John Frederic Daniell
John Frederic Daniell ( born March 12, 1790 in London, † March 13, 1845 ) was a British chemist.
Life and work
He got his first job in a sugar factory. After he had attended a chemistry lecture by William Thomas Brande (1788-1866), he took first own investigations. In 1820 he succeeded in measuring the air humidity using a dew point hygrometer invented by him. 1823 Daniell dealt with atmospheric air currents. In 1831 he was appointed Professor of Chemistry at King's College London.
Daniell's research on the development of constant current sources was carried out in the same time (late 1830s ), in which the first telegraph equipment were procured. The first telegrams were short and could be sent only over relatively short distances. Simple, low batteries were sufficient to transmit the signal. With the rising telegraph traffic and the further spread of the Morse sets higher currents and thus higher performance of the current sources were necessary. Daniells copper -zinc element ( Daniell cell ) (1836 ), and the nitric acid cell by William Grove were successful developments. Daniell elements were mainly built in British and American telegraph systems, because they were the only ones available batteries with low discharge. Additionally, output voltage and current were uniform and the available amperage higher than that of stand- batteries ( voltaic pile ).
1839 Daniell experimented with an existing 70 -cell battery to develop a new method for melting metals. He produced an arc, which sent out so strong UV radiation that it immediately caused a strong sunburn at all concerned. In this experiment, the eyes and other Daniells Present were severely injured. Daniell finally showed that the ion of a metal, rather than the oxide, the electric charge carries when a corresponding metal salt solution is electrolyzed.
Another invention was the " Daniell Hahn" - one powered by hydrogen and oxygen cutting torch.
Daniell was a friend and admirer of Michael Faraday; He dedicated his 1839 published book "Introduction to the Study of Chemical Philosophy".
Daniell died on March 13, 1845 in London, while he attended a meeting of the Council of the Royal Society.
Honors
In 1813 he became a member of the Royal Society, in 1837 the Copley Medal in 1842 and the Royal Medal awarded him.
Were named after him:
- The now obsolete unit of electrical voltage Daniell
- The lunar crater Daniell