SIK WILLIAM CEOOKES ON SCANDIUM. 379 



SCANDIUM CITRATE, 



CH 2 COO N 



\ 



+ 6H 2 O = Sc 4 (C 6 H 4 O 7 ) 3 + 6H 2 O. 



Sc I O C COO 3 



CH 2 - 



COCT 



j 



Ammonium citrate is added to a solution of scandium nitrate in such proportion 

 that no further precipitation takes place on adding either solution. The result is a 

 dense white precipitate, soluble in excess of ammonium citrate solution. 



On boiling the filtrate from the scandium citrate a white precipitate comes down, 

 dissolving again when the liquid cools. 



The citrate precipitated in the cold was well washed with hot water, filtered, and 

 dried. 



When the citrate is dried in the air it contains six molecules of water, and has the 

 composition given above. 



When this salt is dried for some days over sulphuric acid it loses two molecules of 

 water and becomes a 4-hydrate salt. 



The 4-hydrate salt, heated in an air-bath for six hours to 100, loses two more 

 molecules of water, and becomes a 2-hydrate. 



Amdyxix. 



(1) 3'541 gr. of scandium citrate, dried in the air, yielded on ignition T140 gr. of 



scandia, = 07382 gr. of scandium. 



(2) 4'670 gr. of scandium citrate, dried over sulphuric acid for four days, yielded on 



ignition 1'579 gr. of scandia, = 1'0225 gr. of scandium. 



(3) 2797 gr. of scandium citrate, dried over sulphuric acid for four days, yielded on 



ignition 0'939 gr. of scandia, = O'GOSl gr. of scandium. 



(4) 3-541 gr. of scandium citrate, heated to 110 for 24 hours, lost 0'311 gr. of 



water. 



(5) 4'467 gr. of scandium citrate, dried at 100, yielded on ignition 1'579 gr. of 



scandia, = T0225 gr. of scandium. 



(6) 3-379 gr. of scandium citrate, dried at 110 for two days, lost 0'149 gr. of 



water. 



Analysis of the 6 -Hydrate Citrate. 



Theory. Experiment. 



4Sc 176-40 2079 20'85 



3(C 6 HA). 564-10 66 ' 47 \7 9 . 2 l 79-15 



1 108-10 1274/ 



848-60 100-00 100-00. 



3 c 2 



