Sept. 1, 1864.] THE TECHNOLOGIST. 



USES OP OUN-COTTON. 53 



This cotton yarn converted into gun-cotton may be called, therefore, 

 the raw material of commerce. In this form it is not at all explosive 

 in the common sense of the word. You may set fire to a hank of it, 

 and it will burn rapidly with a large flame ; but if you yourself keep 

 out of reach of the flame, and keep other combustibles beyond reach, no 

 harm will happen, and no explosion or concussion will result. If you 

 lay a long thread of it round your garden walk at night, disposing it 

 in a waving line with large balls of gun-cotton thread at intervals, and 

 light one end of the thread, it will form a beautiful firework, the slow 

 lambent flame creeping along with a will-o'-th'-wisp-looking light, only 

 with a measured speed of six inches per second, or 30 feet a minute ; the 

 wind hastening it or retarding it as it blows with or against the line of 

 the thread. This is the best way to commence an acquaintance with this 

 interesting agent. 



Care must be taken not to become too familiar with gun-cotton even 

 in this harmless and playful guise ; cotton dresses will readily catch fire 

 from it, and it should not be treated with less care to keep fire from it 

 than gunpowder. In one respect it is less liable to cause danger than 

 gunpowder. Grains of powder are easily dropped through a crevice, 

 and may be sprinkled about in a scarcely noticeable form, but a hank 

 of gun-cotton is a unit, which hangs together and cannot strew itself 

 about by accident. 



The second form of gun-cotton is an arrangement compounded out of 

 the elementary yarn. It resembles the plaited cover of a riding whip : 

 it is plaited round a core or centre which is hollow. In this form it is 

 match-line, and, although formed merely of the yarn plaited into a 

 round hollow cord, this mechanical arrangement has at once conferred 

 on it the quality of speed. Instead of travelling as before only 6 inches 

 a second, it now travels 6 feet a second. 



The third step in mechanical arrangement is to enclose this cord in a 

 close outer skin or coating, made generally of india-rubber cloth, and in 

 this shape it forms a kind of match-line, that will carry fire at a speed 

 of from 20 to 30 feet per second. 



It is not easy to gather from these changes what is the cause which 

 so completely changes the nature of the raw cotton by mechanical 

 arrangement alone. Why a straight cotton thread should burn with a 

 slow creeping motion when laid out straight, and with a rapid one when 

 wound round in a cord, and again much faster when closed in from the 

 air, is far from obvious at first sight ; but the facts being so, deserve 

 mature consideration. 



The cartridge of a common rifle in gun-cotton is nothing more than 

 a piece of match-line in the second form enclosed in a stout paper-tube, 

 to prevent it being rammed down like powder. The ramming down, 

 which is essential to the effective action of gunpowder, is fatal to that 

 of gun-cotton. To get useful work out of a gun-cotton rifle, the shot 

 must on no account be rammed down, but simply transferred to its 



