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.
Castner's sodium patents appeared, and The Aluminium Co.
Castner had long been interested in aluminium, and was desirous of lowering its price.