THE DETECTION AND WIDE DISTRIBUTION OF YTTRIUM. 
907 
sodic thiosulphate. This precipitated the thoria, zirconia, and alumina. In this 
precipitate some of the scandia might also he found, if present in quantity, but as 
scandic thiosulphate is not completely precipitated, and the earth is present only in 
minute traces, not much scandia, it is probable, was thus carried down. 
This thiosulphate precipitate, treated in the usual way with sulphuric acid, gave no 
citron band in the radiant matter tube. 
47. The filtrate from the thiosulphate was precipitated hot with excess of ammonia, 
and the precipitate after washing treated with sulphuric acid, dried, and heated till 
fumes of sulphuric acid disappeared. The sulphate, whitish with a very pale rose 
tmt, was finely ground, and dissolved with frequent agitation in the smallest possible 
quantity of cold water—an operation which required much time. The solution was 
then precipitated with potassic sulphate, taking all necessary precautions to keep the 
liquid well saturated with potassic sulphate. This operation was allowed to go on for 
about ten days, when the precipitated double sulphates were filtered off and slightly 
washed with a saturated solution of potassic sulphate. The precipitate contained 
cerium, lanthanum, didymium, didymium /3, decipium, samarium, scandium, yttrium a, 
yttrium j3, together with any thorium and zirconium which might have escaped the 
thiosulphate treatment. 
48. The filtrate from the double sulphates was precipitated hot with ammonia, which 
brought down the erbia, liolmia, mosandra, terbia, thulia, ytterbia, and yttria. The 
small quantity of manganese in solution was in this operation completely thrown out. 
49. The insoluble double sulphates (45) were dissolved in hydrochloric acid, 
precipitated hot with ammonia, washed till free from potassium salts, re-dissolved, 
precipitated as oxalates, ignited, and set aside for further examination. On testing in 
the radiant matter tube this mixture of oxides was found to be practically free from 
citron band. 
50. The ammonia precipitate from the sulphates soluble in potassic sulphate (46) 
was well washed till free from potassium salts, and dissolved in excess of nitric acid. 
The concentrated solution gave an absorption spectrum showing lines belonging to 
erbium and allied metals. Having already proved that the body I was seeking was 
not one of those metals which gave an absorption spectrum (42, 43), my first object 
was to find some method by which I could roughly separate this mixture of earths 
into two portions, one giving absorption bands, and the other having no action on the 
transmitted spectrum. I found this was possible by taking advantage of the different 
solubility of the oxalates in nitric acid. 
51. The highly acid solution of the nitrates was fractionally precipitated in the 
following manner :—• 
To the boiling liquid a solution of amnionic oxalate was added drop by drop. The 
precipitate at first formed re-dissolved on stirring. The cautious addition of ammonic 
oxalate was repeated until the precipitate refused to dissolve entirely, but left the hot 
liquid somewhat milky. It was then rapidly cooled with constant stirring, which 
