St Rollox Chemical Works

In 1787, Tennant attended a demonstration of the Claude Louis Berthollet’s chlorine bleaching process that was held by Watt in Birmingham.[4] Tennant took the bleaching process and adapted it by substituting lime instead of potash by solving the problem of lime's inability to form a solution in water.[4] He received a patent No. 2209 on 23 January 1798 for the manufacture of a bleaching liquor by passing chlorine into a well-agitated mixture of lime and water that produced a strong bleaching liquor.[5]

The new process reduced both the cost of the bleaching liquor and reduced the damage caused by the liquor to the cloth.[4] However the new liquid had a short shelf-life, so Tennant and Macintosh decided to licence there new process and toured Lancashire manufacturers to sell the process for £200 each.[6] In the beginning the scheme worked relatively well with each bleach manufacturer reporting they were saving between £1000-£2500 per year.[6] However, the process began to more widely known and number of Lancashire manufacturers decided to use it with obtaining a licence from Tennant.[6] He decided to sue for infringement of patent rights but lost in court.[6] Tennant took the case to the Crown Court in 1802 but lost again.[6] However, in the intervening period, Tennant came up with a new process, that was granted a patent No. 2312 on 30 April 1799[7] for a new bleaching poweder (calcium hypochlorite). At the time Tennant decided to open a new factory to commerically develop the product.[8]

In 1799, Tennant with three business partners, created the legal entity. The first of these, Dr. William Couper, was the legal advisor to the partnership. The second partner was Alexander Dunlop (His brother married Charles' eldest daughter), who served as accountant to the group. The third partner, James Knox, managed the sales department. The chemist Charles Macintosh was the fourth partner.[9] It was decided to locate the new factory at St Rollox in North Glasgow close the Monkland Canal that enabled it to transport coal and ironstone from the coal mines in Lanarkshire.[3]

St Rollox was started as a chloring bleaching manufacturer that used Claude Louis Berthollet potash-chlorine bleaching liquor, that was modified by sustituting the potash with lime to produce a bleach.[3] In 1799, the process changed when the company moved to the Macintosh-Tennant process to produce dry bleaching powder[3][10] in a process that was patented on 30 April 1799.[11] The product was a dry powder was made from chlorine and slaked lime. The powder proved to popular and sold well and this enabled the factory to expand and diversify internally. It began to produce soap and sulphuric acid.[3] When the Salt tax was removed, the factory moved to producing crystal and ash soda using the Leblanc process in the 1820's.[3] This enabled the factory to expand further with the use of platina lined vats to hold the vitriol concentrates instead of the less efficient lead lined, more furnaces, more warehouses and storage space as well as building a canal basis and a railyway terminal.[3] By 1850, further expansion had added a cooperage and an iron foundry to make and repair its own equipment.[3]

In 1871, James McTear, who was the manager at St Rollox, created a chemical process to recover sulphur from the waste piles behind the factory.[12] It involved pumping the waste liquor from the soda heaps into a special vessel, treating it with Sulfurous acid to form an oxide, that was then dissolved with water, then hot hydrochloric acid was used to precipitate the sulphur, that was then dried and fused.[12] The process was reliable, resulting in product that was cheap to produce and was widely used by manufactures, even though it recovered only 27% to 30% of the available sulphur.[12] 1 ton of sulphur could be recovered at a cost of 61shillings at a cost of £2000 for an apparatus, that could produce 35 tons per week and plant iself could produce 100 tons per month.[13] The sulphur was considered of excellent purity and was generally used to make gunpowder.[13]

• Chisholm, Hugh, ed. (1911). "Tennant, Charles" . Encyclopædia Britannica. Vol. 26 (11th ed.). Cambridge University Press.
• Alison, Robert (1892). "The Tennants of St. Rollux". The anecdotage of Glasgow. Glasgow: Thomas D. Morrison.
• Bertram, James G (1884). "Model Establishments - V. The St Rollox Chemical Works, Glasgow". Great industries of Great Britain. Vol. 1. London: Cassell, Petter, Galpin and Company. pp. 296–300.
• Christie, John R.R. (2018). "Chemical Glasgow and its Entrepreneurs, 1760-1860". In Roberts, Lissa; Werrett, Simon (eds.). Compound Histories Materials, Governance and Production, 1760-1840. Cultural Dynamics of Science. Vol. 2. London: 978-90-04-32549-4. pp. 311–332. doi:10.1163/9789004325562_015.
• Chang, Hasok; Jackson, Catherine (2007). An element of controversy: the life of chlorine in science, medicine, technology and war. London: British society for the history of science. pp. 168–174. ISBN 978-0-906450-01-7.
• Harden, Arthur (1898). "Tennant, Charles". In Stephen, Leslie; Lee, Sidney (eds.). Dictionary of National Biography Teach to Tollet. Vol. 56. London: Smith, Elder and Co.
• Hutchinson, Martin (1 January 2023). Forging Modernity. Cambridge, uk: Lutterworth Press. ISBN 978-0-7188-9686-7.
• Reed, Peter (23 March 2016). Acid Rain and the Rise of the Environmental Chemist in Nineteenth-Century Britain: The Life and Work of Robert Angus Smith. Science, technology, and culture, 1700-1945 (1st ed.). London: Routledge. p. 148. ISBN 978-1-317-18582-6.

• Electric Scotland | The Tennants of St. Rollox, and their great chemical work
• Canmore | Glasgow, 229-231 Castle Street, St Rollox Chemical Works