L ART. 15, — M. OGAWA : PEELIMUSTARY 



of tliorianite, viz. thorium, uranium, iron and lead, was boiled 

 with concentrated hydrochloric acid, by which treatment a con- 

 siderable quantity of titanium and antimony passed into solution 

 and was decanted ofi'. The residue was then treated with hydro- 

 fluoric acid in the presence of concentrated sulphuric acid in 

 order to remove the silica and, after ignition and fusion with 

 hydrogen potassium sulphate, the whole mass was dissolved in 

 cold water. 



On boiling the diluted solution, however, a slight turbidity 

 occurred, which was found to be due to the separation of a basic 

 titanium compound. Hydrogen sulphide was then passed through 

 the filtered solution, and some brown precipitate thereby formed 

 was filtered off. To the filtrate, ammonia was added after oxida- 

 tion with nitric acid, and the precipitate formed was dissolved 

 in dilute hydrochloric acid. To this solution, oxalic acid was 

 added, which produced a small quantity of a white precipitate, 

 consisting of the oxalates of thorium, etc., and this was filtered 

 off. Ammonia and ammonium sulj)liide were then added to the 

 filtrate ; the black precipitate thereby formed was dissolved in 

 dilute hydrochloric acid and reprecipitated by ammonium sulphide 

 in the presence of an excess of ammonium carbonate, thus keeping 

 in solution any uranium, which might still be present. The 

 ammonium sulphide precipitate was again dissolved in dilute 

 hydrochloric acid and reprecij)itated by ammonia in the presence 

 of an excess of ammonium chloride. The precipitate, consisting 

 chiefly of the hydroxides of iron, aluminium and zirconium, was 

 dissolved in dilute hydrochloric acid, the solution nearly neutral- 

 ised with sodium carbonate and boiled after the addition of sodium 

 thiosuljDhate. The precipitate now formed was dissolved in hot 

 concentrated hydrochloric acid, the separated sulphur filtered ofl", 



