Palmer — Potassium Ferrlcyanide in Alkaline Solution. 145 



was heated to boiling, which had the effect of making the pre- 

 cipitate more compact. The precipitate was filtered off on 

 asbestos, washed thoroughly, and dissolved in potassium 

 hydroxide. The solution was made strongly acid with sul- 

 phuric acid, whereby the lead was precipitated as the sulphate, 

 while the vanadic acid remained in solution. A current of 

 sulphur dioxide was then passed through the solution until 

 the blue color indicated complete reduction of the vanadium 

 to the tetroxide condition ; and the sulphur dioxide was ex- 

 pelled by boiling in a current of carbon dioxide. The warm 

 solution was then titrated with permanganate until the first 

 pei'manent pink color appeared ; and this could be easily 

 recognized in the presence of the white precipitate of lead 

 sulphate. 



Tills titration gave a measure of the amount of vanadium 

 present ; and by subtracting the number of cubic centimeters 

 of permanganate used in this titi'ation from the number of 

 cubic centimeters used in the preceding titration, the number of 

 cubic centimeters corresponding to the oxidation of the chro- 

 mium from Cr^Og to CrOg was obtained. 



The results of the determinations are given in Table lY. 









Table 



IV. 









V.O5 



CrOs 



V2O. 





CrOs 







taken 



taken 



found 



Error 



found 



Error 





grm. 



grm. 



grm. 



grm. 



grm. 



grm. 



0) 



0-1139 



0-1010 



0-1134 



. — 0-0005 



0-1010 



±0-0000 



(2) 



0-1139 



0-1010 



0-1139 



±0-0000 



0-1017 



+ 0-0007 



(3) 



0-1139 



0-1010 



0-1134 



— 0-0000 



0-1019 



-1-0-0009 



(4) 



0-1139 



0-1010 



0-1142 



-f- 0-0003 



0-1019 



+ 0-0009 



(5) 



0-1139 



0-1010 



0-1131 



— 0-0008 



0-1015 



+ 0-0005 



(6) 



0-1139 



0-1010 



0-1134 



— 0-0005 



0-1016 



+ 0-0006 



(7) 



0-1139 



0-0505 



oai39 



±0-0000 



0-0507 



+ 0-0002 



(B) 



0-1139 



0-0505 



0-1134 



— 0-0005 



0-0507 



+ 0-0002 



(9) 



0-0569 



0-0505 



00565 



— 0-0004 



0-0505 



±0-0000 



(10) 



00569 



0-0505 



0-0563 



— 0-0006 



0-0508 



+ 0-0003 



Am. Jour. Sci.— Fourth Series, Vol. XXX, No. 176.— August, 1910. 

 10 



