This is an appeal from a judgment of the District Court denying, after a trial de novo, 35 U.S.C. § 145, patentability of an electric furnace for heat treating metal products. The ground for the denial was that Dow’s furnace was “merely * * * a combination of elements of well known [prior] art.” The Primary Examiner and the Board of Patent Appeals had earlier come to the same conclusion. We have examined the contentions of the appellant in the light of the record, and find no error which would warrant disturbing the findings of the District Court. Standard Oil Development Co. v. Marzall, 1950, 86 U.S.App.D.C. 210, 181 F.2d 280.

Affirmed.