Читать книгу A Text-book of Paper-making - C. F. Cross - Страница 14

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—On digesting cellulose with nitric acid (sp. gr. 1·3) at 100° C. (212° F.), a considerable quantity of oxalic acid is formed; but after prolonged digestion, a residue remains, which yields but very slowly to the action of the acid. This substance, which is white and flocculent, when thrown upon a filter and washed with water, combines with the latter to form a gelatinous hydrate. It dissolves in dilute alkalis, but without forming a stable compound with the base. It usually amounts to about 30 per cent. of the cellulose acted upon. Its elementary composition is expressed by the formula {14} C18H26O16 (C = 43·4, H = 5·3 per cent.). Treated with a mixture of concentrated sulphuric and nitric acids, it dissolves, and, on pouring the solution into water, the compound C18H23O13(NO3)3 separates as a white flocculent precipitate. In its essential properties therefore β oxycellulose exhibits a close resemblance to cellulose itself. This oxycellulose is distinguished from the members of the cellulose group by dissolving in concentrated sulphuric acid with development of a pink colour. It appears to stand in very close relationship to the group of pectic substances, which are oxidised derivatives of cellulose.

* Cross and Bevan, Chem. Soc. Journ., xliii. p. 23.