Vegetable mold. It contains ulmin and ulmic acid, humin and humic acid. H. Pigments, certain pigmentary bodies of a more or less dark-brown color, produced when carbohydrates are treated with acids or alkalies. When urine is treated with acids in the presence of oxygen, it becomes darker from the formation of some of these humus-pigmented substances by the action of the acids on the carborivdrates.
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