Identifying Tin Minerals

Reduction to Metallic Globule. Take a small amount of the finely powdered mineral and mix it with five or six volumes of sodium carbonate and considerable charcoal dust and fuse intensely on charcoal in the reducing flame. Small bright globules of metallic tin will result. They become covered with an oxide coating on cooling. A white and difficultly volatile tin oxide coating will form on the charcoal. If the tin globule is treated with a little concentrated nitric acid, it will be converted into a white powder, which is metastannic acid.