If Albertus Magnus must be considered an adept in possession of the philosophic stone, there is little doubt that he discovered it to his favourite pupil, St Thomas, the most illustrious of the kings of intelligence who glorified the scholastic period of Christian philosophy. There are some alchemical treatises ascribed to the angel of the schools which he certainly did not write. “That of the ‘Nature of Minerals’ is unworthy of so great a philosopher,” says a certain anonymous authority, “and so is the ‘Comment on the _Turba_.’ But his _Thesaurus Alchemiæ_, addressed to Brother Regnauld, his companion and friend, is genuine. He cites Albert in this as his master in all things, especially in Hermetic philosophy. He addressed other books to Regnauld on the curious sciences, amongst which is a treatise on Judicial Astrology.” This opinion deserves due consideration, yet in all his theological works St Thomas carefully avoided every suspicion of alchemy, persuaded, says the same writer, that it would bring dishonour to his name as the height of human folly. Moreover, in one of his treatises he distinctly states that “it is not lawful to sell as good gold that which is made by Alchemy,” proof positive that he considered the transmutatory art to be simply the sophistication of the precious metal. On the other hand, the _Thesaurus Alchemiæ_, generally attributed to him by adepts, testifies that “the aim of the alchemist is to change imperfect metal into that which is perfect,” and asserts the possibility of the thing. These contradictions scarcely afford convincing proof of a common authorship; but spurious or otherwise, the works on the Hermetic science which are attributed to the angelic doctor are of importance in the history of alchemy. Their leading character is secrecy, and they insist on the preservation of the sublime operation from unworthy men, only the children of light, who live as in the presence of God, being fit for the knowledge or custody of so supernal a mystery. The _Thesaurus Alchemiæ_ has the brevity which characterised St Thomas, for it is comprised in a very few leaves. The other works attributed to him are _Secreta Alchymiæ Magnalia_ and _De Esse et Essentia Mineralium_, together with the comment on the _Turba_. Some of the terms still employed by modern chemists occur for the first time in these supposititious writings of Thomas Aquinas--_e.g._, the word amalgam, which is used to denote a compound of mercury and some other metal. In the tractates addressed to Brother Regnauld, we learn that the students of alchemy are in search of a single substance which absolutely resists the fierce action of fire, which itself penetrates everything, and tinges mercury. The work is a work of the hands, and great patience is required in it. Instruments are necessary, but in the true Hermetic operation there is but one vase, one substance, one way, and one only operation. ROGER BACON.