This term embraces all lands, the title to which is in the United States, including as well land occupied forthe purposes of federal buildings, arsenals, dock-yards, etc., as land of an agriculturalor mineral character not vet granted to private owners. Darker v. Harvey. 181 U. S.4S1. 21 Sup. Ct. 090. 45 L. 1×1. 903; Day Land & Cattle Co. v. State, 63 Tex. 520, 4 S. W. 805.