St Rollox Chemical Works
Charles Tennant stood in a Birmingham workshop on the 23rd of January 1798 when he received patent number 2209 for his new bleaching liquor. He had watched Claude Louis Berthollet demonstrate chlorine bleaching and decided to swap potash for lime. This small change solved the problem of lime failing to dissolve in water. The resulting liquid worked well but lasted only a short time before spoiling. Tennant and Charles Macintosh toured Lancashire manufacturers to sell their process for £200 each. Early adopters reported saving between £1000 and £2500 per year. Widespread copying of the method led Tennant to sue for infringement in court. He lost both the initial case and an appeal to the Crown Court in 1802. Undeterred, he developed a dry powder form of calcium hypochlorite. Patent number 2312 arrived on the 30th of April 1799 for this new invention. Four partners joined him to create a legal entity that same year. William Couper served as legal advisor while Alexander Dunlop handled accounts. James Knox managed sales and Charles Macintosh acted as chemist. They established the factory at St Rollox near the Monkland Canal.
The factory began producing sulfuric acid because it cost £60 per ton and was essential for making chlorine. By 1802, annual output reached specific volumes of vitriol and bleaching powder valued at £7500. Six lead vessels stood inside a three-story building measuring roughly 40 feet by 20 feet high. The upper floor held these vessels while glass retorts concentrated acid below them. Lead evaporating boilers sat on the bottom floor to strengthen the acid. Eight more vessels were added in 1807 bringing the total to 26. A further six arrived in 1811 creating 32 large chambers standing 20 feet high. These chambers used external furnaces burning sulfur to supply gas through flues supplied by Bealy and Radcliffe of Manchester. Salt tax removal in 1825 shifted production toward crystal and ash soda using the Leblanc process. Sulfuric acid reacted with salt to produce sodium sulfate known as saltcake. This cake was roasted with lime and coal to create sodium carbonate or soda ash. The liquid product soaked water for 12 hours before evaporation in lead pans. Platina lined vats replaced less efficient lead ones to hold concentrates. By the early 1860s, the site produced 8000 tons of bleaching powder and 10,000 tons of soda ash annually. Hundreds of tons of soap also rolled off the line each year. The factory changed from the Leblanc process to the Solvay process during the 1870s. After 1892, operations ceased producing soda-based products entirely.
A cloud of acrid yellow smoke hung over the factory day and night throughout the 1820s. A lawyer representing a complainer stated that the smell made her sick and inclined to vomit whenever the wind blew north. Another resident noted that several thousand seedling beeches and six thousand seedling thorns had been destroyed by the fumes. Twenty years later, a local magazine cartoon showed nothing but black ink covering the area under the caption St Rollox . . . a Clear Day. The management received constant complaints about pollution affecting public health. Residents complained that the noxious air poured down upon them from the manufacture of vitriol. They argued that if Mr Tennant would stop making sulfuric acid, they would allow him to continue other processes. The stench became so severe that it caused significant nuisance to nearby communities. The liquid blackness depicted in cartoons reflected the reality of the smog choking the region. People living near the works suffered from respiratory issues and damaged crops due to the emissions.
John Tennant took charge of the plant in 1838 after his father Charles died in October 1838. He faced continual complaints about tainted air despite existing high chimneys lifting fumes over the bog country. While attending church one Sunday, he conceived the idea of building an exceptionally tall chimney. Scottish engineer William Rankine projected the design while Lewis Gordon and L. Hill provided civil engineering plans. Andrew Thomson served as the project's civil engineer. Bricklayer Dugald Campbell McIntyre acted as main contractor though he initially thought the proposition was a joke. Work began on the 29th of June 1841 with concrete foundations laid 20 feet deep into sandstone bedrock. When completed, the structure stood 350 feet tall. It became known as Tennants Stalk and appeared on lists of tallest buildings by 1896 at number seven. The height allowed fumes to disperse higher above the surrounding landscape. This engineering feat aimed to solve the persistent pollution problems plaguing local residents.
For more than 50 years waste piles accumulated behind the factory on an old peat bog within a natural basin of sandstone. Rainfall and springs lixiviated compounds creating yellow liquor flowing into Pinkston Burn then the River Kelvin. A report by University of Glasgow chemist Thomas Anderson in 1865 added pressure to address this pollution. James MacTear created a chemical process in 1871 to recover sulfur from these waste piles. Pumping yellow liquor into special vessels treated it with sulfurous acid to form an oxide. Hot hydrochloric acid precipitated the sulfur which was dried and fused. The product recovered only 27% to 30% of available sulfur but remained cheap to produce. One ton cost 61 shillings to extract using apparatus costing £2000. The plant could produce 35 tons per week or 100 tons monthly. The resulting sulfur had excellent purity and was widely used to make gunpowder. Manufacturers appreciated its reliability despite the low recovery rate. This method turned environmental liability into profitable byproduct for industrial use.
Tennants Stalk had been reduced to 90 feet before lightning struck it in 1922 causing a bulge on one side. Eight workers were employed to remove bricks from the top when the chimney suddenly collapsed killing four men. Authorities decided to dynamite the remains rather than continue manual demolition. The factory closed in the early 1960s due to economic unviability. It was demolished completely in 1964 following the fatal collapse incident. Workers stood ready to blow up the iconic structure during final operations. The site ceased all chemical manufacturing activities after decades of production. No soda-based products emerged after 1892 leaving only sulfuric acid as output. The legacy of Charles Tennant & Co ended with the destruction of their largest European plant. The facility operated continuously from 1799 until its closure in 1964 spanning over 160 years of industrial history.
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Common questions
When did Charles Tennant receive patent number 2209 for his bleaching liquor?
Charles Tennant received patent number 2209 on the 23rd of January 1798. This patent covered a new method using lime instead of potash to create a liquid that dissolved better in water.
What chemicals were produced at St Rollox Chemical Works during the 1860s?
By the early 1860s, the site produced 8000 tons of bleaching powder and 10,000 tons of soda ash annually. Hundreds of tons of soap also rolled off the line each year alongside these products.
Why was the Tennants Stalk chimney built at St Rollox Chemical Works?
The structure stood 350 feet tall to disperse fumes higher above the surrounding landscape after John Tennant conceived the idea in 1841. It aimed to solve persistent pollution problems plaguing local residents who suffered from respiratory issues and damaged crops due to emissions.
How much sulfur could the recovery plant produce weekly by 1871?
The plant could produce 35 tons per week or 100 tons monthly of recovered sulfur. One ton cost 61 shillings to extract using apparatus costing £2000 while maintaining excellent purity for industrial use.
When did the St Rollox Chemical Works cease all chemical manufacturing activities?
The facility operated continuously from 1799 until its closure in 1964 spanning over 160 years of industrial history. No soda-based products emerged after 1892 leaving only sulfuric acid as output before the site closed completely.