mistry had no existence till many centuries after Pliny wrote. And thus, it never occurred to him that there was but one substance, (now known to be elementary,) carbon, which gave the quality of blackness to all the materials which he names, with the exception of one salt of copper, and probably one of iron, (the sulphate,) and Indigo, a purely vegetable substance, the dried coloring matter of a plant in India, (Indicofera anil,) and named by the Romans from the country that produced it, and first made it known to them.
Pedanius Dioscorides, born in Anazarbus, (a city of Cilicia, about fifty miles from Tarsus, the birth-place of the Apostle Paul,) wrote a book on the Materia Medica, or the qualities of drugs, a little after the time when Pliny composed his Natural History. Neither of them seems to have been acquainted with the writings of the other. Apparently, they lived, wrote and died nearly or actually cotemporary, in the same empire, utterly ignorant of each other's existence,—though they are now universally recognized as the two most eminent writers of all antiquity on the subjects of Natural History and the Materia Medica. They both lived in the reign of Nero, and the date of the active or middle part of both their lives may be
