CHARLES-LOUIS BARRESWIL Contribution to physiology

Charles-Louis Barreswil (1817-1870) was a French chemist who studied, alone or with Claude Bernard, physiological phenomena such as the comparative nutritional power of different foods, the digestion process, the composition of gastric juice, the elimination of urea in animals deprived of their kidneys, the presence of sugar in the liver, the composition of the egg and its digestion, the presence of sugar in urine, etc. The nutritional power of a food determined if it was assimilable (i.e. sugar and albumen) or not (i.e. gelatin); in the first case it disappeared completely from the blood and could not be detected in the secretions. Together with Bernard they came to the wrong conclusion that lactic acid was the main component of gastric fluid. Bernard and Barreswil found that after nephrectomy the body had a limited capacity of eliminating the urea as ammonia salts by means of the intestinal fluids. They also discovered that sugar was present in large amounts in the tissues of liver, independently of the nature of the food basket, that egg white contained sugar and was alkaline while yolk had little or no alkali. Barreswil also developed a very accurate saccharimetry method, which eventually led to the Fehling liquor used for differentiating between aldehyde and ketone groups, as well as for testing reducing and non-reducing sugars. He also discovered the existence of calcium saccharate in molasses.