Cellulose nitrates (nitrocellulose). These products are prepared by treating cellulose (usually cotton linters) with a mixture of nitric and sulphuric acids. They are highly inflammable and the more highly nitrated varieties (gun-cottons) are used in explosives; for safety reasons they must be transported damped with alcohol, generally ethyl, isopropyl or
butyl alcohol, or dampened or plasticised with phthalate esters. Cellulose nitrate plasticised with camphor in the presence of alcohol forms celluloid. Celluloid is usually in the form of sheets, film, rods or tubes, or other extruded forms, and is then excluded from this heading
(generally heading 39.16, 39.17, 39.20 or 39.21); it is not suitable for injection moulding and is therefore not put up as a moulding powder.
Cellulose nitrate mixed with other kinds of plasticisers is widely used as the basis for varnishes, and for this purpose may be presented in the form of dry or pasty extracts. Solutions consisting of nitrocellulose in a mixture of ether (diethyl ether) and alcohol (ethanol) are collodions which are also included here. If the solution is partly evaporated celloidin is obtained in a solid form.