The commission, acting through the Secretary of the Interior, is authorized to receive gifts and contributions from States, Territories, societies, organizations, and individuals for the Petersburg National Battlefield: Provided, That all contributions of money received shall be deposited in the Treasury of the United States and credited to a fund to be designated “Petersburg National Battlefield Fund”, which fund shall be applied to and expended under the direction of the Secretary of the Interior, for carrying out the provisions of sections 423, 423a, and 423b to 423h of this title.