n. [ L. nigrificare to blacken; niger black + -ficare (in comp.) to make. See -fy. ] The act or process of making black. [ R. ] Johnson. [ 1913 Webster ]
n. [ Cf. F. nitrification. see Nitrify. ]
☞ The process is going on at all times in porous soils and in water contaminated with nitrogenous matter, and is supposed to be due to the presence of a bacteria, such as members of the genus