Alchemy has often been considered at best a “pseudo-science,” and at worst a practice tied up with fraud, the occult, and the irrational.  Recent studies however have begun to reveal hitherto unrecognized dimensions to the “Noble Act,” and to show how alchemists laid key practical and  theoretical foundations for modern chemistry.  Additionally, important figures of the history of science, such as Robert Boyle and Isaac Newton, spent years striving to uncover alchemical secrets.  This talk will present new findings about what alchemists of the 16^th and 17^th centuries were actually doing and thinking about in their laboratories, and how they concealed their knowledge in a bizarre allegorical language.  It will also demonstrate how observations and coherent theory undergirded belief in the possibility of turning lead into gold, how alchemists guided their practical work rationally, and how modern laboratory replications of decoded alchemical processes can sometimes give very startling results.