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The discovery of stomach acid
English chemist William Prout identifies hydrochloric acid (HCl) as the active digestive component of gastric juices. The discovery is widely debated by chemists, many of whom maintain that lactic acid or acid phosphates are principally responsible for digestion. The difficulties of analyzing pure gastric juices help to sustain resistance to Prout's conclusion. Researchers typically work with samples containing various other juices and food residues, and many find it difficult to believe that living cells could secrete an acid as strong as HCl. In 1852, however, at the University of Dorpat in the Baltic city of Tartu (in what is today the Republic of Estonia), German chemists Friedrich Bidder and Carl Schmidt, produce definitive quantitative evidence that HCl is, in fact, the sole digestive acid; the controversy is settled with finality.