1911 Encyclopædia Britannica/Mohr, Karl Friedrich

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MOHR, KARL FRIEDRICH (1806-1879), German pharmacist, son of a well-to-do druggist in Coblenz, was born on the 4th of November 1806. Being a delicate child he received much of his early education at home, in great part in his father's laboratory. To this may be traced much of the skill he showed in devising instruments and methods of analysis. At the age of twenty-one he began to study chemistry under Leopold Gmelin, and, after five years spent in Heidelberg, Berlin and Bonn, returned with the degree of Ph.D. to join his father's establishment. On the death of his father in 1840 he succeeded to the business, retiring from it for scientific leisure in 1857. Serious pecuniary losses lead him at the age of fifty-seven to become a privatdozent in Bonn, where in 1867 he was appointed, by the direct influence of the emperor, extraordinary professor of pharmacy. He died at Bonn on the 28th of September 1879. Mohr was the leading scientific pharmacist of his time in Germany, and he was the author of many improvements in analytical processes. His methods of volumetric analysis were expounded in his Lehrbuch der chemisch-analytischen Titrirmethode (1855), which won the special commendation of Liebig and has run through many editions. His Geschichte der Erde, eine Geologie auf neuer Grundlage (1866), also obtained a wide circulation. In a paper "Über die Natur der Wärme," published in the Zeitschrift für Physik in 1837, he gave one of the earliest general statements of the doctrine of the conservation of energy in the words: "besides the 54 known chemical elements there is in the physical world one agent only, and this is called Kraft (energy). It may appear, according to circumstances, as motion, chemical affinity, cohesion, electricity, light and magnetism; and from any one of these forms it can be transformed into any of the others."