Pierre Eugène Marcellin Berthelot Biography (1827-1907)


Berthelot was not only an outstanding scientist but also an accomplished historian, philosopher, and public servant. He lived all his life in Paris, France, where his father, a doctor, treated patients in the city's poor neighborhoods. While still a student, Berthelot showed that organic compounds such as phenol could be synthesized from acetic acid which, in turn, could be preparedfrom other chemicals including carbon tetrachloride. Berthelot was one of the first scientists to use the word synthesis to describe the production of organic compounds from their elements. In 1854 Berthelot earned his doctorate with a thesis on the synthesis of natural fats, which he created by combining glycerol with fatty acids.

Berthelot continued his studies, graduated as a pharmacist in 1858, and became a professor of organic chemistry. In addition to his research on fats, Berthelot is known for synthesizing alcohols, which he defined as neutral compounds containing carbon, hydrogen, and oxygen. Traditionally, ethyl alcohol (ethanol) was prepared by fermenting sugars with yeast, but Berthelot showed thatit could be obtained from ethylene, an organic gas. Berthelot also synthesized acetylene gas, which he named although it had been discovered earlier, bypassing hydrogen through an electric arc produced with carbon poles

He published a definitive work on the synthesis of organic chemicals in 1860,concluding that an almost infinite number of organic compounds could be synthesized. Although other chemists had prepared natural organic substances, Berthelot was one of the first to synthesize organic compounds that did not occur in nature. Some scientists still believed that only a living organism couldproduce organic chemicals, and that vegetable and animal substances were essentially different from chemicals made in the laboratory. Berthelot's work helped disprove this theory and showed that the same physical forces operated in both organic and inorganic chemistry.

Berthelot also developed new experimental techniques in the field of thermochemistry , which studies the amount of heat that is released or absorbed during chemical reactions. His most notable contribution was the invention of thebomb calorimeter, a device in which gas is mixed with excess oxygen, compressed, and then sparked. Berthelot's calorimeter measured the heat of combustionmuch more accurately than previous methods. Berthelot also introduced the terms exothermic to describe a reaction that releases heat and endothermic forone that requires heat.

Although Berthelot devoted more time to research than to teaching, he continued to give lectures through the 1860s. During France's war with Prussia in 1870-71, Berthelot was put in charge of the city's defense committee. When thenew French Republic was established, he was elected to the Senate and began an active career in public affairs. Late in his career, Berthelot interpretedancient and medieval manuscripts on alchemy and analyzed metal objects from ancient Egypt and Mesopotamia. He also published a book on Antoine-Laurent Lavoisier (1743-1794), which included excerpts from the renowned chemist's laboratory notebooks. In 1883 Berthelot established a research farm near Paris forstudying agricultural chemistry. In experiments there, he discovered that some plants can absorb nitrogen from the air in the same way that nitrogen compounds are formed in the laboratory. Although Berthelot had been raised as a Catholic, his exposure to philosophy had led him to question his religion. Throughout his life, he resisted clerical influence in education and promoted agreater emphasis on science in the classroom. Berthelot was devoted to his wife, who came from a Protestant family. They were married for 45 years and hadsix children together. When she became ill, he tended her night and day. Less than an hour after her death, he also died. A special law was passed to allow them to be buried together.

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