Laboratory Methods of Inorganic Chemistry, 2nd English Ed. 1928

244 COMPOUNDS OF THE RARE ELEMENTS.

Cerous Chloride, CeCl 3.

Anhydrous cerous chloride is readily obtained from the sulphide by ignit-

ing the latter in a stream of hydrogen chloride gas.

First prepare cerium sulphide in the manner just described;
allow the tube to partly cool, and pass through it a stream of
thoroughly dry hydrogen chloride; then heat it again to dull red-
ness. The transformation is complete when the preparation has
become pure white.
Anhydrous cerous chloride forms a crystalline very hygroscopic
mass.
Anhydrous Ceric Sulphate, Ce(<SO 4 ) 2. Prepare ceric oxide by
igniting ceric ammonium nitrate strongly; pulverize the oxide,
and boil it with a large excess of concentrated sulphuric acid,
whereby it is converted into the deep-yellow crystalline sulphate
without being dissolved. Pour off the excess of acid, wash the
residue by decantation with glacial acetic acid, drain it on a
hardened filter paper, and dry it over lime in a vacuum desiccator.
Ceric sulphate dissolves to a considerable extent but never com-

pletely in water; on boiling the dilute solution an insoluble basic

salt is precipitated. This behavior is utilized, as has been shown,

in the separation of cerium from the other rare earths.

(6) Lanthanum Compounds.

Lanthanum Carbonate from the Lanthanum-Didymium Precipi-

tate. Boil up the precipitate of the potassium double sulphates

with five parts of concentrated nitric acid in a porcelain casserole,

and pour the entire mass into fifteen parts of boiling water. To

the clear solution, which is colored violet by neodymium, add
ammonium oxalate, — taking 0.7 to 0.8 g. to each 1.0 g. of the

double salt, — neutralize the solution with ammonia, and after

some time filter off the precipitate. Wash and dry the latter, and

ignite it over a Fletcher burner in a porcelain or clay crucible,
surrounded by a funnel to prevent loss of heat. Dissolve the

brown oxide thus formed by heating on the water bath with as

little concentrated nitric acid as possible, evaporate the solution

to a sirupy consistency, and dissolve the nitrates in 1 liter of

water.