Abstract: A flocculation, sedimentation, dehydration or retention composition comprising a stable dispersion of about 10 to 50% concentration by weight of a polymeric Mannich base in a mixture of water, a water-insoluble liquid and an emulsifier all present as a water-in-oil emulsion, the Mannich base comprising an NH-active polymer carrying carbonamide groups at least about 10% of which carry radicals of a reaction therewith of formaldehyde and a primary or secondary alkyl- or hydroxyalkyl-amine wherein the alkyl groups have up to about 18 carbon atoms, and a stabilizing amount of a water-soluble salt of a mono- or multivalent amine, alone or in admixture with a mono- or multivalent amine or ammonia, or of an ammonium salt of a mineral acid and ammonia, or of a carboxylic acid amide. The amine of the Mannich base is preferably dimethylamine or diethylamine and is used in approximately the same molar amount as the formaldehyde.