Abstract: A method of chemically milling metal and particularly for chemically milling titanium and titanium alloys which comprises subjecting these metals to the action of an aqueous acidic medium containing ammonium bifluoride and a source of nitrate ions.

Abstract: A process for purifying a salt of sulfonated unsaturated aliphatic carboxylic acid, and in particular, a salt of sulfonated oleic acid wherein unreacted saturated fatty acid impurities are removed by the steps of diluting the mixture of the salt of sulfonated acid and impurities with an amount of water sufficient to provide an aqueous solution containing from about 5 to about 30 percent by weight of the salt, adding a synthetic aliphatic or isoparaffinic hydrocarbon solvent having a boiling point in the range of about 150.degree. C. to about 260.degree. C. in an amount such that the hydrocarbon is present in about 10 to about 50 percent by volume, agitating the mixture for a time sufficient to provide an intimate contact of the solvent with the impurities, holding the mixture in a quiescent state for a time sufficient to allow the water and solvent to separate into layers, and then drawing off the purified aqueous layer.