The precipitate is filtered off,
washed with hot water, dried, ignited, and weighed as zirconia, ZrO_{2}.
This is a white powder, which is insoluble in acids; even in
hydrofluoric acid it is only slightly attacked.
CERIUM.
Cerium occurs as silicate (together with the oxides of lanthanum,
didymium, iron and calcium) in the mineral cerite, which is its chief
source. It also occurs as phosphate in monazite, and as fluoride in
fluocerite. The oxalate is used in medicine. Cerium forms two classes of
salts corresponding to the oxides, cerous oxide (Ce_{2}O_{3}) and ceric
oxide (CeO_{2}). Compounds of cerium with volatile acids yield dioxide
on ignition; and this, on solution in hydrochloric acid, yields cerous
chloride and chlorine.
In the ordinary course cerium is thrown down along with alumina and the
other earths by ammonia. It is separated by dissolving the hydrates in
hydrochloric acid, and oxidizing with chlorine water. On treating with
oxalic acid, cerium, lanthanum, and didymium are precipitated as
oxalates, which on ignition are converted into oxides. These are soluble
in acids. Their solution in hydrochloric acid is nearly neutralised;
acetate of soda is then added, and an excess of sodium hypochlorite. On
boiling, the cerium is precipitated as dioxide, which is filtered off,
ignited, and weighed.
Pages:
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593