Hektoen International

A Journal of Medical Humanities

Justus von Liebig (1803–1873)

Philip Liebson
Chicago, Illinois, United States

Justus Freiherr von Liebig c. 1866. US National Library of Medicine. Via Wikimedia.

An extraordinary chemist, Justus von Liebig influenced the development of organic chemistry, scientific teaching of chemistry, and the application of chemistry to physiology and agriculture. He was one of the forerunners of the German educators who influenced the evolution to the outstanding scientific and educational standards of the late nineteenth and early twentieth century of that country.

Born in Darmstadt, he did not complete his grammar school education nor an apprenticeship as an apothecary. However, within a few years, because of his accomplishments in chemistry, he became a full professor at a German university.

Because of his interest in chemistry, he had gone to Paris on a grant provided by an associate of his father, and there worked in Gay-Lussac’s laboratory and became friends with Cuvier and von Humboldt.

His friendship with von Humboldt led to a full professorship in Giessen, Germany, at the age of twenty-two. Among his early accomplishments, he built the first laboratory for the teaching of experimental chemistry. His later research in organic chemistry and agricultural studies included the development of the Liebig condenser, used in steam distillations, an apparatus for determining carbon, hydrogen, and oxygen content of organic compounds, the use of plant fertilizers, and even the proposed application of silver for mirrors, the last of which eventually replaced mercury and led to high quality optical telescopes. A major accomplishment was the co-discovery of chloroform.

He frequently collaborated with Friedrich Wöhler, who had synthesized urea. Their collaboration led to the concept of isomers, substances with the same chemical composition but with different properties because of the arrangement of atoms. For example, silver cyanate and silver fulminate had the same components but only one was explosive, although Wöhler and Liebig had separately determined that the chemical components were the same. An important concept that organic compounds did not belong just to living organisms, as was demonstrated by Wöhler’s synthesis of urea, but by Liebig’s assertion that other organic compounds, such as sugar, could be artificially produced. A subsidiary concept that he proposed, and later demonstrated by others, was that animals produced fats from sugar.

Liebig’s interest in plant fertilization may have developed from his experience as a child during the summer of 1816 when volcanic eruptions led to winter temperatures and a famine. His later research led to identification of nitrogen, potassium, and phosphorus as essential to plant growth and his proposal of nitrogen-based fertilizer. His interest in human nutrition led to the development of a bouillon extract.

His greatest accomplishment was his establishment of an institute outside of the university to teach practical chemistry and laboratory procedures in a disused barracks in the university town. His analytical research drew students from other German states, Britain, and the United States. One of his students, August Kekulé von Stradonitz, was later responsible for structural representations of organic compounds.

PHILIP R. LIEBSON, MD, graduated from Columbia University and the State University of New York Downstate Medical Center. He received his cardiology training at Bellevue Hospital, New York and the New York Hospital Cornell Medical Center, where he also served as faculty for several years. A professor of medicine and preventive medicine, he has been on the faculty of Rush Medical College and Rush University Medical Center since 1972 and holds the McMullan-Eybel Chair of Excellence in Clinical Cardiology.

Summer 2023



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