Jan. 1, 1865.] THE TECHNOLOGIST. 



260 PROPERTIES AND USES OF GUN-OOTTON. 



arrangement, can make it either a powerful explosive agent or a simple, 

 harmless flame. In the form of loose cotton the mode of ignition has been 

 mentioned. In the form of spun thread, like that of candle-wick, gun- 

 cotton burns slowly, at the rate of six inches per second. If the cotton is 

 in the form of a hollow cone, as the wick of a moderator lamp, it shows a 

 greater amount of explosive power, and burns at the rate of six feet per 

 second ; and inclosed in an india-rubber casing, twenty to thirty feet are 

 consumed in a second. So that the modifications in the degree of explosive 

 force of gun-cotton essential to its application as a substitute for gun- 

 powder, are effected simply by altering the mechanical conditions of the 

 material. Thus, for cannon cartridges, where it is desirable to obtain 

 a gradual action, coarse gun-cotton yarn is wound firmly round a 

 cylinder of wood of such a size that it fills a space allotted to the charge 

 of the gun ; whilst small-arm cartridges are made of cylindrical plaits of 

 fine yarn fitted compactly, one over the other, on a small spindle of 

 wood, or else it is enclosed in a stout paper tube, to prevent it being 

 rammed down. 



On the other hand, in charges for shells, where the greatest disruptive 

 effects are needed, the cotton is used in a condensed form, as plaits ; for 

 quick-matches, a similar mechanical arrangement is adopted : so that, to 

 effect its object, gun-cotton requires room, and, in relation to gunpowder, 

 it needs as much space as one-third or one-fourth the quantity of that 

 explosive material. In mining, gun-cotton is required to produce the 

 most destructive effects, and for this purpose finely-twisted cotton ropes 

 with hollow cores are used, which, for military purposes, are enclosed in 

 cases of sheet metal. Mr. Scott Russell remarks that, to make gun- 

 cotton formidable and destructive, squeeze it and close it up ; to make 

 it gentle, slow, and manageable, you muat give it room. 



In considering the properties which gun-cotton possesses in relation 

 to those of gunpowder, they will be best considered under several 

 heads. 



First, then, as to power or a force to propel a projectile. A charge 

 of gun-cotton weighing 16 ozs. projected a 12 lb. solid shot with a 

 velocity of 1,426 feet per second ; whilst 49 ozs. of gunpowder gave a 

 similar shot a speed of 1,400 feet per second. The Austrian experiments 

 furnish some curious results in this direction ; they show that, as the 

 gun is shortened, an increased charge of gun-cotton is required, yet the 

 effect of the normal powder gun (previously mentioned) may be attained 

 by a tube shortened from 13£ to 9 calibres, therefore lighter guns may 

 be used with this agent. If the disruptive effects of the two are com- 

 pared in this respect, gun-cotton is six times more powerful than gun- 

 powder — 1 lb. of the latter can detach 10 tons, the same quantity of the 

 former can detach 60 tons, of rock — and by putting in the charge loose 

 or compact its action admits of a nice regulation and control. Another 

 great advantage of gun-cotton is, that the explosion is unattended by 

 smoke, which not only renders the atmosphere impure, but, by producing 



