SEC. 6. _And be it further enacted_, That the Secretary of the Treasury shall require the national banks, to whom may be awarded any part or portion of the additional circulating notes authorized by the fifth section of this Act, to deposit, before the delivery thereto of any such notes, with the Treasurer of the United States, as security for such circulation, registered bonds of the description authorized by the third section of this Act, in the proportion of not less than one hundred dollars of bonds for each and every eighty dollars of notes to be delivered; and the Secretary of the Treasury shall require from existing national banks, in substitution of the bonds already deposited with the Treasurer of the United States as security for their circulating notes, a deposit of registered bonds authorized by the third section of this Act to an amount not less than one hundred dollars of bonds for every eighty dollars of notes that have been or may hereafter be delivered to such banks, exclusive of such amounts as have been cancelled. And if any national bank shall not furnish to the Treasurer of the United States the new bonds, as required by this Act, within three months after having been notified by the Secretary of the Treasury of his readiness to deliver such bonds, it shall be the duty of the Treasurer, so long as such delinquency exists, to retain from the interest, as it may become due and payable, on the bonds belonging to such delinquent banks on deposit with him as security for circulating notes, so much of such interest as shall be in excess of four per cent. per annum on the amount of such bonds, which excess shall be placed to the credit of the sinking fund of the United States; and all claims thereto on the part of such delinquent banks shall cease and determine from that date; and the percentage of currency delivered or to be delivered to any bank shall in no case exceed eighty per cent. of the face value of the bonds deposited with the Treasurer as security therefor.