【化】 腐殖酸; 胡敏酸; 里腐酸humic coal腐殖煤
【医】 黑腐酸

[ noun ]
a dark brown humic substance that is soluble in water only at pH values greater than 2
<noun.substance>
the half-life of humic acid is measured in centuries

Humin \Hu"min\, n. [L. humus the earth, ground.] (Chem.)
A bitter, brownish yellow, amorphous substance, extracted
from vegetable mold, and also produced by the action of acids
on certain sugars and carbohydrates; -- called also {humic
acid}, {ulmin}, {gein}, {ulmic} or {geic acid}, etc.