The Late Wisconsin vertebrate history of Prince of Wales Island

In the preparation of a fluoride-free salt of a perfluoroalkane sulphonic acid of the formula RFSO3H, in which RF is a perfluoroalkane radical containing 1 to about 10 carbon atoms, wherein the corresponding perfluoroalkane sulphonyl fluoride is subjected to alkaline hydrolysis in liquid medium to produce an inorganic fluoride along with the perfluoroalkane sulphonic acid, the improvement which comprises adding to the hydrolysis mixture cations which form insoluble fluorides, whereby the insoluble fluorides of said cations precipitate out from the liquid medium having the perfluoroalkane sulphonate dissolved therein, separating the precipitate from the liquid medium, and thereafter isolating the perfluoroalkane sulphonate from the liquid medium. Advantageously the additive is calcium oxide and/or hydroxide.