St Rollox Chemical Works
St Rollox Chemical Works opened in North Glasgow in 1799. By the early 1860s, it was producing 8,000 tons of bleaching powder and 10,000 tons of soda ash every year. Observers called it the largest chemical plant in Europe, if not the world. What turned a small bleaching operation into that scale? And what did it cost the community living around it? The factory began not with a success but with a patent dispute. Charles Tennant's losses in court proved as important as his victories in the laboratory.
In 1787, Tennant attended a demonstration in Birmingham, held by Watt, of Claude Louis Berthollet's chlorine bleaching process. The existing formula used potash, but Tennant substituted lime for it. That change solved the problem of lime's poor solubility in water and opened the path to a cheaper, less cloth-damaging bleach. On the 23rd of January 1798, he received patent number 2209 for his bleaching liquor.
The new liquid had a short shelf life, so Tennant and Charles Macintosh toured Lancashire manufacturers and sold the process for £200 each. Each licensee reported saving between £1,000 and £2,500 per year. As knowledge of the method spread, manufacturers began using it without a licence. Tennant sued for patent infringement and lost. He took the case to Crown Court in 1802 and lost again.
On the 30th of April 1799, Tennant was granted patent number 2312 for a dry bleaching powder, calcium hypochlorite. Unlike the liquor, a dry powder did not carry the same shelf-life constraints. That second patent was the direct reason he decided to open a dedicated factory. He chose a site at St Rollox, beside the Monkland Canal, which could bring coal and ironstone from the Lanarkshire mines directly to the works.
The company took formal shape in 1799 with four founding partners. William Couper served as the legal advisor. Alexander Dunlop, whose brother had married Charles Tennant's eldest daughter, handled the accounts. James Knox managed sales. Charles Macintosh, the chemist, was the fourth.
At £60 per ton, sulfuric acid was expensive, and producing bleaching powder required large quantities of it. Rather than pay those prices indefinitely, Tennant began making his own. By 1802, the factory was generating 252,270 pounds of vitriol per year and selling 151,117 pounds of bleaching powder valued at £7,500.
Six lead vessels, each ten feet high, were installed in a three-storey building by 1803. That building measured 50 feet long by 24 feet wide. The upper floor held the vessels, the middle floor held glass retorts for concentrating acid, and the ground floor contained lead evaporating boilers. Eight more vessels followed in 1807. By 1811, the total had reached 32.
When the salt tax was lifted in 1825, the factory moved into soda production using the Leblanc process. New platina-lined vats, additional furnaces, warehouses, a canal basin, and a railway terminal all followed. A cooperage and iron foundry were added by the 1850s, allowing the works to make and repair its own equipment. Sulfuric acid output by the early 1860s had reached 20,000 imperial gallons per year. The factory was also producing 8,000 tons of soda crystals and hundreds of tons of soap each year.
The factory shifted to the Solvay process in the 1870s. By 1890, that change had contributed to the company merging into the United Alkali Company.
By the 1820s, the management of St Rollox had been receiving complaints about the factory's pollution. A cloud of acrid yellow smoke hung over the works day and night. During an 1822 inquiry, a lawyer read out testimony from a nearby resident. The smell made her sick and inclined to vomit whenever the wind blew from the north. She singled out the vitriol manufacturing and said she would accept the other operations if that one stopped. Another neighbor reported that several thousand seedling beeches and six thousand seedling thorns had been entirely destroyed in a single season.
Twenty years later, a local magazine printed a cartoon of the area with the caption "St Rollox... a Clear Day." The image was solid black ink from edge to edge.
For more than 50 years, waste had accumulated on the old peat bog behind the factory, within a natural basin of sandstone. Rainfall and spring water dissolved compounds from those heaps into what observers called a "yellow liquor," a complex sulfide of calcium. That liquid flowed into Pinkston Burn, into the River Kelvin, and eventually reached the River Clyde.
Shafts were sunk into the sandstone basin, and galleries 300 yards long were cut to drain water from the waste heaps. In 1865, University of Glasgow chemist Thomas Anderson prepared a formal report on the pollution, adding scientific weight to the mounting complaints. Dugald Campbell McIntyre, the chief bricklayer at St Rollox, would soon receive a proposal he initially believed was a joke.
