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its origin. He now undertook the discovery of this. In 1852 he visited all the factories of tartaric acid in Germany and Austria, endeavoring to trace the production of racemic acid to its source. He ascertained that the manufacturers generally had an idea that racemic acid was either potassium or magnesium sulphate, and consequently rejected it in the process of refining tartaric acid. This accounted for the limited quantity which had accidentally found its way to the market. As most of the tartars came from the south of Europe, and had been subjected to a preliminary rectification before shipment, it was further evident that but a moiety of racemic acid ever reached the factories. He pushed on his enquiries, visiting factories and vineyards until he positively located it in the crude tartar, where he found, as he had anticipated, that it was produced abundantly simultaneously with tartaric acid in the fermentation of wines. He wrote of this quest "Never was treasure sought, never adored beauty pursued, with greater ardor."

Having located the natural source of racemic acid, Pasteur next undertook to synthesize it from tartaric acid. This appears an easy problem in light of what every student now knows of the methods for effecting hydration, for constitutionally racemic acid differs from tartaric merely in possessing water of crystallization. In June, 1853, he was able to announce the completion of this great work, which had been accomplished by maintaining cinchona tartrate at a high temperature for several hours. This synthetic product was also optically inactive. It is known as meso-tartaric acid, and is the fourth form of the series. This research brought its author the grand prize of the Académie Française, and the ribbon of the Legion of Honor from the government.

Looking now at the tartaric acids, Pasteur's mind took a wider sweep. He saw that they were typical of all living things, which present asymmetry everywhere, and that they themselves were products of a form of life.

While engaged upon the racemates, he had found that the dextrocrystals alone were altered by fermentation, the lævo-forms remaining unchanged in the liquor. "The reason for this," said he, "can only be because this special ferment feeds, so to speak, more easily on the dextro-forms."

He pondered this problem long before he saw his way clear to its solution. At the same time he sought to unravel the indicated physiological significance of chemical affinities.

In September, 1854, Pasteur was appointed professor of chemistry and dean of the new faculty of sciences at Lille. Upon taking up his duties, he was greatly hampered at first by lack of facilities. The conditions which he encountered would have disheartened any other man. The scientific equipment consisted of a coke-heated stove with which his room was warmed and one student's microscope. This institution