Abstract: The compositions are formed as the reaction product, preferably in an organic solvent, of phosphorous acid or PCl.sub.3 and a water-soluble carboxyl polymer. A precursor of phosphorous acid, which precursor is capable of generating phosphorous acid in aqueous solution, may be used, and preferably, the water-soluble carboxyl polymer has a relatively low molecular weight, preferably in the range from about 400 to about 6000. The molar ratio of the reactants, namely of carboxyl polymer, calculated as carboxyl groups to phosphorous acid is in the range from about 10:1 to about 1:1. The carboxyl polymer, such as polyacrylic acid, may be derived from an .alpha.,.beta.-olefinically unsaturated monomer having a carboxyl group, or the carboxyl polymer such as an acid anhydride polymer may be derived from a monomer readily converted to one having a carboxylic acid group.