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was elected a Fellow in 1857. At one of these meetings, according to Dr. Ruschenberger, he related an incident in the case of a trial for poisoning. He, as an expert witness, contributed to the establishment of the fact that the subnitrate of bismuth sold in the drug stores was contaminated with arsenic, which had not previously been suspected. He became a permanent member of the American Medical Association in 1853, when he attended the meeting at Richmond as the representative of the University of Virginia. He represented the University of Pennsylvania in the meetings of 1853 and 1873, representing also at the latter meeting the medical profession of Philadelphia, and delivering the address of welcome to the delegates. He took an active part in the formation of the Society of the Alumni of the Medical Department of the University of Pennsylvania, and was its treasurer for several years. With his brothers Henry and William he took part, in 1840, in the organization of the Association of American Geologists and Naturalists, which afterward became the American Association for the Advancement of Science. The catalogue of his writings includes four papers under his own name alone in physiology, chemistry, and metallurgy; twelve papers by him and William B. Rogers in chemistry; a paper on the analysis of magnesian limestone by him and Martin H. Boyé; three papers by Dr. H. R. Linderman and him in metallurgy and electricity; a paper by James B. Rogers and him on the alleged insolubility of copper in hydrochloric acid; and seven papers by William B. Rogers and him on subjects in chemistry and meteorology. He also edited the American edition of Lehmann's Physiological Chemistry, which was published in 1855; and he was joint author, with James Blythe Rogers, of a text-book of inorganic and organic chemistry, compiled from the works of Dr. Edward Turner and Dr. William Gregory, which was published in 1816. Besides his regular occupations. Prof. Rogers was sometimes engaged as an expert in criminal trials; frequently delivered lectures, illustrated by experiments, for the benefit of institutions; and often did works of kindness and benevolence. Three instances are mentioned in which he heroically saved persons from drowning. He had a remarkable faculty. Dr. Ruschenberger says, in the use of tools of all kinds, and a respectable talent for mechanical contrivance. He was author of many inventions—notable among them the Rogers and Black steam boiler—and of several modifications and improvements of electrical apparatus. This ability was early manifested, in 1835-'36, in his original experiments on osmosis, in which he demonstrated how changes in the blood are produced by respiration.