THE DETECTION AND WIDE DISTRIBUTION OF YTTRIUM. 
901 
were dissolved in sulphuric acid, the solution neutralised as nearly as possible with 
potash, and digested for several days with excess of potassic sulphate. The solution, 
which at first showed the didymium bands, was then found to be free from didymium. 
32. The insoluble double sulphates were filtered and washed with a cold saturated 
solution of potassic sulphate. The precipitate was boiled for some time in ammonia, 
filtered, dissolved in hydrochloric acid, and precipitated with ammonic oxalate. This 
precipitate was ignited and tested in the radiant matter tube. It gave scarcely a 
trace of citron band (23). The earth was further purified by the potash and chlorine 
method, and was found to consist principally of ceric oxide. 
33. The solution filtered from the insoluble potassio-ceric sulphate (31) was boiled 
with ammonia and ammonic sulphide. A small quantity of a wdrite flocculent earth 
came down—too small a quantity to weigh. Tested in a radiant matter tube, it gave 
the citron band better than either of the above precipitates, showing that by this 
treatment the body had been concentrated (25). 
34. It seemed possible that the earth sought for might be present in larger quantity 
in the thorite, but that it had been gradually carried down mechanically or by mass- 
action rather than chemically, by the numerous operations it had undergone before 
getting it to the final stage. Therefore a fresh quantity of thorite was extracted with 
hydrochloric acid. The solution was precipitated with potassic sulphate, taking the 
usual precautions to secure complete precipitation. A bulky precipitate ensued, which 
contained the thorina and cerium earths. These were separated and tested, and 
found to give only a faint citron band. 
35. The solution of earthy sulphates soluble in potassic sulphate was precipitated 
with ammonic oxalate. The precipitate ignited with sulphuric acid, and tested in 
a radiant matter tube, gave the citron spectrum with great brilliancy (25, 33). 
Chemical facts connected with the citron body. 
36. Certain chemical facts concerning the behaviour of the sought-for element 
which came out during the course of the tentative trials already described had 
considerably narrowed the list amongst which it might probably be found. All the 
evidence tended to show that it belongs to the group of earthy metals, consisting of 
aluminium, beryllium, thorium, zirconium, cerium, lanthanum, didymium, and the 
yttrium family, together with titanium, tantalum, and niobium. The sought-for earth 
is insoluble in excess of potash (25); this excludes aluminium and beryllium. It is 
not precipitated by continued boiling with sodic thiosulphate (17, 27); this excludes 
aluminium, thorium, and zirconium. Fused with acid potassic sulphate, the resulting 
compound is readily soluble in cold water; this excludes tantalum and niobium. 
Evaporating to dryness with hydrochloric acid and heating for some time does not 
render the mass insoluble in water (27); this excludes titanium and silicium. It is 
easily soluble in an excess of a saturated solution of potassic sulphate (25, 33, 34) ; 
this excludes thorium, the cerium group, some of the numerous members of the 
MDCCCLXXXIII. 5 Z 
