Section 4898. Every patent or any interest therein shall be assignable in law by an instrument in writing, and the patentee or his assigns or legal representatives may in like manner grant and convey an exclusive right under his patent to the whole or any specified part of the United States. An assignment, grant, or conveyance shall be void as against any subsequent purchaser or mortgagee for a valuable consideration, without notice, unless it is recorded before any notary public of the several States or Territories or the District of Columbia, or any Commissioner of the United States circuit court, or before any secretary of legation or consular officer authorized to administer oaths or perform notarial acts under section seventeen hundred and fifty of the Revised Statutes, the certificate of such acknowledgment, under the hand and official seal of such notary or other officer, shall be prima facie evidence of the execution of such assignment, grant or conveyance.

An assignment of a patent may be compelled by a bill in equity,45 or under supplementary proceedings,46 but cannot be sold on execution.47

An agreement to assign a patent, whether made before or after its issuance is valid;48 an agreement to assign a patent, is not within the provisions of the Statute of frauds, and need not be in writing,49 but the assignment itself must be under the form prescribed by the Federal statutes.50