on the spark spectra of palladium, rhodium and, ruthenium. 353 



General Results. 



The more important results to which attention may be drawn 

 in the preceding observations of the spectra of palladium, rho- 

 dium and ruthenium are as follows: 



(1) If the lines of each separate metal are compared with 

 one another, it will be noticed that some of them can be grouped 

 together as having the same general appearance of the con- 

 stituents, the same polarisation and essentially identical values 

 of dX/X 2 : and this agreement is well seen amongst the lines 

 which become triplets. Amongst the lines which become doublets, 

 this comparison cannot be so rigid, because, as already stated, 

 there are probably other overlapping constituents. But they may 

 be compared with each other in the same way and also with the 

 stronger constituents of the quadruplets. 



(2) If the lines of the three metals are compared with one 

 another, it will be noticed that there are some which have the 

 same appearance, the same intensity, the same polarisation and 

 the same value of dX/X 2 . The most prominent examples are the 

 quadruplets from palladium 34604 and rhodium 35027, and also 

 the quadruplets from palladium 3258*7 and rhodium 3474*7. 

 Amongst the lines which become triplets and doublets there are 

 some which can be grouped together in a similar way. 



(3) The displacements of the constituents of some of the 

 divided lines are simple multiples of one another. Several 

 instances are noticeable amongst the quadruplets of palladium and 

 rhodium. And in some instances, the value of dX/X 2 for the con- 

 stituents of some lines is a multiple of the value for the constituents 

 of other lines. 



The results of other metals will be published later. 



I have again to thank Professor Liveing for the use of his 

 spectroscope, and Professor Larmor for his interest in the work. 



