The Runcorn Soap & Alkali Company (formerly Johnson's) continued to be successful for some years, being the largest works in Runcorn and one of the largest producers of alkali in the region. The Weston works itself was almost as large as the largest Widnes works of Hutchinson and Gaskell-Deacon1 .
However the Leblanc process was eventually to be superseded by a cheaper, less polluting process, the Solvay or ammonia-soda process. In 1874 John Brunner and Ludwig Mond set up a factory in Northwich using this process2 and, as time went on, it replaced the making of alkali by the Leblanc process. This brought a period of recession for Runcorn in the late 1870s and early 1880s. The Runcorn Soap and Alkali Company built a plant using the Solvay process but, due to a number of factors, including overproduction elsewhere in the world, this was not successful3. In an attempt to support the mutual activities of the Leblanc factories, they were purchased by the United Alkali Company in 1890 (in common with Hazlehurst & Sons and 46 other works)4.
In 1923 the old town works of the Runcorn Soap and Alkali Company were closed down and in 1926 the Weston works were taken over by Castner Kellner. In this year the chemical giant ICI was formed and this resulted in the merger of Castner Kellner's, the United Alkali Company and Brunner-Mond. The Weston works was demolished in 19325 .