WILLIAMSON, ALEXANDER WILLIAM

(b Wandsworth, London, England, 1 May 1824; d, Hindhead, Surrey, England, 6 May 1904)

organic chemistry.

Although he published little, Williamson was the most influential chemist in Great Britain during the period 1850–1870, two critical decades in which chemists released themselves from the stranglehold of Berzelius’ electrochemical dualism, forged a unitary system of inorganic and organic chemistry, created a rational system of atomic weights, developed concepts of valence and structure, and organized themselves professionally. In all these changes and developments Williamson was a leader, as researcher, teacher, critic, and elder statesman.

Williamson was the second of three children of Alexander Williamson, a clerk at East India House who was a friend of the economist James Mill, and Antonia McAndrew, a merchant’s daughter. Throughout his life he was racked by severe physical disabilities: a semiparalyzed left arm, a blind right eye, and a myopic left one. These deficiencies undoubtedly promoted his later disenchantment with detailed laboratory work and encouraged his theoretical and speculative powers, which had been stimulated by his philosophical education. In 1840, following schooling and private instruction at Kensington, Paris, and Dijon, Williamson began medical training at the University of Heidelberg, where he was encouraged to study chemistry by Leopold Gmelin. From 1844 to 1846 he worked with Liebig at Giessen, where he published his first papers on bleaching salts, ozone, and Prussian blue. Apparently he had independent means, and from 1846 to 1849 he established a private research laboratory in Paris, where he fraternized with Laurent, Gerhardt, Wurtz, and Dumas and, on the recommendation of his older childhood friend John Stuart Mill, took private lessons in mathematics from Auguste Comte. The latter regarded Williamson as one of his most promising converts to positivism, but in England Williamson proved a disappointing disciple and advocate.

In 1849, encouraged by Graham and supported by Liebig, Dumas, Laurent, and Hofmann, Williamson applied for the vacant chair of practical chemistry at University College, London. On Graham’s retirement from the chair of general chemistry in 1855 Williamson, rather unfortunately, took both titles. He remainded at University College until his retirement to farming in the countryside at Hindhead in 1887. As far as active research was concerned, however, Williamson’s retirement dated from the completion of his etherification studies in 1854. The reasons for this are complex. Certainly the falling off of his research was not due to any loss of mental power, nor entirely to his absorption in academic politics (where his agitation for university science degrees was successful in 1870), nor yet to his involvement in the affairs of the Chemical and Royal Societies or the British Association for the Advancement of Science. The apparent decline of his work did. however, accompany the development of other practical and engineering interests that ultimately proved fruitless technically and financially, and for which little documentary evidence survives. The only positive results of these enthusiasms were pedagogic: Williamson insisted that his chemistry classes take conducted tours of industrial plants, and he was instrumental in creating a chair of applied chemistry (chemical engineering) at University College.

Many private letters refer to Williamson’s superior and acute intellectual powers. Kekulé, who was in London from 1854 to 1855, found his friendship nd ideas “excellent schooling for making the mind independent,” while Odling was always proud to have followed in his footsteps. Acquaintances were sometimes repelled by his tendency to make cutting remarks; and in arguments he constantly interrupted, so that his opponent’s meaning could not be fully expressed. He was a forceful and dogmatic critic of papers at the Chemical Society, for which he established the valuable system of monthly abstracts of British and foreign papers in 1871. Basically, however, he was a kindly man whose sociability, and that of his wife Emma Catherine Key, made him the natural choice as British host to the first Japanese noblemen who came to England to learn Western ways in 1863.

Williamson announced his elegant theory of etherification to the British Association at Edinburgh in August 1850. At this time there were various rival theories concerning the structures of alcohol and ethyl ether, but in all cases ether was supposed to be formed by the loss of water from alcohol. Williamson’s initial intention, however, was not to Clarify a muddled theoretical situation but to develop practical methods for preparing the homologous higher alcohols. To his “astonishment,” when he used Hofmann’s alkyl radical substitution technique and reacted ethyl iodide with a solution of potassium in alcohol (potassium ethylate [ethoxide]), he obtained ordinary ethyl ether instead of an ethylated alcohol (Williamson’s synthesis).

Influenced by his familiarity with the work of Laurent and Gerhard, Williamson saw that the relationship between alcohol and ether could not be one of the loss or addition of water but, rather, of substitution, since ether contains two ethyl radicals but the same quantity of oxygen as alcohol. Since equal molecular magnitudes were involved, the formulas of these substances had to be expressed in terms of the French chemists’ formula for water, H₂O (instead of HO or H₄O₂):

Williamson saw, however, that this result might still be explained according to a four-volume formulation(H₄O₂)if it were supposed that both potassium ethylate and ethyl iodide contained ether:

This possibility was disproved by using methyl (instead of ethyl) iodide, in which case a mixed ether was formed, not a mixture of ethyl ether and methyl ether:

not

These views were confirmed independently by G.C. Chancel in 1850.

Williamson also explained the process of continuous etherification by the action of sulfuric acid on alcohol. According to the contact theory of Mitscherlich and Berzelius, the sulfuric acid acted merely as a catalyst in this reaction; but according to Liebig’s chemical theory, ether was produced only after the intermediate formation of ethyl hydrogen sulfate. The latter, argued Williamson, played a role in the double decomposition analogous to that of potassium ethylate in his synthesis of ether. He represented the exchanges in two stages:

I.

The sulfuric acid produced in II was recycled for further decompositions.

