Nitro-Explosives: A Practical Treatise | Page 4

we represent the ligno-cellulose
molecule by a C_{12} formula, it will contain four hydroxyl (OH)
groups, or two less than cellulose similarly represented." It contains
11.5 per cent. of nitrogen. The jute nitrates resemble those of cellulose,
and are in all essential points nitrates of ligno-cellulose.
Nitro-jute is used in the composition of the well-known Cooppal
Smokeless Powders. Cross and Bevan are of opinion that there is no
very obvious advantage in the use of lignified textile fibres as raw
materials for explosive nitrates, seeing that a number of raw materials
containing cellulose (chiefly as cotton) can be obtained at from £10 to
£25 a ton, and yield also 150 to 170 per cent. of explosive material
when nitrated (whereas jute only gives 154.4 per cent.), and are in
many ways superior to the products obtained from jute. Nitro-lignin, or
nitrated wood, is, however, largely used in the composition of a good
many of the smokeless powders, such as Schultze's, the Smokeless
Powder Co.'s products, and others.
~The Danger Area.~--That portion of the works that is devoted to the
actual manufacture or mixing of explosive material is generally
designated by the term "danger area," and the buildings erected upon it
are spoken of as "danger buildings." The best material of which to
construct these buildings is of wood, as in the event of an explosion
they will offer less resistance, and will cause much less danger than

brick or stone buildings. When an explosion of nitro-glycerine or
dynamite occurs in one of these buildings, the sides are generally
blown out, and the roof is raised some considerable height, and finally
descends upon the blown-out sides. If, on the other hand, the same
explosion had occurred in a strong brick or stone building, the walls of
which would offer a much larger resistance, large pieces of brickwork
would probably have been thrown for a considerable distance, and have
caused serious damage to surrounding buildings.
It is also a very good plan to surround all danger buildings with
mounds of sand or earth, which should be covered with turf, and of
such a height as to be above the roof of the buildings that they are
intended to protect (see frontispiece).[A] These mounds are of great
value in confining the force of the explosion, and the sides of the
buildings being thrown against them are prevented from travelling any
distance. In gunpowder works it is not unusual to surround the danger
buildings with trees or dense underwood instead of mounds. This
would be of no use in checking the force of explosion of the high
explosives, but has been found a very useful precaution in the case of
gunpowder.
[Footnote A: At the Baelen Factory, Belgium, the danger buildings are
erected on a novel plan. They are circular in ground plan and lighted
entirely from the roof by means of a patent glass having wire-netting in
it, and which it is claimed will not let a splinter fall, even if badly
cracked. The mounds are then erected right up against the walls of the
building, exceeding them in height by several metres. For this method
of construction it is claimed that the force exerted by an explosion will
expand itself in a vertical direction ("Report on Visits to Certain
Explosive Factories," H.M. Inspectors, 1905).]
In Great Britain it is necessary that all danger buildings should be a
specified distance apart; a license also must be obtained. The
application for a license must give a plan (drawn to scale) of the
proposed factory or magazine, and the site, its boundaries, and
surroundings, and distance the building will be from any other
buildings or works, &c., also the character, and construction of all the

mounds, and nature of the processes to be carried on in the factory or
building.[A]
[Footnote A: Explosives Act, 38 Vict. ch. 17.]
[Illustration: FIG. 1.--SECTION OF NITRO-GLYCERINE CONDUIT.
a, lid; b, lead lining; c, cinders.]
The selection of a site for the danger area requires some attention. The
purpose for which it is required, that is, the kind of explosive that it is
intended to manufacture, must be taken into consideration. A perfectly
level piece of ground might probably be quite suitable for the purpose
of erecting a factory for the manufacture of gun-cotton or gunpowder,
and such materials, but would be more or less unsuitable for the
manufacture of nitro-glycerine, where a number of buildings are
required to be upon different levels, in order to allow of the flow of the
liquid nitro- glycerine from one building to another through a system of
conduits. These conduits (Fig. 1), which are generally made of wood
and lined with lead, the space between the woodwork and the lead
lining, which is generally some 4 or 5 inches, being filled with cinders,
connect