Three soils (8 profiles) from various regions of Poland were extd. successively with EtOH-PhH (1:1 mixt.), H(2)SO(4), NaOH, and NaHCO(3) + Na(2)S(2)O(4) to remove humic and fulvic acids and det. the fractional compn. of humus. The org. acids were mostly free or weakly bounded with Fe and Ca.