Merck & Co. to Sell 2 Chemical Units: The world’s largest pharmaceuticals maker said it will sell San Diego-based Kelco and Calgon Vestal Laboratories of St. Louis to concentrate on drug-related operations. The performance of both units continues to be excellent, the company said. Together they accounted for about $400 million of Merck’s $3.5 billion in sales for 1993, a Merck spokesman said. Kelco makes gums and algae-based ingredients for food processing, oil exploration, paper, textiles and personal care products. Calgon Vestal makes ingredients for antiseptic agents.