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Pencil portrait of Stanislao Cannizzaro (1826- 1910), Italian chemist. Cannizzaro was one of the chemists who in the 1860's finally came to understand molecular structure. Cannizzaro had the insight to apply the theories of Avogadro to determine the molecular weight of various gases. These he used to justify the atomic weights proposed by Berzelius, allowing a widespread agreement on the precise compositions of many simple compounds. Cannizzaro also devised a method of converting aldehydes into a mixture of organic acids and alcohols, still called the Cannizzaro reaction. In his later years, Cannizzaro entered politics, as vice-president of the Italian senate.
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