Whenever it is necessary for the United States to acquire title to a tract of land in this state for any purpose, and the state gives its consent to such acquisition, the United States may acquire such land by appropriation; and for such purpose sections 163.01 to 163.22, inclusive, of the Revised Code, are hereby made applicable, and said United States, in appropriating such property, shall, in all respects, be governed by the acts referred to in this section, and such other acts supplemental thereto and amendatory thereof as may be in force when such proceedings take place; provided that the United States may pay the costs, including such reasonable attorney fees as are allowed by the court, to the person whose property is sought to be appropriated, and refuse to make the appropriation, if in their judgment the compensation assessed is too great to justify the appropriation.