GERHARDT, ClIARLES FREDERIC, was born at Strasburg, August 21, 1816, and died there August 19, 1856. After his school years spent at home and in Carlsruhe, where his taste for chemistry was awakened, he was sent to Leipsic to learn business, but he attended Erdrnann's lectures on chemistry as well. Returning home he very noun found that a commercial life was not to his taste, so, after a sharp dispute with a disappointed father, he enlisted in a cavalry regiment. In a few months a military career also became intolerable, and, being bought off by a friend, he went to Giessen to study under Liebig. There he remained eighteen months, displaying such entire devotion to chemistry that he found himself unable to obtain the customary degree. He again thought of entering trade, but Liebig persuaded him to go to Paris, where he arrived in 1838. His good appearance and address recommended him to Dumas and other chemists, and in a short time along with Cahosrs, who became his intimate friend, he published an important memoir on essential oils, distinguished especially by the new views it contained. He soon after left Paris and went to Montpellier, where he was professor in the faculty of science till 1848. He then returned to Paris and opened a school for chemistry, which, however, was not commercially a success. From 1848 to 1855 he resided at Paris, and it was during this time that he published the memoirs and carried on the controversies which have been of such importance in the development of scientific chemistry. In 1855 he was appointed professor at Strasburg, his native place ; but he had held the office for but a short time when he died, after two days' illness. Gerhardt's contributions to chemistry are less discoveries of new facts, than of new ideas which organized and vitalized an inert accumulation of facts. He developed the notion of types of structure and reaction; he discovered the order of organic compounds, which led him to the doctrine of homologous and other series ; and on theoretical grounds he remodelled the whole character of the combining weights upon the two-volume molecular basis. The bare statement, however, of his results gives no idea of the lucidity, the wealth of thought, the grasp of the entire subject which his memoirs and his longer works display. It was by his writings especially that Gerhardt's influence was felt. Although a thorough enthusiast in his subject, clear in his exposition, earnest in his work, weighty in his delivery, he seems to have wanted the qualities of a successful teacher. Nothing is heard of his lectures, or of Ids influence as a professor, - such influence as drew students round Liebig and other great masters. None the less, however, did he stir the thoughts of other chemists to the very depths; and although the unitary system has had its day, yet, in substance at least, if no longer in name, chemistry is still Gerhardt's, and it is not impossible that chemists may return to some of Ids views which at present are not acceptable.