George and Linda Kaufman bought their first piece of early American furniture in 1958, the year the Norfolk couple married. It was a Queen Anne high chest made in New England in the mid-18th century. More than half a century later, that first purchase has spawned a 200-piece collection considered among the finest of its kind in private hands. Today, the National Gallery of Art will announce that the Kaufman collection, including numerous paintings, has been promised to the Washington museum. "It is our national museum," Linda Kaufman said this week from her Norfolk home. "We always wanted to...