338 Prof. McCoy and Dr. Viol : Chemical Properties and 



following, in absence o£ the latter element, have been 

 studied : — 



(1) Rt is completely precipitated with aluminium hydroxide 

 by ammonia. 



(2) Rt is completely precipitated with ferric hydroxide by 

 ammonia and with basic ferric carbonate by excess of sodium 

 carbonate. 



(3) Rt is partly precipitated w T ith barium sulphate in acid 

 solution ; under favourable conditions 50 per cent, of the Rt 

 may be carried down. 



(4) lit is to a slight extent (about 5 per cent.) precipitated 

 with mercuric sulphide or lead sulphide. 



Tliorium X. — On account of the seeming chemical identity 

 of ThX and Ms x every preparation of ThX from thorium 

 must contain more or less Ms x . However, the proportion of 

 the latter will be quite small if thorium is used which has 

 been freed from this pair of products a few days previously. 

 A better plan is to use Rt as the source of the ThX. A 

 single precipitation of an aluminium chloride solution of Rt 

 by pure ammonia carries down all the Rt, and lea\ es nearly 

 all of the ThX in the solution. From such a solution B and 

 may be removed completely by three or four precipitations 

 in it of mercuric sulphide. 



Thorium X is separated from thorium by the following 

 reactions : — 



(1) When thorium is precipitated from a nitrate solution 

 by ammonia, pyridine, sodium thiosulphate, potassium chro- 

 mate, metanitrobenzoic acid, or hydrogen peroxide, nearly 

 all of the ThX is left in the filtrate. 



(2) Precipitation of thorium by means of oxalic acid gives 

 a partial but not complete separation. In one experiment 

 with 25 g. of thorium nitrate about half of the ThX was left 

 in the filtrate. 



(3) Barium sulphate formed in a thorium solution carries 

 down practically all of the ThX. 



(4) Ferric iron removes all of the ThX from a solution of 

 thorium in an excess of the carbonates of sodium under the 

 -conditions given for the separation of Ms^ 



A solution of ThX free from Th shows the following 

 behaviour : — 



(5) ThX is carried down completely by (a) barium sulphate, 

 from barium chloride and sulphuric acid ; (b) ferric carbonate, 

 from ferric chloride and excess of sodium carbonate ; 

 (c) calcium carbonate, from calcium chloride and ammonium 

 carbonate ; (d) ferric phosphate, from ferric chloride and 

 secondary sodium phosphate. 



