
Amatol is a highly
explosive material made from a mixture of
TNT and
ammonium nitrate. The British name originates from the words
ammonium and
toluene (the precursor of TNT). Similar mixtures (one part
dinitronaphthalene and seven parts ammonium nitrate) were known as Schneiderite in France. Amatol was used extensively during
World War I
World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...
and
World War II
World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
, typically as an
explosive in military weapons such as aircraft
bombs,
shells,
depth charges, and
naval mines.
[Brown, G. I. (1998). ''The Big Bang: A History of Explosives''. Sutton Publishing . pp. 158-163.] It was eventually replaced with alternative explosives such as
Composition B,
Torpex, and
Tritonal.
Invention
Following the
Shell Crisis of 1915 in which the UK did not have enough ordnance due to a lack of explosives, a team at the
Royal Arsenal laboratories produced a mixture of ammonium nitrate and TNT, known as Amatol for short. Special factories were constructed for the manufacture of ammonium nitrate by the double decomposition of sodium nitrate and ammonium sulfate in solution followed by evaporative concentration and crystallization. It became the standard filling for shells and bombs, and was later adopted by the US as their principal high explosive.
[*]
Manufacture and use
Amatol exploits
synergy between TNT and ammonium nitrate. TNT has higher
explosive velocity and
brisance, but is deficient in
oxygen. Oxygen deficiency causes black smoke residue from a pure TNT explosion. The oxygen surplus of ammonium nitrate increases the energy release of TNT during
detonation. Depending on the ratio of ingredients used, amatol leaves a residue of white or grey smoke after detonation. Amatol has a lower explosive velocity and correspondingly lower brisance than TNT but is cheaper because of the lower cost of ammonium nitrate.
Amatol allowed supplies of TNT to be expanded considerably, with little reduction in the destructive power of the final product, so long as the amount of TNT in the mixture did not fall below 60%. Mixtures containing as little as 20% TNT were for less demanding uses.
TNT is 50% deficient in oxygen. Amatol is oxygen balanced and is therefore more effective than pure TNT when exploding underground or underwater. Relatively unsophisticated
cannery equipment can be adapted to amatol production. TNT is gently heated with steam or hot water until it melts, acquiring the physical characteristics of a syrup. Then the correct weight ratio of powdered ammonium nitrate is added and mixed in. Whilst this mixture is still in a
molten state, it is poured into empty bomb casings and allowed to cool and solidify. The lowest grades of amatol could not be produced by casting molten TNT. Instead, flaked TNT was thoroughly mixed with powdered ammonium nitrate and then compressed or extruded.
Amatol ranges from off-white to slightly yellow or pinkish brown depending on the mixture used, and remains soft for long periods of storage. It is
hygroscopic, which complicates long-term storage.
[Davis, Tenney L. (1943) ''The Chemistry of Powder & Explosives'' Angriff Press pp.141-153&494] To prevent moisture problems, amatol charges were coated with a thin layer of pure molten TNT or alternatively
bitumen
Bitumen ( , ) is an immensely viscosity, viscous constituent of petroleum. Depending on its exact composition, it can be a sticky, black liquid or an apparently solid mass that behaves as a liquid over very large time scales. In American Engl ...
. Long-term storage was rare during wars because
munitions charged with amatol were generally used soon after manufacture.
Amatol should not be stored in containers made from copper or brass, as it can form unstable compounds sensitive to vibration.
Pressed, it is relatively insensitive but may be detonated by severe impact, whereas when cast, it is extremely insensitive.
Primary explosives such as
mercury fulminate were often used as a
detonator, in combination with an
explosive booster charge such as
tetryl.
The explosive charges hidden in
HMS ''Campbeltown'' during the
St. Nazaire Raid of 1942 contained amatol. The British
X class midget submarines which planted explosive charges beneath the German battleship
''Tirpitz'' in September 1943 carried two "saddle charges" containing four
tons of amatol. Warheads for the German
V-1 flying bomb
The V-1 flying bomb ( "Vengeance Weapon 1") was an early cruise missile. Its official Reich Aviation Ministry () name was Fieseler Fi 103 and its suggestive name was (hellhound). It was also known to the Allies as the buzz bomb or doodlebug a ...
and
V-2 rocket
The V2 (), with the technical name ''Aggregat (rocket family), Aggregat-4'' (A4), was the world's first long-range missile guidance, guided ballistic missile. The missile, powered by a liquid-propellant rocket engine, was developed during the S ...
s also contained amatol.
A derivative of amatol is
amatex, consisting of 51% ammonium nitrate, 40% TNT, and 9%
RDX (which also has a negative oxygen balance).
Ammonite
Amatol is rare today, except in legacy munitions or
unexploded ordnance. Ammonite, a form of amatol, is a civil engineering explosive popular in
Eastern Europe
Eastern Europe is a subregion of the Europe, European continent. As a largely ambiguous term, it has a wide range of geopolitical, geographical, ethnic, cultural and socio-economic connotations. Its eastern boundary is marked by the Ural Mountain ...
and China. Generally comprising a 20/80 mixture of TNT and ammonium nitrate it is typically used for
quarrying or
mining
Mining is the Resource extraction, extraction of valuable geological materials and minerals from the surface of the Earth. Mining is required to obtain most materials that cannot be grown through agriculture, agricultural processes, or feasib ...
.
Because the proportion of TNT is significantly lower than in its military counterpart, ammonite has much less destructive power. In general, a 30 kilogram charge of ammonite is roughly equivalent to 20 kilograms of TNT.
Amatol, New Jersey
Amatol was the name given to a munitions factory and planned community built by the United States government in
Mullica Township, New Jersey during
World War I
World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...
. After the war, the town was dismantled. The
Atlantic City Speedway was built on part of the Amatol site in 1926. The site (including the speedway) is presently (2020) abandoned.
See also
*
Ammonal
*
Minol
*
Hexanite
*
RE factor
References
Sources
* {{cite web, title=Amatol, work=A former World War I munitions factory, located in Mullica Township, NJ, url=http://amatol.atlantic.edu, access-date=14 May 2006
Explosives
Trinitrotoluene
British inventions