Photographic Researches on Phosphorescent Spectra. 237 



" Photographic Kesearches on Phosphorescent Spectra : on Vic- 

 torium, a New Element associated with Yttrium." By Sir 

 William Ceookes, F.RS. Eeceivecl May 2, — Eead May 4, 

 1899. 



[Plate 9.] 



It has long been known that certain substances enclosed in a vacuous 

 glass bulb phosphoresce brightly when submitted to molecular bom- 

 bardment from the negative pole of an induction coil. The ruby, 

 emerald, diamond, alumina, yttria, samaria, and a large class of earthy 

 oxides and sulphides, emit light under these circumstances. Examined 

 in a spectroscope the light from some of these bodies gives an almost 

 continuous spectrum, while that from others, such as alumina, yttria, 

 and samaria, gives spectra of more or less sharp bands and lines. Since 

 1879 I have been working on these phosphorescent spectra, chiefly in 

 connection with the earths of the yttria group, and by chemical frac- 

 tionation I have succeeded in separating from this group bodies whose 

 phosphorescent spectra consist chiefly of single groups of lines, other 

 groups being absent. For the last six years the research has been 

 extended beyond the visible spectrum, and photographs of the ultra- 

 violet portion of the spectra are now being taken with a spectrograph 

 with a complete quartz train. Some of the results of this investigation 

 were exhibited at the soiree of the Koyal Society, on the 3rd of May. 

 A preliminary mention of the discovery of a new element was made in 

 my address to the British Association in September last, when I pro- 

 visionally called it Monium ; but for several reasons I now consider the 

 name Victorium more appropriate. 



The complicated scheme of fractionation carried on for so many years 

 is illustrated in the accompanying diagram (Plate 9). This must be 

 considered only as an indication of the methods employed, and not as 

 an actual representation of every operation through which the material 

 has passed. Crude yttria, from samarskite, gadolinite, cerite, and 

 other similar minerals, is the raw material. The first operation is to 

 free it roughly from earths of the cerium group — an operation effected 

 by taking advantage of the fact that the double sulphates of potassium 

 and the yttrium metals are easily soluble in saturated potassium 

 sulphate solution, while the corresponding double sulphates of the 

 cerium group of metals are difficultly soluble. 



After this preliminary treatment the crude yttria is converted into 

 nitrate, represented by the topmost circle on the diagram. The nitrate 

 is exposed to heat until it fuses to a clear liquid, care being taken to 

 distribute the heat uniformly through the mass. Presently the liquid 

 mass commences to decompose, giving off red vapours. After this has 

 proceeded for a little time the fused mass is carefully poured into 



VOL. LXV. T 



