[C] Baro Urbigerus--“One Hundred Aphorisms demonstrating the preparation of the Grand Elixir.” [D] Aphorismi Urbigerani. [E] Commentary on the “Ancient War of the Knights.” LIVES OF THE ALCHEMISTS. GEBER. The first, and, according to the general concensus of Hermetic authorities, the prince of those alchemical adepts who have appeared during the Christian era, was the famous Geber, Giaber, or Yeber, whose true name was Abou Moussah Djafar al Sofi, and who was a native of Haman, in Mesopotamia, according to the more probable opinion. He is also said to have been a Greek, a Spanish Arabian born at Seville, and a Persian of Thus. Romance represents him as an illuminated monarch of India. According to Aboulfeda, he flourished during the eighth century, but later and earlier periods have been also suggested. His life is involved in hopeless obscurity; but his experiments upon metals, undertaken with a view to the discovery of their constituent elements and the degrees of their fusibility, led him to numerous discoveries both in chemistry and in medicine, including suroxydised muriate of mercury, red oxyde of mercury, and nitric acid. “It is thus that Hermetic philosophy gave rise to chemistry,” says a writer in the _Biographie Universelle_, “and that the reputation of Geber is permanently established, not upon his search for an impossible chimera, but for his discovery of truths founded on actual experience.” With the characteristic prodigality of the Middle Ages, no less than five hundred treatises have been attributed to the Arabian adept. They are supposed to have embraced the whole circle of the physical sciences, including astronomy and medicine. A few fragments, comparatively, alone remain of all these colossal achievements. Cardan included their author among the twelve most penetrating minds of the whole world, and Boerhave spoke of him with consideration and respect in his celebrated _Institutiones Chemicæ_. According to M. Hoefer, he deserves to be ranked first among the chemists and alchemists who flourished prior to Van Helmont. “He is the oracle of mediæval chemists, who frequently did nothing in their writings but literally reproduce their master. Geber for the history of chemistry is what Hippocrates is for the history of medicine.” The name of Geber has been borne or assumed by several writers subsequent to the Hermetic adept; in this way the few extant facts concerning his life have been variously distorted, and books of later date and less value falsely ascribed to him. An astronomical commentary on the _Syntaxis Magna_ of Ptolemy, in nine books, must be included in this number. It is a work of the twelfth century, as may be proved by internal evidence.