The anhydrous _chlorides_ may be obtained by the application of any of the ordinary methods, _e.g._ by heating the oxides with carbon in a stream of chlorine, by heating the carbides in the same gas, by heating the sulphides or hydrated chlorides in hydrogen chloride, or by evaporating the solutions of the hydrated salts to dryness in presence of ammonium chloride, and then igniting till the latter has all been removed. As obtained by any of these methods, they are fusible at a red heat, but only slightly volatile; they are easily soluble in water or alcohol, with disengagement of heat. They are insoluble in most organic solvents, but dissolve to some extent in some bases; the chlorides of the yttrium elements, for example, are readily soluble in pyridine. With such solvents, the chlorides form compounds which may be considered as derived from the hydrated forms, by replacement of the so-called water of crystallisation by the organic base. Conductivity measurements show that the salts are not perceptibly hydrolysed in moderately dilute aqueous solutions, though the values for the equivalent conductivities vary somewhat with the variations in the electropositive character of the elements. In the following table, the equivalent conductivities of the chlorides in solutions of dilution 32 and 1024 at 25°C. are given. It will be seen that the value (λ₁₀₂₄ - λ₃₂) ÷ 10 is in all cases (except for the highly hydrolysed scandium salt) very close to 3, an experimental proof of the trivalent nature of the elements. The values for the chlorides of iron, aluminium and chromium are included; it will be seen that these elements are considerably less positive than the rare earth metals (with the exception, of course, of scandium). Salt λ₃₂ λ₁₀₂₄ λ₁₀₂₄ - λ₃₂ LaCl₃ 105·8 131·5 25·7 CeCl₃ 107·8 135·2 27·6 PrCl₃ 105·5 135·9 30·4 NdCl₃ 103·8 134·3 30·5 YtCl₃ 98·8 123·4 24·6 YbCl₃ 107·4 140·4 33·0 ScCl₃ 116·9 257·9 141·0 AlCl₃ 99·9 138·0 38·1 CrCl₃ 98·4 152·6 54·2 FeCl₃ 117·2 200·7 83·5 From aqueous solutions the chlorides crystallise with six molecules of water, except praseodymium chloride, which has seven. The hydrated salts, when heated to 120° in the air, form insoluble oxychlorides of the general formula ROCl. The chlorides do not show a great tendency to form double salts with other metallic chlorides; on the other hand, they readily form complex compounds with the chlorides of the less electropositive metals, e.g. tin, bismuth, gold, and platinum. Subchlorides of samarium and europium have recently been obtained; in these compounds, for the first time, rare earth metals have been shown to be capable of functioning as divalent elements.