Abstract: A method of fighting fires which comprises applying to the fire a foam produced from an aqueous composition comprising as a surface-active agent the residue of a branched oligomer of tetrafluoroethylene (C.sub.2 F.sub.4).sub.n wherein n is 4, 5, or 6 having a hydrophilic group attached to the residue of the oligomer, said oligomer having at least three CF.sub.3 groups and being characterized by a formula selected from the group consisting of: ##STR1## The surfactants are particularly effective when incorporated in foams derived from other foam-producing materials.

Abstract: A process for making branched, internally-unsaturated liquid perfluoroolefins that are oligomers of tetrafluoroethylene and have an empirical formula (C.sub.2 F.sub.4).sub.n where n is an integer of 4 to 7, comprising contacting tetrafluoroethylene under anhydrous conditions with at least one fluoride which is a source of fluoride ions, said fluoride being selected from the group consisting of the normal fluorides, acid fluorides and fluorosulphinates of the metals potassium, rubidium and caesium and normal fluorides of a tetraalkylammonium ion, at a temperature of 20.degree. C to 170.degree. C in the presence of an inert solvent selected from the group consisting of dimethylformamide, dimethyl sulphoxide, N-methyl pyrrolidone and hexamethylphosphoramide, and recovering said branched, internally-unsaturated liquid perfluoroolefins from the reaction medium.