After completing his collegiate course at Solingen, he attended lectures at the Université de France and Collège de France, in Paris, and financed his schooling by translating. At the Université de France, he assisted Jules Michelet, who succeeded François Guizot as professor of history, in the publication of his Histoire de la France. He came to the United States in 1835, and for ten years resided in the family of Piero Maroncelli, the intimate friend of the revolutionist Silvio Pellico. There he imbibed an ardent love for music and Italian literature and got to know the Carbonari refugees in America. Other significant influences were the social theoristAlbert Brisbane and the theologian George Bush. While attending medical lectures at the University of New York, where he graduated in 1845, he became associated with several eminent homeopathic practitioners, and soon after his graduation he began to translate some of the more important works relating to homeopathy. In 1855 he married Mary Calder, daughter of George Coggeshall of Grand Rapids, Michigan. He was appointed professor of materia medica and therapeutics in the Hahnemann Medical College of Philadelphia in 1857. He had an approach to homeopathy distinct from the Hahnemann school. His translations could be a source of controversy in the homeopathic community; in particular Constantine Hering and Adolph Lippe raised objections because of errors in Hempel's early translations and unauthorized additions from his own experience. When the Hahnemann Medical College was reorganized in 1860, Hempel and some others left. During his stay in Philadelphia, he also published his book, Materia Medica and Therapeutics. On the death of his father-in-law in 1861, he went to Grand Rapids to settle up the estate. He decided to make the change of location permanent and soon had a large homeopathic practice in that city. His health failing, he traveled to Italy and Germany in 1872, but the change was not beneficial, and he returned to Grand Rapids, where he died. Hempel was one of the earliest honorary members of the British Homeopathic Society, and was the recipient of diplomas and certificates of membership from many medical colleges and associations. His translations and original works permit him to be called the father of English homeopathic literature.
