Researches on the molecular dissymmetry of natural organic products : presented to the Chemical Society of Paris, January 20 and February 3, 1860 / by L. Pasteur ; translated from "Leçons de chimie professées en 1860" by W.S.W. Ruschenberger.

  • Pasteur, Louis, 1822-1895.
Date:
[1862]
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Licence: Public Domain Mark

Credit: Researches on the molecular dissymmetry of natural organic products : presented to the Chemical Society of Paris, January 20 and February 3, 1860 / by L. Pasteur ; translated from "Leçons de chimie professées en 1860" by W.S.W. Ruschenberger. Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

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    it. Excepting the hemihedric faces, there is a perfect resem- blance between the two forms. Who could doubt after that, the relations of molecular arrange- ments of these two salts ? Is it not evident that we have here to deal with a malic acid identical to the natural, except the simple suppression of its molecular dissymmetry ? This is the natural malic acid untwisted, if I may so express it. The natural acid, in the arrangement of its atoms, is a wind- ing stair; this one is the same stair, formed of the same steps, but straight, instead of being spiral. It might now be asked if the new malic acid is not the para- tartaric of the series, that is, the combination of the right malic acid with the left malic acid. That is scarcely probable; for then not only with an inactive body we would have made an active body, but would have made two, one right and one left. Besides, I have ascertained that just as there exists a non- dissymmetric inactive malic acid, so there is also a non-dissym- metric inactive tartaric acid, very different from paratartaric acid, and which cannot be resolved into right tartaric and into left tartaric acids. Here it cannot be doubted that we have to deal with right or left tartaric acid rendered non-dissymmetric. I have also discovered inactive amylic alcohol, which yields a whole series of inactive products corresponding to the series of active amylic alcohol. Thanks to the discovery of inactive bodies, we are in posses- sion of a fruitful idea: a substance is dissymmetric, right or left, by certain modes of isomeric transformations, which must be sought and discovered in each particular case; it may lose its molecular dissymmetry, untwist itself, to use a coarse illus- tration, and effect in the arrangement of its atoms a disposition with a superposable image. So that every dissymmetric sub- stance offers four varieties, or rather four distinct subspecies : the right body, the left body, the combination of the right and the left, and the body which is neither right nor left, nor formed by the combination of the right and left. VII. This general conclusion from the preceding studies, throws new light upon our ideas of molecular mechanism. We see that