Thornton, Jr. — Separation of Thorium from Iron. 153 



ferron " solution was then added gradually with constant 

 stirring till present in some excess — 15 cm 3 being the volume 

 actually used. The precipitate, after having been thoroughly 

 coagulated by stirring, was thrown onto a paper filter and 

 washed with a 1 per cent solution of ammonium acetate. The 

 moist paper with its contents was then placed in a tared 

 platinum crucible, dried at 100-110° C, and ignited first with 

 the Bunsen burner and then with the blast lamp to constant 

 weight. In this way the results of Table I were obtained, which 

 are within the limit of error for ordinary analytical work. 



Table I. 



The Estimation of Thorium try Means of the "Cupferron" Reagent. 



ThOa ThO., Vol. of 



taken found Error C 2 H 3 2 NH4 Solution 



No. grin. grm. grm. grm. em 3 



1 0-0925 0-0924 —0-0001 15 500 



2 0-0923 0-0917 —0-0006 15 500 



The thorium salt of nitrosophenylhydroxylamine* differs a 

 good deal in properties from the corresponding compound of 

 either titanium or zirconium. In the case of the two last 

 elements a high concentration of free sulphuric acid is con- 

 sistent with total precipitation; while in the case of thorium 

 extremely small concentrations of the same acid exert a marked 

 solvent effect on the precipitate. Although very similar in 

 appearance to the zirconium precipitate, the thorium pre- 

 cipitate is rather different in texture. Whereas the former 

 permits filtration by suction, the latter passes through the 

 paper in small quantities under the influence of very light 

 pressure. This is unfortunate from a manipulative standpoint, 

 since the precipitate cannot be drained at the puinp — neces- 

 sitating the removal of included water by slow drying. 



In the second series of experiments thorium was separated 

 from iron. Known quantities of iron were taken by weighing 

 off portions of pure dry ferrous ammonium sulphate. The 

 solution (about 150 cm 3 ), containing sufficient tartaric acid to 

 hold up the bases in ammoniacal solution, was made slightly 

 alkaline with ammonium hydroxide, and colorless ammonium 

 sulphide was added in moderate excess. After settling, the 

 ferrous sulphide Avas filtered off and washed ten times with 

 water containing a little colorless ammonium sulphide. Five 

 cubic centimeters of sulphuric acid (1 : 1) was then added and 

 the hydrogen sulphide thus liberated was removed by boiling. 

 After cooling to room temperature, 25 grams of ammonium 



*[C 6 H 6 (NO).N.O]jTh, assuming a formula analogous to the one proposed 

 by Bellucci and Grassi for the titanic derivative. 



