Eve of Pentacost
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Bible Encyclopedias
Humus
1911 Encyclopedia Britannica
or (a Latin word meaning the ground), a product of decomposing organic matter. It is especially present in peat bogs, and also occurs in surface soils, to which it imparts a brown or black colour. It is one of the most important soil-constituents from the agricultural point of view; it is the chief source of nitrogenous food for plants, and modifies the properties of the soil by increasing its water-holding capacity and diminishing its tenacity. Little is known with regard to its chemical composition. By treating with a dilute acid to remove the bases present, and then acting on the residue with ammonia, a solution is obtained from which a mineral acid precipitates humic acid; the residue from the ammonia extraction is termed humin. Both the humic acid and humin are mixtures, and several constituents have been separated; ulmic acid and ulmin, in addition to humic acid and humin, are perhaps the best characterized.
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Chisholm, Hugh, General Editor. Entry for 'Humus'. 1911 Encyclopedia Britanica. https://www.studylight.org/encyclopedias/eng/bri/h/humus.html. 1910.
