The oxychloride, bromides, and other compounds were subsequently discovered; here we need only notice Moissan's preparation of the trifluoride and Thorpe's discovery of the pentafluoride, a compound of especial note, for it volatilizes unchanged, giving a vapour of normal density and so demonstrating the stability of a pentavalent phosphorus compound (the pentachloride and pentabromide dissociate into a molecule of the halogen element and phosphorus trichoride).
When ignited in a current of hydrogen it yields tiianium trifluoride, TiF 3, as a violet powder.
Bismuth trifluoride, BiF3, a white powder, bismuth tribromide, BiBr 3, golden yellow crystals, bismuth iodide, Bi13, greyish-black crystals, are also known.
Antimony trifluoride, SbF 3, is obtained by dissolving the trioxide in aqueous hydrofluoric acid or by distilling antimony with mercuric fluoride.
Halogen Compounds.-Phosphorus trifluoride, PF 3, discovered by Davy, may be obtained mixed with the pentafluoride; by direct combination of its elements; from the tribromide and arsenic trifluoride (Maclvor); from the tribromide and zinc fluoride, and from dried copper phosphide and lead fluoride (H.