Prout, William

PROUT, WILLIAM

(b. Horton, Gloucester shire, England, 15 January 1785; d. London, England, 9 April 1850)

chemistry, biochemistry.

Prout was the eldest of three sons of John Prout, a tenant farmer whose fortunes had increased through the inheritance of land, and his wife Hannah Lim brick[?]. Educated at local charity schools until the age of thirteen, Prout worked on his father’s farm until about 1802, when he attended the private classical academies of Rev. John Turner at Sheraton, Wiltshire, and Rev. Thomas Jones at Bristol. In 1808, on Jones’s recommendation, he entered Edinburgh University to study medicine; he graduated in 1811 with an unoriginal dissertation on fevers. He completed his medical training at St. Thomas’s and Guy’s hospitals in London, where he set up practice after gaining the licentiate of the Royal College of Physicians on 22 December 1812. During 1814 Prout gave a successful course of public lectures on animal chemistry in his London home and met Alexander Marcet, who praised him in letters to Berzelius. There is some evidence that from 1816 until 1817 he edited Annals of Medicine and Surgery with his friend John Elliotson.

When his father died in 1820, Prout passed the Horton estate, which he inherited, to his surviving brother. Little is known of Prou’s personal life in London. He became a very successful, but not wealthy, physician who specialized in digestive and urinary complaints. His reputation in medicine and chemistry in Great Britain and on the Continent was considerable, both as an experimentalist and as a theorist. Unfortunately, deafness made him avoid scientific contacts after 1830. He subsequently made little effort to keep abreast of the rapid developments that took place in biochemistry and chemistry between 1830 and 1850; and although much of his biochemical research had foreshadowed that of Liebig and his school, Prout found himself eclipsed by their achievements during this period.

An extremely religious man, Prout was invited to write one of the eight Bridgewater treatises, which had the general title On the Power, Wisdom and Goodness of God, as Manifested in the Creation. An accomplished organist who composed music for his family, he also possessed artistic talents. He married Agnes Adam (1793–1863), the daughter of Alexander Adam, the Edinburgh educator; they had seven children, one of whom became a military surgeon.

Prout received the M.D. from Edinburgh (1811), and was a fellow of the Royal Society (1819) and of the Royal College of Physicians (1829). He was a Copley medalist of the Royal Society (1827) and a Gulstonian lecturer at the Royal College of Physicians (1831). He served on the Council of the Royal Society, and on several of its committees and on those of the British Association for the Advancement of Science. For a time he was an active member of the Medico-Chirurgical Society of London.

Prout’s contribution to the concept of the unity of matter, which he adopted as a student, played a dominant role in the development of the theory of the elements and the fortunes of the atomic theory. Prout was much influenced by Humphry Davy’s speculations on “undecompounded bodies” (1812) and by Dalton’s atomic theory as modified by Berzelius. He hoped to develop a “mathematical” chemistry analogous, perhaps, to the scheme expressed tentatively by Thomas Thomson in his First Principles (1825). The inspiration to improve Gay-Lussac’s and Berzelius’ methods of organic analysis came largely from his attempt to find the mathematical laws that govern the formation of organic compounds from the elements carbon, hydrogen, oxygen, and nitrogen. In 1817, 1820, and 1827 Prout published accounts of elaborate and expensive analytical methods. His organic analyses were renowned for their accuracy, and he remained skeptical of Liebig’s simple and successful technique (1830).

Between 1815 and 1827 Prout published a series of important papers on urine and digestion that opened up the areas of purine and metabolic chemistry. He found a boa constrictor’s excrement to be 90 percent uric acid; he also extracted extremely pure urea from urine and attempted to synthesize it in 1818, ten years before Wöhler’s accidental success. In 1821 Prout published a concise textbook on urine; but a similar work on digestion, partly printed in 1822, was withdrawn from publication. In 1840, however, Prout published a long and successful practical textbook of urinary and digestive pathology.

