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atomic weight 48.1 TITANIUM [symbol T...

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Originally appearing in Volume V26, Page 1018 of the 1911 Encyclopedia Britannica.
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atomic See also:

weight 48.1 See also:TITANIUM [See also:symbol Ti (0 = 16)]  , a metallic chemical See also:element . Its See also:discovery as an element was due to See also:William Gregor in 1789 who found in the See also:mineral See also:ilmenite or menachinite a new See also:earth, which was regarded as the See also:oxide of a new See also:metal, menachin . Independently of him See also:Klaproth in 1793 discovered a new metal in See also:rutile, and called it See also:titanium; he subsequently found that it was identical with Gregor's element . Klaproth, however, was unable to prepare the pure oxide, which was first accomplished in 1821 by See also:Rose . The See also:isolation of the pure metal is of much later date . Titanium, although See also:pretty widely diffused throughout the mineral See also:kingdom, is not found in abundance . The commonest titanium mineral is rutile or titanium dioxide, TiO2; See also:anatase and See also:brookite are crystalline allotropes . Titanium is most frequently found associated with See also:iron; ilmenite (Ger . Titan-eisen) is FeTiO3, perofskite (Ca,Fe)TiO3, and the metal occurs in most magnetic iron ores . The titanates are well marked in the mineral See also:king-dom . Ilmenite is isomorphous with geikielite, MgTiO3, and pyrophanite, MnTiO3; many of the " rare minerals "—aeschynite, euxenite, polycrase, &c.—contain titanates (and also niobates) . Silicates also occur; See also:sphene or titanite, CaTiSiO5, is the commonest; keilhauite is rarer .

The isolation of metallic titanium is very difficult since it readily combines with See also:

nitrogen (thus resembling See also:boron and See also:magnesium) and See also:carbon . In 1822 See also:Wollaston examined a specimen of those beautiful See also:copper-like crystals which are occasionally met with in iron-See also:furnace slags, and declared them to be metallic titanium . This view had currency until 1849, when See also:Wohler showed that the crystals are a See also:compound, Ti(CN)2.3Ti3N2, of a See also:cyanide and a nitride of the metal . An impure titanium was made by Wohler and Sainte-Claire Deville in 1857 by See also:heating to redness fluotitanate of See also:potassium (see below) in the vapour of See also:sodium in an See also:atmosphere of dry See also:hydrogen, and extracting the alkaline fluoride formed by See also:water . The metal thus produced formed a dark See also:brown amorphous See also:powder resembling iron as obtained by the reduction of its oxide in hydrogen . In 1887 Nilson and Petersson (Zeit. phys . Chem . 1, p . 25) obtained a purer product by heating the chloride with sodium in a See also:steel See also:cylinder; it then formed yellow scales with a bluish See also:surface See also:colour . H . See also:Moissan (See also:Comet. rend., 1895, 120, p . 290) obtained a still purer metal by igniting the oxide with carbon in the electric furnace .

The product has a brilliant See also:

white fracture, a specific gravity of 4.87, very friable, but harder than See also:quartz or steel . Moissan (ibid., 1906, 142, p . 673) has distilled this metal in a very intense electric furnace . When heated in See also:air it See also:burns brilliantly with the formation of the oxide . It combines directly with the See also:halogens, and dissolves in See also:cold dilute sulphuric See also:acid, in hot strong hydrochloric acid and in aqua regia, but less readily in nitric acid . Its most curious See also:property is the readiness with which it unites with nitrogen . Several nitrides have been de-scribed . Ti3N4 is a copper-coloured powder obtained by heating the ammonio-chloride TiC13.4NH3 in See also:ammonia . TiN2 is a dark See also:blue powder obtained when the oxide is ignited in an atmosphere of ammonia; while See also:TiN is obtained as a See also:bronze yellow See also:mass as hard as the See also:diamond by heating the oxide ih an atmosphere of nitrogen in the electric furnace . In its chemical relations, titanium is generally tetravalent, and occurs in the same sub-See also:group of the periodic See also:classification as See also:zirconium, See also:cerium and See also:thorium . It forms several oxides, TiO2, Ti203 and TiO3 being the best known; others (some of doubtful existence) have been described from See also:time to time . Titanium iioxide, TiO2, occurs in nature as the three distinct mineral See also:species rutile, brookite and anatase .

