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, 23[8], 527-579, contains valuable information on this subject.]

Besides the nitrate, A. Luck[A] has proposed to use other esters of cellulose, such as the acetate, benzoate, or butyrate.  It is found that cellulose acetate forms with nitro-glycerine a gelatinous body without requiring the addition of a solvent.  A sporting powder is proposed composed of 75 parts of cellulose nitrate (13 per cent.  N.) mixed with 13 parts of cellulose acetate.

[Footnote A:  Eng.  Pat. 24,662, 22nd November 1898.]

The discovery of gun-cotton is generally attributed to Schoenbein (1846), but Braconnot (in 1832) had previously nitrated starch, and six years later Pelouse prepared nitro-cotton and various other nitro bodies, and Dumas nitrated paper, but Schoenbein was apparently the first chemist to use a mixture of strong nitric and sulphuric acids.  Many chemists, such as Piobert in France, Morin in Russia, and Abel in England, studied the subject; but it was in Austria, under the auspices of Baron Von Lenk, that the greatest progress was made.  Lenk used cotton in the form of yarn, made up into hanks, which he first washed in a solution of potash, and then with water, and after drying dipped them in the acids.  The acid mixture used consisted of 3 parts by weight of sulphuric to 1 part of nitric acid, and were prepared some time before use.  The cotton was dipped one skein at a time, stirred for a few minutes, pressed out, steeped, and excess of acid removed by washing with water, then with dilute potash, and finally with water.  Von Lenk’s process was used in England at Faversham (Messrs Hall’s Works), but was given up on account of an explosion (1847).

Sir Frederick Abel, working at Stowmarket and Waltham Abbey, introduced several very important improvements into the process, the chief among these being pulping.  Having traced the cause of its instability to the presence of substances caused by the action of the nitric acid on the resinous or fatty substances contained in the cotton fibre, he succeeded in eliminating them, by boiling the nitro-cotton in water, and by a thorough washing, after pulping the cotton in poachers.