A Lead Etching Effect

Abstract

THE observations described below have been made in the course of the metallographical examination of some samples of ancient lead of Roman origin (ca. second century A.D.). These leads, hailing from Corbridge, Northumberland, and Pentre Ffwrndan, Flintshire, appear to have been left in the furnaces in which they were produced, and were evidently, at the end of furnace operations, in an oxidized condition, for they now contain patches of red litharge, which occupy blow-holes and rifts in the metal. This litharge has been isolated and its identity proved by tests and also analytically, two preparations from different sources being found to contain 95.6 and 97.7 per cent of PbO, the balance being mainly infiltrated carbonates of iron and calcium.