Chemistry, Inorganic & Organic, with Experiments (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1913 Excerpt: ...of their oxalates, even in acid solution, and by the ease with which their anhydrous sulphates form supersaturated 432 CERIUM solutions at 0, which deposit crystallised hydrates when heated. It is upon the? characteristics that the extraction of the earths from the minerals is mostly based. The powdered mineral is heated carefully with H2S04 so as to obtain a mixture containing the sulphates of the rare earths in an anhydrous state. The mass is quickly powdered and introduced into ice-water, wherein the rare earth sulphates dissolve. The acidified solution is treated with HZS to separate heavy metals, iron is oxidised, and oxalic acid is added to precipitate the rare earth oxalates. If the sulphate solution is strong enough, the two groups may be partially separated by heating it, when the hydratfd sulphates of the cerite earths crystallise. The separation of the rare earths from each other presents a most difficult problem owing to the great chemical similarity between them; there are no group reagents or specific reagents for these earths, such as exist for the oxides of metals of other groups. Cerium alone stands apart in that it forms a peroxide by means of which it can be separated (v.i.). The mixture of the remaining earths must be subjected to some process which takes advantage of the very small differences existing in the basicity of the oxidi.i or in the solubility of their salts. The basicity of the oxides diminishes in the following order: --La, Pr, Nd, Ce"" Yt, Sa, Gd, Tb, Ho, Er, Tm, Yb, So, Ceiv. By adding ammonia or an alkali to a solution of the mixed oxides in HC1 in successive portions in deficiency of the amount required to precipitate the whole of the oxides--in other words, by subjecting the solution to fractional precipitation...