116 



Mr. W. Crookes. 



[Feb. 1% 



in advance of those (Grfi) to which it is antagonistic ; the line of Gcd 

 therefore appears earlier in the phosphoroscope than that of Gj3 r 

 although were calcium not present the line of Gfi would appear first. 



Experiments were now tried with definite mixtures of yttria and 

 lime as ignited sulphates, to see where the special influence of lime 

 on GrS ceased. 



Yttrium. 



Calcium. 





Per cent. 

 97* 



95 



90 

 80 



60 

 50 

 40 

 30 

 10 



5 



1 



Per cent. 



5 



10 

 20 



40 1 

 50 l 

 60 J 

 70 1 



90 y 



95 J 

 99 



Order of appearance in the phosphoroscope. — GfjS, Ga, 

 Gcd, and Grj. The citron line of Gd is only to be 

 seen at a high speed, and is then very faint. 



Order of appearance in the phosphoroscope.- — Ga, G$, 

 and Gd (citron and blue) together, and lastly G// (red) . 

 At a very high speed the green lines of G/8 become 

 far more luminous than any other line. 



Order of appearance. — Go and Ga together, then G£, 

 and lastly Grr]. 



Order of appearance. — GS and Ga simultaneously, then 

 Gfi, and lastly Grj. The residual phosphorescence 

 last for 30 seconds after the current stops. The light 

 of this residual glow is entirely tbat of GS. The line 

 of G/3 comes into view at an interval of 0*0045 

 second. At 0'00175 second the line of Grj is just 

 visible. 



Order of appearance. — Gd and Gra together, then G/3 

 and Grj together. 



Order of appearance. — Gd, Ga, Gfi. 



Order of appearance. — Gd, Ga. The green lines of Gr/3 

 could not be seen in the phosphoroscope ; they would 

 probably be obliterated by the stronger green of the 

 continuous spectrum given by the calcium. 



The action of barium on yttrium was now tried. The following 

 mixtures (as ignited sulphates) were made : — 



Yttrium. 



Barium. 





Per cent. 



95 

 90 

 80 



70 

 60 

 50 

 40 

 30 

 25 



Per cent. 

 5 



10 < 

 20 



30 ° 



40 



50 



60 * 

 70 



75 J 



In the phosphoroscope the Gr/3 fine appears earliest, but 

 the blue Ga line is the next to be seen, whilst the red 

 line of Gr\ is the latest in appearing. As the per- 

 centage of yttrium increases the blue line more and 

 more overtakes the red and increases in brightness. 



Spectrum similar to the above. As the percentage of 

 yttrium increases the spectrum grows brighter. In 

 the phosphoroscope the earliest line to appear is the 

 Gr/3 green, then the Gi) red, and next closely follow- 

 ing it the Gra blue. 



