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N September 28, 1879, the earthly career of a man closed at Bonn, Germany, whose numerous original researches and contributions to pharmacy, chemistry, chemical analysis, geology, and other branches of the physical and applied sciences, have placed him in the foremost ranks of scientific investigators. was born November 4, 1806, at Coblentz, on the Rhine, where his father was an apothecary. After having completed the full course of the gymnasium of his native city, he entered, in 1823, his father's establishment as an apprentice. In 1828 he went to the University of Heidelberg, where he applied himself to the study of philosophy, the natural sciences, and pharmacy, and where, by the influence and guidance of Leopold Gmelin, his interest was particularly drawn to chemistry; he subsequently studied at the Universities of Berlin and Bonn, and in 1831 graduated as doctor of philosophy. After having passed the state-examination as apothecary, in 1832, he returned to Coblentz, and became the assistant, and, in 1840, the successor of his father, in business.

Mohr's first literary production was an essay on the nature of caloric and the conservation of force, published in "Baumgaertner's Journal," in 1837, in which the principle of the unity of natural forces and the law of equilibrium, now generally adopted, were for the first time exactly and fully defined, and, five years afterward, were established on a firm mathematical basis by Robert Mayer, of Heilbronn, and, still later and more fully, by the experimental researches of Joule, in England.

His application to practical pharmacy led Mohr to again enter the field of pharmaceutical and chemical research; he undertook the completion of the comprehensive work "Pharmacopœia Universalis," projected by Professor P. L. Geiger, who died in 1836, shortly after the publication of the first part of that work, embracing the crude drugs and simple chemicals. The second part, by Mohr, was published in 1845, and contained the formulary of pharmaceutical and chemical preparations of the various European pharmacopœias in use during the preceding seventy-five to eighty years, and including, of American works, the United States Pharmacopœias of 1820 and 1830, Coxe's "American Dispensatory," and Ellis's "Formulary." His application to the details of practical pharmacy and of chemical operations, his wonderful skill and inventive mind, resulted in the improvement and completion of old, and in the construction of a large number of novel