“ And be it further enacted, That the President of the United States, with the advice and consent of the Senate, shall appoint three commissioners, residents of the District of Columbia, any two of whom have power to act, who shall receive the petitions above mentioned, and who shall investigate and determine the validity and value of the claims therein presented, as aforesaid, and appraise and apportion under the provision hereto annexed the value in money of the several claims by them found to be valid ”