"I'm boiling mercury and using arsenic, antimony and lead," says Hopkins' [Larry Principe], only half kidding. Working under a fume hood in a small lab on the Homewood campus, Principe is currently trying to unlock the 400-year-old secret of an object known to alchemists as "the Bolognian stone."

While studying the writings of a 17th-century German alchemist named Wilhelm Homberg, Principe learned that Homberg had rediscovered the method for making the Bolognian stone -- which scientists today recognize as barium sulphate.

Photo(s); 1. An ingot of an alloy of copper and antimony was made from a formula used by [Isaac Newton]. 2. Larry Principe (right), a Johns Hopkins professor of chemistry and history, and [Bill Newman], a historian of science at Indiana University, attended the alchemy conference in Philadelphia.; Credit: 1. INDIANA UNIVERSITY 2. JOSEPH KACZMAREK : ASSOCIATED PRESS