The following list from the article on “Pharmaceutica” in Smith’s _Dictionary of Greek and Roman Antiquities_ contains probably the titles of all the ancient treatises on drugs that are extant: “1. Περὶ Φαρμάκων, _De Remediis Purgantibus_; 2. Περὶ Ἑλλεβορισμοῦ, _De Veratri Usu_ (these two works are found among the collection that goes under the name of Hippocrates, but are both spurious); 3. Dioscorides, Περὶ Ὕλης Ἰατρικῆς, _De Materia Medica_, in five books (one of the most valuable and celebrated medical treatises of antiquity); 4. id. Περὶ Εὐπορίστων, Ἁπλῶν τε καὶ Συνθέτων, Φαρμάκων, _De Facile Parabilibus, tam Simplicibus quam Compositis, Medicamentis_, in two books (perhaps spurious); 5. Marcellus Sideta, Ἰατρικὰ περὶ Ἰχθύων, _De Remediis ex Piscibus_; 6. Galen, Περὶ Κράσεως καὶ Δυνάμεως τῶν Ἁπλῶν Φαρμάκων, _De Simplicium Medicamentorum Temperamentis et Facultatibus_, in eleven books; 7. _id._ Περὶ Συνθέσεως Φαρμάκων τῶν κατὰ Τόπους, _De Compositione Medicamentorum secundum Locos_, in ten books; 8. _id._ Περὶ Συνθέσεως Φαρμάκων τῶν κατὰ Γένη, _De Compositione Medicamentorum secundum Genera_, in seven books; 9. _id._ Περὶ τῆς τῶν Καθαιρόντων Φαρμάκων Δυνάμεως, _De Purgantium Medicamentorum Facultate_ (perhaps spurious); 10. Oribasius, Συναγωγαὶ Ἰατρικαί, _Collecta Medicinalia_, consisting originally of seventy books, of which we possess now only about one third; 11. _id._ Εὐπόριστα, _Euporista ad Eunapium_, or _De facile Parabilibus_, in four books, of which the second contains an alphabetical list of drugs; 12. _id._ Σύνοψις, _Synopsis ad Eustathium_, an abridgment of his larger work in nine books, of which the second, third, and fourth are upon the subject of external and internal remedies; 13. Paulus Ægineta, Ἐπιτομῆς Ἰατρικῆς Βιβλία Ἕπτα, _Compendii Medici Libri Septem_, of which the last treats of medicines; 14. Joannes Actuarius, _De Medicamentorum Compositione_; 15. Nicolaus Myrepsus, _Antidotarium_; 16. Cato, _De Re Rustica_; 17. Celsus, _De Medicina Libri Octo_, of which the fifth treats of different sorts of medicines; 18. Twelve books of Pliny’s, _Historia Naturalis_ (from the twentieth to the thirty-second), are devoted to Materia Medica; 19. Scribonius Largus, _Compositiones Medicamentorum_; 20. Apuleius Barbarus, _Herbarium, seu de Medicaminibus Herbarum_; 21. Sextus Placitus Papyriensis, _De Medicamentis ex Animalibus_; 22. Marcellus Empiricus, _De Medicamentis Empiricis, Physicis, ac Rationalibus_.” Although the Greeks and Romans knew little of chemistry as we understand the term, they must have possessed considerable skill in the art of secret poisoning, either with intent to kill or to obtain undue influence over certain persons.