Bérard, Jacques Étienne
(b. Montpellier, France, 12 OCtober 1789; d. Montpellier, 10 June 1869)
Bérard was the son of Étienne Bérard, a chemical manufacturer and associate of Chaptal, by whom he was recommended to the chemist Berthollet as a laboratory assistant. About 1807 young Bérard went to live in Berthollet’s house at Arcueil, near Paris, and he soon became a member of the Society of Arcueil. He took advantage of his proximity to paris to study at the newly reestablished university and was sucessively bachelier-ès-letter (1811) and licencié-ès-science. He returned to Montpellier in 1813 and received the M.D. on 9 July 1817. He became and later in the faculty of medicine. He was elected a correspondent in the chemistry section of the Paris Académie des Sciences on 20 December 1819.
Bérard first published work (1809-1810) was on the analysis of salts and a study of solubilities, research that he undertook at the behest of Berthollet. His value for the density of nitric oxide was used by Gay-Lussac as a datum in the establishment of his law of combining volumes of gases. Bérard collaborated with Malus in a study of infrared and ultraviolet radiation, finding that both can be polarized.
Bérard’s best-known research is that carried out in collaboration with Franrcois Delaroche on the specific heats of gases. This won the prize offered by the First Class of the Institute in 1811. To compare the specific heats of gases, they passed them through a spiral tube immersed in a copper calorimeter filled with water. The rise in temperature of the water when a current of hot gas under constant pressure was passed through the spiral was taken to be proportional to the specific heat. Their method was essentially that used earlier by Lavoisier. The accuracy of their results, although fair, was impaired by their failure to ensure that the gases were dry.
In 1821 the Académie des Sciences awarded Bérard a prize for his work on the ripening of fruit. This was the first scientific investigation of the effect of different atmospheres on the ripening of fruit. Bérard recognized that harvested fruits use oxygen and give off carbon dioxide. He stated that fruit does not ripen in the absence of oxygen, at least for a limited period, and therefore suggested that some fruits could be stored for a period of up to three months by placing them in a sealed jar with a paste of lime and ferrous sulfate, which was supposed to remove the oxygen.
I. Original Works. Bérard’s works include “Sur les élémens de quelques combinaisons, et principalement des carbonates et souscarbonates alcalins,” in Annales de chimie71 (1809), 41-69; “Sur I’eau contenu dans la soude fondur,” ibid., 72 (1809), 96-101; “Mémorie sur la détermination de la chaleur spécifique des différens gaz,” ibid., 85 (1813), 72-110, 113-182, written with François Delaroche; “Mémoire sur les propriétés physiques et chimiques des divers rayons qui composent la Iumière solaire,” ibid., 309–325. “Observations sur les oxlates et suroxalates alcalins,” ibid., 73 (1810), 263–289; “Mémoire sur les propriétés des différentes espére solaire,” in Mémories de la Société d’Arcueil, 3 (1817), 1–47; “Mémoire sur la maturation des fruits,” in Annales de chimie et de physique, 16 (1821), 152–183, 225–252; and “Lettre à M. Gay-Lussac sur les usines de gaz inflammable de la houille,” ibid., 28 (1825), 113–128.
II. Secondary Literature. Further information on Bérard is in Mauirce Croland, The Society of Arcueil. A View of French Science at the Time of Napoleon I (Cambridge, Miss., 1697). Bérard’s work on the ripening of fruit is discussed in Dana G. Dalrymple, The Development of Controlled Atmosphere Storage of Fruit (Washington, D. C., 1967), pp. 3–4.