The salt separates from solutions containing hydrofluoric acid in large plates, which are greenish yellow in colour.
Ceric fluoride, CeF 4 H 2 O, is obtained when the hydrated dioxide is dissolved in hydrofluoric acid and the solution evaporated on the water bath (B.
The filtrate, which may be collected in glass vessels if an excess of hydrofluoric acid has been avoided, deposits the greater part of the salt on cooling.
Moissan in 1886 by the electrolysis of pure anhydrous hydrofluoric acid containing dissolved potassium fluoride.
The salts of hydrofluoric acid are known as fluorides and are easily obtained by the action of the acid on metals or their oxides, hydroxides or carbonates.
Hydrobromic and hydriodic acids were investigated by Gay Lussac and Balard, while hydrofluoric acid received considerable attention at the hands of Gay Lussac, Thenard and Berzelius.
Thorium fluoride, ThF 4, is obtained as a heavy white insoluble powder by dissolving the hydrate in hydrofluoric acid and evaporating.
It is then dissolved in hydrofluoric acid and heated in order to expel silicon fluoride; finally the columbium, tantalum and titanium fluorides are separated by the different solubilities of their double fluorides (C. Marignac, Ann.
By dissolving the dioxide in hydrofluoric acid a syrupy solution is obtained which probably contains titanofluoric acid, H 2 TiF 6.
A characteristic property of the alkaline fluorides is their power of combining with a molecule of hydrofluoric acid and with the fluorides of the more electro-negative elements to form double fluorides, a behaviour not shown by other metallic halides.