1864. ] Russevt on Gun-cotton. 409 
to the mechanical structure which is given to it, or the mechanical 
arrangements of which it is made a part. It was General Lenk who 
discovered that structure was quality, and mechanical arrangement 
the measure of power, in gun-cotton ; and in his hands, a given quan- 
tity of the same cotton becomes a mild, harmless, ineffectual firework, 
a terrible, irresistible, explosive agent, or a pliable, powerful, obedient 
workman. 
The first form which General Lenk bestowed on gun-cotton was 
that of a continuous yarn or spun thread. Gunpowder is carefully 
made into round grains of a specific size. Gun-cotton is simply a 
long thread of cotton fibre, systematically spun into a yarn of given 
weight per yard, of given tension, of given specific weight. A hank 
of a given length is reeled, just like a hank of cotton yarn to be made 
into cloth, and in this state gun-cotton yarn is bought and sold like 
any other article of commerce. 
This cotton yarn converted into gun-cotton may be called, there- 
fore, 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 the reach of the flame, and keep other combusti- 
bles beyond reach, no harm will happen, and no explosion or concus- 
sion 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 6 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 
