Читать книгу A Text-book of Paper-making - C. F. Cross - Страница 18

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—In the natural decay of cellulosic structures a large quantity of marsh gas is formed, and solid products are formed, which are usually known as humic or ulmic substances. These bodies are amorphous, are largely dissolved by alkaline solutions, and are attacked by chlorine gas in presence of moisture, yielding yellow coloured chlorinated derivatives whose composition has a general resemblance to the chlorinated compounds obtained from the compound celluloses, to be hereafter described.

The most important part which ulmic substances play in the economy of nature, is in the composition of soils. It is doubtful whether they act directly as fertilisers, but by their action upon the mineral constituents of soils they contribute to the supply of these necessary elements of growth to the plant.