In 1655, Samuel Hartlib, the educational reformer and friend of Milton and Pepys, published a small collection of miscellaneous tracts entitled Chymical, Medicinal, and Chyrurgical Addresses. One exception to the general anonymity of the nine works he included is Gabriel Plattes's short piece bearing the long title, A Caveat for Alchymists, or, a Warning to all ingenious Gentlemen, whether Laicks or Clericks, that study for the finding out of the Philosophers Stone; shewing how that they need not to be cheated of their Estates, either by the perswasion of others, or by their own idle conceits. Very little is known about Plattes, other than that he, like Hartlib, was interested in improving the practical arts of agriculture and mining and published a few titles on these topics before the Restoration. He is said to have died in poverty and neglect (see the DNB, s.v. “Plattes, Gabriel”). Plattes makes his didactic purpose in writing the Caveat abundantly clear at the beginning and end of the tract; we suspect, however, that entertainment – including a wholly unsatisfactory summary of Chaucer's Canon's Yeoman's Tale in the “fourth Cheat” – was no less important. The text, slightly abbreviated and modernized, is taken from Hartlib's collection.