Transfer this buffered solution to a 250-ml. separatory funnel, dilute to 50 ml., and add 75 ml. of ethyl acetate. Cool the mixture by placing in a refrigerator for 0.5 hour, or if this is impossible, in cold running water. When cool, add 1 ml. of 1 M ( 3.8Yc) hydrogen peroxide. After shaking the funnel vigorously for 0.5 minute, allow the layers to separate, and draw off the aqueous solution. Repeat the extraction of the aqueous layer a t least twice, using 15 ml. of ethyl acetate each time. Combine the ethyl acetate fractions. Add 1 ml. of lOY0 potassium hydroxide solution to the blue solution of perchromic acid, and shake until the blue color is replaced by yellow. Extract the \-ellow chromate with water, and boil the solution for 10 mink e s . Dilute to 50 ml. and determine the chromium with sdiphenylcarbazide.For the analysis of synthetic samples, 100 mg. of vanadic acid as ammonium metavanadate and known weights of sexivalent chromium from 0.1 to 3 nig. were used. The samples were prepared by mixing the proper amounts of standard solutions of vanadate and dichromate.In the range from 0.1 to several per cent, the results are in good agreement n-ith the known values.