Zosimus, the experimenter, the historian and biographer of Plato, Olympiadorus, and Stephanus, authors of important memoirs on the art of making gold. For that purpose they employed, according to the manuscripts, a projecting powder endowed with the mysterious power of impregnating bodies. This powder was prepared in the Thebaid, at places which, according to Agatharcides, were centers of metallurgical enterprises.
In the ninth century all the documents are found in the hands of the Arabs, who became the depositories and continuers of Grecian science. Mussulman civilization has handed down to us the history of the mythic alchemists, their mysterious formulas, and the practices which they adopted for blanching and yellowing metals—that is, for changing them into silver and gold. In their conceptions of matter, the Arabs of Spain and Syria followed in part the philosophical systems of pagan Greece; and their authors freely quoted Aristotle, Heraclitus, Xenocrates, Diogenes, and Democritus. The story of their doctrines and brilliant discoveries is told in all histories of chemistry.
M. Berthelot's detailed review of the positive facts which alchemy received from antiquity makes it manifest that Egypt left an inestimable treasure to the world. The priests of Thebes and Memphis made great advances in the knowledge of the art of extracting metals, of forming alloys, and of making vessels and tools out of them. They distinguished crude gold from refined gold, and could work that metal up into a variety of articles. They fed the hope that they might be able to obtain it by coloring asemon, or silver, yellow. Of the latter metal they made money, the value of which was guaranteed by an impressed image. They extracted gold and silver from electrum, a mineral containing both substances, but which presented to their eyes the appearance of a metal like them. This was what led them to the notion of transmutation.
The Egyptians designated as chesbet several kinds of blue or green sapphires colored with cobalt or copper. They made incrustations, amulets, necklaces, and various ornaments of them. They succeeded in compounding an artificial chesbet resembling the natural stone. A fact worthy of remark in the matter is, that this was done by "the assimilation of a colored substance, a precious stone, an enamel, a vitrified color, with metals." This assimilation suggested the new idea of dyeing; "for the imitation of the sapphire rests on the coloring of a large mass, colorless by itself, but constituting the vitrifiable basis, which we dye by the aid of a small quantity of coloring matter. With enamels and colored glasses thus prepared, the natural precious stones were reproduced; they were covered with figures, with objects of earth or stone, and were incrusted with metallic objects."