The brilliant demonstration in 1824 that the gastric juices of animals contain hydrochloric acid appeared incredible to many of Prout’s contemporaries. Yet in 1827 they readily adopted his classification of foodstuffs into water, saccharinous (carbohydrates), oleaginous (fats), and albuminous (proteins). Although Prout promised detailed analyses of the three organic aliments, only those of the saccharinous class were published by him. As a vitalist, Prout maintained that organized bodies (which were composed from organic substances) contained “independent existing vital principles.” Under the influence of these teleo-logic agents, the four aliments were transformed into blood and tissues. Prout termed the processes of digestion and blood formation “primary assimilation.” “Secondary assimilation” (Liebig’s “metamorphosis of tissues”) included both the process of tissue formation from blood and the destruction and removal of unwanted parts from the animal system. The absorption and removal of water from processed aliments were the principal chemical features of chylification and sanguification, respectively. Organization of processed aliments could not occur, however, without the presence and admixture of minute amounts of water or of elements other than carbon, hydrogen, oxygen, and nitrogen. In 1827 Prout coined the word “merorganized” to denote the isomerism and vitalization of organic substances by the presence of these incidental materials. For some years this concept was a serious alternative to the structural interpretation of isomerism.

Much of this metabolic theory was speculative, as was the corpuscular theory upon which it was based. In unpublished lectures (1814) Prout supposed that hydrogen might be converted by electricity into other elements and the imponderable fluids: caloric, light, and magnetism. In 1815 he published an unsigned article in which he reconciled information on the combining weights of substances with their combining volumes when in real or imaginary gaseous states. After several dubious assumptions and adjustments, Prout calculated that the atomic weights of all elements were integral when the atomic weight of hydrogen was taken as unity. In a correction (1816) he added that hydrogen might be the primary matter from which all other “elements” were formed.

Prout quickly identified himself as the author of these papers; and the two hypotheses, of integral atomic weights and of the unity of matter, became known ambiguously and singularly as Prout’s hypothesis. It was a continuous source of inspiration to chemists and physicists until the work of F. W. Aston on isotopes in the 1920’s T. Thomson, J.-B, Dumas, J. C. Marignac, and L. Meyer supported Prout, and Berzelius, E. Turner, J. S. Stas, Mendeleev, and T. W. Richards opposed him. But whatever the attitude of individual scientists toward the hypotheses or their modifications, they stimulated the improvement of analysis and enforced interest in atomic weights and, therefore, in the atomic theory. They also gave impetus to the search for a system of classification of the elements, and, when the periodic law was achieved, they encouraged speculations about the evolution of the elements and structural theories of the atom. Few hypotheses have been so persistently fruitful.

Prout left it to others, notably T. Thomson, to work out the consequences of his suggestions; but in 1831 he added that there was no reason why the material unit of condensation might not be smaller than hydrogen (perhaps half or one-quarter of hydrogen). This offered a convenient explanation of such anomalous, nonintegral atomic weights as chlorine and copper, and it was used by Marignac and Dumas.

In his Bridgewater treatise (1834; 3rd ed., 1845) Prout revealed that his hypotheses were only part of an elaborate corpuscular philosophy in which spherical particles were imagined to revolve spontaneously, with mutually repulsive forces and velocities that were inversely proportional to their masses. In addition, there were attractive forces that were directly proportional to the masses of the rotating particles. Like Aepinus and Mossotti, Prout supposed that the force of gravitation was the difference between the attractive and repulsive forces. The model remained a speculation, because there was no way of determining angular velocities independently of atomic weights.

This polarity theory also involved Prout in conclusions similar to those drawn by Avogadro in 1811: that at the same temperature and pressure, equal volumes of all gases contain equal numbers of molecules, and that all molecules of elementary gases contain at least two submolecules, or atoms. Like Avogadro, Prout deduced from this that the ratio of the weights of two equal volumes of different gases, at the same temperature and pressure, was equal to the ratio of their molecular weights. Prout was attacked for these views by the chemist William Charles Henry; but Prout’s support for Avogadro was without much influence, largely because he compromised with equivalent weights and because he was opposed to the use of chemical formulas.

Prout’s other significant contributions included unpublished thoughts on the unity of sensations (1810), on the distinction between taste and flavor (1812), on elaborate self-experiments regarding carbon dioxide output (1813, 1814), on a study of the chemical changes in an incubating egg (1822), on the neologism “convection” (1834), and on the design of the Royal Society’s standard barometer (1831–1836).

