9781422277652

respect: some rotated the plane of polarized light to the right and others to the left. They were of a similar asymmetrical shape, and in fact were mirror images of one another. Pasteur had the idea that racemic acid did not rotate the plane of light at all because it was a mixture of equal quantities of these two types of acid. The two kinds of rotation canceled one another out. The importance of this discovery was that it showed that similar organic chemicals could exist in two forms that differed only in that their crystals were mirror images and rotated light in different directions. We know now that the polarization happens not only in crystals but also in solutions of the substances. The actual molecules of the two forms are mirror images of one another in three dimensions. As a result of his brilliant work, Pasteur was made Professor of Physics at the Lycée in Dijon. He arrived there in November 1848. However, he did not stay long, for in January he was appointed Professor of Chemistry at Strasbourg. The new rector of the Academy of Strasbourg was named Laurent. He was an amiable and warm-hearted man. He and his wife and their two unmarried daughters welcomed Pasteur as a frequent guest to their home. Only two weeks after Pasteur arrived in Strasbourg, he made up his mind to marry the second daughter. His proposal was accepted, and the young couple was married on May 29, 1849.

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