MÃ moire sur les acides aspartique et malique In Comptes Rendus, Vol. XXXIII, 1851, pp 217-221. Complete issue (SÃ ance du Lundi 25 Aout 1851, No. 8, pp 217-252)

FOUNDATIONAL PAPER IN STEREOCHEMISTRY. This work is part of Pasteur's groundbreaking series on tartaric and paratartaric acid, in which he established the molecular basis of asymmetry in certain crystals and the phenomenon of racemization. Early in his career, Pasteur s investigation of tartaric acid led to the first resolution of what are now known as optical isomers, paving the way for the modern understanding of molecular structure in organic compounds. Pasteur s guiding principle throughout his career was that optical activity was characteristic of organic compounds and generally absent from inorganic substances. Convinced of a connection between molecular and crystalline asymmetry, he was particularly fascinated by the fact that optically active compounds such as tartaric acid with its asymmetrical crystals were exclusively produced by living organisms. This led him to hypothesize that natural asymmetrical forces, such as the Earth's rotation or magnetism, might underlie the handedness observed in biological molecules. During the late 1840s, Pasteur conducted an extensive series of studies exploring the relationship between optical activity, crystalline structure, and chemical composition especially in tartaric and paratartaric acids, of which this paper is a key contribution. His findings highlighted the profound link between optical activity and life, inspiring new methods and approaches to chemical structure and composition. As the Dictionary of Scientific Biography (DSB 10) states, "Pasteur opened the way to a consideration of the disposition of atoms in space, and his early memoirs constitute founding documents of stereochemistry." In 1849, while investigating tartaric acid, a substance found in the sediments of fermenting wine, Pasteur encountered a puzzling problem. Scientists at the time used polarized light to study crystalline substances, observing that dissolved tartaric acid rotated the plane of polarized light. However, paratartaric acid another compound with the same chemical composition showed no such effect. While many assumed the two substances were identical, Pasteur s meticulous observations revealed otherwise. Examining paratartaric acid under a microscope, he discovered two distinct types of crystals, which, though nearly identical, were mirror images of one another. By carefully separating them into two groups and dissolving each separately, he demonstrated that both solutions rotated polarized light but in opposite directions. When mixed together, the effect was canceled out. This discovery demonstrated that chemical composition alone does not determine a compound s behavior its three-dimensional structure is equally crucial. Pasteur s pioneering work on paratartaric acid thus laid the foundation for the field of stereochemistry, fundamentally altering the way scientists understand molecular structure. Also includes Rapport sur un MÃ moire de M.L. Pasteur relative aux acides aspartique et malique In Comptes Rendus, Vol. XXXIII, 1851, pp 549-567. Complete issue (SÃ ance du Lundi 24 Novembre 1851, No. 21, pp 549-588). Also tipped in is an English translation (in small 8vo). 4to bound in green wrappers with printed labels on cover wrapper. Excellent.…