Barium and strontium have also been produced by electrometallurgical methods, but the processes have only a laboratory interest at present.
Somewhat less volatile than the last-named group are the chlorides (MC1 2) of barium, strontium and calcium.
On the preparation of pure strontium salts, see Adrian and Bougarel, Journ.
When boiled with alkaline carbonates it is converted into strontium carbonate.
Crystals of barytes are orthorhombic and isomorphous with the strontium and lead sulphates (celestite and anglesite); they are usually very perfectly developed and present great variety of form.
The next group may contain the white calcium, barium and strontium carbonates.
Beryllium and magnesium are permanent in dry air; calcium, strontium and barium, however, oxidize rapidly on exposure.
Ammonium carbonate is added to the filtrate; this precipitates calcium, strontium and barium.
The so-called alkaline earth-metals are the elements beryllium, magnesium, calcium, strontium and barium.
Soc. chim., 1902, 27, p. 1141); calcium and strontium similarly form hydrides CaH 2, SrH 2 at a dull red heat (A.