366 Browning and Goodman — Estimation of Yanadium. 





VsOs taken. 



Y2O5 found 





grm. 



grm. 



(') 



01621 



0-1618 



(2) 



0-1620 



0-1624 



(3) 



0-1614 



0-1622 



(*) 



0-1619 



0-1606 



(5) 



0-1604 



0-1597 



(6) 



0-1618 



0-1615 



C?) 



0-1298 



0-1305 



(«) 



0-1294 



0-1-297 



(9) 



0-1618 



0-1618 



(10) 



0-2588 



0-2575 



12) 



0-2722 



0-2726 



032'73 



0-3269 



Error. 



Tartaric acid* 



grm. 



grm. 



0-0003 — 



2 



0-00O44- 



2 



0-0008 4- 



2 



0-0013 — 



1 



0-0007 — 



2 



0-0003 — 



3 



0-0007 4- 



1 



0-0003 + 



1 



oooo± 



2 



0-0013- 



3 



0-0004 4- 



2 



0004 — 



2 



We next tried the effect of treating a solation of sodium 

 tungstate in the same manner. We found that after the boil- 

 ing with tartaric acid, neutralizing, adding iodine and allowing 

 to stand as before, the amount of free iodine present, as shown 

 bj the amount of arsenious oxide solution necessary to destroy 

 it was the same as that originally added, showing that no 

 reduction had taken place. Accordingly a series of determi- 

 nations of vanadium in the presence of tungsten was made 

 which is recorded in the following table : 



Y2O6 taken. 



V2O5 found. 



Error. 



Sodium tungstate. 



Tartar! 

 acid. 



grm. 



grm. 



grm. 



grm. 



grm. 



(1) 0-1618 



0-1615 



0-0003 — 



1 



a 



(2) 0-1615 



0-1606 



0-0009 — 



1 



3 



(3) 0-1618 



0-1624 



0-0006 + 



1 



3 



(4) 0-1619 



0-1624 



0-0005 + 



1 



3 



(5) 0-1627 



0-1623 



0-0004 — 



1 



3 



(6) 0-1621 



0-1624 



0-0003 +^ 



1 



4 



(7) 0-2587 



0-2574 



0-0013 — 



1 



4 



(8) 0-2587 



0-2589 



0-0002 + 



1 



4 



The results above show that vanadium may be easily deter- 

 mined by this method in the. presence of tungsten without any 

 evident interfering action on the part of the latter element. 



When the same method of treatment was applied in the 

 presence of molybdenum in the form of ammonium molybdate^ 

 the majority of the determinations gave large plus errors, and 

 a few experiments made with the molybdate alone seemed to 

 show a noticeable reduction of the molybdic acid. In the fol- 

 lowing table the results 'are tabulated. In experiments (3), 

 (4) and (5) the mixtures were not boiled with tartaric acid, but 

 warmed on a steam bath, with, however, no very apparent pre- 

 vention of the reducing action. 



