Thornton — Separation of Titanium from Iron. Ill 



material is very brittle and on attempting to fold the paper 

 and introduce it into the crucible particles are likely to fly 

 away and be lost. In experiments (1) and (4) the filtration was 

 carried out on asbestos in the perforated platinum crucible. 

 Due to the above mentioned property, a little titanic oxide was 

 found on the outer surface of the crucible after ignition. This 

 method of filtration was therefore abandoned. Table I con- 

 tains the results of three experiments. 







Table I. 









Ti0 2 



Ti0 2 





Tartaric 



No. 



taken 



found 



Error 



acid 





grin. 



grm. 



grrn. 



grm. 



1. 



0-1428 



0-1426 



— 0-0002 



.-_ 



2. 



0-1428 



0-1429 



+ 0-0001 



0-5 



3. 



0-1066 



0-1063 



— 0-0003 



0-4 



In the second series of experiments actual separation of titan- 

 ium from iron was carried out. To facilitate the reduction of 

 the iron the solution, to which tartaric acid equal to three times 

 the weight of the titanic oxide and ferric oxide present had 

 been added, was neutralized by ammonium hydroxide, 1 to 

 2 cm3 of sulphuric acid (1 : 1) added, and the volume made up to 

 about 100 om \ Hydrogen sulphide was then introduced till the 

 solution appeared colorless. If the iron is not thus reduced 

 before its precipitation, titanium will be thrown down in part 

 also.* The solution was then made ammoniacal and more 

 hydrogen sulphide introduced, until the iron had been com- 

 pletely precipitated as ferrous sulphide — leaving the solution, 

 however, alkaline to test-paper. The ferrous sulphide was 

 filtered off and washed ten times with very dilute colorless 

 ammonium sulphide. The filtrate was acidified with 25 cm3 of 

 sulphuric acid (1 : 1), the hydrogen sulphide boiled out, the acid 

 partially neutralized with ammonium hydroxide so as to leave 

 about 2-5 cm3 of sulphuric acid (1:1) for every 100 om3 of the 

 solution, and the " cupferron " added in the cold. Table II 

 contains the results of four experiments. 



Error 

 grm. 



— 0-0004 

 + 0-0002 

 + 0-0002 



— 0-0002 





Ti0 2 



No. 



taken 





grm. 



4. 



0-1428 



5- 



0-1428 



6. 



0-1066 



7. 



0-1063 





* Cathrein, A. 



Table II. 





Fe 2 3 



Ti0 2 



taken 



found 



grm. 



grm. 



0-2267 



0-1424 



0-2267 



0-1430 



0-2267 



0-1068 



0-2267 



0-1061 



Zeitschr. Kryst., vi, 243, 1882; vii, 250, 1883. 



