28 



SIB WILLIAM CEOOKES ON SCANDIUM. 



Theory. Experiment. 



Sc 2 . 

 3SeO, 



517-8 



17-03 

 82-97 



100-00 



17-18 



82-82 



100-00 



SCANDIUM NITRATE, 



Sc(N0 3 ) 3 ,4H 2 0. 



When hydrated, scandia easily dissolves in dilute nitric acid ; after ignition it 

 dissolves with the aid of heat in moderately strong nitric acid. The salt is very 

 soluble in water and in alcohol, and is extremely deliquescent. The acid solution, 

 over sulphuric acid, dries up to a viscous gummy mass, in which appear groups of 

 stellate crystals. A neutral aqueous solution evaporated on the water-bath, on cooling, 

 deposits colourless prismatic crystals. 



Scandium nitrate decomposes more easily by heat than the nitrate of any other of 

 the rare earths. The crystals deposited from an almost neutral solution get pasty at 

 100, but do not run to liquid. In vacuum at 100 the crystals give off water, and frit 

 together, but do not become liquid. Dried on a water-bath, and heated in a tube 

 immersed in melted paraffin with a thermometer by its side, they show signs of 

 melting at 125. They commence to liquefy at 150, and when stirred with a platinum 

 wire the crystals run together and form an opaque white liquid. 



When scandium nitrate is partly decomposed by heat, and the melted mass extracted 

 with hot water and well boiled, a basic nitrate then deposits, which is difficult to filter 

 owing to its clogging fineness. 



The hydrated nitrate, gradually heated in a silica crucible, fuses and boils, becomes 

 opaque and evolves much water. If the heating is stopped at the proper time, the 

 anhydrous nitrate is left, the whole of the water having been driven off. On 

 continuing the heat nitrous vapours come off and the liquid becomes clear and liquid 

 like w^ater. Increasing the heat turns the liquid brown and drives off more nitrous 

 vapours, ebullition becomes sluggish, the fused mass gets white and opaque, and 

 finally there remains a white residue of scandia. 



For analysis the nitrate was thrice re-crystallised and repeatedly dried between 

 blotting-paper. 



Analysis. 



(1) 11-136 grs., gradually heated to full redness, left 2'537 grs. of scandia, 



= 1'6429 grs. of scandium. 



(2) 25-978 grs. left 5'914 grs. of scandia, = 3'8297 grs. of scandium. 



