Justus Von Liebig, baron, a German chemist, born in Darmstadt, May 12, 1803, died in Munich, April 18, 1873. While a youth he was taught in the gymnasium of his native town; and, after spending ten months in an apothecary's establishment, he entered in 1819 the university of Bonn. Afterward at Erlan-gen he obtained the degree of M. D. By the assistance of the grand duke of Hesse-Darmstadt he was enabled in 1822 to visit Paris, where he devoted two years to the study of chemistry. In 1824 he read a paper before the French institute on the chemical composition of fulminates, which attracted the attention of Humboldt, and by his influence Liebig was appointed adjunct professor of chemistry at Giessen. In 1826 he was made professor in the university, and soon established a laboratory for teaching practical chemistry, the first of the kind in Germany. It became a resort for students from different parts of the world, and especially from England, among whom are found the names of Lyon Playfair, Gregory, and Johnston. Hofmann, Will, and Fresenius were his assistants.

In 1832 Liebig with Prof. Geiger of Heidelberg established the Annalen der Pharmacie, to which he continued to be a contributor till near the time of his death, and scarcely a volume of which up to 1862 does not contain some important paper by him. In 1838 he visited England, and at the meeting of the British association for the advancement of science read a paper on lithic acid, in which he announced the discovery by Wohler of the composition of urea and the method of making it artificially. The association requested him to draw up two reports, one on isomeric bodies, the other on organic chemistry. The response was made in 1840, in a work dedicated to the British association, entitled Die organische Chemie in Hirer Anwendung auf Agricultur (Brunswick, 1840), which was translated into English from the manuscript by Dr. Lyon Playfair, under the title " Chemistry in its Application to Agriculture and Physiology." In the preface Liebig states that his object in the work was "to develop, in a manner correspondent to the present state of science, the fundamental principles of chemistry in general, and the laws of organic chemistry in particular, in their applications to agriculture and physiology; to the causes of fermentation, decay, and putrefaction; to the vinous and acetic fermentations; and to nitrification.

The conversion of woody fibre into wood and mineral coal, the nature of poisons, contagions, and miasms, and the causes of their action on the living organism, have been elucidated in their chemical relations." This work was soon followed by the Chemische Briefe, which was translated into English under the title "Familiar Letters on Chemistry and its Relations to Commerce, Physiology, and Agriculture." The effect of these letters in Germany, as stated by Liebig in his preface to the English edition of 1843, was " to lead to the establishment of new professorships in the universities of Gottingen and Wi'irzburg for the express purpose of facilitating the application of chemical truths to the practical arts of life, and of following up the new line of investigation and research, the bearing of chemistry upon physiology, medicine, and agriculture, which maybe said to be only just begun." In June, 1842, Liebig presented to the British association a second report in response to their request of 1838. This was entitled Die Thier-chemie oder organische Chemie in ihrer Anwendung auf Physiologie und Pathologie (Brunswick, 1842). It was translated into English from the author's manuscript by Prof. William Gregory and published as " Animal Chemistry, or Chemistry in its Application to Physiology and Pathology." Great practical good resulted from Liebig's investigations, which soon led to a better appreciation of the nature and proper application of medicines and food.

This particular subject continued to occupy his attention, and papers frequently appeared in the Annalen and other scientific journals presenting the results of further investigations. These were embodied in two works, Chemische Un-tersuchungen uber das Fleisch und seine Znhe-reitung zum Nahrungsmittel (Leipsic, 1847), and Die Ursachen der Saftebewegung im thieri-schen Organismus (Brunswick, 1848), translated by Prof. Gregory, "Researches on the Chemistry of Food," and "The Motions of the Juices in the Animal Body." The nature of the animal tissues and of the liquid compounds of the body was fully investigated in these works, and the passage of their elements from one to another was carefully traced. The practical application is found in the observations upon the cooking of food, and the suggestions by which this process may be conducted with greater economy and more exact knowledge of the objects to be attained in the effect of the aliment upon the system. Liebig engaged with others in several publications besides those named. With Poggendorff he compiled the Handworterbuch der Chemie (9 vols., Brunswick, 1887-'64), and he contributed to Geiger's Handhuch der Pharmacie (Heidelberg, 1839) the portion devoted to organic chemistry, which afterward appeared as a separate work.

He also furnished in 1841 the organic portion of Dr. Turner's "Elements of Chemistry." In 1848 he established, in connection with Prof. Kopp, an annual report on the progress of chemistry, which, with the aid of others as contributors, has been continued to the present time. In 1S55 appeared his Grundsatze der Agriculturchemie, in 185G Theorie und Praxis der Landwirthschaft, and in 1859 Naturwis-senschaftliche Briefe uber die moderne Land-wirthschaft, translations of which have been published in several languages. Liebig gave much attention to the subject of the utilization of the sewage of cities; and his letters setting forth the continual loss in fertilizing material which is experienced in all the great food-producing countries of the world, and which must be greatly augmented when the supplies of guano are exhausted, were read with no little interest by scientific and thoughtful men. The sewage of cities he regarded as the best source from which to restore this loss. Of late years his name has acquired a wide publicity in connection with his extractum carnis or " essence of meat." One of his favorite subjects was that of fermentation, and his explanation of the phenomena as being due to the action of a substance whose molecules are in a state of transition upon the fermenting body was long and ably maintained, and cannot be said to be yet superseded, although there is a general tendency to the adoption of the strictly germ theory of Pasteur. His last investigation on the subject was published in 1870, in which he ably upholds his theory against Pasteur's explanation, and his views and arguments are as forcibly and clearly expressed as we find them in his early publications.

His last communication to the Annalen is a notice of the discovery of chloroform, published in March, 1872, in which he calls attention to the fact that it was discovered by himself in 1831, and not by Soubeirain, as is generally supposed in Europe. - The influence which Liebig exerted on the progress of discovery in chemistry is due to his high powers of generalization united to indomitable perseverance. As a critic he was unsparing and sometimes bitter, but paid the greatest respect to truth and candor. As an author he was remarkable for the grace and lucidity of his style, among the best examples of which are his "Familiar Letters on Chemistry." He was an enthusiast in regard to America, where he had many more readers than in any other country, and is said to have entertained at one time the idea of making the United States his residence. Many honors were conferred upon him by learned societies, public institutions, and individuals. By Louis II., grand duke of Hesse-Darmstadt, he was made a baron in 1845. Professorships were offered him in England, and at Heidelberg, Vienna, and other places. But he remained at Giessen till 1852, when he accepted the professorship of chemistry at Munich and the presidency of the chemical laboratory.

In 1860 he was appointed president of the academy of sciences of Munich, as successor of Thiersch; and in 1861 he was elected foreign associate of the French academy of sciences. His collected works were published in 1874 simultaneously at Leipsic and Heidelberg.