John Frederic Daniell invented a voltaic cell, now named the Daniell cell after him, that maintained its charge much longer than the existing electric cells at the time. This invention bolstered the telegraph industry through its infancy, allowing for sustained transmissions with its constant current. Earlier, he had invented the dew-point hygrometer to measure atmospheric humidity. In testament to his unprecedented intelligence, the Royal Society inducted him into its ranks at a very early age, and King’s College created a professorship in chemistry for Daniell, its first such chair, despite the fact that he had never attained a postsecondary education.
Daniell was born on March 12, 1790, in London, England. His father was a lawyer. Daniell’s relatives gave him his first job at their sugar refinery and resin factory, where he first encountered the chemical process. Chemistry lectures by William T. Brande inspired him to pursue his own chemical investigations. The excellence of this independent research brought him to the notice of the prestigious Royal Society, which inducted him into its fellowship in 1814, when he was a mere 23 years old.
Daniell conducted meteorological research in addition to his chemical studies, and in 1820, he invented a device to measure the humidity of the atmosphere, a dew-point hygrometer. Three years later, he published Meteorological Essays, a collection of his papers on Earth’s atmosphere, the trade winds, and instructions for constructing meteorological instrumentation. What distinguished this text was Daniell’s use of physical laws to explain atmospheric phenomena, as well as his meticulous exactitude in meteorological observations and measurements. On a practical note, his suggestion that the moisture of hothouses required monitoring led to a transformation in the management of hothouses. He revised this text to include a discussion on radiation for its second edition, which came out in 1827.
In 1831, King’s College in London appointed Daniell as its first professor of chemistry on the strength of his research and writings, and despite the fact that he lacked academic credentials. In the mid-1830s, he turned his attention to electric cells in response to the demand for more consistent and longer lasting power sources for the burgeoning telegraph industry. At the time, telegraphy depended on the voltaic cell, invented by alessandro volta in 1797, which lost its potential once the energy was drawn, due to hydrogen bubbles gathering on the copper plate and creating resistance to the free flow of the circuit. Voltaic cells thus had an extremely brief shelf life, forcing telegram messages to remain exceedingly brief lest the energy supply fail mid-message.
In 1836, Daniell devised a new type of cell consisting of a negative zinc amalgam electrode immersed in a dilute solution of sulfuric acid contained in a porous pot, surrounded by a solution of copper sulfate contained in copper with a positive copper electrode immersed in it. The porous pot allows hydrogen ions to pass through to the copper sulfate, but it prevents the mixing of the two electrolytes. This cell, now known as the Daniell cell, sustained a constant current over long periods of time and thus served as a perfect energy source for telegraphy. British and American telegraph companies employed the Daniell cell exclusively, though other constant current cells were developed thereafter (namely, Grove’s nitric acid depolarized cell and Sand batteries). Interestingly, telegraph operators measured the cell’s power by the degree of pain it induced upon contact with their nerves.
In 1839, Daniell attempted to fuse metals by means of a 70-cell battery. However, this arrangement generated such a powerful electric arc that the ultraviolet rays damaged Daniell’s vision, as well as harming the eyes of other observers, who walked away from the experiment with an artificial sunburn. He followed up on these investigations more carefully to demonstrate that a metal’s ion, not its oxide, carries the electric charge in electrolysis of metal-salt solutions.
Daniell dedicated his 1839 book, Introduction to the Study of Chemical Philosophy, to the eminent chemist, Michael Faraday, who was a close friend. The Royal Society granted Daniell its Rumford Medal in 1832, and then after he had invented his eponymous cell, the society presented him its Copley Medal in 1837. He died on March 13, 1845, in London.
