SEC. 3. _And be it further enacted_, That the Secretary of the Treasury be, and he is hereby, authorized to issue, on the credit of the United States, from time to time, coupon or registered bonds, of such denominations not less than fifty dollars as he may think proper, to the amount of $500,000,000, redeemable in coin, at the pleasure of the Government, at any time after twenty years, and payable in coin at sixty years from date, and bearing interest at the rate of four per cent. per annum, payable semiannually in coin; and such bonds may be disposed of at the discretion of the Secretary, either in the United States or elsewhere, at not less than their par value, for coin, or for United States notes, national-bank notes, or fractional currency; or may be exchanged for any of the obligations of the United States, of whatever character, that may be outstanding at the date of the issue of such bonds. And if in the opinion of the Secretary of the Treasury it is thought advisable to issue a larger amount of four per cent. bonds for any of the purposes herein or hereinafter recited than would be otherwise authorized by this section of this Act, such further issues are hereby authorized: _Provided_, That there shall be no increase in the aggregate debt of the United States in consequence of any issues authorized by this Act. SEC. 4. _And be it further enacted_, That the bonds authorized by this Act shall be exempt from all taxation by or under national, State, or municipal authority. Nor shall there be any tax upon, or abatement from, the interest or income thereof. SEC. 5. _And be it further enacted_, That the present limit of $300,000,000 as the aggregate amount of issues of circulating notes by national banks be, and the same is hereby, extended, so that the aggregate amount issued and to be issued may amount to, but shall not exceed, $500,000,000; and the additional issue hereby authorized shall be so distributed, if demanded, as to give to each State and Territory its just proportion of the whole amount of circulating notes according to population, subject to all the provisions of law authorizing national banks, in so far as such provisions are not modified by this Act: _Provided_, That for each dollar of additional currency issued under the provisions of this Act there shall be withdrawn and cancelled one dollar of legal-tender issues.