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Originally appearing in Volume V26, Page 1018 of the 1911 Encyclopedia Britannica.
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SOC. 1907, ii. 557.) Titanium fluoride, TiF4, is a fuming colourless liquid boiling at 284°, obtained by distilling a mixture of titanium oxide, fluorspar and sulphuric acid; by heating barium titanofluoride, BaTiF5 (Emrich, Monats., 1904, 25, p. 907) ; and by the action of dry hydrofluoric acid on the chloride (Ruff and Plato, Ber., 1904, 37, p. 673). By dissolving the dioxide in hydrofluoric acid a syrupy solution is obtained which probably contains titanofluoric acid, IhTiF6. The salts of this acid are well known; they are isomorphous with the silico-, stanno- and zircono-fluorides. They are obtained by neutralizing the solution of the acid, or by fusing the oxide with potassium carbonate and treating the melt with hydrofluoric acid. Potassium titanofluoride. K2TiFs-H2O, forms white, shining, monoclinic scales. When ignited in a current of hydrogen it yields titanium trifluoride, TiF3, as a violet powder. Titanium chloride, TiC14, is obtained as a colourless fuming liquid of 1.7604 sp. gr. at o° C.. boiling at 116.4° under 753.3 mm. pressure (T. E. Thorpe), by heating to dull redness an intimate dry mixture Of the oxide and ignited lamp-black in dry chlorine. In the method of A. Stabler and H. Wirthwein, the titanium mineral is fused withcarbon in the electric furnace, the carbides treated with chlorine, and the titanium chloride condensed. The distillate is freed from vanadium by digestion with sodium amalgam. Other methods are due to E. Vigouroux and G. Arrivaut (Abst. Journ. Chem. Soc., 1907, ii. 97, 270) and Ellis (ibid., p. 270). By passing chloroform vapour over the heated dioxide the tetra- di- and tri-chlorides are formed, together with the free metal and a gaseous hydride, TiH4 (Renz, Ber., 1906, 39, p. 249). When dropped very cautiously into cold water it dissolves into a clear solution. According to the amount of water used, TiC13OH, TiCl2(OH)2, TiCI(OH)3 or titanic acid is formed. The solution when boiled deposits most of its oxide in the meta-hydrate form. It forms addition compounds similar to those formed by stannic chloride, and combines with ammonia to form TiCI4.8NH3 and TiC14.6NH3, both of which with liquid ammonia give titanamide, Ti(NH2)4. Titanium dichloride, TiCl2, obtained by passing hydrogen over the trichloride at a dull red heat, is a very hygroscopic brown powder which inflames when exposed to air, and energetically decomposes water. Titanium trichloride, TiCla, forms involatile, dark violet scales, and is obtained by passing the vapour of the tetrachloride mixed with hydrogen through a red-hot tube, or by heating the tetrachloride with molecular silver to 200°. It is a powerful reducing agent. Titanium tetrabromide, TiBr4, is an amber-coloured crystalline mass. The tetraiodide, TiI4, is a reddish brown mass having a metallic lustre. The di-iodide, TiI2, is obtained as black lamella by passing the vapour of the tetraiodide over heated mercury in an atmosphere of hydrogen (E. Defacqz and H. Copaux, Compt. rend., 1908, 147, p. 65). Sulphides are known corresponding to the best-known oxides. Titanium sesquisulphate, Ti2(SO4)i.8H2O, obtained by concentrating the violet solution formed when the metal is dissolved in sulphuric acid, is interesting since it forms a caesium alum, CsTi(SO4)2.12H2O. It gives the normal sulphate as a yellow, deliquescent, amorphous mass when treated with nitric acid. Acid solutions of titanates are not precipitated by suiphuretted hydrogen ; but ammonium sulphide acts on them as if it were ammonia, the suiphuretted hydrogen being liberated. Titanium oxide when fused with microcosmic salt in the oxidizing flame yields a bead which is yellowish in the heat but colourless after cooling. In the reducing flame the bead becomes violet, more readily on the addition of tin; in the presence of iron it becomes blood-red. Titanic oxides when fused on charcoal, even with potassium cyanide, yield no metal. Rose determined the atomic weight to be 47.72 (H = i ). A redetermination in 1885 by T. E. Thorpe gave the value 47.7 (see Journ. Chem. Soc., 1885, p. 108).
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