Nicholas Theodore de Saussure publishes experiments on ..
1804:Nicholas Theodore de Saussure publishes experiments on photosynthesis,and described the balanced equation of the process.
De Saussure, Nicolas-Théodore ..
Nicolas-Théodore was attracted to chemistry by Lavoisier's discoveries, and he adopted Lavoisier's new system of chemistry early in life. He became interested in the chemistry and physiology of plants, including gas exchange and the ways that different soils affected their growth. His early papers on these subjects laid the groundwork for some of the chapters in his magnum opus, ("Chemical Research on Plant Growth"), published in 1804. This book was the first summation of the fundamental process of and a major contribution to the understanding of plant physiology. In contrast to some of his predecessors in the field of photosynthesis research, Saussure based his conclusions on extensive quantitative data that he had collected.
In , Saussure showed that the increase in the mass of a plant as it grows could not be due only to the uptake of , but was also a result of the incorporation of water into plant dry matter. In addition, Saussure demonstrated that plants obtain their carbon from the carbon dioxide in the atmosphere, not through uptake from in the soil, as his immediate predecessors in photosynthesis research had generally believed. He also showed that plants require mineral nutrients, which they take up from the soil, and nitrogen, although he did not trace the source of plant nitrogen definitively to the soil. Saussure's finding that the source of plant minerals was the soil disproved the widely held view that mineral substances in plants arose from vague "transmutations" within the plant. His work enabled completion of the basic, overall chemical equation of photosynthesis, according to which carbon dioxide and water, in the presence of light, are converted by a green plant into fixed carbon (such as , food for the plant), with gaseous released as a byproduct. Based on his accomplishments in plant chemistry and physiology, Saussure is considered the last of the major early pioneers of photosynthesis research, completing the work begun by his predecessors, including , , , and .