[270] Chem. News, 1898, 77, 161; ibid. 1901, 83, 197.
[271] See Meyer and Koss, Ber. 1902, 35, 3740; and Marc, ibid. 2370.
[272] Loc. cit.
[273] Compt. rend. 1912, 154, 510.
The chloride, NdCl₃,6H₂O, is obtained by crystallisation from aqueous solutions; it is also precipitated by addition of water to an alcoholic solution. It forms large deliquescent rose-coloured crystals; 100 parts of water at 13° dissolve 246·2 parts of the salt, the saturated solution having the density 1·741; at 100°, 511·6 parts are dissolved. The solution resembles those of the other chlorides of the group in that it readily dissolves the rare earth oxalates. When heated in a current of hydrogen chloride of 130°, the hexahydrate yields a monohydrate, NdCl₃,H₂O; at 160° the anhydrous chloride is obtained as a very deliquescent rose-coloured powder, which melts at a red heat to a clear red liquid. The anhydrous chloride forms an additive compound NdCl₃,12NH₃, when exposed to the action of ammonia at low temperatures;[274] by gradually heating this, a large number of other additive compounds are formed, containing smaller quantities of ammonia.
[274] Matignon and Trannoy, Compt. rend. 1906, 142, 1042.
The anhydrous iodide, NdI₃, has been obtained[275] by passing hydrogen iodide over the heated anhydrous chloride, and also by heating the carbide in iodine vapour. It fuses to a black liquid, which at a higher temperature suddenly becomes transparent.
[275] Matignon, ibid. 1905, 140, 1637.
The bromate, Nd(BrO₃)₃,9H₂O, which is exactly similar to the analogous compound of praseodymium, forms rose-coloured hexagonal prisms, melting at 66·7°.
The sulphate, Nd₂(SO₄)₃,8H₂O, is isomorphous with the corresponding salt of praseodymium, but is considerably less soluble. Only the one hydrate is known.