Hydrated sulphates of composition CoS04.6H20, CoSO 4.4H 2 O and CoS04 H 2 0 are also, known.
Rend., 1904 seq.) by fractional crystallization of the nickel double nitrates, the ethyl sulphates, and the bismuth double nitrates of the terbium earths.
The metals comprising this group are never found in the uncombined condition, but occur most often in the form of carbonates and sulphates; they form oxides of the type RO, and in the case of calcium, strontium and barium, of the type R02.
As the atomic weight of the element increases, it is found that the solubility of the sulphates in water decreases.
The salts of all the metals of this group usually crystallize well, the chlorides and nitrates dissolve readily in water, whilst the carbonates, phosphates and sulphates are either very sparingly soluble or are insoluble in water.