St Rollox Chemical Works was a Georgian industrial manufacturer of chemicals that was owned and operated by Scottish industrialist Charles Tennant and was described as the largest plant in Europe, if not the world.
Formation
In 1787, Tennant attended a demonstration of the Claude Louis Berthollet’s chlorine bleaching process that was held by Watt in Birmingham. 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. 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.
The new process reduced both the cost of the bleaching liquor and reduced the damage caused by the liquor to the cloth. 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. In the beginning the scheme worked relatively well with each bleach manufacturer reporting they were saving between £1000-£2500 per year. However, the process began to more widely known and number of Lancashire manufacturers decided to use it with obtaining a licence from Tennant. He decided to sue for infringement of patent rights but lost in court. Tennant took the case to the Crown Court in 1802 but lost again. However, in the intervening period, Tennant came up with a new process, that was granted a patent No. 2312 on 30 April 1799 for a new bleaching powder (calcium hypochlorite). At the time Tennant decided to open a new factory to commerically develop the product.
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. 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.
Operation
St Rollox was started as a chlorine bleaching manufacturer that used Claude Louis Berthollet potash-chlorine bleaching liquor, that was modified by sustituting the potash with lime to produce a bleach. In 1799, the process changed when the company moved to the Macintosh-Tennant process to produce dry bleaching powder The powder was made from chlorine and slaked lime that became known as Tennants bleaching salt. It was produced by mixing 4 parts of water, 4 1/2 parts salt, 2 parts of manganese and 4 parts of sulphuric acid known as "Vitriol" in a leaden vessel heated in water bath. The powder proved to be popular and sold well and this enabled the factory to expand and diversify internally. At the time, sulphuric acid cost £60 per ton and large quantaties were needed in the production of chlorine, so Tennant decided to start producing it. By 1802 the factory was producing 252,270lbs of vitriol per year and selling 151,117lbs of bleaching powder per year, valued at £7500.
In 1803, St Rollox had installed six lead vessels to produce the bleach, measuring 10 x 12 feet by 10 feet high In 1803, the house that contained the vessels was of three floors about 50 foot long by 24 feet, the upper floor contained the vessels, the floor below the glass retorts for concentrating acid and the bottom floor contained the lead evaporating boilers used to bring the acid up to strength for the glass retorts. In 1807, a further eight more were added. By 1809, production capacity had been increased further, with 26 vessels in total. This was further increased by six in 1811, taking the total number to 32 and were much larger, measuring 60 x 14 x 12feet high, arranged in sets of two or three. The chambers were constructed to use external furnaces that burnt the sulphur and supplied gas by use of a flue. These were supplied by Bealy and Radcliffe of Manchester.