This is a suit under R.S. § 4915, 35 U.S.C.A. § 63, to obtain a patent on Sebrell and Thies application No. 722,480, filed April 26, 1934, for a water-proofing composition adapted for coating flexible wrapping materials such as paper and cloth. The composition is made by reacting rubber in solution with chlorostannic acid or a halide of an amphoteric metal. Some of the claims use the name “Pliolite.” Some call for heat-sealing. The Patent Office and the District Court were of opinion that the appealed claims lack invention, in view of Geer patent No. 1,744,881, Gentile patent No. 1,804,-556, and an article by Sebrell, one of the applicants, and other authors, in Industrial and Engineering Chemistry, Vol. 19, p. 1033. We cannot say that their opinion is clearly wrong. Abbott v. Coe, 71 App.D.C. 195, 109 F.2d 449.

Affirmed.