William Morris, a 19th-century artist specializing in rich tapestries and wall coverings, is well-known even today for his designs, which often featured leafy green patterns and twisting vines. But according to a new scientific investigation, Morris used arsenic to derive the green pigments he needed for his work, and the deadly chemical sickened some of his clients, depite Morris’s protestations that arsenic was not toxic. In truth, the artist knew better: he was on the board of an arsenic mining company, where he had been told all about the dangers of exposure.