Abstract
Metallic chromium was dissolved in perchloric acid for its conversion to chromic acid and aluminum was coprecipitated with chromium hydroxide at pH 5.56.0 by using 20 mg chromium (III) as a carrier. A majority of chromium was removed as chromyl chloride and the residual chromium together with several disturbing elements were removed with DDTC extraction (Table IX and X).
The remaining trace of chromium was masked with citric acid (Table VII and VIII), and Ti, V, Nb, and Ta were inactivated with hydrogen peroxide (Table II). Aluminum was extracted with chloroform at pH 9 as its oxinate and was determined by measuring the absorbancy at 390 mμ.
Aluminum in high purity chromium and commercial products by the thermit process weredetermined (Table XII and XIV).
The conditions for coprecipitation and extraction of aluminum, and for removing of disturbing elements have been investigated in detail.
