DECOLORIZING, in practical chemistry and chemical tech nology, the removal of coloured impurities from a substance. Charcoal, preferably prepared from blood, is frequently used; when shaken with a coloured solution it often retains the coloured substances, leaving the solution clear. Thus the red colour of wines may be removed by filtering the wine through charcoal; the removal of the dark-coloured impurities of crude sugar may be similarly effected. Other "decolorisers" acting through purely chemical reactions are sulphurous acid, permanganates and man ganates, all of which have received application in the sugar in dustry. (See CHARCOAL and ADSORPTION.) BIBLIOGRAPHY."Decolourising Carbons." T. E. Thorpe, Dictionary Bibliography."Decolourising Carbons." T. E. Thorpe, Dictionary of Applied Chemistry, vol. ii. p. 487, Longmans, 1921.