The National Union Convention.
--The Federal National Executive Committee, appointed at the Chicago Convention which nominated Abe Lincoln for President, held a meeting in Washington City on the 22d, Senator Morgan of New York presiding. The object of the meeting was so fix the time and place for holding the next National Convention. The attempt to have it called at Columbus, Ohio, was abandoned. Philadelphia, New York, and Baltimore, were taken into consideration, and it was finally agreed that the Convention should meet in the city of Baltimore, on the 7th day of June next.
