[401] Zeitsch. anorg. Chem. 1913, 80, 7; Meyer and Weinheber, Ber. 1913, 46, 2672.
Pure yttria is quite white, and gives rise to colourless salts, which in solution show no absorption spectrum in the visible region. A very large number of yttrium compounds have been prepared, of which sufficiently detailed accounts have been given in the general description of rare earth compounds. For an exhaustive treatment, the reader is referred to Abegg’s ‘Handbuch.’
The metal has probably not been obtained in the pure state; impure yttrium has been obtained by Winkler[402] by the action of magnesium on the oxide, and by Cleve[403] by the action of sodium on a mixture of the chloride with common salt, and by electrolysis of the mixture of fused chlorides. It is described as a greyish metal, resembling iron in appearance; it oxidises in the air and readily decomposes boiling water. The hydroxide is thrown down as a gelatinous precipitate by alkalies; ammonia throws down basic salts, but in presence of hydrogen peroxide an hydrated peroxide is obtained. The oxide absorbs carbon dioxide from the air, and liberates ammonia from ammonium salts.
[402] Ber. 1890, 23, 772.
[403] Bull. Soc. Chim. 1874, [ii.], 21, 344; Cleve and Höglund, ibid. 1873, [ii.], 18, 193; see also Popp, Annalen, 1864, 131, 359.
The anhydrous chloride has been prepared by many authors; it melts at a relatively low temperature, 680°, and is the most easily volatilised of all the rare earth chlorides. After fusion, it forms a mass of brilliant white lamellæ.[404] It is characterised by the ease with which it dissolves in pyridine. From aqueous solution it separates as the hexahydrate, YtCl₃,6H₂O, which melts at 160°. The bromide separates from solution as the enneahydrate, YtBr₃,9H₂O; the bromate[405] also separates with 9 molecules of water of crystallisation.
[404] Compt. rend. 1902, 134, 1308.
[405] James and Langelier, J. Amer. Chem. Soc. 1909, 31, 913.
The nitrate cannot be obtained anhydrous; the normal hydrate, Yt(NO₃)₃,6H₂O, loses 3 molecules of water at 100°, but further heating converts it into basic salts. A basic nitrate, 3Yt₂O₃,4N₂O₅,20H₂O, is described by James and Pratt[406] as stable at ordinary temperatures, and in contact with solutions of the normal nitrate. The sulphate octohydrate is isomorphous with analogous compounds of the rare earth elements, and with the selenate, Yt₂(SeO₄)₃,8H₂O; the latter compound can also form an enneahydrate. The phosphate, YtPO₄, occurs in nature in the mineral xenotime, and has been obtained in the laboratory in the crystalline form; many other phosphates have been prepared. The platinocyanide, Yt₂[Pt(CN)₄]₃,21H₂O, has the characteristic red colour with greenish-blue fluorescence.
[406] J. Amer. Chem. Soc. 1910, 32, 873.