4. Nitrostarch is also a good explosive for sabotage for the
same reasons as TNT. It is slightly less powerful than TNT, but it is more
sensitive to flame, friction, and impact.
5. Compositions C3 and C4 are yellow and white respectively,
and are odorous and plastic. They have about the same sensitivity as TNT,
but they are more powerful.
(3) Initiating Devices.
There are two general types of initiating
devices. One is that which produces flames (for use with low explosives).
The other is that which detonates (for use with high explosives).
(a) Flame-Producing Devices.
1. A
safety fuse consists of a powder core wrapped in paper or
cloth fiber. It
is usually waterproofed. It is the medium through which
flame is conveyed
for the direct or indirect firing of a low explosive. An
example of direct
firing is black powder. An example of indirect firing is
the ignition of a
blasting cap to detonate dynamite.
2. A miner's squib is a thin paper tube of powder sealed at
one end with a wax plug; the other end contains a fuse or wick.
The wax
plug is pinched off at the time the squib is used. The fuse burns slowly,
and when it reaches the powder, a flame shoots out the open end.
3. An electric squib consists of an aluminum tube one and one-
half inches long with leg wires protruding from one end. When an electric
current is applied to the leg wires, the firing element flashes.
It then
ruptures the tube and sends an intense flame into the explosive.
(b) Detonating Devices.
1. A blasting cap (nonelectric) is a small tube closed at one
end and loaded with a charge of an explosive. It can be detonated by the
spit or sparks from a safety fuse. Blasting caps are sensitive to shock,
friction, and heat, and they are dangerous when not properly handled. For
use, a length of safety fuse is inserted in the open end.
2. Electric blasting caps are similar in appearance to
nonelectric caps, except that they are fired by electric current. They have
the same sensitivity as nonelectric caps, and great care must be used in
storing and handling them.
They come in various numerically designated
sizes; Number 8 is the one in common use.
3. Detonating fuse or cord is a fuse which has an explosive
core. It requires a blasting cap to detonate, and the extreme violence of
the action is enough to detonate a high explosive in contact with it. It is
usually wrapped around or taped to the charge to be detonated. It is used
for the simultaneous firing of a number of shots at some distance apart.
MP1002
3-4
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