Berthelot found 160 tracts by Greek alchemists. Also, various distinguished scientists continued to believe in the transmutation of metals as late as the seventeenth century. Second, thirteenth century alchemy was less superstitious and more scientific than in previous periods, whether among the Greeks or more recently among the Arabs. This fact has been rather obscured because the editors and publishers of books on alchemy in the sixteenth century preferred to print such treatises as made great pretensions and were full of mystic language. Thus the productions of charlatans got into print and the more sober works of rational investigators remained for the most part neglected in manuscripts. These, however, have now been studied by Berthelot with the following results.
Whereas Greek tracts on alchemy are all in an archaic enigmatic style, "combining in one undecipherable medley terms of obscure meaning, magical formulas, astrological notions, citations from mystic authors, and cryptic allusions to a philosophy long since buried too deep for present resurrection"; on the contrary, the thirteenth century treatises are full of positive details and rational argument. Moreover, the medieval alchemists are careful to refute those who deny the possibility of transmuting metals, while it does not seem to have entered the heads of the Greek alchemists that any one should doubt the truth of their art. Third, this progress is not due to the Arabs. Berthelot discovered only one treatise in Arabic which contained precise and minute details about chemical substances and operations. As a rule the Arabian alchemists wrote "theoretical works full of allegories and declamations." For a long time several works important in the history of chemistry as well as of alchemy were regarded as Latin translations from the Arab Geber, who was consequently regarded as a pioneer in the history of science. Berthelot discovered the Arabic manuscripts which turned out to be of little value and largely copied from Greek sources. On the other hand, the Latin works which had gone under Geber's name were produced in the thirteenth and fourteenth centuries by men who seem, like Adelard of Bath, to have preferred to attribute their own ideas to the Arabs.
Let us examine for a moment with Berthelot the chief of these treatises. It is "a systematic work, very well arranged." "Its modest method of exposition" differs greatly from "the excessive and vague promises of the real Geber." It refutes scepticism as to alchemy in a long scholastic discussion typical of the thirteenth century. But this is no mere scholastic treatise. Parts of it possess "a truly scientific character" and show "the state of chemical knowledge and theory with a precision of thought and expression unknown to previous authors." The writer "defines carefully silver, lead and the other metals, and traces the characteristic features of their chemical history as far as it was then known. If you leave out a few incorrect details connected with trans-
