No moneys of this state belonging to any sinking fund or other fund shall be invested by the state treasurer in any form of security without the prior approval of such investment by the state board of finance. The state board of finance, prior to approving any such investment shall make an investigation of the validity of any such security, including the authority for the issuance thereof and all proceedings leading up to such issuance, and of the adequacy of the means provided for the payment of principal and interest of such security, and shall by resolution adopted at a meeting of said board recite its findings on all said matters.