Associations for carrying on the business of banking under title 62 of the Revised Statutes may be formed by any number of natural persons, not less in any case than five. They shall enter into articles of association, which shall specify in general terms the object for which the association is formed, and may contain any other provisions, not inconsistent with law, which the association may see fit to adopt for the regulation of its business and the conduct of its affairs. These articles shall be signed by the persons uniting to form the association, and a copy of them shall be forwarded to the Comptroller of the Currency, to be filed and preserved in his office.