Phosphor-Tin: Sponge Tin and Stick Phosphorus Layered in Charcoal and Heated in a Sealed Crucible (Berthold, US 658,230)

Phosphorus is hard to get into bronze without fire and fumes. Berthold packs sponge tin and sticks of phosphorus in layers of charcoal in a sealed crucible; as it heats, the tin melts and soaks up the phosphorus. Result: phosphor-tin with about 10 % phosphorus, ready to add to molten copper. Source: Berthold, US 658,230 (1900). Danger: white phosphorus is poisonous and catches fire in air. Picture drawn by Youblob.