Whether it achieved its goal of preserving the legacy of the Corcoran Gallery is debatable, but the landmark agreement that broke apart Washington’s oldest private museum has been an absolute bonanza for the National Gallery of Art.

After its board of trustees approves the next round of acquisitions on Oct. 1, the National Gallery of Art will have accessioned about 40 percent of the Corcoran’s collection, including priceless pieces by Edgar Degas, Frederic Edwin Church, John Singer Sargent and Carrie Mae Weems.