1887.] 



On Radiant Matter Spectroscopy, 



127 



the phosphoroscope when baryta or strontia is present ; the citron 

 line of GS being entirely suppressed, while the blue line of G« is 

 brought out with enhanced brilliancy. For these reasons I am in- 

 clined to regard Go. as a separate body, although the evidence in 

 favour of this view is not so strong as in the case of some of its other 

 associates. 



G/3. — An earth phosphorescing with green light, and showing in 

 the spectroscope a close pair of greenish-blue lines of a mean wave- 

 length of 545. This earth can be separated by chemical fractionation 

 from the other constituents of yttrium. It concentrates at the most 

 basic end, and is present in the samarium which invariably makes its 

 appearance at this end of the fractionation of yttrium. It is one of 

 the prominent lines in Ya, where also it accompanies some of the 

 samarium lines. G/3, however, is not a constituent of samarium, for 

 it is easy to purify samarium by chemical means so that it does not 

 show a trace of the G/3 green lines, although it is very difficult to get 

 G/3 free from some of the samarium lines. The residual phosphor- 

 escence of G/3 is very considerable, and its green lines show first in 

 the phosphoroscope when only yttrium is present. The addition of 

 lime keeps back the glow of G/3, and brings forward that of Gc. 

 Strontium and barium act on G/3 very differently to lime. A small 

 quantity of strontium brings forward the residual glow of G/3, whilst 

 in large quantities strontium keeps the phosphorescence of G/3 back 

 to the last. 



G7. — An earth phosphorescing with a green colour, and showing in 

 the spectroscope a green line having a wave-length of 564. This is 

 one of the least definite of all the supposed new bodies. It appears 

 to be a constituent of samarium, occurring in the fractionation of 

 yttrium among the most basic constituents connecting yttrium and 

 samarium. Its point of maximum intensity is, chemically, very well 

 marked, and is at a different part of the fractionation scheme to those 

 of the other lines of samarium, especially Ge. On dilution with lime 

 the phosphorescent line of G7 vanishes before that of Ge. 



G£. — An earth phosphorescing with a citron-coloured light, and 

 showing in the spectroscope a citron line having a wave-length of 574. 

 GS is one of the least basic of all the bodies associated in yttrium, 

 occurring almost at one extremity of the fractionation. It is not 

 very difficult to separate chemically Ge> from all the other accompany- 

 ing bodies except the one which I have called Ga. (giving the deep 

 blue line). Not only can G£ be obtained free from the other four con- 

 stituents of yttrium, but the body called by M. de Marignac Ya. is a 

 proof that the other four components of yttrium can be obtained quite 

 free from G8. Lime intensifies the phosphorescence of G<5, and 

 deadens that of G/3, while strontium has the opposite action. The 

 behaviour of G<5 in the phosphoroscope, when mixed with lime, 



VOL. xlii. K 



