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Rey, Jean


(b. Le Bugue, France, ca. 1582/1583; d. 1645 or after)


After graduating M. A. at Montaubin, Rey studied medicine at Montpellier, obtaining an M.D. in 1609. Few details are known of his life as a physician, excpet that he seems to have been highly regarded. His fame rests solely on his Essays de Jean Rey docteur en médicine. Sur la recherche de la cause pour laquelle l’estain & le plomb augmentent de poids quand on les calcine (Bazas, 1630), a reply to apothecary Pierre Burn’s request for an explanation of why tin and lead increased in weight when heated. Much of the Essays consists of argument based on “reason” and on analogy. For instance, one support for Rey’s principal tenet—that the four “elements” of matter (earth, air, fire, and water) possesed the property of heaviness— was the ready separation, on standing, of a mixture of black enamel, solution of potassium acid tartrate, oil of turpentine, and aqua vitae, which, Rey said, represented the four elements.

The “heaviness” of air explained the increased weight on calcination; it resulted denser, heavier, and in some measure adhesive by the vehement and long-continued heat of the furnace. Rey’s only experiment appears in the section of the Essays dismissing other possible explanation for the weight increase. He excluded furnace carbon partly on the ground that he obtained a weight increase when calcining tin on molten iron at his brother’s ironworks.

The fascination of the Essays lies in its succinctness; and the matrix of ideas presented—at a time of far-reaching changes in science—appeals to reason, observation, and experiment, as well as to the skepticism about earlier writings. The Essays created some contemporary reaction, but its intrinsic interest lies in its anticipation of Lavoisier’s recognition in 1772 that calcination involves combination with air. In 1775 Pierre Bayen drew attention to the be a forgery. Later, however, he spoke of it with admiration.


There have been a number of reprints of the Essays since the first (Paris, 1777), with additional notes by Nicolas Gobet. The most recent, The Essays of Jean Rey (London, 1951), has an extensive introduction and full notes by Douglas McKie. MeKie includes not only all the details available on Rey’s life (from the studies of Gabriel Lafon and Henri Teulie) and on the impacy of the Essays, but also details of its printing history. See also D. McKie, in Ambix, 6 (1957–1958), 136–139.

A full account of the work of Rey, with extensive bibliography, is in J.R.Partington, A History of Chemistry, II (London, 1961), 631–636.

J. K. Crellin

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