No compensation shall be allowed any member of the said commission, except such reasonable expenses as they may incur in the performance of their duties; and no member of said commission shall be directly or indirectly interested financially in any school under care of said commission, or in the education and maintenance of said soldiers' orphans, nor in furnishing supplies to or for the same, nor in the purchase of lands, erection of buildings, or equipment of the same.
24 P.S. § 2684