Preparation of copper and silver to be alloyed for production of coins. Copper melted (1) while apprentice (9) soaks birch twigs in water. When copper poured on twigs it forms grains. It is then ready to be alloyed with silver being heated at (7). From 1683 English edition of Lazarus Ercker Beschreibung allerfurnemisten mineralischen Ertzt of 1580. Copperplate engraving