Abstract: As a tall-oil-soap skimming aid, there is added to black liquor resulting from the pulping of coniferous trees a terpolymer of (a) an alpha-beta-unsaturated acid, (2) an alkylate of an alpha-beta-unsaturated acid, and (3) allyl alcohol. The acid contains 3 to 4 carbon atoms and comprises about 60 to about 88 percent by weight of the terpolymer. The alkylate comprises about 6 to 28 parts by weight of the terpolymer, being an ester of the abovementioned acids, the ester having an alkyl portion containing 1 to 18 carbon atoms. Allyl-alcohol units are present in the terpolymer to an extent of 4.5 to 20 weight percent. The terpolymer can be produced by free-radical polymerization in accordance with the customary procedures. With the use of such a copolymer, the proportion of tall oil recovered from black liquor is very substantially increased.