# Dictionary of National Biography, 1885-1900/Prout, William

​PROUT, WILLIAM (1785–1850), physician and chemist, was born on 15 Jan. 1785 at Horton, Gloucestershire, whcre his family had been settled on their own property for some generations. His early education was neglected, but he graduated M.D. at Edinburgh on 24 June 1811 with a thesis on intermittent fevers. He was admitted L.R.C.P. on 22 Dec. 1812, and settled in London. He had devoted himself from an early age to chemistry, and in 1813 delivered a course of lectures on this subject at his house in London to a small audience, which included Sir Astley Paston Cooper [q. v.] Of physiological chemistry he was one of the pioneers, and began in 1813 to publish investigations in this subject. In 1815, in an anonymous memoir on the 'Relation between the Specific Gravities of Bodies in their Gaseous State and the Weights of their Atoms,' Prout pointed out that there were grounds for believing that the atomic weights of all the elements are exact multiples of either the atomic weight of hydrogen or half that of hydrogen; and revived the view that hydrogen corresponds to the πρώτη ύλη of the ancients (Thomson, Annals of Philosophy, 1815 vi. 321, 1816 vii. 111). He supported his view by the publication of a few not particularly satisfactory experiments; but he made many others. In 1831 he suggested that hydrogen itself may be formed from 'some body lower in the scale' (Letter quoted in Daubeny's Atomic Theory, 2nd edit. p. 471). The view with regard to the atomic weights is known as Prout's 'hypothesis' or 'law'.
In 1815 Prout discovered that the excrement of the boa-constrictor contains 90 per cent. of uric acid, a fact of considerable physiological importance, and in 1818 he prepared pure urea for the first time (Thomson, Annals, x. 352). On 11 March 1819 Prout was elected F.R.S. on the proposition of Alexander Marcet, William Hyde Wollaston [q. v.], and others. In 1820 he wrote that he had analysed 'almost every distinct and well-defined substance' to be found in organised bodies. In 1821 he published his 'Inquiry into … Gravel, Calculus, and other Diseases of the Urinary Organs,' which he recast in a third edition in 1840, under the title 'On … Stomach and Urinarv Diseases;' this was republished in 1843 and 1848. The treatise, which is of value, is practical, and contains little speculation (Daubeny). On 23 Dec. 1823 he announced his classical discovery of the existence in the stomach of free hydrochloric acid, a most important factor in digestion. Of his scientific papers, which mostly deal with the chemistry of the blood and the urine, the last appeared in 1829, and he henceforward devoted himself chiefly to medical work and practice. On 28 June 1829 he was admitted F.R.C.P. In 1831 he delivered a course of Gulstonian lectures on the 'Application of Chemistry to Physiology, Pathology, and Practice,' which were reported in the 'London Medical Gazette,' and led to a heated controversy in the same journal (vols. viii. and ix.) with Dr. Alexander Philip Wilson Philip [q. v.] (Munk). In 1834 Prout published as a Bridgewater ​ treatise his 'Chemistry, Meteorology, and the Function of Digestion considered with reference to Natural Theology' (2nd edit. 1834; 3rd edit. 1845). The book has little value from either a scientific or a theological point of view. Prout died on 9 April 1850, in Sackville Street, Piccadilly, and was buried at Kensal Green.
Some years before his death he became deaf, and abandoned society. A good portrait of him by Hayes and a miniature (of which a copy was made by Henry Phillips, jun., for the Royal College of Physicians) are in the possession of his family.
While Prout's work in physiological chemistry and medicine is notable, it is as the inventor of 'Prout's hypothesis,' which has up till now remained a subject of discussion among chemists, that he is chiefly remembered. It was welcomed and supported by Thomas Thomson, M.D. (1773-1852) [q. v.], but rejected by Berzelius, though not without hesitation; by Edward Turner (1796-1837) [q. v.]; and by Frederick Penny. Revived again by Dumas and Stas in 1839 and 1840, and supported by Marignac, it was thought at one time to be finally overthrown by the redetermination of atomic weights by Stas, which was undertaken to test its validity between 1860 and 1865. Recently, however, it has again been brought forward by competent chemists, but its validity is still undetermined (Mendeleéf, Principles of Chemistry, ii. 406). It has proved a powerful stimulus to the exact experimental investigation of atomic weights.
The Royal Society's catalogue enumerates thirty-four papers by Prout.
[Besides the sources mentioned, Prout's own papers; Munk's Coll. of Phys. iii. 110, 400; Gent. Mag. 1850. ii. 442; Sketch of the Philosophical Character of Prout in Daubeny's Miscellanies, ii. 123; Archives of the Royal Society; Thomson's Annals of Philosophy, 1816, vii. 17; Daubeny's Atomic Theory, 1st edit. p. 62, 2nd edit. p. 49; Œuvres Complètes de J.S. Stas, Pref. pp. 308, 419 and passim; Liebig's Organic Chemistry of Physiology and Pathology, 1842, pp. 112, 139; Kopp's Gesch. der Chemie, ii. 392; Becker's Atomic Weight Determinations, 1880, pp. 139 et seq., and Clarke's Recalculation of the Atomic Weights, 1882, pp. 261 et seq., both in the Smithsonian Collection; Mendeléef in Trans. Chem. Soc. 1889, p. 643; Turner in Phil. Trans. 1833, pp. 523 et seq.; Penny in Phil. Trans. 1839. pp. 13 et seq.]
P. J. H.