The Secretary of the Interior is authorized and directed to acquire, on behalf of the United States, by gift or purchase, the site of the birthplace of George Washington Carver, distinguished Negro scientist, located near Diamond, Missouri, together with such additional land or interests in land and any improvements thereon as the Secretary may deem necessary to carry out the purposes of sections 450aa to 450aa-2 of this title. In the event the Secretary is unable to acquire such property, or any part thereof, at a reasonable price, he is authorized and directed to condemn such property, or any part thereof, in the manner provided by law.