Carbon 44.0 per cent. 44.2 per cent.
Hydrogen 6.3 " 6.4 "
Oxygen 49.7 " 49.4 "

These numbers represent the composition of the ash free cellulose. Nearly
all forms of cellulose, however, contain a small proportion of mineral
matters, and the union of these with the organic portion of the fibre or
tissue is of such a nature that the ash left on ignition preserves the
form of the original. "It is only in the growing point of certain young
shoots that the cellulose tissue is free from mineral constituents"
(Hofmeister).

Cellulose is a very inert body. Cold concentrated sulphuric acid causes it
to swell up, and finally dissolves it, forming a viscous solution.
Hydrochloric acid has little or no action, but nitric acid has, and forms
a series of bodies known as nitrates or nitro-celluloses. Cellulose has
some of the properties of alcohols, among them the power of forming
ethereal salts with acids. When cellulose in any form, such as cotton, is
brought into contact with strong nitric acid at a low temperature, a
nitrate or nitro product, containing nitryl, or the NO_{2} group, is
produced. The more or less complete replacement of the hydroxylic hydrogen
by NO_{2} groups depends partly on the concentration of the nitric acid
used, partly on the duration of the action. If the most concentrated
nitric and sulphuric acids are employed, and the action allowed to proceed
for some considerable time, the highest nitrate, known as hexa-nitro-
cellulose or gun-cotton, C_{12}H_{14}O_{4}(O.NO_{2})_{6}, will be formed;
but with weaker acids, and a shorter exposure to their action, the tetra
and penta and lower nitrates will be formed.[A]

[Footnote A: The paper by Prof. Lunge, _Jour. Amer. Chem. Soc._, 1901,