humic acid

noun

1. a brown, melanin-tinted mixture of polymers, found in lignite, peat, and soils, where it acts as a cation exchange agent: used in drilling fluids and inks.

Word History and Origins

Origin of humic acid¹

First recorded in 1835–45

Example Sentences

This deposit, if obtained from light brown peat, is ulmic acid; if from black peat, it is humic acid.

From Project Gutenberg

There is in this fermentation a large quantity of cold sour humic acid formed, which seriously impairs the value of the manure.

From Project Gutenberg

His peat or humic acid tannage was patented by him about 1905, and is now worked on a commercial scale.

From Project Gutenberg

In soils that are acid through the accumulation of humic acid nitrification does not go on, and bacterial life is repressed.

From Project Gutenberg