Caro, Heinrich

SUBJECT AREA: Chemical technology, Textiles

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b. 13 February 1834 Poznan, Poland

d. 11 October 1911 Dresden, Germany

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German dyestuffi chemist.

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Caro received vocational training as a dyer at the Gewerbeinstitut in Berlin from 1852, at the same time attending chemistry lectures at the university there. In 1855 he was hired as a colourist by a firm of calico printers in Mulheim an der Ruhr, where he was able to demonstrate the value of scientific training in solving practical problems. Two years later, the year after Perkin's discovery of aniline dyes, he was sent to England in order to learn the latest dyeing techniques. He took up a post an analytical chemist with the chemical firm Roberts, Dale \& Co. in Manchester; after finding a better way of synthesizing Perkin's mauve, he became a partner in the business. Caro was able to enlarge both his engineering experience and his chemical knowledge there, particularly by studying Hofmann's researches on the aniline dyes. He made several discoveries, including induline, Bismark brown and Martius yellow.

Like other German chemists, however, he found greater opportunities opening up in Germany, and in 1866 he returned to take up a post in Bunsen's laboratory in Heidelberg. In 1868 Caro obtained the important directorship of Badische Anilin-Soda- Fabrik (BASF), the first true industrial research organization and leading centre of dyestuffs research. A steady stream of commercial successes followed. In 1869, after Graebe and Liebermann had showed him their laboratory synthesis of the red dye alizarin, Caro went on to develop a cheaper and commercially viable method. During the 1870s he collaborated with Adolf von Baeyer to make methylene blue and related dyes, and then went on to the azo dyes. His work on indigo was important, but was not crowned with commercial success; that came in 1897 when his successor at BASF discovered a suitable process for producing indigo on a commercial scale. Caro had resigned his post in 1889, by which time he had made notable contributions to German supremacy in the fast-developing dyestuffs industry.

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Further Reading

A.Bernthsen, 1912, obituary, Berichte derDeut

schen Chemischen Gesellschaft, 45; 1,987–2,042 (a substantial obituary).

LRD