SIR WILLIAM CROOKES ON SCANDIUM. 35 



operation was repeated on the residue several times. Ultimately the most soluble 

 and the least soluble earths were separated and their spectra photographed. 

 The most soluble earth was nearly all scandia, with a little yttria, and traces of 

 ytterbia, titania, and lime. The least soluble contained more yttria than scandia, but 

 not mucli of either. By a repetition of this process it would not be difficult to effect 

 a good separation of scandia and yttria ; I think the fused nitrate process is simpler 

 and quicker. 



When crude scandium oxalate is boiled in a solution of ammonium oxalate a partial 

 separation of the earths is effected, but it is less complete than when ammonium 

 carbonate is used as a solvent. This is a very good method for separating scandia 

 from zirconia, as hardly a trace of the zirconia is to be seen in the portion insoluble in 

 hot ammonium oxalate. 



According to NILSON (' Comptes Rendus,' vol. xci., p. 121), the precipitated oxalate 

 is slightly soluble in weak acids, and even in water. I have verified this observation ; 

 care must be taken not to over-wash the oxalate, or loss will ensue, and the filtrates 

 should be kept and worked again for scandium. 



The precipitated oxalate, dried in the air, contains 5 molecules of water. 



Analysis. 



(1) 22'445 grs., ignited at a yellow heat, left G'988 grs. of scandia. 



(2) 21 '873 grs. ignited left G'806 grs. of scandia. 



Theory. Experiment. 



7l)~ (2). 



ScA . . . 136-20 30-79 :JM3 3fl2 



3C 8 (>, . -]. : j OG . 08 09-21 G8-87 <!8'88 



5 H 2 O 



442-28 100-00 lOO'OO lOO'OO 



When the 5-hydrated oxalate is allowed to dry at the ordinary temperature over 

 sulphuric acid, it loses 2 molecules of water and becomes a 3 -hydrate 



Analysis. 

 7-G39 grs. left on ignition at a yellow heat 2'529 grs. of scandia. 



