CHAPTER III.

NITRO-CELLULOSE, &c.

Cellulose Properties—­Discovery of Gun-Cotton—­Properties of Gun-Cotton—­ Varieties of Soluble and Insoluble Gun-Cottons—­Manufacture of Gun-Cotton—­ Dipping and Steeping—­Whirling out the Acid—­Washing—­Boiling—­Pulping—­ Compressing—­The Waltham Abbey Process—­Le Bouchet Process—­Granulation of Gun-Cotton—­Collodion-Cotton—­Manufacture—­Acid Mixture used—­Cotton used, &c.—­Nitrated Gun-Cotton—­Tonite—­Dangers in Manufacture of Gun-Cotton—­ Trench’s Fire-Extinguishing Compound—­Uses of Collodion-Cotton—­Celluloid—­ Manufacture, &c.—­Nitro-Starch, Nitro-Jute, and Nitro-Mannite.

The Nitro-Celluloses.—­The substance known as cellulose forms the groundwork of vegetable tissues.  The cellulose of the woody parts of plants was at one time supposed to be a distinct body, and was called lignine, but they are now regarded as identical.  The formula of cellulose is (C_{6}H_{10}O_{6})_{X}, and it is generally assumed that the molecular formula must be represented by a multiple of the empirical formula, C_{12}H_{20}O_{10} being often regarded as the minimum.  The assumption is based on the existence of a penta-nitrate and the insoluble and colloidal nature of cellulose.  Green (Zeit.  Farb.  Text.  Ind., 1904, 3, 97) considers these reasons insufficient, and prefers to employ the single formula C_{6}H_{10}O_{5}.  Cellulose can be extracted in the pure state, from young and tender portions of plants by first crushing them, to rupture the cells, and then extracting with dilute hydrochloric acid, water, alcohol, and ether in succession, until none of these solvents remove anything more.  Fine paper or cotton wool yield very nearly pure cellulose by similar treatment.

Cellulose is a colourless, transparent mass, absolutely insoluble in water, alcohol, or ether.  It is, however, soluble in a solution of cuprammoniac solution, prepared from basic carbonate or hydrate of copper and aqueous ammonia.  The specific gravity of cellulose is 1.25 to 1.45.  According to Schulze, its elementary composition is expressed by the percentage numbers:—­

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).