Rogers also made a careful investigation and estimation of the probable total production of the Consolidated Virginia and California Mine in Nevada. He was further, from 1874 to 1879, or for about six years, a member every year of the Annual Assay Commission. He was for twelve years one of the chemists to make an analysis and daily photometric test of the illuminating gas supplied to Philadelphia.
In 1877 Prof. Rogers was elected Professor of Medical Chemistry and Toxicology in Jefferson Medical College; and, to accept the offer, resigned the position which he had for a quarter of a century held in the university. His entrance into this institution was the occasion of a flattering demonstration at the time of the opening of the course of 1877-'78 with an introductory lecture. “It was estimated that not less than twelve hundred physicians, students, and others were crowded into the hall. At the conclusion of the lecture a silver vase was presented to him as a token of the respect felt for him by the great class of medical students.”
Prof. Rogers became a member of the Academy of Natural Sciences of Philadelphia in 1837; was interested in its proceedings through most of his life; attended its meetings at irregular intervals for many years in succession; participated in its discussions, and delivered lectures to promote its interests. Many of his verbal communications are noted in its proceedings from 1859 to 1862. He was a member of the Franklin Institute from April, 1838, except when living away from Philadelphia; became a life member in 1855; one of the Board of Managers in 1857; was one of the vice-presidents for seventeen years from 1858; was chosen president in 1875; and on retiring from that office in 1879 was returned to the Board of Managers for the rest of his life. “He was particularly active in the work of the institute, delivered courses of lectures on chemistry before its classes, assisted in the management of its public exhibitions, served on several of its standing and on many of its special committees, the most notable of which were one on tests of the efficiency of dynamo-electric machines, and another on the dangers of electric lighting.” At the celebration of the semi-centennial anniversary of the foundation of the society, February 5, 1874, he delivered an address on the history of scientific discoveries and their practical applications in the half century, in which he pointed out how the work of the institute had contributed to the progress of science and the diffusion of knowledge.
He was elected a member of the American Philosophical Society in 1855 and a member of its Council in 1859. He was a frequent attendant at its meetings, served on several of its committees, and often took part in its discussions. He was less often present at the meetings of the College of Physicians, of which he