Aluminium encyclopaedia


In his work Historica naturalis the Roman historian Plinius the Elder (23-79 A.D.) described natural alum stone and the salts obtained from it as "alumen"; the salts were probably used by the Egyptians around 1000 B.C., and later by the Greeks as well as the Chinese, as binders in artists" colour paints and textile dyes. In the Middle Ages, alum found widespread use for these applications and also as a tanning agent and as styptic medication. In the middle of the 18th century the German chemist Andreas Sigismund Marggraf (1709-1782) discovered that clay and the alum obtained from it both contain the same base material, alumina (aluminium oxide), an oxide (a compound with oxygen) of what was then an unknown metal. When the British natural scientist Davy demonstrated the existence of the metal for the first time, he first called it "alumium" and then later "aluminum" before Oersted in 1825 and Wöhler in 1827 coined the term "aluminium".

Originally alum only stood for potassium alum: this is potassium aluminium sulphate, a sulphur"oxygen compound. Later one also included all double salts of the same type and crystal structure as potassium alum (salts are chemical compounds of metals and non-metals, double salts contain two metals). Today, potassium alum is increasingly being replaced by the aluminium compound aluminium sulphate as a colour binder. This and other aluminium-containing alums are being used in large quantities in medication and deodorants, in the production of sugar and paper and in the purification of waste- and drinking-water.