_Cellulose and nitric acid: β Oxycellulose._[3]—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} C_{18}H_{26}O_{16} (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 C_{18}H_{23}O_{13}(NO_{3})_{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. [Footnote 3: Cross and Bevan, Chem. Soc. Journ., xliii. p. 23.] _Alkalis._—Concentrated solutions of the caustic alkalis in the cold attack and disintegrate cellulose but slowly. The action is in many cases merely superficial. Dilute solutions of the alkalis are without action upon cellulose even at the boiling temperature, unless the condition of oxidation is super-added; in this case, acid bodies are found. The extreme product of the oxidation of cellulose in presence of the caustic alkalis is oxalic acid; this acid has indeed been prepared on the commercial scale by the “fusion” of cellulosic substances, with mixture of sodium and potassium hydrates. Malic acid has been obtained as an intermediate product of this decomposition. By potassium permanganate in presence of potassium hydrate, both in solution, finely divided cellulose is oxidised to a syrupy mixture of acids resembling in composition and properties Frémy’s meta-pectic acid. A similar decomposition is effected by concentrated solutions of the hypochlorites, employed cold. _Water at High Temperature._—Cellulose itself is only slightly affected by exposure to a temperature of 200° C. (392° F.) but in contact with water at this temperature, in sealed glass[4] most part into dark brown insoluble products, a portion, however, passing into solution in the water, imparting to it a deep yellow colour. A large quantity of carbonic acid is {15} formed, and the solution contains in addition to formic acid an appreciable quantity of pyrocatechol. The formation of this aromatic substance from cellulose is, perhaps, the most noticeable feature of the decomposition.