The Sceptical Chymist or Chymico-Physical Doubts and 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. - Boyle, Robert, 1627-1691 (Project Gutenberg, 2007)