GUN COTTON

Pyroxyline. A highlv inflammable and explosive substance, discovered by Schonbein, obtained by steeping clean cotton wool for a few minutes in a mixture of the strongest sulphuric and nitric acids in equal proportions; it is then thoroughly washed, and cautiously dried at a temperature of 212°. The original appearance of the cotton is little changed, but it has now become explosively inflammable, and when kindled by a spark it very suddenly flashes off with greater rapidity and energy than gunpowder, for which it has been proposed as a substitute, but the sad accidents which have occurred in the attempts to manufacture it upon a large scale have hitherto prevented its employment. When used in a gun it is much more energetic, weight for weight, than gunpowder; but, like fu minating mer. cury, it is apt, from the extreme suddenne of its explosion, 'to burst the gun. It appears to be pre-eminently fitted for blasting rocks. The composition of gun cotton has not been very satisfactorily determined; by some it has been considered as a nitrate of lignine; that is, as a direct atomic combination of lignine and nitric acid, represented by the formula C24 Hje Ojg + 5NO5. Porret thinks that the cotton acquires oxygen from the nitric acid, and forms a new basic compound which he call i ligne a, and he regards gun cotton as a hyponitrite oJ ligne a. Gun cotton is soluble in ether, and furnishes a glutinous liquor which has been used as an adhesive appli. cation in surgery, and even as a substitute for common sticking plaister, or goldbeater's skin. This solutior has been called Collodion. When spread ujion a surfac* the ether evaporates and leaves the gun cottoi in tl)( form of a transparent film, still very inflammable and explosive, and like the gun cotton itself, becoming highly electric on friction. [s. 1389]