Robert Bunsen, German Chemist, late 19th century.

Photogravure after a painting by J Marx. Bunsen (1811-1899) was Profesor of Chemistry at Heidelberg from 1852 onwards. His research supported the theory that organic groups partially correspond to the simple atoms of inorganic compounds. The cacodyl compounds involved are malodorous, toxic and flammable and caused him to nearly die of arsenic poisoning. With Gustav Kirchhoff he pioneered using spectroscopy in chemical analysis, and discovered Rubidium and Caesium. He was a pioneer in photochemistry and also invented the filter pump. From a collection published by Photographische Gesellschaft, Berlin, 1910.