(b. Vendôme, France, 30 December 1800; d. Paris, France, 5 January 1885)
Dessaignes, the third son of Jean-Philibert Dessaignes, was born at the Collège of Vendôme, a school his father helped establish. In Paris he studied law, receiving his degree when he was twenty-one. Instead of practicing law, however, he immediately enrolled in medical school, where he was diverted still further by a strong interest in chemistry, undoubtedly stimulated by the then preeminent position in research of French chemists. It was not until he was thirty-five that he received a degree in medicine, defending a thesis on the action of various chemical substances on humans. While still a medical student, he exploited his early investigations into metabolic processes. He was able to pursue his interests by having been appointed tax collector in the city of Vendôme, a sinecure in which his law degree was of service.
At thirty-seven Dessaignes married Mlle. Renou, whose brother became the director of the Observatory at Saint Maur. Mme. Dessaignes died soon after the birth of their only son. Dessaignes then devoted well over ten years of his life—as well as most of his savings and income—to the creation of a private laboratory in which he performed the experiments which brought him to the attention of the scientific world.
Dessaignes was awarded the 1860 Jecker prize, consisting of a citation and a cash award of 2,000 frances, for his elucidation of the structure of a number of important, naturally occurring organic acids, such as hippuric, succinic, butyric, and malic acids, as well as quercitol, a desoxyinositol obtained from acorns. He shared the prize with Berthelot, with whom he evidently had formed a warm relationship. The prize brought him attractive offers to teach, but he elected to continue his research. He was named a chevalier of the Legion of Honor in 1863 and, at the request of the Académie des Sciences, became a correspondent for chemistry in 1869. Although he had by then ceased all laboratory work, he remained close to the Paris circle of chemists and was honored at a scientific congress at Blois in September 1884, an occasion marked by a laudatory speech by Friedel on behalf of the Academy. That December he developed bronchitis and, although he promptly recovered, was left in a weakened condition. He died after suffering a respiratory collapse; his son, who had become a professor in the school of medicine of Paris, survived him.
Dessaignes was fortunate to have grown up in a place and at a time when French science—especially French chemistry—had reached a peak. The invigorating intellectual climate of Paris, his father’s academic influence, and his freedom from financial worries all combined to give Dessaignes the leisure and opportunity to work in the mainstream of science.
Dessaignes studied, determined the structure, and synthesized several important organic substances, principal among these being hippuric acid. This substance was first isolated by J. Liebig in 1829 from horse urine, thus its name. It occurs in the urine of many herbivorous animals, to a lesser extent in that of humans. It was soon found that by administering benzoic acid by mouth the amount of hippuric acid recoverable from human urine could be increased, a laboratory exercise occasionally still used in undergraduate biochemistry courses. Dessaignes found upon hydrolyzing hippuric acid with either acids or bases that he obtained benzoic acid and glycine. The synthesis followed when Dessaignes reacted benzoylchloride and the zinc salt of glycine and obtained a product identical with naturally occurring hippuric acid. The importance of hippuric acid lay in the realization that the body could eliminate unwanted or dangerous foreign materials by reactions with bodily substances to form compounds which could be excreted readily. Such detoxification mechanisms are observed in almost all vertebrates.
Dessaignes also studied the oxidation and reduction of various compounds, converting malic into succinic acid and tartaric into malic acid, all four carbon acids found widely in plant tissues. A knowledge of the transformations between these acids paved the way for the elucidation of metabolic cycles vital to cellular respiration, which, however, awaited the work of Krebs in the twentieth century.
Dessaignes was the sole author of twenty-five articles and coauthor of three others (two with J. Chautard and one with Schmidt). His papers show marked analytical insight and careful, precise experimentation. His life was that of an enlightened but solitary amateur of science in an age which honored perseverance and modesty.
I. Original Works. A complete list of Dessaignes’s papers may be found in the Catalogue of Scientific Papers. Royal Society of London for 1800–1863. J. C. Poggendorff, III, contains a shorter list. Many of the papers were published in substantially the same form in several journals.
II. Secondary Literature. An obituary notice of Dessaignes is in Comptes rendus hebdomadaires des séances de l’Académie des sciences, 100 (1885), 18, and was reprinted in Bulletin. Société chimique de France, 43 , (1885), 145.
R. Christian Anderson