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1 Tennant, Charles
[br]b. 3 May 1768 Ochiltree, Ayrshire, Scotlandd. 1 October 1838 Glasgow, Scotland[br]Scottish inventor of bleaching powder.[br]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.[br]Further ReadingL.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 -
2 Maxwell, James Clerk
[br]b. 13 June 1831 Edinburgh, Scotlandd. 5 November 1879 Cambridge, England[br]Scottish physicist who formulated the unified theory of electromagnetism, the kinetic theory of gases and a theory of colour.[br]Maxwell attended school at the Edinburgh Academy and at the age of 16 went on to study at Edinburgh University. In 1850 he entered Trinity College, Cambridge, where he graduated four years later as Second Wrangler with the award of the Smith's Prize. Two years later he was appointed Professor at Marischal College, Aberdeen, where he married the Principal's daughter. In 1860 he moved to King's College London, but on the death of his father five years later, Maxwell returned to the family home in Scotland, where he continued his researches as far as the life of a gentleman farmer allowed. This rural existence was interrupted in 1874 when he was persuaded to accept the chair of Cavendish Professor of Experimental Physics at Cambridge. Unfortunately, in 1879 he contracted the cancer that brought his brilliant career to an untimely end. While at Cambridge, Maxwell founded the Cavendish Laboratory for research in physics. A succession of distinguished physicists headed the laboratory, making it one of the world's great centres for notable discoveries in physics.During the mid-1850s, Maxwell worked towards a theory to explain electrical and magnetic phenomena in mathematical terms, culminating in 1864 with the formulation of the fundamental equations of electromagnetism (Maxwell's equations). These equations also described the propagation of light, for he had shown that light consists of transverse electromagnetic waves in a hypothetical medium, the "ether". This great synthesis of theories uniting a wide range of phenomena is worthy to set beside those of Sir Isaac Newton and Einstein. Like all such syntheses, it led on to further discoveries. Maxwell himself had suggested that light represented only a small part of the spectrum of electromagnetic waves, and in 1888 Hertz confirmed the discovery of another small part of the spectrum, radio waves, with momentous implications for the development of telecommunication technology. Maxwell contributed to the kinetic theory of gases, which by then were viewed as consisting of a mass of randomly moving molecules colliding with each other and with the walls of the containing vessel. From 1869 Maxwell applied statistical methods to describe the molecular motion in mathematical terms. This led to a greater understanding of the behaviour of gases, with important consequences for the chemical industry.Of more direct technological application was Maxwell's work on colour vision, begun in 1849, showing that all colours could be derived from the three primary colours, red, yellow and blue. This enabled him in 1861 to produce the first colour photograph, of a tartan. Maxwell's discoveries about colour vision were quickly taken up and led to the development of colour printing and photography.[br]BibliographyMost of his technical papers are reprinted in The Scientific Papers of J.Clerk Maxwell, 1890, ed. W.D.Niven, Cambridge, 2 vols; reprinted 1952, New York.Maxwell published several books, including Theory of Heat, 1870, London (1894, 11th edn, with notes by Lord Rayleigh) and Theory of Electricity and Magnetism, 1873, Oxford (1891, ed. J.J.Thomson, 3rd edn).Further ReadingL.Campbell and W.Garnett, 1882, The Life of James Clerk Maxwell, London (the standard biography).J.J.Thomson (ed.), 1931, James Clerk Maxwell 1831–1931, Cambridge. J.G.Crowther, 1932, British Scientists of the Nineteenth Century, London.LRD
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