COMMENTARY. We shall now give a brief explanation of the medicinal earths of the ancients, and for a fuller account of them we would beg to refer to the Appendix to Dunbar’s ‘English and Greek Lexicon,’ to Hill’s ‘Annotations on Theophrastus on Stones,’ and to Sprengel’s ‘Notes on Dioscorides.’ Of the ancient writers, Dioscorides and Galen give the fullest account of them. The Arabians, also, especially Rhases, Avicenna, and Serapion, treat of them in the most ample manner, but supply little additional information. Geoffroy says of the _Lemnian earth_, that it is “a fat, viscid, slippery clay, of a pale red colour.” The Lemnian ruddle (μίλτος) was the red Armenian bole, consisting of silex, alumine, oxyd of iron, &c. The Lemnium Sigillum was the Lemnian earth, made into cakes and stamped with a seal, as a guarantee of its purity. The _Cretan earth_ is white chalk. The _Samian earth_, as Sprengel states, appears to have been pure argil; Kidd supposes it to have been pipeclay. The kind called aster was globose and thick. The _Chian_, _Selenusian_, and _Pnigitid earths_, are also argils, more or less pure. The Sinopic ruddle was a compact kind of ochre or marl, nearly resembling the Lemnian earth. Pliny ranks the _Cimolian earth_ among the chalks or clays (cretæ.) Sprengel and Kidd suppose it an argil. The purple Cimolian earth of the ancients was our steatitis or _soap-rock_. From Dioscorides’s account of the _Melian earth_, it appears to have consisted principally of alum, and was different from the _Terra Melia_ of Theophrastus. The _Ampelites_ would seem to have been a bituminous earth, formed from stone-coal, probably resembling cannel coal. The _Armenian earth_, as Matthiolus remarks, was different from the _Armenian bole_ now brought from the East. The ancient is described to be a very dry clay, having the appearance of stone, and very triturable, like lime. It was much celebrated as a remedy for the plague. See Galen, Aëtius, and Serapion. It was introduced into practice by Galen. It is clear, as Dr. Hill remarks, that it was the _yellow Armenian bole_ which Galen used; the red being first used by the Arabians. Dr. Hill found it an excellent astringent and absorbent. The _Eretrian earth_ was an impure argil, of a snow-white colour. Geber makes frequent mention of _magnesia_. Γήρας ὄφεως, _Senecta Serpentis_, the Slough of a Serpent, is decidedly desiccative: when boiled with vinegar it, therefore, cures toothache. That of the asp, when triturated with honey and rubbed in, sharpens the powers of vision. * * * * *