Castner , Hamilton Young

(1858–1898) American chemist

Born in New York City, Castner studied at Brooklyn Polytechnic and at Columbia University, New York. He started as a chemical consultant in 1879 and moved to Britain in 1886 when he failed to gain any backing in America for his process for the production of sodium.

Henri Sainte-Claire Deville had developed a system in which caustic soda could be reduced to sodium with charcoal at high temperatures. However he ran into a variety of practical difficulties, which were satisfactorily cleared up by Castner. Castner intended to use the sodium for producing aluminum by reduction of aluminum chloride – at the time aluminum was a very expensive metal. A factory was opened in 1888 at Oldbury, Birmingham, to manufacture 100,000 lbs of aluminum per annum. But it was too late for, two years earlier, Charles Hall in America and Paul Héroult in France had independently discovered a cheap way to produce aluminum by electrolysis. Castner quickly had to invent some uses for his sodium, for which there was little demand at the time. One was the manufacture of sodium peroxide (by burning sodium in air), used as a bleach. By passing ammonia over molten sodium and charcoal he produced sodium cyanide, which was used in the extraction of gold.

By the early 1890s, with the growing demand for his products, his problem was an inability to produce enough sodium. He solved this with a new method of making sodium by the electrolysis of brine using a mercury cathode. The process had been anticipated by Carl Kellner (1851–1905) in Austria; rather than litigate the two chemists cooperated and in 1897 set up the Castner–Kellner Alkali Company in Runcorn, Cheshire, where there was a cheap and abundant supply of salt. In the year of his death it was already producing 20 tons of caustic soda a day with the production also of 40 tons of bleaching powder daily as a byproduct.