After World War I, demand for zinc and for sulphuric acid greatly fell, and after running into commercial difficulties it was taken over by a group of British industrialists with interests in metals and chemicals, under whom it was revived. In 1929 the NSC was bought by Australia's Imperial Smelting Corporation, which in 1949 merged with Zinc Corporation to become Consolidated Zinc. After the consolidation, the smaller NSC plants were closed down to concentrate production on Avonmouth - now known as the Britannia smelting works - where the famous Imperial Smelting Process was developed. From 1967, the Avonmouth Works was home to the largest and most efficient zinc blast furnace in the world.