Among other early alchemists we may mention also =Africanus=, the Syrian; =Synesius=, Bishop of Ptolemais, and the historian, =Olympiodorus= of Thebes. Geber. § =32.= In the seventh century the Arabians conquered Egypt; and strangely enough, Alchemy flourished under them to a remarkable degree. Of all the Arabian alchemists, =Geber= has been regarded as the greatest; as Professor Meyer says: “There can be no dispute that with the name _Geber_ was propagated the memory of a personality with which the chemical knowledge of the time was bound up.”[44] Geber is supposed to have lived about the ninth century, but of his life nothing definite is known. A large number of works have been ascribed to him, of which the majority are unknown, but the four Latin MSS. which have been printed under the titles _Summa Perfectionis Mettalorum_, _De Investigatione Perfectionis Metallorum_, _De Inventione Veritatis_ and _De Fornacibus Construendis_, were, until a few years ago, regarded as genuine. On the strength of these works, Geber has ranked high as a chemist. In them are described the preparation of many important chemical compounds; the most essential chemical operations, such as sublimation, distillation, filtration, crystallisation (or coagulation, as the alchemists called it), &c.; and also important chemical apparatus, for example, the water-bath, improved furnaces, &c. However, it was shown by the late Professor Berthelot that _Summa Perfectionis Mettalorum_ is a forgery of the fourteenth century, and the other works forgeries of an even later date. Moreover, the original Arabic MSS. of Geber have been brought to light. These true writings of Geber are very obscure; they give no warrant for believing that the famous sulphur-mercury theory was due to this alchemist, and they prove him not to be the expert chemist that he was supposed to have been. The spurious writings mentioned above show that the pseudo-Geber was a man of wide chemical knowledge and experience, and play a not inconsiderable part in the history of Alchemy. [44] ERNST VON MEYER: _A History of Chemistry_ (translated by Dr. McGowan, 1906), p. 31. Other Arabian Alchemists. § =33.= Among other Arabian alchemists the most celebrated were =Avicenna= and =Rhasis=, who are supposed to have lived some time after Geber; and to whom, perhaps, the sulphur-mercury theory may have been to some extent due. The teachings of the Arabian alchemists gradually penetrated into the Western world, in which, during the thirteenth century, flourished some of the most eminent of the alchemists, whose lives and teachings we must now briefly consider. [Illustration: PLATE 7. [by de Bry] PORTRAIT OF ALBERTUS MAGNUS. _To face page 44_]] Albertus Magnus (1193-1280).