Tennant, Charles

SUBJECT AREA: Chemical technology, Textiles

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b. 3 May 1768 Ochiltree, Ayrshire, Scotland

d. 1 October 1838 Glasgow, Scotland

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Scottish inventor of bleaching powder.

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After education at the local school, Tennant went to Kilbachan to learn the manufacture of silk. He then went on to Wellmeadow, where he acquired a knowledge of the old bleaching process, which enabled him to establish his own bleachfield at Darnly. The process consisted of boiling the fabric in weak alkali and then laying it flat on the ground to expose it to sun and air for several months. This process, expensive in time and space, would have formed an intolerable bottleneck in the rapidly expanding textile industry, but a new method was on the way. The French chemist Berthollet demonstrated in 1786 the use of chlorine as a bleaching agent and James Watt learned of this while on a visit to Paris. On his return to Glasgow, Watt passed details of the new process on to Tennant, who set about devising his own version of it. First he obtained a bleaching liquor by passing chlorine through a stirred mixture of lime and water. He was granted a patent for this process in 1798, but it was promptly infringed by bleachers in Lancashire. Tennant's efforts to enforce the patent were unsuccessful as it was alleged that others had employed a similar process some years previously. Nevertheless, the Lancashire bleachers had the good grace to present Tennant with a service of plate in recognition of the benefits he had brought to the industry.

In 1799 Tennant improved on his process by substituting dry slaked lime for the liquid, to form bleaching powder. This was patented the same year and proved to be a vital element in the advance of the textile industry. The following year, Tennant established his chemical plant at St Roll ox, outside Glasgow, to manufacture bleaching powder and alkali substances. The plant prospered and became for a time the largest chemical works in Europe.

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Further Reading

L.F.Haber, 1958, The Chemical Industry During the Nineteenth Century, London: Oxford University Press.

F.S.Taylor, 1957, A History of Industrial Chemistry, London: Heinemann.

Walker, 1862, Memoirs of Distinguished Men of Science of Great Britain Living in 1807– 1808, London, p. 186.

LRD