American Cyanamid Co. v. Marzall

Froth flotation was well known to the prior art. This is not disputed. The appellant’s assignors put froth flotation to practical and successful use in the elimination of contaminants or solid particles from lubricating and cooling emulsions, called lubricating or emulsion coolants. The District Court in an action filed by-appellant pursuant to Rev.Stat. § 4915 (1878), as amended, 35 U.S.C.A. § 63, found that the discovery of this new usefulness of froth flotation did not amount to patentable invention and dismissed the action. The effect was to leave undisturbed the Patent Office decision…