This article analyzes Marie de Gournay’s discourse on alchemy. The few pages that this learned woman devotes to this curious art reveal an original doctrine that could be de- scribed as skeptical alchemy. Gournay envisions a practice that aims less at material production than at a salutary exercise for the mind against dogmatism. But this skeptical alchemy is part of a strong prescriptive framework that focuses on warding off the danger of the threatening figure of the charlatan. The difficulty lies in maintaining a delicate balance between an openness to wonder and the rejection of credulity.