GUN-COTTON. [From Supplement.] During the last few Tears, great improvements have been effected in the manufacture and application of this material, and in conse quence, its use is rapidly extending, especially in Great Britain, where it is fonnd of great advantage in mining operations, owing to its not producing smoke when exploded. For the improvements as well as the invention of gun-cotton, we are indebted to Ger many and Austria, the most important improvement being that of baron Leek, con sisting chiefly in the following precautions in the manufacture: 1. A perfect cleansing and drying of the cotton. 2. The use of the most concentrated and purest acids pro curable commercially. 3. Steeping the cotton a second time in a mixture of the strong acids. 4. Continuance of this steep for 48 hours. 5. A thorough purification of the gun-cotton from free acid by washing in a running stream for several weeks. This may be supplemented by washing in a weak solution of potash, but is not absolutely neces sary. The following are the important advantages insured by the new method of making gun-cottou: For Purposes of Artdletv.-1. The same initial velocity of the projectile can be obtained a charge of gun-cotton one-fourth of the weight of gunpowder, 2, There is no smoke from the explosion of gun-cotton. 3. Gun-cotton does not foul the gun. 4. Gun-cotton does not heat the gun to the injurious degree of gunpowder. 5. Gun cotton gives the same velocity to the projectile with much smaller recoil of the gull. 6. Gun-cotton will produce the same initial velocity of projectile with a shorter length of barrel. 7. In projectiles of the nature of explosive shells. gun-cotton has the advantage of breaking the shell more equally into much more numerous pieces than gunpowder. 8. When gun-cotton is used in shells instead of gunpowder, a quantity equal in weight to one-third of the latter produces double the explosive force.
For Ciril Engineering and Mining.-9. In driving tunnels through hard rock, a charge of gun-cotton of given the exerts double the explosive force of gunpowder, so as to render a smaller number of holes necessary. 10. Guncotton also may be so used as, in its explosion, to reduce the rock to much smaller pieces than gunpowder, and so facilitate its removal. 11. As gun-cotton produces no smoke, the work can proceed much more rapidly, and with less injury to the health of the miners. 12. In working coal-mines, the advantages of bringing down much larger quantities of material with a given charge, and the absence of smoke in the explosion, enable a much greater quan tity of work to be done in a given time at a given cost. 13. The weight of gun-cotton
required to produce a given effect in mining is only one-sixth part of the weight of gunpowder. 14. In blasting rock under water, the wider range and greater force of is given charge is a great element in cheapening the cost of submarine work. 15. The peculiar local action of gun-cotton, to which the effects of gunpowder show no analogy, enables the engineer to destroy and remove submarine stones and rocks without the preliminary delay and expense of boring chambers for the charge.
For Military Engineering.-16. The smaller weight of gun-cotton offers great advan tages in facility of transport, the weight being one-sixth that of gunpowder, 17. The peculiar localized action of gun-cotton enables the engineer to destroy bridges and pali sades, and to remove every kind of obstacle with great facility. .18. For submarine explosion, either in attack or defense, gun-Cotton has the advantage of a much wider range of destructive power than gunpowder. 19. For the same purpose, gun-cotton, from its lightness, has the advantage of keeping afloat the water-tight case in which it is contained, while the gunpowder sinks to the bottom.
For oral Wayare.-20. Where guns are close together, as in the batteries of ships and caseinated forts, the absence of smoke removes the great evil of time firing of one gun impeding the aim of the next, and thus gun-cotton facilitates rapid tiring, 21. Between-decks also, the absence of smoke allows continuous rapid firing to be main tained. The absence of fouling and of heating arc equally advantageous for naval as fat military artillery. Of late, gun-cotton has come to be extensively used for charging torpedoes of various kinds, especially in the Eliglish, American, and German naval service.
General Advantages.—Time, damp, and exposure do not alter its qualities when care fully prepared. Being made in the form of rope, yarn, or, according to the most recent improvement, in compressed disks, accidents cannot arise front spilling, as in gunpow der. As it can be exploded in a wet condition, provided a small quantity close to the detonating apparatus be dry, gun-cotton can be stored wet, and the risk of accidents can in this way be in a great measure avoided. The dreadful explosion at the gun cotton mills, Stowmarket, in 1871, threw doubts on the safety of this substance. Ilow ever, the works at Stowmarket were rebuilt, and government manufactures this explosive in large quantities at Waltham Abbey. Gun-cotton is not now much in demand for artillery purposes, but it is more or less used for mining and quarrying in several parts of England.