The percentage of cellulose yielded by this method is, in the case of jute, usually 2–3 per cent. higher than by the bromine method. Moreover, if the temperature be maintained at 0° C. (32° F.), by placing the fibre, which is to be exposed to the action of the gas, in contact with pounded ice, the percentage may be still further increased, amounting {20} in some cases to 80–82. Corresponding to this increased yield, the cellulose is obtained in long filaments. It will be seen, therefore, that the cellulose isolated by chemical treatment from a _compound cellulose_ is affected both in character and quantity by the process employed, and it is affected in a much greater degree than the cellulose itself exposed to the same treatment, _after isolation_. The composition of the cellulose obtained in this way differs from that of celluloses, such as cotton, which exist in the plant in an isolated and more fully formed condition; it contains 43 per cent. C and 6 per cent. H, corresponding to the formula n [3 C_{6}H_{10}O_{5}H_{2}O.] The composition of this cellulose will be seen to be identical with that of certain of the oxycelluloses previously described; and its properties are, moreover, those of an oxycellulose. These facts go to show that the jute fibre substance, and the substances allied to it, are compounds of cellulose with other molecules, _i.e._ they are _compound celluloses_. They may be conveniently grouped under the term _ligno-cellulose_. _Dilute Mineral Acids._—Under the action of dilute sulphuric or hydrochloric acid (5–10 per cent.) at 60°–80° C. (140°–176° F.), a considerable portion of the fibre substance is dissolved. The action of either reagent is of course purely hydrolytic; and the hydrolysis is of the simplest character, since the substance dissolved as well as the residual fibre are found to have the same percentage composition. Moreover, the residual fibre, though having undergone a profound structural modification, and having been converted into a disintegrated mass of brittle fragments, still preserves the chemical characteristics of the original, unaltered. Thus it is converted by the action of chlorine into a similar complex of derivatives, yielding on resolution by sodium sulphite solution 75 per cent. of cellulose; also when acted upon by alkaline hypobromite it yields bromoform. Under the action of these hydrolytic reagents, therefore, the fibre shows itself to be essentially a chemical whole. At the boiling temperature, these acids resolve as well as dissolve the fibre substance, and the volatile products are acetic acid and the peculiar aldehyde {21} _furfural_ C_{4}H_{3}O.COH. The yield of this aldehyde may be raised with suitable precautions to 15–20 per cent. of the raw fibre. The action of dilute nitric acid upon the fibre differs from that of the above-mentioned acids, in effecting its resolution into soluble derivatives and insoluble cellulose; the yield of the latter when the reaction is conducted at 60° C.