TRICITY, CONDUCTION OF, Liquids; and ELECTROLYSIS). It con tains some ideas which later investigations have shown to require modification, but forms the foundation upon which all subse quent theories of conductivity of solutions have been built. The revolutionary nature of the theory, which required, for instance, that free sodium ions should exist in a solution of sodium chloride, prevented its being speedily accepted, and it may be said that it was neglected rather than actively opposed.
Arrhenius himself has put on record an anecdote which throws light on the attitude towards his views when they were new : "I came to my professor, Cleve, whom I admired very much, and I said, `I have a new theory of electrical conductivity as a cause of chemical reactions.' He said, `This is very interesting,' and then he said, `Good-bye.' He explained to me later that he knew very well that there are so many different theories formed, and that they are almost all certain to be wrong, for after a short time they disappeared ; and therefore, by using the statistical man ner of forming his ideas, he concluded that my theory also would not exist long." In 1887 he published a much revised, extended and consolidated version of his theory of electrolytic dissociation, entitled "Uber die Dissociation der in Wasser gelosten Stoffe" in the Zeitschrif t fur physikalische Chemie, which had just been founded. Arrhenius' first thesis had won him the support of Ostwald (q.v.), in whose institution he worked in 1886, and in 1887 he entered into an inti mate friendship with van't Hoff (q.v.). The theories of van't Hoff on osmotic pressure and of Ostwald on the affinity of acids ac corded admirably with the views of Arrhenius, and these three friends fought together in unselfish alliance for the new doctrines, which ultimately won general acceptance. Arrhenius had a genius for friendship, and in the 4o years between 1887 and his death met practically all the great men of science, and won their affection no less than their regard.
In 1891 Arrhenius declined a professorship at Giessen and was appointed lecturer at the Stockholm university : in 1895 he was elected to a professorship there. From 1887 to 1902 he also ful filled the office of rector of the university. During this time he was occupied in extending the application of the doctrine of electro lytic conductivity to a variety of problems of chemical action, and also, on the supposition that in certain conditions air conducts electrolytically, to the phenomena of atmospheric electricity. In 190o he published his Ldrobok i tizeoretik electrokemi (Treatise on theoretical electrochemistry) which was translated into German and English and his Lelirbuch der kosmischen Physik (Treatise on Cosmic Physics) appeared in 1903. In the same year he was awarded the Nobel prize for chemistry.
Arrhenius was a man of very wide interests, and about this time he began to turn his attention to problems of the chemistry of liv ing matter. In 1904 he delivered at the University of California a course of lectures designed to illustrate the applications of the methods of physical chemistry to explaining the reactions of toxins and antitoxins. These lectures were published in 1907 under the title Immunochemistry, and in 1915 he published further contribu tions to exact biochemistry under the title Quantitative Laws in Biological Chemistry, in which he again devoted much attention to toxins. He was also much occupied with problems of cosmogony. In his Worlds in the Making (1908), an English translation of Das H'erden der Welten (1907), he combated the generally accepted doctrine that the universe is tending to what Clausius termed Wiirmetod (death of heat) through exhaustion of all sources of heat and motion, and suggested that by virtue of a mechanism which maintains its available energy it is self-renovating, energy being degraded in bodies which are in the solar state, but elevated or raised to a higher level in bodies which are in the nebular state. He further put forward the conception that life is universally dif fused, constantly emitted from all habitable worlds in the form of spores which traverse space for years or ages, the majority being ultimately destroyed by the heat of some blazing star, but some few finding a resting-place on bodies which have reached the hab itable stage. He was one of the first to stress the important part which the pressure of light must play in cosmic physics, and pointed out that the repulsion of the tails of comets from the sun could be explained by this pressure. Astronomical problems, especially the question of the habitability of Mars, are discussed in his Destinies of the Stars (1918) .
With the Nobel prize in 1903 Arrhenius may be said to have re ceived universal recognition as one of the great men of his time. In 1905 he refused a full professorship and private laboratory in Berlin, and was appointed director of the Nobel Institute for Physical Chemistry at Experimentalfaltet, just outside Stockholm, a post which he held until his death on Oct. 1, 1927. In 1910 he was made a foreign member of the Royal Society, and in the course of his later career he received numerous honorary doctor ates in both the old and new world, as well as the Davy medal of the Royal Society and the Faraday medal of the Chemical Society. He delighted both to visit his colleagues abroad and to receive his contemporaries and students at his home. A genial humour characterized both his discourses and his private conversation, and few men more than Arrhenius were welcome at scientific dis cussions in any land.
Besides the books mentioned above Arrhenius wrote Theories of Solution (1912). He also published, in 1926, Erde and W eltall, a combined and revised reissue of Das Werden der Welten and Der Lebenslauf der Planeten. A German translation of his original thesis on Galvanic Conduction in Electrolytes was published as No. i6o of Ostwald's Klassiker in 1907. A study of the life and work of Arrhenius, written by Ostwald, appeared in the Zeitschri f t fur physikalische Cliemie in 1909, and there is much about him in Professor Ernst Cohen's study, Jacobus Henricus van't Hoff, published in Leipzig in 1912. (E. N. DA C. A.)