GUN COTTON was first announced by Professor Schonbein, and shown by him to the Natural History Society of Basle in 1846. Shortly after this Bcelt zer, Otto, and Morel, discovered similar explosive compounds, all of which may fairly be traced to Pelouse and Brae caurd's discovery of Xvloidine. It has been looked on as identical with the lat ter, but IV correctly, for gun cotton dis solves in acetic acid, while xyloidine does not. Schonbein made it originally by dipping cotton in nitric acid, sp. gr. 1.49, which after immeroion for ten mi nutes it was rinsed in a large quantity of cold water, to free it from any adher ing acid; and then carefully dried. Dr. Ellet, Professor of Chemistry in Univer city of South Carolina, adopted as an im provement the use of sulphuric acid., with the view of keeping the nitric acid concentrated. Dr. Taylor, of London, adopted a similar plan ; nitre was after wards added to the mixed acids. In order to obtain a good gun cotton it is necessary 1st. To steep purified cotton in a mix ture of equal parts of nitric and sul phuric acids.
2d. The duration of immersion is not important : the best samples have been ten minutes steeped.
3d. A mixture may be used in which cotton has been previously immersed, re viving it if necessary.
4th. The cotton must not be above the level of the liquid.
5th. It mast be dried slowly, and not exposed, especially when damp, to a tem perature exceeding 6th. By washing in water saturated with nitre or chlorate of potass its power is a little increased, but it is not worth the additional expense.
Burned on the hand it causes no sen sible pain, leaves no stain, and produces no smoke ; dipped in water and pressed, and afterwards dried between two leaves of blotting paper, it preserves its fulmi nating properties. It explodes on being heated to 850°, or on bringing a red hot body in contact with it : a dry piece of the cotton laid upon gunpowder may be exploded without igniting the powder. This is due to the rapidity of the explo sion. Mr. E, F. Tesehemacher and
R. Forrett have found gun cotton to con sist uniformly of nitric acid and liquin, in the proportion of 60 of the former to 40 of the latter. Properly exploded in a narrow glass tube so as to collect the gaseous product, 52.33 grains of the cot ton were found to give 100 c. i. of gas, of which the composition was remark able, consisting of Carbonic 14286, or 2 vole.
Cyanogen 7.193, or 1 vol.
Nitric oxide 35715, or 5 vole.
Carbonic oxide 35.915, or 5 vole.
Nitrogen . or 1 vol.
Besides which a sublimate of oxalic acid and a quantity of water was formed in tho combustion.
Exposed to a heat, between 200° and 300°, it became brown, and lost its explosive property. Steaming it, seems to increase its power.
Examined under the microscope, there is no difference visible between cotton so prepared and that enacted on by acid. Under the action of polarized light there is, however, a marked difference. The fibres of ordinary cotton are then bril liantly illuminated on a dark colored ground, while the gun cotton is dark and colorless, and invisible at every half turn of the prism.
In practice, it has not fulfilled all that was originally predicted of it ; it is unfit for gunnery and fire-arms of any kind, but is admirably adapted for mining and blasting.
The advantages of its use are : its cleanliness, the rapid combustion, and non residuum ; the absence of any bad smell ; its lightness ; the possibility of handling it without danger at a distance from the fire ; the absence of dust, and its indisputable force, which is triple that of gunpowder of equal weight. The disadvantages aro : bulk, increased in flammability, the disadvantage of evolv ing vapor its explosion ; it wets theguns and cannon just as gunpowder fouls them.
Gun cotton dissolved in ether forms a good varnish for covering wounds, or giving a thin film to cover any surface, and is a powerful deoxidizer, reducing salts of silver and a few other metals very rapidly.