354 SIR WILLIAM CROOKES ON SCANDIUM. 



when heated, slightly soluble in hot water and insoluble in cold water. The air dried 

 salt is anhydrous, and has the composition given above. 



Analysis. 



4'236 gr. of the air-dried salt were dissolved in hydrochloric acid and the solution 

 boiled until sulphurous acid ceased to be driven off. Ammonia in excess was 

 added, and the whole boiled. The scandia was filtered, washed, and ignited. 

 It weighed 17G5 gr. = T1430 gr. of scandium. 



Theory. Experiment. 



2Sc 88-20 26-86 26'98 



3SO 3 240-21 73-14 73'02 



328-41 100-00 100-00 



SCANDIUM BOKATE, 

 ScBO, 



Scandium hydroxide ground with a solution of boric acid undergoes no apparent 

 change. Slight combination takes place on boiling the mixture, but no definite 

 compound is produced. 



Re-crystallised boric acid and scandia were mixed together, the acid being in 

 excess, and the whole heated to bright redness for an hour in a platinum crucible. 

 The mixture fused to a clear liquid, and on cooling the melt was extracted with 

 boiling water, filtered, and washed. The residue on the filter was shaken up with 

 much water, levigated, and poured on to a filter, and thus was separated, until only 

 the larger heavy particles were left behind. The scandium borate thus prepared is 

 in the form of a white powder, having the appearance under the microscope of minute 

 transparent spheres. In transmitted polarised light each spherulite shines like a 

 point of light on the dark field when the analyser is crossed, each point alternately 

 disappearing and reappearing as the stage is rotated. 



The analysis of the borate at first presented difficulties. It dissolves easily in 

 dilute acids, and on adding ammonia a precipitate, chiefly of scandium hydroxide, is 

 formed, but the hydroxide carries down with it variable quantities of borate. The 

 plan finally adopted was to dissolve the borate in dilute hydrochloric acid and 

 precipitate hot with ammonia. The precipitate was filtered, washed, and dried. The 

 precipitated hydroxide was then ignited in a platinum crucible, hydrofluoric acid was 

 poured on, and it was kept at a gentle heat for some hours. Strong sulphuric acid 

 was added, and the mixture was gradually heated till dry. The residual scandia was 

 then ignited strongly and weighed. 



