The Sceptical Chymist

by Robert Boyle

or Chymico-Physical Doubts & Paradoxes, Touching the Spagyrist's Principles Commonly call'd Hypostatical; As they are wont to be Propos'd and Defended by the Generality of Alchymists. Whereunto is præmis'd Part of another Discourse relating to the same Subject.

The Sceptical Chymist, published by Robert Boyle in 1661, is the book in which chemistry began to separate itself from alchemy. Cast as a dialogue in a garden between Carneades, who speaks for Boyle, and defenders of the old systems, it attacks the Aristotelian doctrine that all bodies are composed of the four elements and the alchemists' doctrine that they are composed of the three principles of salt, sulphur and mercury. Boyle argues from experiments with fire, distillation and solution that neither theory accounts for what actually happens, and he proposes that an element should be understood as a substance that cannot be broken into simpler ones. The style is leisurely and the argument careful. The full text is available to read online in your browser on Vinteuil, and the first chapter is free.