Gooch & Scott — Determination of Vanadic Acid. 435 



Table V. 



Reduction of Vanadic Acid by the Rotating Zinc Cylinder: 

 Preliminary Experiments. 



v 2 5 



v 2 o s 







Eevolu- 



Approx- 





taken as 



found by 





Period 



tions of 



imate 



Cone. 



ammonium 



KMn0 4 





of 



• anode: 



strength 



H 2 S0 4 



vanadate 



(corrected) 



Error 1 



eduction 



number 



of current 



present 



grm. 



grm. 



grm. 



A 



min. 



per inin. 



amp. 



cm 3 





Reduction at room temperature. 







0-0781 



0-0218 



—0-0563 



1 



800 



2 



5 



0-0782 



00249 



—0-0533 



1 



800 



2 



5 



0-0781 



0-0455 



—00325 



2 



800 



2 



5 



0-0777 



00654 



—0-0123 



4 



800 



2 



5 



0-0782 



0-0839 



+0-0157 



6 



800 



2 



5 



00780 



00994 



+0-0214 



6 



800 



2 



5 



0-0781 



01140 



+0-0359 



8 



800 



2 



5 



B. 

 Reduction begun at boiling temperature. 

 0-0779 0-0782 +0-0003 1 800 2 



0-0775 



00779 

 00775 

 0-0780 

 00776 

 00776 



0-0777 

 0-0777 

 0-0778 

 0-0780 



00776 

 00775 



0-0785 

 0-0785 



0-1208 +0-0429 



0-0746 

 0-0882 

 0-0664 

 01155 

 00917 



0-0678 

 01070 

 0-0756 

 0-0918 



00399 

 00751 



0-0790 



0-0838 



—00033 

 +00107 

 —0-0116 

 .+0-0379 

 +00141 



—0-0099 

 +0-0293 

 —0-0022 

 +0-0138 



—00377 

 —0-0024 



+00005 

 +0-0053 



800 



800 

 800 

 800 

 800 

 800 



800 

 800 

 800 

 800 



300 



800 



800 



800 



2 

 2 

 2 

 2 

 2 



None 



1 

 1 



2-5 

 2-5 

 2-5 

 2-5 

 2-5 



1 

 1 



2-5 

 2-5 



5 

 5 



solution), filtered from the precipitated silver, heated 

 to boiling, and titrated with standard permanganate. 

 A* correction amounting regularly to 0-18 cm. 3 of the per- 

 manganate solution, as determined in blank, has been 

 applied in every case. 



These results indicate the extreme rapidity and accu- 

 racy with which vanadic acid in the presence of sulphuric 



