Chardenon, Jean Pierre

(b. Dijon, France, ca. 22 July 1714 [date of baptism]; d. Dijon, 16 March 1769),

chemistry, medicine.

The son of Guillaume Chardenon and Marguerite Canquoin, Chardenon became a surgeon in Paris, but poor health led him to adopt the less arduous profession of physician. He practiced in Dijon, and in 1744, four years after its foundation, he was elected to the Academie des Sciences, Arts et Belles-Lettres de Dijon, in which he served as scientific secretary from 1752 to about 1762. He read papers on medical and surgical topics and was interested in the chemical aspects of medicine.

While discussing the way in which fat was formed in animals, Chardenon considered the nature of oil. Some early chemists had thought that oil was a chemical element or principle, since it was found in all three kingdoms of nature, but Chardenon refuted this by showing that it could be decomposed by heating into acid, water, phlogiston (some of which was in the charcoal that remained in the residue after combustion), and earth. These four substances could not be recombined by affinity (rapport), and they must therefore have originally been combined by an agency (action), which could only have operated in the vegetable and animal kingdoms—an indication that Chardenon believed in some kind of vitalism. Mineral oil, he said, must have been formed by the decay of vegetable matter below the surface of the earth.

In 1761 Chardenon discussed the way in which mercury compounds acted as poisons and medicaments. He concluded that they affected bodily humors because of the high density of mercury, for it had been demonstrated in physics that the action of one body on another was related to its mass.

This Newtonian approach to certain phenomena is also apparent in Chardenon’s discussion of the cause of the weight increase of metals on calcination, deposited with the Dijon Academy in a sealed note on 6 August 1762 and read at several meetings in 1763 and 1764. He criticized two earlier theories: one, credited to Boyle, that the increase was caused by absorption of fire particles; the other, advanced by Laurent Béraut in 1747, that “salts” from the air were deposited on the metal. Chardenon believed that the only change during calcination was the loss of phlogiston, and he explained the gain in weight by assuming that phlogiston was specifically lighter than air and that a metal weighed in air would therefore become heavier when it lost its phlogiston, just as a fishing net suspended by cork, which is specifically lighter than water, would become heavier if the cork were detached. This natïve theory took no account of the volume of the cork or the relative volumes of the metal and the calx, and it was further complicated by Chardenon’s belief that gravity did not act uniformly on all kinds of matter.

The theory implied that the gain in weight of a metal on calcination would be proportional to its phlogiston content, and Chardenon intended to test this by measuring the amount of phlogiston, in the form of charcoal, required to prepare each metal from its calx. He died before he could do this, but his work was continued by Guyton de Morveau, his colleague in the Dijon Academy. Chardenon’s theory was published but received little attention; Guyton’s revised version, however, was more widely read and criticized.

BIBLIOGRAPHY

I. Original Works. Chardenon’s only works to be published in his lifetime were an abstract of his memoir on calcination, “Extrait de la seance publique de 1’Academie de Dijon, le 9 décecembre 1764,” in Mercure de France (July, 1765), pt. 2, pp. 127–134; and a further criticism of Béraut’s theory, “Lettre de M. Chardenon surl’ augmentation de poids des matières calcinées,” in Journal des Sçavans (1768), pp, 648–658. The complete memoir was published posthumously as “Mémoire sur l’augmentation de poids des matiéres calcinés,” in Mémorires de l’Académie de Dijon, 1 (1769), 303–320. A memorial lecture and abstracts of three other papers by Chardenon were also published: “Éloge de Mr.[Jean-Baptiste] Fromageot [1724–1753],” ibid., cxiii-cxxxix; “Usage des énervations des muscles droits du bas-ventre,” ibid., lxxxiv-lxxxvi; “Sur les huiles,” ibid., 2 (1774), ix-xiv; and “Sur les noyés,” ibid., lv-lvi.

The archives of the Dijon Academy, now in the Archives départementales de la Côte-d’Or, Dijon, contain in dossier no. 123 correspondence concerning Chardenon’s theory of calcination, as well as the manuscripts of the complete text of “Sur les huiles” and an unpublished “Analise d’une résidence trouvée dans un vase qui contenoit de l’eau de neige évaaporee à l’air libre.” Abstracts of two unpublished papers are included in the minute books: “Réflexions sur les poisons et particulièrement sur le sublimé corrosif,” in Registre 11 (26 June 1761), ff. 18r-18v; and “Essai sur les embarras du canal intestinal, et sur les moyens de les détruire ou d’en éloigner les funestes effects,” Registre II (10 August 1764), ff. 156v–157v., Other papers are recorded in the minute books only by their titles, with no details of their contents.

II. Secondary Literature. There are several references to Chardenon in H. Maret, “Histoire de l’Académic des sciences, arts et belles lettres de Dijon,” in Mémoires de l’Académie de Dijon1 (1769), i-xli; his early career is mentioned in Richard de Ruffey, Histoire secrète de l’Académie de Dijon (de 1741 à 1770), M. Lange, ed. (Paris, 1909), pp.106–107. Chardenon’s theory of calcination is discussed in detail by J.R. Partington and D. Mckie in “Historical studies on the Phlogiston Theory. Part I,” in Annals ofScience, 2 (1937), 373–379. They give the dates of his baptism and death in a note at the end of “Historical Studies on the Phlogiston Theory. Part II,” in Annals of Science, 3 (1938), 58; on the death certificate he was described as a doctor of medicine of Montpellier, but the University of Montpellier has no record of the dates of his attendance or graduation.

W. A. Smeaton