Alchemy and chemistry in the 16th and 17th centuries

identified as potassium nitrate) played a prominent part in the history of chemistry, as it stimulated experimental investigation of the vital component of air. This research programme was carried out in England in the second half of the seventeenth century, mostly by Robert Boyle and John Mayow. The latter's theory of nitro-aerial particles as the component of air necessary to combustion and respiration is the object of two chapters of the present book, where the author explains Mayow's experiments and theories in the light of modem chemistry. He comes to the conclusion that Mayow's theory of nitre, which derived from Sendivogius, paved the way for the discovery of oxygen at the end of the eighteenth century. Sendivogius is placed at the very beginning of a long period of research which started with the recognition of the role of nitre as a substance containing a "secret food of life" (p. 204) and brought about the discovery of oxygen. For Szydlo, Sendivogius was "fully familiar with practical chemistry, and was capable of describing his ideas in a manner that can be interpreted using the language and concepts of modem chemistry" (p. 97). He states that Sendivogius's chemistry was experimental and that it was free from the mystical connotations which can be found in Renaissance and early modem authors. Sendivogius's chemical ideas are summarized in three points: (1) the study of air and its role in life; (2) the identification of the "central salt" (nitre) as the vital ingredient of air; (3) the preparation, from that salt, of the universal solvent, necessary to the transmutation. Sendivogius's sources, like the Tabula Smaragdina, Theophrastus Paracelsus and Joseph Duchesne, are not neglected by the author. None the less, they are taken into account as a pre-history of the nitre theory, rather than as part of a larger scientific and philosophical background. The obvious links between the notion of nitre and the controversial doctrines of anima mundi and spiritus mundi are not investigated in the book, which focuses on "successful" scientific theories. Included, is a complete bibliography of Sendivogius's works (including translations) as well as summaries and English translations of several of his tracts.