Educator Indian Journal of Chemical Technology Vo l. I 0. July 2003, pp. 424-434 James Dewar-More than a flask Jaime Wi sniak Department of Chemical Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel 841 05 James Dewar (1842-1923) is widely known for his pioneering work i.n cryogenics, of being the first to achieve the liquefaction of hydrogen, by the flask that carries his name, and by his studies about the behaviour of living organisms and materials under conditions of extreme cold. Although he was an excellent experimentalist, he did not leave many significant theoretical contributions. 12 Life and career ' James Dewar (Fig. I) was born on September 20, 1842, in Kinkardine-on-Forth, Scotland, the youngest of seven sons of Thomas Dewar and Ann Eadie Dewar. When he was ten years old he went skating and fell through ice in a frozen lake and when rescued walked about in hi s wet clothes until they were dry so that his family would not know about his accident. As a result he contracted rheumatic fever, which crippled him; he had to go on crutches for a couple of years and was left with a damaged heart. During this period he was in much contact with the village carpenter and practiced his hands in making violins. He always regarded th e training he thus received as the most important part of hi s education and the foundation of the great manual dexterity, which he displayed in hi s 1 work and hi s lectures • By the time he was fifteen he had lost both parents and went to li ve with one of hi s brothers who owned a drapery shop in Kincardaine. He stayed with him until he was admitted to the Dollar Academy in Clack­ mann shire. At school he was a very distinguished student and was awarded many prizes, one of them in Fig. I- James Dewar ( 1842-1923). By permission of Edgar Fahs Peter Guthrie Tait's (1831-1901) class; with whom he Smith Collection, University of Pennsy lvani a Li brary. would later do research on high vacuum. After graduation he went to Edinburgh University demonstrator for Lyon Playfair ( 181 8-1898). where he li ved with hi s brothers Alexander, then professor of chemistry from 1867 to 1868. Pl ayfair nearly through hi s medical course. Eventually hi s retired in 1868 (to serve in Parliament, he occupi ed brother was appointed assistant to professor James various positions such as Postmaster General and Syme (1799-1870), and through him James was Lord in Waiting of Queen Victoria) and Dewar was probably in full touch with medicine. appointed assistant to hi s successor, Alexander Crum He graduated from Edinburgh as a chemist in 1861 Brown (1838-1922). Dewar taught the medical and stayed on for almost a decade, first as tutorial laboratory class. assistant to James David (1828-1876) and then as In 1869 Dewar was appointc:d Lecturer ( 1869- 1873) and then Professor in the Royal Vererinary E-mail: wisr.iak @bgum ai l.bgu.ac. il College. Between 1873 and I 875 he was appointed Wisniak: James Dewar-More then a flask Educator assistant chemist to the Highland and Agricultural He was appointed Director of the Davy Faraday Society of Scotland and delivered district lectures for Research Laboratory of the Royal Institution ( 1896- this body. He was put in charge of analysing manure, 1923) and was President of the Chemical Society, of foodstuff and fertilizers, lecturing the agricultural the Society of Chemical Industry, and of the British association on chemistry and answering any specific Association. inquiries. He was member of the Royal Institution of Great During the period 1867-1875, he did research on a Britain, honorary member of the Institution of Civil variety of subjects in chemistry, biology and physics. Engineers, member of the Institution of Electrical He was associated with William Dittmar (1833-1892), Engineers, and member of the British Association. Arthur Gam gee ( 1841-1909) on physiological Dewar was knighted in 1904. chemistry; John Gray McKendrick (1841-1929) on the physiological effect of light on animals; and with Awards Tait on the production of vacuum and in experiments The Royal Society awarded to Dewar its three most with William Crookes's (1832-1919) newly invented prestigious medals: Rumford (1894), Davy (1909), radiometer. · and Copley (1916). He received the first Hodgkins In 1875 he was appointed Jacksonian professor of Gold Medal of the Smithsonian Institution (1899); the natural experimental philosophy in the University of Gunning Victoria Jubilee Prize of the Royal Society Cambridge and became the colleague of George of Edinburgh (1904); the first Lavoisier Gold Medal Downing Liveing (1827-1924). Two years later he of the French Academy of Sciences (1904); the also became Fullerian professor of chemistry at the Matteuci Medal of the Societa ltaliana delle Scienze Royal Institution, London, replacing John Hall (1906); the Albert Medal