ELISHA MITCHEIvL SCIENTIFIC SOCIETY. 61 



excess of the precipitant, but zirconium hydroxide was 

 thrown down on boiling. If the boiling- was kept up 

 until no more sulphur dioxide came off, immediately on 

 permitting the liquid to come into contact with the air, 

 a scum of oxide of iron formed. Next, the boiling was 

 not continued so long — the precipitate when burned, 

 however, still contained some iron. Besides the results 

 obtained were low, as may be seen b}' these analyses: — 



Number. Found. Used. 



150 0.0463 0.0535 



152 0.0871 0.1070 



156 0.0453 0.0535 



The hydroxide is, doubtles-, parth^ soluble in an ex- 

 cess of the sulphite, even after boiling. 



V. By Sulphur Dioxide. 



The method of precipitation of zirconium from a 

 chloride solution on addition of sulphurous acid in ex- 

 cess affords an excellent means of separating zirconium 

 from iron. The zirconia precipitated b}^ sulphur diox- 

 ide in larg-e excess and boiled two to three minutes, 

 was, after filtration, washed four or five times with 

 hot water. The further necessar}^ precautions have 

 been given above. The iron was titrated in the filtrate. 



The experiments gave these results. 



