Hermann Fehling (physician)

Hermann Fehling (1811-1885) was a German chemist, best known for developing Fehling's solution, a reagent used to differentiate between aldehyde and ketone functional groups, and more broadly, to test for reducing sugars in solution. Born in Lübeck, Germany, he studied pharmacy at the University of Heidelberg and later worked as an assistant to Justus von Liebig in Giessen. In 1839, he was appointed Professor of Chemistry at the Polytechnic School in Stuttgart, a position he held for over 45 years.

Fehling's work extended beyond the development of his eponymous reagent. He made significant contributions to agricultural chemistry, particularly in the analysis of milk, wine, and other food products. He conducted research on the composition of beer and developed methods for the quantitative determination of sugar content. His work provided valuable insights into the chemical processes involved in food production and processing.

Fehling's solution, a mixture of copper(II) sulfate, sodium potassium tartrate (Rochelle salt), and sodium hydroxide, remains a widely recognized and utilized reagent in chemistry and biochemistry laboratories. The test involves adding Fehling's solution to a solution suspected of containing a reducing sugar. If a reducing sugar is present, the copper(II) ions in the solution are reduced to copper(I) oxide, resulting in the formation of a brick-red precipitate. The intensity of the precipitate is proportional to the concentration of reducing sugar present.

Fehling's publications include numerous articles in scientific journals, reflecting the breadth of his research interests. He is remembered as a skilled experimentalist and a dedicated teacher who made significant contributions to the fields of analytical chemistry and agricultural chemistry.