To the Senate of the United States:
In answer to the resolution of the Senate of the 15th instant, adopted in executive session, I transmit confidentially a report from the Secretary of State and the documents* by which it was accompanied. Pursuant to the suggestion in the report, it is desirable that such of the papers as may be originals should be returned to the Department of State.
*Instructions and correspondence relative to the negotiation of the treaty with Mexico of December 30, 1853, etc
Franklin Pierce, Special Message Online by Gerhard Peters and John T. Woolley, The American Presidency Project https://www.presidency.ucsb.edu/node/201955