The act of March 3, 1863, authorized the Secretary of the Treasury to receive deposits of gold coin and bullion in sums not less than $20, and to issue certificates therefor in denominations not less than $20, said certificates to be receivable for duties on imports. Under this act deposits of gold were received and certificates issued until January 1, 1879, when the practice was discontinued by order of the Secretary of the Treasury. The purpose of the order was to prevent the holders of United States notes from presenting them for redemption in gold, and re-depositing the gold in exchange for gold certificates. No certificates were issued after January 1,1879, until the passage of the bank act of July 12, 1882, which authorized and directed the Secretary of the Treasury to receive gold coin and bullion and issue certificates. This act, however, provided that "the Secretary of the Treasury shall suspend the issue of gold certificates whenever the amount of gold coin and gold bullion in the Treasury, reserved for the redemption of United States notes, falls below one hundred millions of dollars." The act of March 14, 1900, reenacted this provision, and further provided that the Secretary may, in his discretion, suspend such issue whenever and so long as the aggregate amount of United States notes and silver certificates in the general fund of the Treasury shall exceed $60,000,000. It provided further that of the amount of such certificates outstanding one-fourth, at least, shall be in denominations of $50 or less. The amount of gold certificates now outside the Treasury is $464,806,629. The act of July 12, 1882, made them receivable for customs, taxes, and all public dues.