Handbook for Light Artillery

by A. B. Dyer

GUNCOTTON.

Compressed Guncotton.—Clippings and other waste from cotton-mills are thoroughly purified from oil and fatty matters by treatment with alkali and extraneous substances removed. The material is then opened up by a carding-machine and cut into suitable lengths. After thorough drying and when quite cold small quantities at a time are immersed in a cool mixture of 1 nitric acid (s. g. 1.52) and 3 sulphuric acid (s. g. 1.85). The excess of acid is then removed and the cotton carefully washed, reduced to pulp, purified, and compressed into given weights and shapes by a powerful hydraulic press, and weighs 60 lbs. per cubic foot.

The disks or slabs can be cut into smaller sizes with a sharp saw or knife without danger, care being taken to press them between boards while so doing to prevent their falling to pieces.

It has from 2 to 2½ times the strength of gunpowder for equal weights when the charges are well tamped, and 4 times the strength of gunpowder when the charges are untamped; it ignites at a lower temperature than gunpowder, as it may explode at 277° F. and must explode at 400° F.; it is comparatively insensible to shocks—caissons containing dry guncotton have been frequently inflamed by the penetration of a bullet from a military rifle, but never exploded,[11] while wet guncotton in a condition for service cannot possibly be ignited by the same means even at the shortest ranges.

Wet guncotton is not easily ignited, burns up quietly in the open air, is not sensitive to friction; but if fired by a strongly charged percussion-cap it will explode with great violence. It does not deteriorate when wet and is then perfectly safe to handle. It is therefore stored in a wet state (as it cannot be exploded except by the detonation of other disks of dry guncotton); but it should not be exposed to a temperature that will freeze the water in the cakes, if possible. While frost has no effect on dry guncotton, it causes a mechanical disintegration of the wet compressed variety.

In the field the slabs are carried wet; the disks dry and packed in hermetically sealed tins. These disks are used as primers, and have attached to them, when used, a fulminate fuze.

To Fire Guncotton, the fuze is cut to the required length and inserted in the hollow end of the detonator, especial care being taken to push it down so as to rest on the quick-match; the tube is then slightly bent to prevent the fuze from being withdrawn. The small end of the detonator is then gently inserted into the primer (the dry disk) so as to fill the entire length of the hole in the latter. If it is loose, a piece of paper or grass must be wrapped round to make it fit tight. The primer must be placed in close contact with the charge to be fired. Care must be taken that no sparks from the fuze can fall on the charge, which might then burn instead of exploding. Bear in mind that a moist primer is certain to cause failure.

The charge should be in close contact with the object to be demolished.

Transportation.—The handling of high explosives should be done under the immediate supervision of persons thoroughly familiar with the proper methods to be pursued and who will exercise great care and judgment. High explosives should be packed in light wooden boxes properly marked. The French have a wagon containing about 350 lbs. attached to a horse-battery accompanying the cavalry division, acting independently, and two such wagons with the artillery-park. Care is taken that they are not placed too near the other ammunition and are in the safest place under careful observation.

On a steamer place the explosives in a well-ventilated place remote from the engine.

On railways, if the weather be hot, there should be good ventilation and ice in the car, so placed that water cannot reach the explosives.

In winter protect from freezing if possible. Packing in straw or sawdust may be useful. Under no circumstances should cases of fuzes be in the same car, or in the vicinity of the explosive. The packages of guncotton should not be exposed to the sun—cover with paulins, put under shade-trees.

Storage.—At military posts, in ordinary service magazines over which are erected light wooden roofs, so as to insure a draught during hot weather.

The usual precautions against fire and for storage of ordinary powder must be taken; and neither fuzes, caps, nor detonators of any kind should ever be allowed in the magazine containing the explosives. Dry guncotton should not be stored in the same magazine with wet guncotton. Before being placed in the magazine the boxes should be given a coat of paint or shellac, to protect them from moisture. They should also be placed on skids and the space between the skids partially filled with sawdust, to absorb any exuding nitro-glycerine. If any powder should be spilled on the floor, or nitro-glycerine exude and be absorbed by the sawdust, it should be removed at once and burned. The boxes should be turned over every month or two, and if kept long on hand they should be opened and the explosive tested from time to time.

When guncotton is received, pour into each package enough water to cover it, or otherwise immerse it. Let the water remain for 15 minutes; then pour it off and hermetically close the box. This should be done every three months.

Packages of guncotton stained brown or yellow, giving off nitric fumes, or showing other signs of decomposition, should be removed and immersed in water. If decomposition be far advanced, they should be removed to a safe place and burned.