What role did Benjamin Franklin play in the 1790 debate over slavery?

Joseph Ellis notes in his book Founding Brothers: The Revolutionary Generation that during the Constitutional Convention, Benjamin Franklin had wanted to introduce a statement of principle in the Constitution condemning slavery and the slave trade to commit the government to eventual emancipation. Several northern delegates, however, persuaded Franklin not to introduce the statement on the grounds that it put the fragile Sectional Compromise that held the Consitutional Convention together at risk.