Young, Sydney

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(b. Farnworth, near Widnes, Lancashire, England, 29 December 1857; d. Bristol, England, 8 April 1937)

physical chemistry.

Young was a pioneer in the separation and specification of pure organic compounds, and clarified crucial thermodynamical relationships for solids and liquids. The third son of a merchant, he spent five years at a private school in Southport and two years at the Royal Institution School in Liverpool. After being in business for over two years, he entered Owens College, Manchester, in 1876, studying chemistry under Henry Roscoe and Carl Schorlemmer. In 1880 Young graduated B. Sc. of London University. He then became elected an associate of Owens College in 188 1. Young spent the semester 1881 ,–1882 at Strasbourg, where he was one of the first to assist Rudolph Fittig in an extended investigation “of the relations between lactones and the corresponding acids.”1 In 1883 he obtained the D. Sc. from London University and in 1893 he was elected fellow of the Royal Society.

Young had been appointed lecturer and demonstrator of chemistry at University College, Bristol, under William Ramsay in the autumn of 1882, and lie succeeded to that professorship in 1887. Young married Grace M. Kimmins in 1896 and they had twin sons.

Young was stimulated by Thomas Carnelley’s observation of “hot” ice in 1881. He proved that the volatilizing point of ice depended upon the pressure and showed “that the volatilising point-pressure curve is identical with the vapour pressure curve constructed from the data calculated on theoretical grounds by James Thomson and by Kirchhoff.”2 This result for ice, whereby the graph representing the vapor pressure at different temperatures also represents the volatilizing point as a function of pressure, was extended to other volatile solids as well as to substances such as benzene. Young and Ramsay in partnership at Bristol published an exhaustive series of researches concerning the vapor pressures of liquids, thereby clarifying the vexed question of whether Kopp’s quantitative laws held at all pressures. In 1885 Ramsay and Young derived an empirical equation that relates the ratio of absolute temperature of two liquids at a given vapor pressure, say Ta/Tb,to the same at another vapor pressure, say Ta/Tb, so that

Ta/Tb = Ta’/Tb’ + c(TaTa’),

where c is constant.

Showing that c is very small or even negligible for two closely related chemical substances (they used chloro- and homobenzenes), one can say that Ta/Tb = Ta’/Tb’. The significance is that this ratio is constant at all vapor pressures and that the ratio of the boiling points of two similar substances is the same, no matter what the external pressure. Later, Young tested van der Waals’ equation of state noting that it was “strictly true” only for closely related substances, such as the four halogen derivatives of benzene. In the case of non-associated substances “the ratio of the actual to the theoretical density at the critical point should be the same for all unassociated substances”3, and van der Waals had determined the ratio RTc/pcVc = 2.67. The actual values of this ratio tend to range between 3 and 4 being much higher in the case of associated substances. Modifying the equation of state, Conrad Dieterici in 1899 succeeded in obtaining the theoretical ratio 3.695.4 For this work Young devised a new method, improving upon the law of Cailletet and Mathias, for determining the critical densities of liquid and saturated vapor.

From 1885, the potential for extracting paraffin hydrocarbons from petroleum and a general need for substances in the purest possible state led Young to devise improved techniques of fractional distillation. He designed and constructed his own efficient still heads, having become an expert glassblower while at Strasbourg. He examined the vapor pressures, boiling points, and behavior on distillation of mixed liquids including azeotropic mixtures. He also developed a new method of dehydrating ethyl alcohol using benzene and made fundamental contributions concerning the separation and specification of the various hydrocarbons of petroleum5. In 1904 Young proposed that the difference in boiling points between two successive homologues of most unassociated compounds is not constant, as Kopp had maintained in 1842, but is a function of the absolute temperature, approximating the empirical formula

where T is the absolute boiling point of the lower member. Most of Young’s publications appeared during his twenty-one years at Bristol. Succeeding James Emerson Reynolds at Trinity College, Dublin, in 1903, he assumed a post not conducive to continued research, but he did advance the development of the practical applications of his separation techniques6. Although Young established no “school,” he was the first to prove that pure organic compounds are no less unique than inorganic elements ; and through his techniques he exerted a profound, albeit often indirect, influence on all subsequent research concerning their purification.7


1. E. von Meyer, A History of Chemistry (London, 1891), 410-411.

2. “On the Volatilisation of Solids,” in A. Keitner.Menschen rind Menschenn erk, II. 453.

3. Ibid.,453-454.

4. A. Findlay, Introduction to Physical Chemistry, 3rd ed. (London, 1953), p. 85.

5. The industrial implications of this patented dehydration process using a third liquid seem first to have been appreciated and adopted by the firm of C. A. F. Kahlbaum, Chemische Fabrik, Berlin. Young received special recognition in 1933 from the Petroleum Division of the American Chemical Society, which expressed high appreciation of his work on dis-tillation, on the composition of petroleum, and on the specification of numerous hydrocarbons.

6. Young elaborated a quantitative analysis of the process in Fractional Distillation (1903; 1918) and included industrial applications in Distillation, Principles and Processes (1922).

7. J. Timmermans, “Sydney Young,” 13–14.


I. Original Works. Most of Young’s more than 100 publications are listed in W. R. G. Atkins, “Sydney Young,” in Obituary Notices of Fellows of the Royal Society of London, 2 (1938), 370-379, also abbreviated in Dictionary of National Biography, 1931-1940, 932-933. His books include Fractional Distillation (London, 1903); Stoichiometry (London, 1908; 2nd ed., 1918); and Distillation, Principles and Processes (London, 1922), written with Ernest Briggs, T. H. Butler, T. H. Durrans, F. R. Henley, James Kewley, and Joseph Reilly; 2nd ed. condensed and translated into German as Theorie und Praxis der Destillation (Berlin, 1932). His scientific “autobiography” is “On the Volatilisation of Solids and the Thermic Properties of Mixtures of Liquids,” in A. Keitner, ed., Menschen and Menschenwerke, II (Vienna, 1925), 453-454, preceded by a German version, 451-453, and followed by a French version, 455-456. This is preceded by a brief autobiographical résumé, 450-451, in the three languages. Two autobiographical letters, dated 8 Nov. 1892 and 13 Feb. 1893, accompanied by his list of publications, are in the Krause Album, IV, held in the Sondersammlungen of the library of the Deutsches Museum, Munich.

II. Secondary Literature. Young’s successor at Bristol, F. Francis, considered his work in detail in Journal of the Chemical Society (1937), 1332-1336; and there is an anonymous obituary in Nature,180 (1957), 1451. His work on critical constants is considered in W. Nernst,Theoretische Chemie (Stuttgart, 1921), 241–246. The importance of Young’s research and influence on the purification of organic compounds is stressed in J. Timmermans, “Sydney Young,” in Endeavour,6 (1947), 11 – 14. A discussion of subsequent developments pertaining to the distillation of hydrocarbons at high pressures is in the article on M. Benedict in Modern Men of Science, I (New York, 1966), 31. Young’s research on boiling points in relation to the work of his contemporaries is considered in S. Smiles, The Relations Betxveen Chemical Constitution and Some Physical Properties (London, 1910), ch.7. The significance of Young’s experimental results for theoretical chemistry is considered in H. Davies, “On Some Applications of the Law of the Rectilinear Diameter,” in Philosophical Magazine, 6th ser.,24 (1912), 418–421 : and G. Le Bas, “The Unit-Stere Theory,” ibid.,14 (1907), 340– 346.

Thaddeus J. Trenn