Validating certain conveyances heretofore made by Central Pacific Railway Co., a Corporation, and its lessee, Southern Pacific Co., a corporation, involving certain portions of right-of-way, in the County of Alameda, State of California, acquired by Central Pacific Railway Co. under the Act of Congress approved July 1, 1862 (12 Stat. L. 489). As amended by the Act of Congress approved July 2, 1864 (13 Stat. L. 356).