Williamson’s impressive study has been rightly seen as laying the foundation for twentieth-century mechanistic studies. Historically it had a number of important consequences. First, Williamson completely rejected the notion of a catalytic force and opted for chemical intermediates in catalyzed reactions. In this stand he echoed Comte, for whom catalysis was a metaphysical fancy improper to the positive stage that chemistry was achieving. Second, Williamson was led to visualize atoms and molecules in motion, and not as the static particles of traditional Daltonism. The mechanism of etherification was inconceivable unless it was viewed as a process of continuous atomic exchange. Such a viewpoint proved to be a major step toward the reunification of chemistry with physics via the kinetic theory of gases, the ionic theory of electrolytes, and the revival of Berthollet’s law of mass action. Williamson developed his views on dynamic atomism only in a series of lectures; confirmatory experiments with slow double decompositions were abandoned after a severe explosion. Finally, and most important, the study suggested that analogies for the structures of both organic and inorganic substances should be based on the inorganic type, water.

Echoing Laurent’s use in 1846 of a water analogy, Williamson argued in 1851 that “water may be assumed as a very general type and standard of comparison, by viewing other bodies as formed from it by the replacement of one or more atoms of hydrogen in water by the equivalent of various simple or compound radicals” (Papers on Etherification, 40). For instance,

Through the work of Odling and Gerhardt this formal analogy with water completed the unification of organic and inorganic chemistry (the “new type theory”); and through the admission of valence by Frankland, Kekulé, and Odling it permitted the emergence of the real structural formulas that Williamson saw as the ultimate goal of positive chemistry. The use of multiples of water, suggested by Williamson in 1851, gave a ready explanation for differences of basicity and was confirmed by him in 1856, when the chlorination of sulfuric acid produced chlorosulfonic acid:

Similarly, his “prediction” of a class of anhydrous organic acids formed by the replacement of the H of acetic acid was dramatically confirmed by Gerhardt in 1852, when he reacted acetyl chloride with potassium acetate:

During the 1860’s Williamson, who was a devout atomist, did much to eradicate the predominant skepticism of his fellow chemists. His proselytism culminated in a famous clash with his friend B.C. Brodie, Jr., at the Chemical Society in 1869. Brodie’s interest in notation and nomenclature was shared by Williamson, who faced the problems involved when writing his chemistry textbook (1865). In 1864 he introduced parentheses into formulas to enclose reaction-invariant groups, such as Ca(CO₃)₃: abolished the Berzelian “plus” sign in compounds: and proposed the suffix “-ic” for the base of all salts (including hydrogen) to avoid cir-cumlocution–for instance, “sodic chloride” for “chloride of sodium” and “hydric sulphate” for “sulphuric acid.” Although the latter convention was adopted by several British chemists, it did not survive into the twentieth century.

BIBLIOGRAPHY

I. Original Works. Thirty-five papers by Williamson are recorded in Royal Society, Catalogue of Scientific Papers, VI, 379–380; VIII, 1244–1245; XI, 817; XIX, 637. The major ones are conveniently collected as Papers on Etherification and on the Constitution of Salts, Alembic Club Reprint no. 16 (Edinburgh, 1902; reiss., 1949). This reprint unfortunately does not include “On Dr. Kolbe’s Additive Formulae,” in Journal of the Chemical Society,7 (1855), 122–129, published in reply to A. W. H. Kolbe, “Critical Remarks on Williamson’s Water, Ether and Salt Theories,” ibid., 111–121–German original in Justus Liebigs Annalen der Chemie,90 (1854), 44–61. These papers exemplify the clash between the type and radical theories. Williamson published two books: a political tract written with his father-in-law. T. Hewitt Key, Invasion Invited by the Defenceless State of England (London, 1858): and Chemistry for Students (Oxford, 1865; 2nd ed., 1868; 3rd ed., 1873), for which Problems From Williamson’s Chemistry With Solutions (Oxford, 1866) was also issued.

Williamson’s correspondence with Brodie is printed in W. H. Brock, ed., The Atomic Debates (Leicester. 1967), 95–96, 119–120. The bulk of Williamson’s papers, which were in the possession of his son, Dr. Oliver Key Williamson, were stolen during a native rebellion in Africa (private information from J. Harris, 1963). For surviving letters and referee’s reports, consult the Royal Society, Royal Institution, and Imperial College Archives, London.

II. Secondary Literature. There are two detailed and very find obituaries by Williamson’s pupils: Edmund Divers, in Proceedings of the Royal Society,78A (1907), xxiv–xliv, with portrait; and G. Carey Foster, in Journal of the Chemical Society,87 (1905), 605–618; the German trans. in Berichte der Deutschen Chemischen Gesellschaft,44 (1911), 2253–2269, has an unusual photograph, Williamson’s relationship with Comte is discussed by W. M. Simon, “Comte’s English Disciples,” in Victorian Studies,8 (1964–1965), 161–162; and by Brock (see above), 145–152, who also treats Williamson’s atomism extensively. For Williamson’s friendship with Laurent and Gerhardt, see the nonindexed E. Grimaux and C. Gerhardt, Jr., Charles Gerhardt : sa vie, son oeuvre, sa correspondance (Paris, 1900), 218, 220–221 (letter of 1851), 240–243, 249–250, 263–264, 412–413, and 558; and with Kekulé, see R. Anschütz, August Kekulé, I (Berlin, 1929), Possim, The context of Williamson’s work is fully discussed in J. R. Partington, A History of Chemistry, IV (London, 1964), ch. 14; J. S. Rowe, “Chemical Studies at University College, London” (Ph.D. diss., London, 1955), 211–328^e; and C. A. Russell, A History of Valence (Leicester, 1971), ch. 3. See also J. Harris and W. H. Brock, “From Giessen to Gower Street: Towards a Biography of Williamson,” in Annals of Science,31 (1974), 95–130.

W. H. Brock