Orichalcum Público Deposited
The terms first,t second, and third brass (or bronze), applied to Roman coins according to their sizes, is convenient but unscientific. The first brass, or Great Brass, is in reality the Sestertius; the Second Brass, or Middle Brass, is the Dupondius and As; and the Third Brass, or Small Brass, is the Semis and other small coins.
It should further be remembered that the latter class is of copper; the larger coins are neither brass nor bronze, but composed of orichalcum, a mixture of copper and zine.
- Frey's Dictionary (American Journal of Numismatics, Vol. 50, 1916)