THE PREPARATION OF CERTAIN FERRIOXALATES. 263 



The PREPARATION of CERTAIN FERRIOXALATES. 

 By G. J. Burrows and E. E. Turner. 



[Read before the Royal Society of N. S. Wales, December 7, 1921.'] 



Salts of ferrioxalic acid have generally been prepared by 

 dissolving ferric hydroxide in the required acid oxalate. 

 Whereas the alkali salts are extremely soluble in water, 

 the barium salt is only sparingly so, and this fact suggested 

 a rapid method of obtaining these salts in a pure state, 

 starting from either ferric sulphate or ferric alum. With 

 ferric sulphate as the starting point, barium ferrioxalate 

 is readily obtained by heating in aqueous solution, the 

 calculated quantities of ferric sulphate barium hydroxide, 

 and oxalic acid, and extracting the barium ferrioxalate 

 witli boiling water. The salt obtained in this way crystal- 

 lised in slender pale green needles, and on analysis gave 

 the following results: — 



Found : Ba 32*5, Fe 9*02, 2 4 41*7 per cent. 

 Ba 3 [Ere(0. 2 4 )3] 2 12H 2 requires: Ba 324, Fe 8*84, 2 4 

 41'7 per cent. 



Hydrates of this compound containing seven, twenty- 

 one, and twenty-two molecules of water have been pre- 

 viously described by various authors. 



The barium salt was also obtained in a similar manner 

 from ferric ammonium sulphate. In this case, in addition 

 to the normal barium salt, a barium ammonium ferrioxalate 

 was also obtained by the spontaneous evaporation of the 

 filtrate from the barium salt. In solubility it is inter- 

 mediate between the barium and ammonium salts, and 

 crystallises in bright green prisms which gave the follow- 

 ing results on analysis: — 



