COMMENTARY. Matthiolus determines it to be the _Lapis Lazuli_, and Sprengel agrees with him that it was a mineral containing copper and some impurities, and nearly allied to the _L. Laz._ Serapion describes the ἀρμένιον by the name of _Lapis Lazuli_, and, in fact, the ἀρμένιον and κύανος seem to have been nearly the same thing. He recommends it as a purgative which evacuates black bile. Rhases, in his chapter on the Lapis Lazuli, gives the observations of Dioscorides and Galen on the ἀρμένιον, and in his chapter on the _Lapis Armenus_, he compares it to the _Lapis Lazuli_ (Cont. l. ult. i, 393, 404.) The following is Sprengel’s account of the armenium and cyanus: “Armenium est cuprum carbonicum terreum, lapidi Lazuli simile. Id in australibus petris arenosis, has ipsas penetrans mineram æris arenosam format. Ea vocatur κύανος.” (Ad Dioscor. v, 105.) From what has been stated, any person acquainted with mineralogy can have no difficulty in deciding that the _cyanus_ and _armenium_ were varieties of the mineral called “blue copper” by Jameson, that is to say, the “blue carbonate of copper” of Cleaveland (566.) For further information regarding it, we would refer to Matthiolus and Sprengel (Ad Dioscor. l. c.), Beckmann (Hist. of Invent.), and our article under this head in the Appendix to Dunbar’s Greek Lexicon. Our author copies his account of it from Galen. Dioscorides recommends it only as an external application, possessed of repressing, moderately septic, escharotic, and ulcerative powers. (v, 106.) The Arabians, who, however, evidently do not distinguish properly this mineral from the lapis lazuli, recommend it as an emmenagogue and purgative. When boiled with lentils, Avicenna says, it acts as an emetic in the case of a person who has swallowed any poison. He also prescribes it in asthma and pain of the kidneys. See Avicenna (ii, 2, 56); Rhases (Cont. l. ult. i, 692); Serapion (c. 389.) The later Greek writers on medicine, like the Arabians, confound this substance with the lapis lazuli. See Theophanes Nonnus (c. 125, 143); Myrepsus (i, 30.) The former of these prescribes it as a specific in the plague. In modern times also the cyanus or blue copper has been confounded with the lapis lazuli. See Lewis (M. M. ii, 50.) Κύκλάμινος,