The first writer who mentions the possibility of transmuting metals would appear to be a Greek divine called Æneas Garæus, who lived towards the close of the fifth century, and who wrote a commentary on Theophrastus. He was followed by Anastatius the Sinaite, Syncellus, Stephanus, Olimpiodorus; and, says Boerhaave, “a crowd of no less than fifty more, all Greeks, and most or all of them monks.” “The art seemed now confined to the Greeks, and among them few wrote but the religious, who from their great laziness and solitary way of life were led into vain, enthusiastical speculations, to the great disservice and adulteration of the art.... They all wrote in the natural style of the Schoolmen, full of jargon, grimace, and obscurity.” Experimental alchemy, as distinguished from industrial chemistry, may, as already stated, be said to have originated with the Arabians. At first, alchemy was regarded as a branch of the art of healing, and its professors were invariably physicians who occupied themselves with the preparation of chemical medicines. In fact, in the beginning its true aim was regarded as that which Paracelsus and the school of iatro-chemists subsequently defined it to be. Under the rule of the Caliphs the study of chemistry made considerable progress, and its literature was greatly augmented. The most notable name in the history of chemistry during the eighth century was =Abu-Moussah-Dschabir-Al-Sufi=—otherwise =Geber=—(born 702, died 765), who is stated to have been either a native of Mesopotamia, or a Greek and a Christian, who afterwards embraced Mahometanism, went to Asia, and acquired a knowledge of Arabic. According to Leo Africanus, a Greek who wrote of the antiquity of the Arabs, Geber’s book was originally written in Greek and translated thence into Arabic, and he was not known by the name Geber, which signifies a _great man_ or a _prince_, till after this version. Latin translations of what purported to be his works were first published in the early part of the sixteenth century, and an English rendering appeared in 1678. According to this it would seem that Geber regarded all the metals as compounds of “sulphur” and “mercury,” the differences between them depending upon the relative proportion and degree of purity of these constituents. He is said to have distinguished them by the astrological names of the planets: thus gold became _Sol_, silver _Luna_, copper _Venus_, iron _Mars_, tin _Jupiter_, and lead _Saturn_. That an occult connection of the metals with the stars existed was part of the creed of alchemy, and the influence of that belief is still traceable in chemical, and especially in pharmaceutical, literature; as, for example, in such terms as _Lunar caustic_, _Martian preparations_, _Saturnine solutions_, _etc._