Heinrich Magnus, German chemist and physicist, mid 19th century.
© Science Museum / Science & Society Picture Library
Photograph of Heinrich Magnus (1802-1870). In 1831 Magnus became a lecturer of physics at Berlin University, by 1834 he had been promoted to profesor. His work was diverse and covered many areas including thermoelectricity and electrolysis. He was the first person to prepare a platino-ammonium compound- 'Magnum's green salt' and in 1837 noticed that the ratio of oxygen to carbon dioxide in blood was higher in the arteries.