LIEBIG, WbiK, Jt'STtTS VON. Baron i31. One of the greatest chemists of the nine teenth century. He was horn at Darmstadt, Ger many. the son of a dealer in dyestuffs. He early showed a strong predilection for natural science. At the age of fifteen he became apprenticed to an apothecary at Heppenheim, near Darmstadt. Soon after he entered the University of Bonn. then went to Erlangen, where he took his doctor's degree in 1822. In that year he published a paper 011 fulminating mercury, and in 1823 went to Paris. where, by further researches on the fulminates. he soon attracted the attention of Alexander von Humboldt. Humboldt introduced Liehig to Gay-Lussae. Mr-wird, and Dulong, and the young German chemist was hospitably re ceived in the laboratory of Gay-Lussac. At the recommendation again of Humboldt, Liebig was made professor of chemistry at the Uni versity of Giessen (1524), where he remained for more than a quarter of a century, attracting students from all parts of Germany and from foreign countries. In 1845 the Grand Duke of Besse raised him to the rank of baron. In 1852 he became professor of chemistry at Munich. and in 1860 president of the Academy of Sciences and curator-general of the scientific collections of Bavaria. He remained in Munich until his death.
When Liebig hegan his career chemistry was in its infancy. Above all, organic analysis was in an extremely undeveloped state; so that a great deal of ingenuity was required in carrying out what arc now very simple analytical determina tions. At the time of Liebig's death chemistry, both pure and applied, had developed beyond all expectations; and Liebig had contributed more than any one of his contemporaries to its pro digious growth. Liebig established the first laboratory where students might receive a thor ough practical training in chemistry, to supple ment the instruction given in the lecture-room (see LABORATORY) , and in Liebig's own laboratory some of the most distinguished nineteenth-cen tury chemists were trained. Another great ser Tice was his introduction of thew-ell-known method )f organic analysis. (See CHEMISTRY, section 9rganic Chemistry.) The number of carbon com pounds discovered and studied by Liebig himself was very great. He analyzed many important natural alkaloids; investigated the action of chlorine on alcohol and discovered chloral and chloroform; studied the products of oxidation of alcohol and discovered ahlehyde; determined the basicity of many organic acids: investigated the chemical composition of urine and the derivatives of uric acid; analyzed the juice of flesh, etc. His theory of the constitution of alcohol, ether. and chlo•oethane. and the celebrated research carried out jointly with \Viihler (q.v.) on the benzoyl compounds. gave a powerful impulse to tim de velopment of chemical theory. Among his con tributions to chemical technology may be men tioned his method of making the cyanide of potassium, a compound extensively used in elec troplating and in the manufacture of ferroey anides. The discovery of aldehyde, mentioned above, has led to important improvements in the manufacture of mirrors and of vinegar.
The phenomena of animal and vegetable life formed one of Liehig's favorite branches of re search, and he was the first to advanee the theory that the activity of physical and chemical forces is the same in the organized as in the mineral world. He proved experimentally that
animal heat is nothing hut the energy liberated by the combustion in the organism mainly of fats and carbohydrates. Foods which serve as fuel and supply the heat of the body he termed respiratory foods. Nitrogenous substances. which —as he showed—serve to build up the tissues of the body. he termed plastic foods. He was also the first to prove that the transformation of inorganic into organic substances takes place exclusively in the organisms of plants, from which animals receive ready-formed the principal substances of their flesh and blood. Plants, on the other hand, receive their nourishment from the soil and the air, the former supplying them with the sulphates, sulphites. and phosphates of sodium, potassium, ealcium.maly,nesium, and iron : while the atmospheric air supplies them with carbonic acid, water, ammonia, and nitric acid. It thus became clear that, in order to maintain the fertility of the soil, the saline ingredients necessary fur the growth of plants must from time to time be restored to it, either in isolated form or in the form of the sewage of towns, in which they are contained in considerable quan tity. The importance to agriculture of the manufacture of saline fertilizers, which has thus originated in Liebi,g's researches, is inestimable, and Liebig may justly be considered as one of the founders of agricultural chemistry. See CHEMISTRY, AGRI(' ELTERA L.
Liebig's Chemistry in Its Application to Agri culture and Physiology appeared in Brunswick and in London in 1540. The second part of this epoch-making work was published under the title, The Natural Law of Husbandry (Brunswick, 1862; London, 1863). Ibis Animal Chemistry, or Chemistry in Its Application to Physiology and Pathology, appeared in 1842 I Brunswiek and London; • 3d German ed., Brunswick, 1846). An English translation of his paper on foods ap peared in London in 1847, under the title. Re searches on the Chemistry of Food. The cele brated Handbook of Organic Analysis was pub lished in Brunswick and in London in 1853. Liehig's publications further include: Hand worterbuch der Chem ie. the compilation of which he began in conjunction with Poggendorff(9 vols., Brunswick, 1S36-64, and a later edition) ; Handbuch der organisehen Chemie (Heidelberg. 1839-43) ; Theorie and Praxis, in der Landwirt schaft (Brunswick. 1856) ; Naturwisscnschaft liche B•iefe -fibe• die moderne L«mlwirtschaft (Leipzig, 1859), etc. The celebrated Chemische Bricfe (Familiar Letters on Chemistry) first appeared in the A ugsburgcr Allgemeine Zeitung (6th German ed. Leipzig. 1575) ; it has ;men translated into most European languages. The list of Liebig's scientific papers comprises more than 300 titles, each paper forming a valuable contribution to organic• science. In his private life Liebig was kind and hospitahle, noble in thought and generous in feeling. Numberless honors were bestowed upon him. Consult. Hof mann. The Life-Work of Liebig in Experimental and Chemistry (London, 1876).