ESTIMATION OF VANADIUM 275 



a ferrous sulfate solution by dissolving 2.183 grams of piano wire 

 in sulfuric acid and making the volume to one liter. Titrate the 

 vanadic mixture with this solution until a drop of the clear liquor, 

 removed and brought in contact with potassium ferricyanid, shows 

 a distinctive blue-green color. 



One cubic centimeter of the ferrous sulfate solution is equiva- 

 lent to 0.002 gram of vanadium, 0.002888 gram of vanadium di- 

 oxid, and 0.003648 gram of vanadium pentoxid. The ferrous 

 sulfate solution may also be made and standardized by any of the 

 approved methods in common use. 



The method described by Blair, designed especially for the es- 

 timation of vanadium in iron and steel, is conducted in the follow- 

 ing manner: 36 Five grams of the drillings are dissolved in 50 

 cubic centimeters of nitric acid of 1.24 specific gravity. The solu- 

 tion is evaporated to dryness in a porcelain dish and heated there- 

 after until the nitrates are nearly decomposed. After cooling, 

 the dried mass is transferred to a mortar and finely ground 

 with 30 grams of dry sodium carbonate and three grams of 

 sodium nitrate. The finely ground materials are placed in a 

 platinum dish and fused for an hour at a high temperature. 

 Spread the fused mass over the sides of the dish while cooling, 

 and afterwards dissolve in hot water, filter, and wash until the 

 volume is a little over half a liter. Add nitric acid to decompose 

 carbonates, but not completely, and boil to get rid of carbon 

 dioxid, being careful to keep the mass always slightly alkaline. 

 Add nitric acid, drop by drop, until slightly in excess, and then 

 sodium carbonate to marked alkalinity, boil, and filter. Add a 

 slight excess of nitric acid to the filtrate, and the development of 

 a yellow color will indicate the presence of vanadic acid. Add 

 to the solution a small quantity of mercurous nitrate and then an 

 excess of mercuric oxid, suspended in water to render the solu- 

 tion neutral and insure the complete precipitation of mercurous 

 vanadate. The mercurous salt also precipitates phosphoric, 

 chromic, tungstic, and molybdic acids which may be present. 

 Boil, filter, and wash the precipitate with hot water, dry, and 

 ignite. Fuse the residue with sodium carbonate and a little 

 nitrate. Dissolve the fused mass, after cooling, in a little water 

 54 The Chemical Analysis of Iron, 6th Edition, 1906 : 203. 



