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

BERYLLIUM HYDROXIDE. 221

lengths as ordinates, and connect the separate points by a smooth

curve. One millimeter on the plot may be taken to represent

one scale division, and one-half millimeter on the other axis to

represent one unit of wave length. From this curve the •wave

length may be read that corresponds to each division on the

scale.

If the lithium preparation is pure it shows only the line 671,

and eventually the weaker line at 610, when subjected to the

spectroscopic test. If it still contains calcium a red line appears
at 616, and green bands at about 500. Rubidium is recognized

by red lines at 795 and 780; caesium by the yellowish-red lines

622, 601, 584, and the blue lines 459 and 456.

163. Beryllium Hydroxide from Beryl.
     Beryl is essentially a beryllium aluminum silicate, 3 BeO.Al 2 O 3 .6 SiO 2 ,
     and is most readily decomposed by treatment with acid ammonium fluoride,
     whereby silicon fluoride escapes as a gas, aluminum goes into the difficultly
     soluble aluminum fluoride, and beryllium into the soluble beryllium fluoride.
     The beryllium fluoride is transformed into the sulphate, and the latter is dis-
     solved in water and freed from traces of aluminum by means of concentrated
     ammonium carbonate solution. Beryllium remains in the solution as a double
     compound with ammonium carbonate. The small amount of iron present is
     precipitated by adding ammonium sulphide, and the beryllium is finally
     thrown from the filtrate in the form of hydroxide.

Treat 50 g. of finely powdered beryl in a large platinum dish

with 200 g. of neutral ammonium fluoride and 300 g. of concen-
trated hydrofluoric acid, and heat the mixture under the hood

on a Babo funnel until thick vapors escape freely. Continue

the heating and gradually increase the temperature until the

escape of vapors practically ceases, allow the porous mass to
cool, rub' it to a powder with a platinum spatula or a wooden

stick, and heat again until nothing more is vaporized. Boil the

residue, which amounts to about 37 g., five times with water,

allowing the sediment to settle and decanting the clear liquid

through a plaited filter after each extraction. About 15 g. of

aluminum fluoride remain undissolved after this treatment.

Evaporate the filtrate in a platinum dish, heat the residue with

30 g. of concentrated sulphuric acid until thick fumes of sulphur

trioxide escape, and dissolve the dry sulphate in 100 to 200 c.c. of
water. Stir this solution slowly into a cold solution of 150 g. of