prism between the 

 source of light and the quartz lens. 



* Tram. Camb. Phil. Soc. Vol. xx, No. viii, p. 193. 

 VOL, XIII. PT. VI. 22 