BIBLIOGRAPHY

I. Original Works. A list of 34 papers by Prout is recorded in the Royal Society Catalogue of Scientific Papers, V, 34–35. To them should be added W[illiam] P[rout], “The Sensations of Taste and Smell.” in London Medical and Physical Journal, 28 (1812), 457–461; and the unsigned “On the Relation Between Specific Gravities of Bodies in the Gaseous State and the Weights of Their Atoms,” in Annals of Philosophy, 6 (1815), 321–330, and 7 (1816), 111–113. The latter is repr. with an unsigned intro. in L. Dobbin and J. Kendall, Prout’s Hypothesis, Alembic Club Reprint no. 20 (Edinburgh, 1932), and in facs. in D. M. Knight, Classical Scientific Papers. Second Series (London, 1970). Note also Prout’s Gulstonian lectures, “On the Application of Chemistry to Physiology, Pathology and Practice,” in Medical Gazette, 8 (1831), 257–265, 321–327, 385–391; and his letter to Daubeny (1831), in C. Daubeny, An Introduction to the Atomic Theory (Oxford, 1831), 129–133; 2nd ed. (Oxford, 1850), 470–474.

Prout’s books were De febribus intermittentibus (Edinburgh, 1811), his M.D. thesis; An Inquiry Into the Nature and Treatment of Gravel, Calculus, and Other Diseases (London, 1821), 2nd ed. retitled Inquiry … Treatment of Diabetes, Calculus and Other Affections (London, 1825), 3rd ed. retitled On the Nature and Treatment of Stomach and Urinary Diseases (London, 1840), 4th ed. retitled On the Nature … Stomach and Renal Diseases (London, 1843; 5th ed., London, 1848). See also Chemistry, Meteorology and the Function of Digestion, eighth Bridgewater Treatise (London, 1834; 2nd ed., 1834; 3rded., 1845; 4th ed., 1855).

There are letters and papers of Prout’s at the Royal Society, the Royal College of Physicians, and the Wellcome Institute for the History of Medicine, London.

II. Secondary Literature. There were three principal obituaries: an unsigned one in Medical Times, 1 (1850), 15–17; an unsigned one in Edinburgh Medical and Surgical Journal. 76 (1851), 126–183; and C. Daubeny, “On the Great Principles Either Suggested or Worked out by Dr. William Prout,” in Edinburgh New Philosophical Journal, 53 (1852), 98–102, repr. in Daubeny’s Miscellanies, II (London, 1867), 123–127. The only comprehensive study is W. H. Brock, ’The Chemical Career of William Prout,” Ph.D. thesis (Leicester, 1966).

Important articles on Prout are O. T. Benfey, “Prout’s Hypothesis,” in Journal of Chemical Education, 29 (1952), 78–81; W. H. Brock, “The Life and Work of William Prout,“in Medical History, 9 (1965), 101–126; “The Selection of the Authors of the Bridgewater Treatises,” in Notes and Records. Royal Society of London, 21 (1966), 162–179; “Dalton Versus Prout: The Problem of Prout’s Hypotheses,” in D. S. L. Cardwell, ed., John Dalton and the Progress of Science (Manchester, 1968), 240–258; “Studies in the History of Proufs Hypotheses,” in Annals of Science, 25 (1969), 49–80, 127–137, which reprints Prout’s essay “De facultate sentiendi” and other notes; and “William Prout and Baromctry,” in Notes and Records. Royal Society of London, 24 (1970), 281–294; W. V. Farrar, “Nineteenth-Century Speculations on the Complexity of the Chemical Elements,” in British Journal for the History of Science, 2 (1965), 297–323; A. M. Kasich, “Prout and the Discovery of Hydrochloric Acid in Gastric Juice,” in Bulletin of the History of Medicine, 20 (1946), 340–348; D. F. Larder, “Prout’s Hypothesis, a Reconsideration” in Centaurus, 15 (1970), 44–50; and J. R. Partington, A History of Chemistry, III (London, 1962), 713–714, and IV (London, 1964), passim.

Two portraits of Prout are reproduced in G. Wolstenholme, The Royal College of Physicians Portraits (London, 1964), 346–348.

W. H. Brock