E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
A species of earth of a yellowish-grey colour, found in the island of Lemnos, said to cure the bites of serpents and other wounds. It was called terra sigillata, because it was sealed by the priest before being vended. Philoctets was left at Lemnos when wounded in the foot by Herculs.