Thornton — Separation of Titanium from Iron. 175 



with boiling water. In the usual manner the precipitate was 

 ignited to titanic oxide and brought to constant weight over 

 the Meker burner. Duplicate determinations gave the follow- 

 ing results : 



m-, • i •. . l Titanic oxide 

 Titanic sulphate soln. k 



(a) 25 cm3 O 37-308 grms. 0-1427 grm. 0-5226$ 



(b) 25 omS O 27-319 grms 0-1428 grm. 0-5227$ 



Since these two values agreed so closely, (b) was arbitrarily 

 taken as correct. The second solution was standardized by 

 taking two weighed portions of 25 cm3 and 24 cm3 respectively and 

 determining the titanium in one (a) by the acetate method given 

 above and in the other (b) by the " cupf erron " method of 

 Bellucci and Grassi* (the exact technique of which will be given 

 presently). Duplicate determinations gave the following 

 results : 



m., • t i , , Titanic oxide 

 Titanic sulphate soln. A 



(a) 25 cm3 =o= 27-814 grms. 0-1066 grm. 0'3832$ 



(b) 2 4 cm3 O 26-667 grms 9-1022 grm. 0-3832$ 



Since these two determinations agreed exactly, the value here 

 obtained was taken as correct. 



A solution of ferric sulphate was prepared by dissolving 

 Baker's analyzed ferric ammonium sulphate in water, adding 

 25cm 3 £ concen trated sulphuric acid per liter to prevent the 

 formation of basic salt, filtering, and making up to definite 

 volume. In one portion (a) of 25 cm3 the iron was determined by 

 titration with potassium permanganate after reduction by zinc 

 — the potassium permanganate having been previously stand- 

 ardized against sodium oxalate.^ In another portion (b) of 

 25 cm3 the iron was determined by precipitation with redis- 

 tilled ammonium hydroxide in a platinum basin and ignition 

 of the precipitate to ferric oxide. Parallel determination gave 

 the following results : 



Ferric sulphate soln. Ferric oxide 



(a) 25 cm3 ._ 02267 grm. 



(b) 25 cm3 0-2269 grm. 



The value obtained in (a) by the volumetric method was arbi- 

 trarily taken as correct. 



* Loc. cit. 



f The sodium oxalate was obtained from the Bureau of Standards, Wash- 

 ington, D. C. 



