42 



SIR WILLIAM CEOOKES ON SCANDIUM. 

 Theory. 



Experiment. 



Sc 



C w 192-000] 



H ]8 15-120 ' 



O 5 80-000 



3H 3 O .... 54-048 j 



44-100 



11-45 



(1). 

 11-42 



}- 341-168 88-55 



385-268 



100-00 



88-58 



100-00 



(8). 



11-44 



88-56 



100-00 



Attempts to estimate the water were unsuccessful, as the phenyl-acetate turned 

 brown and commenced to decompose when heated above 160, at which temperature' 

 the whole of the three molecules of water were not expelled. 



SCANDIUM PYROMELLITATE, 

 C () ?I 3 {CO()Sc(()H) a } 4 2H a O - Sc 4 C 10 H 10 16 ,2H 2 0. 



This salt comes down when ammonium pyromellitate is added to a solution of a 

 soluble scandium salt. Tt is formed also by allowing pyromellitic acid to act on 

 scandium hydroxide with the aid of gentle heat. Scandium pyromellitate is a white 

 amorphous powder, insoluble in water and alcohol, but soluble in dilute acids. 



Of the two molecules of water of hydration one is driven off at 100 and the 

 remaining molecule at 140. The dried salt can be heated to 220 without 



decomposition. 



Analysis. 



(1) 14-304 grs. of scandium pyromellitate dried at 1 40 for some hours lost 0'847 grs. 



of water ; when ignited to full redness, treated with nitric acid, and ignited 

 again, it left 6'515 grs. of scandia, = 4'2190 grs. of scandium. 



(2) 11 "485 grs. of scandium pyromellitate dried at 100 lost 0"350 gr. of water, 



and, when ignited as above, left 5 '170 grs. of scandia, = 3 "3480 grs. of 

 scandium. 



(3) 7"614 grs. of scandium pyromellitate heated to 220 for three hours lost 



0'464 gr. of water, and, when ignited as already described, left 3'501 grs. of 

 scandia, = 2 '2672 grs. of scandium. 



Theory. 



Experiment. 



176-400 

 386-080 



18-016 

 18-016 



598-512 



29-47 

 64-51 



3-0 

 3-C 



100-00 



(1). 



29-50 



64-58 

 5-92 



100-00 



(2). 

 29-15 



64-83 



J 3-05 "I 

 12-97J 



100-00 



(3). 



29-78 



64-13 

 6-09 



100-00 



