Section 6
SEC. 6. A sinking fund shall be established in such tanner that the total annual contributions thereto, accrued as at such rate of interest as may be determined by the secretary of Finance in consultation with the Monetary Board, shall be sufficient to redeem at maturity the bonds issued under this Act. Said fund shall be under the custody of the Central Bank of the Philippines which shall invest the same in such manner as the Monetary Board may approve; shall charge all expenses of such investment to said sinking funds; and shall credit the same with the interest on investments and other income belonging to it.