Several high chimneys already stood at St Rollox, intended to lift the factory's fumes high over the bog. They were not tall enough. In October 1838, Charles Tennant died, and his son John Tennant, born in 1796, became general manager. Pollution was foremost in his mind. One Sunday in church, the idea came to him: an exceptionally tall chimney that would carry the fumes far above the district.
William Rankine, a Scottish engineer, projected the chimney. Lewis Gordon and L. Hill designed it, with Andrew Thomson serving as civil engineer. McIntyre provided an estimate once he was persuaded the proposal was serious, and that estimate was accepted.
On the 29th of June 1841, work began. Concrete foundations went down 20 feet into the bed of sandstone below the site. When complete, the chimney measured 455.5 feet tall.
Tennant's Stalk was eventually reduced in height to just 90 feet. In 1922, lightning struck the chimney and a bulge appeared in its wall. Eight workers were brought in to remove bricks from the top. The chimney suddenly collapsed, killing four of them. The remains were dynamited, and the factory ran for another four decades before its own end.
In 1871, James MacTear, the manager at St Rollox, created a chemical process to recover sulfur from the waste heaps behind the factory. The yellow liquor was pumped from the soda heaps into a special vessel. It was treated with sulfurous acid to form an oxide, dissolved with water, and then treated with hot hydrochloric acid to precipitate sulfur, which was dried and fused.
MacTear's method recovered 27-30 percent of the available sulfur from the waste. One ton could be produced at a cost of 61 shillings, using an apparatus that cost £2,000 to build. That apparatus could produce 35 tons per week; the full plant was capable of 100 tons per month.
After the United Alkali Company merger in 1890, St Rollox continued trading as Charles Tennant and Co. In 1892, it ceased producing soda-based products and concentrated only on sulfuric acid. The company was incorporated as Charles Tennant and Co Ltd in 1913.
In the early 1960s, the factory was closed as no longer economically viable and was demolished in 1964. Sulfur from MacTear's recovery process had long since found a steady market; manufacturers purchased it primarily to make gunpowder.
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Common questions
What was St Rollox Chemical Works and where was it located?
St Rollox Chemical Works was an industrial chemical manufacturer in North Glasgow, Scotland. It opened in 1799 and operated until the early 1960s, producing bleaching powder, sulfuric acid, soda ash, and other chemicals before being demolished in 1964.
Who founded St Rollox Chemical Works?
St Rollox Chemical Works was founded by Scottish industrialist Charles Tennant in 1799. He established the factory with three business partners: William Couper as legal advisor, Alexander Dunlop as accountant, and James Knox as sales manager. The chemist Charles Macintosh was the fourth founding partner.
What was Tennant's Stalk at St Rollox Chemical Works?
Tennant's Stalk was a chimney built at St Rollox Chemical Works to carry factory fumes above the surrounding Glasgow neighborhoods. Construction began on the 29th of June 1841, and when complete it stood 455.5 feet tall. It was projected by William Rankine and designed by civil engineers Lewis Gordon and L. Hill.
Why was St Rollox Chemical Works considered the largest chemical plant in Europe?
St Rollox Chemical Works grew into one of the largest chemical plants in Europe through continuous 19th-century expansion. By the early 1860s, it was generating 8,000 tons of bleaching powder and 10,000 tons of soda ash per year, alongside 20,000 imperial gallons of sulfuric acid and hundreds of tons of soap. Observers at the time called it the largest plant in Europe, if not the world.
How did St Rollox Chemical Works address its pollution problems?
Tennant's Stalk, a 455.5-foot chimney completed in 1841, was built to carry chimney fumes above the surrounding neighborhoods. Decades of chemical production also left waste heaps that leached a sulfide liquor into the River Kelvin and the River Clyde. In 1871, manager James MacTear developed a chemical process to extract sulfur from those waste heaps, recovering 27-30 percent of the available sulfur at a cost of 61 shillings per ton.
When did St Rollox Chemical Works close and why?
St Rollox Chemical Works closed in the early 1960s as it was no longer economically viable and was demolished in 1964. The factory had merged into the United Alkali Company in 1890, and from 1892 produced only sulfuric acid, having ceased its earlier range of chemical output.
All sources
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