Atramentum; the Indian, as Dioscorides says, is of the class of slightly refrigerating medicines, and of those which occasion the rupture of phlegmons and swellings, and cleanse ulcers. * * * * * COMMENTARY. Dioscorides describes two distinct substances by the name of Ἰνδικόν. The one is the vegetable pigment, still called Indigo; the other was probably a red mineral of copper, some variety, we suppose, of the mineral called “tetrahedral red copper ore” by Jameson, or “red oxide of copper” of Philips. Dioscorides recommends it in much the same cases as our author. (v, 107.) The other Greek authorities scarcely treat of it. Our author seems evidently to refer to Indian ink. The Arabians confound together the dye-producing plants, and accordingly treat of the woad (Isatis tinctoria) along with the plant which produces indigo. See Serapion (c. 47), and under _Isatis_ in this section. Averrhoes’s description is very indistinct, so that it is difficult to know what to make of his _Indicum_. (Collig. v, 42.) Avicenna in one place alludes to the mineral pinguent of our author, which he calls Tinctura Inda. (ii, 2, 689.) We beg to refer our readers to Beckmann’s ‘History of Inventions’ for much curious information under the head of _Indigo_. Μελαντηρία, Atramentum metallicum, is powerfully astringent with subtilty of parts. * * * * * COMMENTARY. Dioscorides gives a pretty circumstantial description of three or four varieties of it, and yet none of them can be recognized with any degree of certainty. One thing only is certain, that they must all have contained more or less of copper, being found in mines of copper. As far as we can judge, the mineral named “ferruginous arseniate of copper” by Cleaveland, is the most likely to be the melanteria of Dioscorides. He says it has the same caustic powers as misy. (v, 117.) Galen calls it only powerfully astringent and of subtile parts; and hence Sprengel inclines to set down his melanteria as being different from that of Dioscorides; but between the action of a strong astringent and a weak caustic, the distinction is not great. In describing the melanteria, Aëtius follows Galen, and Oribasius Dioscorides. There is no mention of it in the works of Hippocrates, Celsus, and Pliny. The Arabians confuse their description of it by mixing together those of misy, chalcitis, and sori along with it, under the head of _Atramentum sutorium_. See Avicenna (ii, 2, 47.) Serapion also fails to give any distinct account of it. (De Miner.) Μέλαν ᾧ γράφομεν, Atramentum scriptorium, _Writing Ink_; this, too, is decidedly desiccant; but when dissolved in oxycrate and rubbed in, it straightway relieves burns. * * * * *