This is an appeal from a judgment of the District Court denying, after a trial de novo under 35 U.S.C. § 145, patentability of a visible penetrant method of non-destructive testing, a method by which the existence and location of minute cracks and flaws may be readily detected. The ground for the denial in the District Court was that the subject matter of the claims was nonpatentable over prior art and patents, and, in the case of one of the claims (No. 11), unpatentable on the ground of double patenting. The Primary Examiner and the Board of Patent Appeals had reached the same conclusion. 1

An examination of the record discloses, no error which would warrant disturbing the findings of the District Court. See Standard Oil Development Co. v. Marzall, 1950, 86 U.S.App.D.C. 210, 181 F.2d 280; Esso Standard Oil Co. v. Sun Oil Co., 1956, 97 U.S.App.D.C. 154, 229 F.2d 37.

Affirmed.