G. Edgar — Estimation of Iron and Vanadium. 79 



Art. VIII. — The Estimation of Iron and Yanadium in 

 the Presence of One Another • by Graham Edgar. 



[Contributions from the Kent Chemical Laboratory of Yale Univ. — clxxvi.] 



The difficulties in the separation of vanadic acid from iron 

 were early recognized. In 1877 Bettendorf* noted that am- 

 monium hydroxide precipitates from a solution containing these 

 substances a yellow vanadate of iron not entirely decomposed 

 by an excess of the reagent. He therefore added an excess of 

 ammonium phosphate and boiled the solution, whereby the iron 

 was converted into ferric phosphate and precipitated as such 

 on the addition of ammonium hydroxide, while the vanadium 

 remained in solution. Carnotf used repeated precipitation by 

 ammonium hydroxide, ammonium acetate or ammonium sul- 

 phide, this process serving to remove iron but not aluminium 

 or chromium. According to Classen, J vanadic acid may be 

 separated from iron in ores by fusion with sodium carbonate 

 and sodium nitrate, and extraction of the melt with water, 

 the vanadium going into solution as sodium vanadate. Accord- 

 ing to Arnold,§ in the analysis of steel, a fusion with sodium per- 

 oxide and extraction with water serves to obtain the vanadic 

 acid in solution, free from iron. Fritcherle,| in the analysis of 

 carnotite, precipitated iron together with uranium and vana- 

 dium with an excess of sodium carbonate, then added sodium 

 hydroxide and boiled for some time, the vanadic acid alone 

 going into solution. Blum, i[ in separating vanadium from 

 rather large amounts of iron, as in pig iron, states that the 

 separation is only complete when, after precipitation of the 

 iron as hydroxide or basic acetate, the precipitate is redissolved, 

 tartaric acid added and the iron precipitated by means of an 

 excess of ammonium sulphide, the solution being allowed to 

 stand for several hours. Campagne** separates the greater 

 part of the iron in ferrovanadium and vanadium steel by 

 repeated extraction of the hydrochloric acid solution with ether, 

 afterward determining the vanadium by repeated evaporation 

 with concentrated hydrochloric acid, removal of this acid by 

 means of sulphuric acid, and titration with potassium perman- 

 ganate. He states that if it be desired to determine the iron pres- 

 ent, the original solution, without extracting with ether, may 



*PoggendorfE's Ann. der Phy., clx., 126-131. 

 f Chem. News, lvi, 16 

 j; Amer. Chem. Journal, vii, 349-353. 

 £ Electrochemist and Metallurgist, March-April 1902. 

 || Chem. News, lxxxii, 258. 

 •[Zeitschr. Anal. Chem., xxxix, 156-157. 

 **Ber. der Dtsch. Chem. Gesel., xxxvi, 3164. 



