Rare earth, acetates, citrate solution

The required rare earth acetate-citrate solution is prepared from the crude material as described in part A for a pure europium compound. The electrolytic cells may be increased in size to handle any required quantity of solution. Electrolysis is carried out under conditions paralleling those described in part A. 

These difficulties are overcome when solutions of certain rare earth acetates in aqueous potassium citrate are used as electrolytes. Such solutions may be made alkaline without causing precipitation of rare earth hydrous oxide. 

Europium amalgam is very easily prepared by this method. Simultaneously, some potassium amalgam is formed. After the electrolysis, the latter may be removed nearly completely by action of water, which scarcely attacks europium amalgam as long as any potassium amalgam remains. Ytterbium and samarium are the only other rare earth metals that yield amalgams by the electrolysis of their acetate-citrate solutions. The electrical efficiency is high for europium, considerably less for ytterbium, and small for samarium. 

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