These opinions passed from the Greeks to the Arabians, when, under the califs of the family of Abassides, they began to turn their attention to science, about the beginning of the ninth century; and when the enlightened zeal of the Fatimites in Africa, and the Ommiades in Spain, encouraged the cultivation of the sciences. From Spain they gradually made their way into the different Christian kingdoms of Europe. From the eleventh to the sixteenth century, the art of making gold and silver was cultivated in Germany, Italy, France, and England, with considerable assiduity. The cultivators of it were called _Alchymists_; a name obviously derived from the Greek word _chemia_, but somewhat altered by the Arabians. Many alchymistical tracts were written during that period. A considerable number of them were collected by Lazarus Zetzner, and published at Strasburg in 1602, under the title of “Theatrum Chemicum, præcipuos selectorum auctorum tractatus de Chemiæ et Lapidis Philosophici Antiquitate, veritate, jure, præstantia, et operationibus continens in gratiam veræ Chemiæ et Medicinæ Chemicæ Studiosorum (ut qui uberrimam unde optimorum remediorum messem facere poterunt) congestum et in quatuor partes seu volumina digestum.” This book contains one hundred and five different alchymistical tracts. In the year 1610 another collection of alchymistical tracts was published at Basil, in three volumes, under the title of “Artis Auriferæ quam Chemiam vocant volumina tria.” It contains forty-seven different tracts. In the year 1702 Mangetus published at Geneva two very large folio volumes, under the name of “Bibliotheca Chemica Curiosa, seu rerum ad Alchymiam pertinentium thesaurus instructissimus, quo non tantum Artis Auriferæ ac scriptorum in ea nobiliorum Historia traditur; lapidis veritas Argumentis et Experimentis innumeris, immo et Juris Consultorum Judiciis evincitur; Termini obscuriores explicantur; Cautiones contra Impostores et Difficultates in Tinctura Universali conficienda occurrentes declarantur: verum etiam Tractatus omnes Virorum Celebriorum, qui in Magno sudarunt Elixyre, quique ab ipso Hermete, ut dicitur, Trismegisto, ad nostra usque tempora de Chrysopoea scripserunt, cum præcipuis suis Commentariis, concinno ordine dispositi exhibentur.” This Bibliotheca contains one hundred and twenty-two alchymistical treatises, many of them of considerable length. Two additional volumes of the Theatrum Chemicum were afterwards published; but these I have never had an opportunity of seeing. From these collections, which exhibit a pretty complete view of the writings of the alchymists, a tolerably accurate notion may be formed of their opinions. But before attempting to lay open the theories and notions by which the alchymists were guided, it will be proper to state the opinions which were gradually adopted respecting the origin of Alchymy, and the contrivances by which these opinions were supported.