The combustible metal-that is, the lead-and the part that will oxidise, are thoroughly oxidised; the litharge would flow out in a fused state into a vessel placed to receive it, and the platinum remains behind.
"The Chemical History Of A Candle"
Michael Faraday
Many of the best Egyptian bronzes offer a surprising resistance to damp, and oxidise with difficulty.
"Manual Of Egyptian Archaeology And Guide To The Study Of Antiquities In Egypt"
Gaston Camille Charles Maspero