Complex sentence: Dioscorides' ambix (De materia medica) is a helmet-shaped lid for gathering condensed mercury, for Athenaeus (~ 225 C.E.) it is a bottle or flask, with later chemists it denotes various parts of crude distillation devices.
Split into simpler sentences: Dioscorides' ambix (described in his "De materia medica") is a helmet-shaped lid for gathering condensed mercury. For later chemists it denotes various parts of crude distillation devices.