436 Gooch & Scott — Determination of Vanadic Acid, 



Table VI. 



Reduction of Vanadic Acid by means of the Rotating Cylinder 



of Zinc and Correction by Silver Sulphate. 



v 2 o 5 



v 2 o 5 







Revolutions of 



taken as 



found by 





Period 



reducing 



ammonium 



XMn0 4 





of 



cylinder: 



vanadate 



(corrected) 



Error 



reduction 



number 



grm. 



grm. 



grm. 





per minute 



0-0780 



00799 



—00001 



1 min. 10 sec 



850 



0-0777 



0-0777 



0-0000 



1 " 10 " 



850 



00779 



00777 



—0-0002 



1 " 15 " 



850 



0-0776 



00777 



+0-0001 



1 " 15 " 



850 



0-0779 



0-0780 



+0-0001 



1 " 15 " 



850 



acid may be reduced by the rotating zinc rednctor. 

 Experiments with an amalgamated zinc cylinder showed 

 that in this case the reduction proceeds similarly but 

 much more slowly. 



It has been shown that while vanadic acid may be 

 reduced within a reasonable time, in presence of dilute 

 sulphuric acid, by the action of massive silver of consider- 

 able area in the boiling solution, the reduction may be 

 made very rapid with the aid of rapidly rotating anodes 

 of silver or copper in the electrolytic cell, or by a rapidly 

 rotating reducer of zinc, over-reduction being corrected 

 by the action of silver sulphate. 



