1887.] On Radiant Matter Spectroscojiy. Hi) 



to the electric discharge in vacuo, and have noted the results. As 

 the superficial phosphorescence apart from the composition of the 

 emitted light has formed the subject of several recent papers by my 

 friend M. Lecoq de Boisbaudran, before the Academie des Sciences, 

 it may be useful if I place on record some of the more striking 

 facts which have thus come under my notice. The bodies are 

 arranged alphabetically, and, unless otherwise explained, were tested 

 in the radiant matter tube in the form of ignited sulphates. 



Alumina, in any of the forms which give the crimson line (\6942 

 — 6937) has a very persistent residual glow. In the phosphoroscope 

 rubies shine with great brilliancy. This phosphorescence of alumina 

 has recently been the subject of a paper read before the Royal 

 Society.* 



Antimony oxide with 95 per cent, of lime (in the form of ignited 

 sulphate). White phosphorescence, the spectrum showing a broad 

 space in the yellow, cutting the red and orange off. In the phos- 

 phoroscopes the residual glow is very strong, and of a greenish colour. 

 The spectrum of the residual light shows that the red and orange 

 are entirely obliterated, leaving the green and blue very luminous. 

 Antimony oxide with 99 per cent, of lime gives a pale yellowish phos- 

 phorescence, which on heating turns red. In other respects it is like 

 the 5 per cent, mixture. 



Arsenious acid with 99 per cent, of lime gives a greenish-white 

 phosphorescence like pure calcium sulphate. 



Barium 5 per cent., calcium 95 per cent. — The sulphates phos- 

 phoresce green, with specks of. yellow and violet. The spectrum is 

 continuous, with slight concentration in the red, great concentration 

 in the green, and in the orange a broad black band hazy at the 

 edges. 



Bismuth 15 per cent., calcium 85 per cent., phosphoresces of a bright 

 reddish-orange. The spectrum shows a tolerably sharp and broad 

 dark band in the red and orange, and a strong concentration of light 

 in the green and blue ; the spectrum being continuous and divided 

 into two parts by a black band in the yellow, as in the case of the 

 antimony- calcium spectrum. In the phosphoroscope the red and 

 orange disappear and the green and blue remain. Bismuth 7 per 

 cent., calcium 93 per cent. — The action is similar to the 15 per cent, 

 mixture, except the colour of the phosphorescence, which is whiter. 

 In the phosphoroscope the red and orange below the dark band is cut 

 off. With 2 per cent, of bismuth the same phenomena occur. With 

 0'5 bismuth the phosphorescence is greenish-blue and the spectrum 

 is continuous, with strong concentrations in the orange and green. 

 The phosphoroscope cuts off the red and orange. 



* ' Roy. Soc. Proc.,' vol. 42, 1887, p. 25. 



