In 1886, however, Castner replaced the carbonate by caustic soda, and materially cheapened the cost of production; but this method was discarded for an electrolytic one, patented by Castner in 1890.
In Castner's process (as employed at Oldbury and Niagara Falls and in Germany) fused caustic soda is electrolysed.
A solution in hydrochloric acid, consisting of the chloride and hydrogen peroxide, is used for bleaching straw under the name of soda-bleach; with calcium or magnesium chlorides this solution gives a solid product which, when dissolved in water, is used for the same purpose (Castner, Journ.
Soc., 1856, p. 30) electrolysed an equimolecular mixture of potassium and calcium chlorides (which melts at a lower temperature than potassium chloride) also between carbon electrodes; whilst Castner's process, in which caustic potash is electrolysed, is employed commercially.
Castner's sodium patents appeared, and The Aluminium Co.