Nicolas-Théodore de Saussure

Nicolas-Théodore de Saussure (14 October 1767 - 18 April 1845) was a Swiss chemist and student of plant physiology who made seminal advances in phytochemistry.

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The eldest son of Horace-Bénédict de Saussure, he was born in Geneva. He lived quietly and avoided society; yet like his ancestors he was a member of the Genevan representative council, and gave much attention to public affairs. In the latter part of his life he became increasingly reclusive, and died in the city of his birth.

While a young man, Nicolas-Théodore accompanied his father in his Alpine journeys and assisted him by the careful determination of many physical constants. He was attracted to chemistry by Lavoisier's discoveries, but he never became as great. He took a leading share in improving the processes of ultimate organic analysis; and he determined the composition of ethanol, ether and some other commonly occurring substances. He also studied fermentation, the conversion of starches into sugars, and many other processes of minor importance. The majority of his 36 published papers dealt with the chemistry and physiology of plants, the nature of soils, and the conditions of vegetable life, and were republished under the title Recherches chimiques sur la vegetationism ("Chemical investigations of vegetationism").

Saussure showed that the increase in mass of the plant as it grows could not be due only to uptake of CO₂, but also to the uptake of water. Thus the basic reaction by which photosynthesis is used to produce food (such as glucose) was outlined.

The plant genera Saussurea and Saussuria are named after him.

His sister, Albertine Necker de Saussure, is a noted early writer on the education of women.

This article incorporates text from the Encyclopædia Britannica Eleventh Edition, a publication now in the public domain.