Phoenix-squares

Rutile assumes tetragonal forms isomorphous with cassiterite, SnO2 (and also See also:

zircon, ZrSiO4) ; anatase is also tetragonal, and brookite or thorhombic . Rutile is the most See also:stable and anatase the least, a See also:character reflected in the decrease in See also:density from rutile (4.2) and brookite (4.0) to anatase (3.9) . The minerals are generally found together—a feature rarely met with in the See also:case of polymorphs . They have been obtained artificially by Hautefeuille by the interaction of titanium fluoride and See also:steam . At a red See also:heat rutile is produced, at the boiling point of See also:zinc brookite, and of See also:cadmium anatase . It is apparent that these minerals all result in nature from pneumatolytic See also:action . Amorphous titanium oxide may be obtained in a pure See also:form by fusing the mineral, very finely powdered, with six times its See also:weight of potassium bisulphate in a See also:platinum crucible, then extracting the melt with cold water and boiling the filtered See also:solution for a See also:long time . Titanic oxide separates out as a white See also:hydrate, which, however, is generally contaminated with ferric hydrate and often with tin oxide . A better method is Wohler's, in which the finely powdered mineral is fused with twice its weight of potassium carbonate in a platinum crucible, the melt powdered and treated in a platinum See also:basin with aqueous hydrofluoric acid . The alkaline titanate first produced is converted into crystalline fluotitanate, K2TiF6, which is with difficulty soluble and is extracted with hot water and filtered off . The filtrate, which may be collected in See also:glass vessels if an excess of hydrofluoric acid has been avoided, deposits the greater See also:part of the See also:salt on cooling . The crystals are collected, washed, pressed and recrystallized, whereby the impurities are easily removed .

The pure salt is dissolved in hot water and decomposed with ammonia to produce a slightly ammoniacal hydrated oxide; this, when ignited in platinum, leaves pure TiO2 in the form of brownish lumps, the specific gravity of which varies from 3:9 to 4.25, according to the temperature at which it was kept in igniting . The more intense the heat the denser the product . The oxide is fusible only in the oxy-hydrogen See also:

flame . It is insoluble in all acids, except in hot concentrated sulphuric, when finely powdered . If the sulphuric acid solution be evaporated to dryness the See also:residue, after cooling, dissolves in cold water . The solution, if boiled, deposits its titanic oxide as a hydrate called See also:meta-titanic acid, TiO(OH)2, because it differs in its properties from orthotitanic acid, Ti(OH)4, obtained by decomposing a solution of the chloride in cold water with alkalis . The ortho-See also:body dissolves in cold dilute acids; the meta-body does not . If titanic oxide be fused with excess of alkaline carbonate a titanate, R2TiO3, is formed . This salt is decomposed by -water with the formation of a solution of See also:alkali See also:free of titanium, and a residue of an acid titanate, which is insoluble in water but soluble in cold aqueous mineral acids . The titanates are very similar to the silicates in their tendency to assume complex forms, e.g. the potassium salts are K2TiO2.4H2O, K2Ti3Oi.3H2O and K2Ti6O13•2H2O . Titanium monoxide, TiO, is obtained as See also:black prismatic crystals by heating the dioxide in the electric furnace, or with magnesium powder . Titanium sesquioxide, Ti2O3, is formed by heating the dioxide in hydrogen .

A hydrated form is prepared when a solution of titanic acid in hydrochloric acid is digested with copper, or when the trichloride is precipitated with alkalis . Titanium trioxide, TiOa, is obtained as a yellow precipitate by dropping the chloride into See also:

alcohol, adding hydrogen peroxide, and finally ammonium carbonate or potash . When shaken with potash and air it undergoes autoxidation, hydrogen peroxide being formed first, which converts the trioxide into the dioxide and possibly pertitanic acid; this acid may contain sexavalent titanium (see W . Manchot and See also:Richter, Ber., 1906, 39, pp . 320, 488, and also See also:Faber, Abst . Journ . Chem .

End of Article: atomic weight 48.1 TITANIUM [symbol Ti (0 = 16)]
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