Two former board chairmen at the Baltimore Museum of Art, Charles Newhall III and Stiles Colwill,  claim to have rescinded planned gifts of $50 million over the museum’s decision to deaccession works from its collection, with the museum denying it had any knowledge of the pledged donation.  “While we appreciate that Charles Newhall is expressing that he had intended on making such a pledge, this was not negotiated or recorded with the museum,” Clair Zamoiski Segal, chairwoman of the board of trustees.