Marcellin Berthelot

BERTHELOT, Marcellin (Marcelin Berthelot, 1827–1907), one of the greatest chemists, known for his work on the systematic application of synthesis in organic chemistry, thermochemistry, explosives, and the application of general and organic chemistry to biological and agricultural problems. The son of a physician, Berthelot initially studied medicine, then turned to the study of chemistry under the guidance of Balard and Pelouze. In 1859, Berthelot received a chair of organic chemistry created specially for him at the Higher School of Pharmacy in Paris; in 1864, he moved to the same chair at the Collège de France, which he occupied until his death. A member of the French Academy of Sciences and numerous foreign academies and scientific societies, Berthelot was also a prominent political figure: during the siege of Paris, he studied methods for the preparation of explosives and saltpeter, and in 1878 he was elected president of the explosives commission. In 1886, he served as Minister of Public Education, and in 1895 as Minister of Foreign Affairs. Berthelot holds the exceptional credit of transforming organic chemistry—which (in his own expression) before him was an analytical science—into a synthetic discipline and introducing the synthetic method into organic chemistry as the basis for elucidating the structure and obtaining new compounds. Berthelot's classic works in this regard include the production of alcohol from ethylene, the production of formic acid from carbon monoxide and water, the synthesis of acetylene from hydrogen and carbon in an electric arc flame, and the production of benzene from acetylene. Berthelot also developed the method of reduction with hydriodic acid, which makes it possible to obtain corresponding hydrocarbons from various compounds. Berthelot's work in thermochemistry is of immense importance, leading him to the invention of the calorimetric bomb (see Calorimetric bomb) and to the establishment of the thermodynamically important "principle of maximum work" in chemical reactions. These works led Berthelot to most interesting investigations into the heat of combination of hemoglobin with oxygen, and it turned out that this process releases one-seventh of the heat that would be released if the oxygen bound by hemoglobin oxidized carbon. These studies by Berthelot, along with studies on the thermodynamics of the release of carbon dioxide from blood in the lungs, are of paramount importance for elucidating the mechanism of gas exchange in the lungs. Of exceptional biological interest and practical importance for agriculture is Berthelot's discovery that the fixation of atmospheric nitrogen occurs in the soil, specifically through the agency of bacteria residing there. In addition to experimental work, Berthelot left behind extremely valuable studies on the history of chemistry, particularly concerning alchemy.