GLYCONIC acids, glycaric acids and glycuronic acids and certain related hydroxy acids show a marked tendency to produce streaked spots on paper chromatograms. This may be eliminated by incorporating in the developing solvent certain organic acids such as formic acid or acetic acid1 to suppress ionization of the carboxyl group. The developing solvents incorporating formic or acetic acid vary in composition with time, due to slow esterification of the acid when an alcohol is present; for this reason R F values are variable. Moreover, the number of suitable acidic developing solvents is limited. In order to be able to use any developing solvent for the separation of acids, we have coated the filter paper with alginic acid. Whatman No. 1 filter paper is dipped into a 1 per cent aqueous ammonium alginate solution and after removing the excess of this solution the paper is dipped into N hydrochloric acid which causes precipitation of alginic acid. The paper so treated is washed with water or ethanol to remove excess hydrochloric acid and allowed to dry in the air.