Arnold asserts that argent vive is the medicine of all the metals, that vulgar sulphur is the cause of all their imperfections, that the stone of the philosophers is one, and that it is to be extracted from that in which it exists. It exists in all bodies, including common argent vive. The first physical work is the dissolution of the stone in its own mercury to reduce it to its _prima materia_. All the operations of the _magnum opus_ are successively described, including the composition of the white and the red elixirs, and the multiplication of the metallic medicine. The marcasite frequently mentioned by Arnold is thought to be identical with bismuth. He was acquainted with the preparation of oil of turpentine, oil of rosemary, and performed distillations in a glazed earthen vessel with a glass top and helm. JEAN DE MEUNG. Poet, alchemist, and astrologer, a man of some fortune, and issued from an ancient family, Jean de Meung was one of the chief figures at the Court of King Philippe le Bel. He was born, according to the latest authorities, about the middle of the thirteenth century, and his continuation of the _Roman de la Rose_, which Guillaume de Lorris had begun some time before the year 1260, was undertaken not in his nineteenth year, as generally stated, but about or a little before the age of thirty, and at the instance of the French King. The Romance of the Rose, “that epic of ancient France,” as Éliphas Lévi calls it, has been generally considered by alchemists a poetic and allegorical presentation of the secrets of the _magnum opus_. It professes, at any rate, the principles of Hermetic Philosophy, and Jean de Meung was also the author of “Nature’s Remonstrances to the Alchemist” and “The Alchemist’s Answer to Nature.” Hermetic commentaries have been written upon the romance-poem, and tradition has ascribed to the author the accomplishment of great transmutations. The sermon of Genius, chaplain and confessor to Dame Nature, in the Romance, is an exhibition of the principles of chemistry, as well as a satire on the bombastic and unintelligible preaching which was in vogue at that period. From verse 16,914 to verse 16,997 there is much chemical information. The year 1216 is the probable period of the poet’s death. The story told of his testament has only a foundation in legend, but it is worth repeating as evidence of the general belief in his skill as an alchemist.