Browning and Goodman — Estimation of Vanadium. 359 



form of apparatus into potSissium hydroxide and weighs. 

 From this weight the amount of vanadic acid originally pres-' 

 ent may be readily calculated. 



We have applied the method of oxidation with standard 

 iodine described in the tartaric acid process to the residue 

 after boiling with oxalic acid. The method of treatment was 

 identical with that outlined at the beginning of this paper. 

 The results which follow in the table are for the most part sat- 

 isfactory and the method is certainly more easily applied than 

 Friedheim's process, the potassium hydroxide absorption appa- 

 ratus being unnecessary. 











Sodium 











Ammonium tung- 



V2O5 taken. 



YsOs found. 



Error. 



Oxalic acid. 



molybdate. state. 



grm. 



grm. 



grm. 



grm. 



grm. grm. 



(1) 0-1806 



0-1803 



0-0003 - 



1 





(2) 01950 



0-1955 



0-(005 + 



1 





(3) 0-1959 



0-1955 



0-0004- 



1 





(4) 0-1950 



0-1959 



0-0009 4- 



1 





(5) 0-1954 



0-1977 



0-0023 4- 



1 





(6) 0-1956 



0-1960 



0-0004 + 



1 





(7) 0-1956 



0-1964 



0-0008 + 



1 





(8) 0-1956 



0-1957 



0-0001 + 



1 





(9) 0-3900 



0-3899 



0001 — 



2 





(10) 0-3897 



0-3917 



0-0020 + 



2 





(11) 0-3903 



0-3905 



0-0002 + 



2 





(12) 0-1954 



0-1959 



0-0005 + 



2 





(13) 1957 



0-1960 



0-0003 + 



. 2 





(14) 0-1954 



0-1961 



0-0007 + 



2 





(15) 1806 



0-1818 



0-0012 + 



3 



_. 



(16) 0-1807 



0-1827 



0-0020 + 



3 



._ 



(17) 0-1809 



0-1803 



0-0006- 



3 





(18) ()-i956 



0-1961 



0-0005 + 



3 



1 



(19) 0-3611 



0-3617 



0-0006 + 



5 



- - - _ 



(20) 0-3616 



0-3626 



0-0010 + 



5 



1 



Having applied successfully both tartaric acid and oxalic 

 acid in the manner described, the action of citric acid applied 

 in the same manner suggested ilself as a fitting conclusion to 

 the study of the action of this class of organic acids In this 

 case, as in the others, the reduction of the vanadic acid is 

 easily and quickly effected, but the oxidation with the iodine 

 is slower than in the presence of alkaline oxalates and tar- 

 trates. In the case of oxalic acid on standing about fifteen 

 minutes with the excess of iodine, when tartaric acid has 

 been used, the bleaching of the iodine continues from thirty to 

 forty-five minutes, but in the presence of the alkaline citrate 

 the time required is tully an hour. A large excess of tartaric 

 or oxalic acids does not seem to materially affect the results, 



