As part of the Association for Industrial Archaeology’s annual conference in Chester, from the 5th to the 10th September 2014, there will be a one day seminar on the archaeology of the textile finishing and chemical industry. This theme was inspired by the county’s role in the development of the British chemical industry. Cheshire’s oldest industry is salt production and the historic process was done by boiling the naturally occurring brine from the springs of the Weaver Valley so that evaporation would produce salt crystals. Salt was used in the preservation of food stuffs and the curing process of leather, whilst later, in the 19th century, it became one of the principle ingredients for the soap, glass and alkali manufacturing industries and the Weaver Navigation the main export route. Its exploitation in Cheshire was thus central to the development of the 19th and 20th century British chemical industry.
Although the natural brine springs of the Weaver Valley were exploited in the Iron Age, Roman and Medieval periods, mass production did not start until the early 18th century. The discovery of rock salt around 1690 and the development of the Weaver Navigation after 1720 cemented Northwich’s primary manufacturing position. Until the late 19th century manufacturing was done on large, iron, open salt pans, heated by several furnaces from below. Although a brine pumping station survives at Middlewich (the single element of the Murgatroyd open-pan salt works left) the only surviving example of an open-pan salt works is the Lion Salt Works, at Marston north of Northwich, which closed in 1981. Here are several ranges of timber buildings with brick foundations housing the salt pans and salt stores. Timber was used to lessen the corrosive impact of the salt-laden atmosphere on the structures. The site lies by the canal, which supplied the coal needed for the furnaces, and was renovated by Cheshire West and Chester Council. Winsford emerged as the centre of the industry in the late 19th century when brine pumping replaced mining. Water was circulated through boreholes sunk into the salt deposits and bought back to the surface as a brine solution from which the salt could be evaporated, or used directly in the chemical industry. British Salt at Middlewich, which is the only works left in the town, uses a vacuum process developed in the early 20th century to boil the brine under pressure whilst Meadowbank Mine in Winsford continues to mine salt.
The Leblanc process for making soda (sodium carbonate) from salt in the 1820s led to the growth of a chemical industry either side of the Mersey Estuary. Though the first works was in Liverpool in 1822 St Helens and Widnes were the focus of the industry because of the ready availability of coal via the Sankey Canal and the Mersey. Spike Island at Widnes, now the home of Catalyst, the chemical museum, has remains of this industry including the 1860 process building erected by John Hutchinson, the remains of pyrites kilns, the bases of acid towers and the canal basin. The Solvay process developed by Ernest Solvay in 1863 replaced the Leblanc method. It used towers in which carbon dioxide was blown through a solution of common salt saturated with ammonia. The resultant sodium bicarbonate was heated in furnaces to produce soda. Works using this process were established at Widnes and Winnington by J T Brunner and Ludwig Mond. In 1897 the Castner-Kellner Company began production at Runcorn using an electrolysis production method for creating soda. The demand for alkalis was led by the soap industry which produced products initially for the textile finishing industries and later for home use. Salt in the form of soda was the main ingredient in soap manufacture. A soap manufacturing plant was built at Bank Quay in Warrington by Joseph Crosfield in 1815. There is still a chemical works on this site. The most famous of the North West soap works, established at Port Sunlight by William Hesketh Lever in 1888, is now just over the board in the Wirral.
All the alkali producing sites became part of ICI in the 20th century. The early 21st century industry is focussed in just a few areas. North of Northwich the Tata Works (formerly ICI) at Marston and Winnington survive in production, whilst a salt mine also survives at Winsford. 20th century chemical developments also reflected the rise of the oil economy. An oil refinery at Stanlow, Ellesmere Port, remains in use along with its storage depot at Eastham by the Manchester Ship Canal.