Side A: Production of synthetic soda ash began here, in America’s second plant, on November 1, 1900, by Columbia Chemical Company to support Pittsburgh Plate Glass Company (now PPG Industries), marking birth of PPG’s diversified chemical operations. Principal founder John Pitcairn, first works manager Hugh Allen Galt. Plant subsequently added other chemicals. World’s deepest limestone mine (2200 feet beneath surface) established 1944. Soda ash discontinued 1973.