alum
/ˈæləm/(亦作potash alum)
noun
mass noun
1- Chemistry a colourless astringent compound which is a hydrated double sulphate of aluminium and potassium, used in solution in dyeing and tanning【化】明矾。
1.1
- Chem. formula: AlK(SO4)2·12H2O.化学分子式： AlK(SO4)212H2O.
1.2
- count noun any of a number of analogous crystalline double sulphates of a monovalent metal (or group) and a trivalent metal二硫酸盐类。
词源
late Middle English: via Old French from Latin alumen, alumin- related to aluta 'tawed leather'.