50.5 MB (1.4 MB compressed)
3881 x 4550 pixels
32.8 x 38.6 cm ⏐ 12.9 x 15.2 in (300dpi)
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Peter Griess. Portrait of Johann Peter Griess (1829-88), German chemist and discoverer of azo dyes. Griess was educated at the universities of Jena and Marburg. He became an assistant of the German chemist August von Hofmann at the Royal College of Chemistry in London, Britain, in 1858. In 1862 he took up an industrial post at a brewery, staying there for the rest of his career. In 1862 he discovered that aromatic amines (like aniline) react with nitrous acid to form diazonium salts. These in turn reacted with phenols to produce azo dyes. The first dye, Manchester or Bismarck brown, was discovered within a year but Griess received no reward for his achievement.
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