We do not reach the question of the interpretation and application of the tax regulations relied upon by appellee, for we agree that appellant has failed, as a matter of proof, to show that the taxing statute, entirely apart from these regulations, was applied to it with the alleged unconstitutional effect. Cf. United States v. Raines, 1960, 362 U.S. 17, 80 S.Ct. 519, 4 L.Ed.2d 524.

Judgment will be entered affirming the judgment of the Supreme Court of Puerto Rico.