Dynamite
.
Dynamite is an explosive material based on nitroglycerin,
using diatomaceous earth (AmE:
kieselgur; BrE: kieselguhr), or another absorbent
substance such as powdered shells, clay, sawdust, or wood pulp. Dynamites using
organic materials such as sawdust are less stable and such use has been
generally discontinued. Dynamite was invented by the Swedish chemist
and engineer Alfred Nobel in Geesthacht,
Germany, and patented in 1867. Its name was coined by Nobel from the Ancient Greek word
δύναμις dýnamis,
meaning "power".
Dynamite is a high explosive,
which means its power comes from detonation rather
than deflagration. Dynamite is mainly used in the mining,quarrying, construction,
and demolition industries,
and it has had some historical usage in warfare. However the unstable nature of
nitroglycerin, especially if subjected to freezing, has rendered it obsolete
for military uses. Popular familiarity with dynamite led tometaphoric uses,
such as saying that a particular issue is "political dynamite".
Dynamite consists of three parts nitroglycerin,
one part diatomaceous earth and a small admixture of sodium carbonate.
This mixture is formed into short sticks and wrapped in paper. A blasting cap
and fuse of any length are then inserted down the middle. Nitroglycerin by
itself is a very strong explosive, and in its pure form it is extremely
shock-sensitive (that is, physical shock can cause it to explode), and degrades
over time to even more unstable forms. This makes it highly dangerous to
transport or use in its pure form.
Absorbed into diatomaceous earth or
sawdust, nitroglycerin is less shock-sensitive. Over time, the dynamite will
"weep" or "sweat" its nitroglycerin, which can then pool in
the bottom of the box or storage area. (For that reason, explosive manuals recommend
the repeated turning over of boxes of dynamite in storage.) Modern packaging
helps eliminate this by placing the dynamite into sealed plastic bags, and
using wax coated cardboard. Crystals will form on the outside of the sticks
causing them to be even more shock, friction or temperature sensitive. This
creates a very dangerous situation. While the risk of an explosion without the
use of a blasting cap is minimal for fresh
dynamite, old dynamite is dangerous.
Dynamite is usually sold in the form of
cylinders about 8 in (20 cm) long and about 1.25 in
(3.2 cm) in diameter, with a weight of about 0.5 lb troy
(0.186 kg). Other sizes also exist. The maximum shelf life of
nitroglycerin-based dynamite is recommended as one year from the date of
manufacture under good storage conditions. Another form of dynamite consists of
nitroglycerin dissolved in nitrocellulose and
a small amount of ketone. This form of dynamite is similar to cordite and gelignite,
and is much safer than the simple mix of nitroglycerin and diatomaceous earth. Military
dynamite achieves greater stability by avoiding the use of
nitroglycerin and uses much more stable chemicals.
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