of the Royal Society of Arts Gladstone (1827-1902). (1908); the Medal of the Society of Chemical Jndu stry According to Armstrong' "Dewar was not great as ( 1918); and the Franklin Institute Medal (1919). a teacher. His mind was of too original and impatient a type. He never suffered fools gladly and students are Scientific activities too apt to be foolish, even to ape the part of superior Dewar is widely known for his pioneering work in beings. His forte lay in directing competent hands, not cryogenics, the first to achieve the liquefaction of in forming them. He worked himself and through hydrogen, by the flask that carries his name, and hi s skilled assistants, not through pupils. He was violently studies about the behaviour of living organisms and impatient of failure in manipulation, and his work was materials under conditions of extreme cold. Although almost entirely manipulatory. He, therefore, never he was an excellent experimentalist, he did not created a school." distinguish with theoretical contributions. He left us In 1871 Dewar married Helen Rose Banks, the with more than 265 scientific papers in the many daughter of an Edinburgh printer; they had no areas he was active. children. Here are described ~orne of his most important James Dewar died on March 23, 1923, while at contributions. work, at the Royal Institution on Albemarle Street. He was 82 years old. By his express wish his remains The structure of benzene were cremated at Golder's Green. One of the first incursions of Dewar into organic chemistry was related to the oxidation of unsaturated Honours hydrocarbons. He was aware that a common method James Dewar received many honours for his for determining the structure of a compound was by contributions to science and industry. He was oxidation and analysis of the products. In the case of awarded many honorary degrees, among them, M.A., benzene derivatives, although the synthesis and Honoris Causa (1875), Cambridge; honorary LL.D. analysis of its derivatives confirmed each other, the from Glasgow, St. Andrews, Edinburgh and structure of the principal nucleus remained Aberdeen; and honorary D.Sc., Victoria, Oxford, and unexplained. For many years Agustin Kekule ( 1829- Dublin. He was nominated Fellow of Peterhouse 1896) had tried to solve the riddle and in 1865 he had College, Fellow of the Royal Society of London, of suggested that benzene consisted of a ring of six the Royal Society of Edinburgh, of the Institute of carbon atoms decorated with six peripheral hydrogen Chemistry, of the Chemical Society, and of the atoms; the carbon atoms were arranged in a closed Society of Chemical Industry. chain with the carbon bonds bound two and one 425 Educator Indian J. Chem. Techno!.. Jul y 2003 separately. Now, if the formula was examined graphically, it became evident that benzene had to have three symmetrical groupings, C2H2 (acetylene). Dewar reasoned3 that if Kekule's model was correct then oxiqation would separate the carbon atoms in .. pairs and yield the corresponding oxidized product, ., C2Hc0 4, oxalic acid. He tried oxidizing benzene with ·,..:· potassium permanganate in a sealed tube at 150°C, •:It but no ·reaction occurred; addition of aqueous . potassium permanganate to an aqueous solution of ~a• phenyl alcohol (phenol) resulted in immediate ... decomposition, the solution became alkaline and .•.. • manganese peroxide precipitated. Acidulation of the . I· . liquid phase and addition of calcium acetate .· precipitated calcium oxalate. Dewar believed that by controlled oxidation of phenol several substances might be produced, such as oxalic and fumaric acids. He added that if the resisting nucleus in benzene was C4H2, then he would expect that mellitic (C4H 20 4) acid would be formed. 3 In this publication Dewar did not present any J • . significant experimental results that helped nail down \~::/ (/ . / ·. the chemical structure of benzene. But his paper has ..... ·~ ... an especial feature that illustrated his understanding .. of the problem as well as his manual skills. He described the construction a simple mechanical arrangement adapted to illustrate the structure in non­ saturated hydrocarbons. His device consisted of a seri es of narrow thin bars of brass of equal length, where it was possible to join every two of the bars in Fig. 2-Structures of benzene as sugg:!sted by Dewar th e centre by a nut. This primary structure represented using hi s kit. a single carbon atom with its four places of attachment. In order to make the combination look The chemical action of light like an atom, Dewar added a thin round disk of Dewar did work on the chemical action of li ght on blackened brass under the central nut. When a number plants and its physiological effects on the retina and 45 of carbon atoms were now joined together, all the the optical nerve · .