Franz von Soxhlet

Franz von Soxhlet ( born January 13, 1848 in Brno, † May 5, 1926 in Munich) was a German agricultural chemist.


Soxhlet, the son of a textile manufacturer, studied agricultural chemistry at the University of Leipzig and received his PhD in 1872 with a thesis on the chemistry of milk. Following (1873 ) he worked as a research assistant at the Agricultural - chemical experimental station in Vienna. From 1879 he was a professor at the Technical University of Munich, also ( to 1913 ) Director of the " Agricultural Central Research Station for Bayern". At the University of Halle he received his doctorate in 1894 as a doctor of medicine. His research focus was the sterilization of milk, in 1886 he constructed an apparatus for the sterilization of milk for infants. Other results of his work were the so-called Soxhlet apparatus and the Säuregradmaß SH value.


Soxhlet, first published in 1873 studies on the biochemistry of milk and 1876 about the making of butter. An important work employed in 1879 with fats (lipids ). From this investigation later found the Soxhlet apparatus with which the fat content of dried foods can be determined arose.

In 1881, he developed a device that allowed for the direct determination of the fat content of milk. The chemical composition of margarine was in 1887 by Soxhlets work area. However, his main interest was in the milk, so he examined lactose (1880, 1892) and acidity ( 1897).

Soxhlet went early 1890s assumed that his sterilization apparatus could make milk completely germ-free and made so that doctors and parents for attention. However, Carl Flügge dismissed shortly after that, even with Soxhlets method organisms remain in the milk, which multiply in a short time and could harm the infant.

Regardless of Franz von Soxhlet pioneered the pasteurization of milk. He was the first scientist who proved the milk proteins casein, albumin, globulin and lactoprotein and the milk sugar lactose. The difference between cow's milk and human milk 1893 was the subject of his investigations. From 1900 on, he dealt with the influence of calcium salts on the occurrence of the metabolic disorder rickets. In one of his last works dealt by Soxhlet in 1912 with the relationship between iron content in human and cow's milk and the incidence of anemia in children. He was an honorary doctorate from the Medical Faculty of the University of Halle.

Soxhlet has always tried with boldness and sharpness to maintain the financial independence of the agricultural experiment stations. Widely in agriculture, he was known for his action against the agricultural chemist Paul Wagner, the director of the Agricultural Experiment Station in Darmstadt. This he was accused of having falsified the analysis results in favor of the fertilizer phosphate manufacturers (via the public clash see Paul Wagner).

Writings (selection )

  • The chemical differences between cow and human milk and the means of adjustment. Munich and Zurich in 1883.
  • About children milk and infant nutrition. Munich 1886.
  • About Margarine: Report to the General of the Comité country wirth economic association in Bavaria. Munich 1895.
  • Education about the " propaganda " of funds Kalisyndikats and my exclusion from the fertilizer Committees of the German Agricultural Society. Munich 1910.