Charles Tennant (3 May 1768 – 1 October 1838) was a Scottish chemist and industrialist. He discovered bleaching powder and founded an industrial dynasty. He was born at Laigh Corton, Alloway, Ayrshire to John Tennant and his second wife Margaret McClure. Charles was the ninth of John Tennant’s sixteen children. He was fortunate to receive schooling both at home and at the Ochiltree parish school. He was apprenticed by his father to a masterhandloom weaver. This was a highly paid occupation, requiring great skill and considerable intelligence.
Charles was quick to learn his trade (weaving) but also to see that the growth of the industry far surpassed the development of bleaching methods, which were very primitive. An important aspect of the weaving industry was bleaching cloth. At that time this involved treatment with stale urine and leaving the cloth exposed to sunlight for many months in so called bleaching fields. Huge quantities of unbleached cotton piled up in the warehouses. Charles left his well paid weaving position to try to develop improved bleaching methods. This led him to start his own bleaching fields in 1788, at Darnley, near Barrhead, Renfrewshire. From his father he inherited an untiring capacity for work.
Having acquired his bleachfield, Charles turned his mind and energy to developing ways to shorten the time required in bleaching. Others had already done much work on this problem and managed to reduce bleaching time from eighteen months to four by replacing sour milk with sulphuric acid in the bleaching process. Further, in the last half of the eighteenth century, bleachers started to use lime in the bleaching process, but only in secret due to possible injurious effects from the lime. Charles had the original idea that a combination of chlorine and lime would produce the best bleaching results. He worked on this idea for several years and was finally successful.
His method proved to be effective, inexpensive and harmless. He was granted patent #2209 on 23 January 1798. He continued his research and developed a bleaching powder for which he was granted patent #2312 on 30 April 1799. While still working in the bleachfields around the year 1794, Charles formed a partnership with four friends. Charles Macintosh, an excellent chemist, was the fourth partner. He is known for his technique of macintosh waterproofing and he also assisted in the invention of bleaching powder. Charles was indeed fortunate to have partners.
With the chemist Charles Macintosh (1766–1843) he helped establish Scotland’s first alum works at Hurlet, Renfrewshire. In 1798 he took out a patent for a bleach liquor formed by passing chlorine into a mixture of lime and water. This product had the advantage of being cheaper than the one generally used at the time because it substituted lime for potash.
Immediately after granting of the patent on bleaching, Charles and his partners purchased land on the Monkland Canal, just north of Glasgow, to build a factory for the production of bleaching liquor and powder. From the first it was a splendid success. Production increased from fifty-two tons the first year, 1799, to over nine thousand two hundred tons the fifth year. Later a second plant was built at Hebburn, raising production of bleaching powder alone to twenty thousand tons by 1865.
Despite several business losses; Charles continued to expand his horizons during his time. When the partnership ended he purchased the company. As a forward thinking business man, he was in a class by himself. His company, during the 1830s and 1840s was the largest chemical plant in the world. A great deal of unrest followed the Napoleonic wars, which had the effect of increased wealth for the manufacturing classes but poverty for the working classes. He worked for many years in the reform movement, but it was not until he reached the age of sixty-four that his effort bore fruit with the passage of the Reform Bill of 1832. His ideas and active support helped create one of the most productive periods of social progress and reform, in almost every area, in Scotland’s history.
He died on 1 October 1838. He was, beyond question, an entrepreneur of amazing ability. His dedication to his work, his family and his sense of what was right and fair lasted until the day he died. He was quick to champion those less fortunate, and the reforms he initiated and supported made the lives of his countrymen better.
The principal product being bleaching powder (calcium hypochlorite), which was sold worldwide. By 1815 the business was known as Charles Tennant & Co. and had expanded into other chemicals, metallurgy and explosives.