The writings of Rhasis, like those of Geber, enlarge on the planetary correspondences, or on the influence exerted by the stars in the formation of metallic substances beneath the surface of the earth. The explicit nature of the recipes which he gives may be judged by such directions as _Recipe aliquid ignotum, quantum volueris_. It is to him, nevertheless, that we owe the preparation of brandy and several pharmaceutic applications of alcohol. He was the first to mention orpiment, realgar, borax, certain combinations of sulphur, iron, and copper, certain salts of mercury indirectly obtained, and some compounds of arsenic.[G] He was also a zealous promoter of experimental methods. FOOTNOTES: [G] Figuier, _L’Alchimie et les Alchimistes_, pp. 95, 96. ALFARABI. The middle of the tenth century was made illustrious by one of those celebrated men who do honour to the sciences in which they engage. This was Abou-Nasr-Mohammed-Ibn-Tarkan, commonly called Farabi and Alfarabi--a man of universal genius, who penetrated all subjects with equal facility, fathoming the most useful and interesting sciences, and passing for the greatest philosopher of his time. He was born at Farab, now known as Othrar, in Asia Minor. He was of Turkish origin, but repaired to Bagdad to acquire a more perfect knowledge of Arabic; there he devoted himself with zeal and enthusiasm to the study of the Greek philosophers under Abou Bachar Maltey, an expounder of Aristotle. From Bagdad he proceeded to Harran, where John, a Christian physician, was teaching logic. In a short time Alfarabi surpassed all his other scholars, but he left Harran and visited Damas, thence penetrating into Egypt. Early attracted towards the secrets of nature, he spent a great portion of his life in incessant wanderings, collecting the opinions of all the philosophers he could meet with on these and on kindred subjects. He despised the world, and took no pains to acquire wealth, though he wrote upon alchemy, that is, if the Hermetic works which are attributed to him be genuine. His erudition and indefatigable activity are attested by his other writings, which variously treat of philosophy, logic, physics, astronomy, and mathematics. His chief reputation is based on a sort of encyclopædia, where he gives a description, with an exact definition, of all the arts and sciences; and on a celebrated musical treatise, wherein he ridicules the pythagorean speculations upon the music of the spheres, and proves the connection of sound with atmospheric vibrations. According to several authorities, he was protected and supported in his later years by the cultured and enlightened Seïf Eddoula, who is represented as Prince of Damas, but who seems to have been Sultan of Syria, and to have made the acquaintance of the scholar in the following curious manner.