This news from Washington: Yesterday, Exxon and Mobil completed the largest industrial merger in history, shortly after the federal government approved the deal and ordered the two companies to sell an estimated $2 billion to $3 billion worth of gas stations, pipelines, terminal ports and a refinery. The $81 billion merger combines the nation’s two largest oil companies into a new energy behemoth whose combined revenues last year were $146 billion. The merger also reunites two of the biggest chunks of the old Rockefeller oil empire that was shattered in 1911 for antitrust violations.