SIR WILLIAM CROOKES ON SCANDIUM. 23 



SCANDIUM BROMATE. 



Bromic acid readily dissolves scandium hydroxide, but on evaporating the solution 

 it decomposes, leaving an amorphous gummy mass without crystalline appearance. 



SCANDIUM SULPHATE, 



Sc 2 (SO 4 ) 3 ,GH 2 O. 



Scandium hydroxide easily dissolves in dilute sulphuric acid ; after ignition the 

 oxide dissolves with difficulty in dilute, but readily in strong acid, with evolution of 

 heat. The excess of sulphuric acid must he driven off carefully, when the anhydrous 

 sulphate is left behind in the form of a fine white powder. 



NlLSON gives the formula of the anhydrous salt, Sc 2 O tf ,3S() a . He says : " It loses 

 acid at a high temperature, and leaves pure scandia. The salt treated with water 

 only gives at first a milky liquid, the anhydrous salt combines very slowly with water, 

 and then re-dissolves. On heating, a clear solution is immediately obtained." 

 According to CLEVE, " Sulphuric acid gives with scandia a white and bulky mass of 

 sulphate, resembling thorium sulphate when it separates by heat. The sulphate does 

 not form distinct crystals." It is very soluble in water, and a strong solution when 

 heated does not deposit crystals, in that respect differing from most of the other rare- 

 earth sulphates. The solution may be evaporated to a super-saturated syrup, which, 

 standing in the cold for some hours, deposits crystals of the G-hydrate. TOO parts of 

 the saturated solution at 12 were found to contain 44 '5 parts of anhydrous scandium 

 sulphate. Scandium sulphate is not deliquescent in the ordinary air of a room even 

 in damp weather, and is insoluble in alcohol. On mixing 100 grs. of anhydrous 

 scandium sulphate with the same quantity of water, the temperature rose in a few 

 minutes from 14 to 21. 



On adding absolute alcohol to a strong solution of scandium sulphate the solution 

 becomes milky, and a heavy oily-looking liquid sinks to the bottom. This may be 

 separated by filtration through paper moistened with alcohol, when the residue is left 

 as a viscous liquid which on exposure to the air becomes thicker. This oily-looking 

 liquid has the composition of the 6-hydrate sulphate. 



When strongly heated, the sulphate decomposes, leaving pure scandia. It is, how- 

 ever, difficult to drive off all the sulphuric acid from the sulphate even by heating the 

 crucible containing it before the blowpipe. The best way to decompose scandium 

 sulphate is first to ignite it to the highest temperature of a Bunsen burner, then to 

 moisten with water and add a little ammonium carbonate. Dry and ignite again, and 

 pure scandia is left free from sulphuric acid. 



NILSON says : " This salt separates from a syrupy solution in small globular 

 aggregates. It is inalterable in the air, it loses four molecules of water at 100, 



