1A colorless astringent compound that is a hydrated double sulfate of aluminum and potassium, used in solution medicinally and in dyeing and tanning. Also called potash alum.
- Chemical formula: AlK(SO4)2.12H2O
More example sentences
- It could also be treated by rubbing salt, brain or potash alum into the surface to produce a very pale leather.
- Astringent varieties contain alum, which makes your mouth pucker when the fruits are eaten before they're fully ripe.
- I have no idea how it's manufactured, but it's a kind of alum, a double sulfate of aluminum in crystal salt form.