Cellulose hot-dog casings, World War I gas masks, silicone rubber and investigations into air pollution. While they don’t appear to have anything in common, these and numerous other developments are products of research conducted at the Mellon Institute of Industrial Research, an internationally renowned nonprofit research laboratory that operated in Pittsburgh for more than 50 years. Established in 1913, the Mellon Institute merged with Carnegie Tech in 1967 to form Carnegie Mellon University (CMU). CMU and the American Chemical Society (ACS) will celebrate the Mellon Institute of Industrial Research as a National Historic Chemical Landmark in recognition of its numerous research accomplishments and legacy of scientific training. A ceremony will be held at 3:30 p.m., March 28 in the Mellon Institute Conference Room.