TENNANT, CHARLES (1768–1838), Scottish industrial chemist, was born at Ochiltree, Ayrshire, on the 3rd of May 1768. He started in business as a bleacher at Darnley, and in 1798 took out a patent for a bleach liquor formed by passing chlorine into a mixture of lime and water. This product had the advantage, as compared with the Eau de Javelles, then generally used, that a cheaper base, lime, was substituted for potash in its preparation; but when he attempted to protect his rights against infringement his patent was held invalid on the double ground that the specification was incomplete and that the invention had been anticipated at some bleach-works near Nottingham. In 1799 he patented a more convenient material in bleaching powder or “chloride of lime,” formed by the action of chlorine on slaked lime, and for its manufacture founded at Glasgow in 1800 the well-known St Rollox chemical works, now merged in the United Alkali Company. He died at Glasgow on the 1st of October 1838.
His grandson the iron-master, Sir Charles Tennant (1823–1906), was M.P. for Glasgow from 1878 to 1880 and for Peebles and Selkirk from 1880 to 1886; he was created a baronet in 1885.