Amatol is a highly

explosive material An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An exp ...

made from a mixture of

TNT Trinitrotoluene (), more commonly known as TNT, more specifically 2,4,6-trinitrotoluene, and by its preferred IUPAC name 2-methyl-1,3,5-trinitrobenzene, is a chemical compound with the formula C6H2(NO2)3CH3. TNT is occasionally used as a reagen ...

and

ammonium nitrate Ammonium nitrate is a chemical compound with the chemical formula . It is a white crystalline salt consisting of ions of ammonium and nitrate. It is highly soluble in water and hygroscopic as a solid, although it does not form hydrates. It is ...

. The British name originates from the words

ammonium The ammonium cation is a positively-charged polyatomic ion with the chemical formula or . It is formed by the protonation of ammonia (). Ammonium is also a general name for positively charged or protonated substituted amines and quaternary a ...

and

toluene Toluene (), also known as toluol (), is a substituted aromatic hydrocarbon. It is a colorless, water-insoluble liquid with the smell associated with paint thinners. It is a mono-substituted benzene derivative, consisting of a methyl group (CH3) at ...

(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 (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...

and

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

, typically as an

explosive An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An expl ...

in military weapons such as aircraft

bomb A bomb is an explosive weapon that uses the Exothermic process, exothermic reaction of an explosive material to provide an extremely sudden and violent release of energy. Detonations inflict damage principally through ground- and atmosphere-t ...

s, shells,

depth charge A depth charge is an anti-submarine warfare (ASW) weapon. It is intended to destroy a submarine by being dropped into the water nearby and detonating, subjecting the target to a powerful and destructive Shock factor, hydraulic shock. Most depth ...

s, and

naval mine A naval mine is a self-contained explosive device placed in water to damage or destroy surface ships or submarines. Unlike depth charges, mines are deposited and left to wait until they are triggered by the approach of, or contact with, any ...

s.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 Composition B, colloquially Comp B, is an explosive consisting of castable mixtures of RDX and TNT. It is used as the main explosive filling in artillery projectiles, rockets, land mines, hand grenades and various other munitions. It was also use ...

Torpex Torpex is a secondary explosive, 50% more powerful than TNT by mass. Torpex comprises 42% RDX, 40% TNT and 18% powdered aluminium. It was used in the Second World War from late 1942, at which time some used the names Torpex and RDX interchangeab ...

, and

Tritonal Tritonal is a mixture of 80% Trinitrotoluene, TNT and 20% aluminium Powder (substance), powder, used in several types of ordnance such as air-dropped bombs. The aluminium improves the total heat output and hence Impulse (physics), impulse of the ...

Invention

Following the

Shell Crisis of 1915 The Shell Crisis of 1915 was a shortage of artillery shells on the front lines in the First World War that led to a political crisis in the United Kingdom. Previous military experience led to an over-reliance on shrapnel to attack infantry in th ...

in which the UK did not have enough ordnance due to a lack of explosives, a team at the

Royal Arsenal The Royal Arsenal, Woolwich is an establishment on the south bank of the River Thames in Woolwich in south-east London, England, that was used for the manufacture of armaments and ammunition, proofing, and explosives research for the Britis ...

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 USA as their principal high explosive.*

Manufacture and use

Amatol exploits

synergy Synergy is an interaction or cooperation giving rise to a whole that is greater than the simple sum of its parts. The term ''synergy'' comes from the Attic Greek word συνεργία ' from ', , meaning "working together". History In Christia ...

between TNT and ammonium nitrate. TNT has higher

explosive velocity Explosive velocity, also known as detonation velocity or velocity of detonation (VoD), is the velocity at which the shock wave front travels through a detonated explosive. Explosive velocities are always faster than the local speed of sound in the ...

and

brisance In explosives engineering, brisance (; , ) is the shattering capability of a high explosive, determined mainly by its detonation pressure. Practical uses Brisance is of practical importance for determining the effectiveness of an explosion in f ...

, but is deficient in oxygen. Oxygen deficiency causes black smoke residue from a pure TNT explosion. The

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...

surplus of ammonium nitrate increases the energy release of TNT during

detonation Detonation () is a type of combustion involving a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. Detonations propagate supersonically through shock waves with ...

. 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 Canning is a method of food preservation in which food is processed and sealed in an airtight container (jars like Mason jars, and steel and tin cans). Canning provides a shelf life that typically ranges from one to five years, although un ...

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 Melting, or fusion, is a physical process that results in the phase transition of a substance from a solid to a liquid. This occurs when the internal energy of the solid increases, typically by the application of heat or pressure, which inc ...

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 Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption or adsorption from the surrounding environment, which is usually at normal or room temperature. If water molecules become suspended among the substance ...

, 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 Asphalt, also known as bitumen (, ), is a sticky, black, highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term a ...

. Long-term storage was rare during wars because

munitions Ammunition (informally ammo) is the material fired, scattered, dropped, or detonated from any weapon or weapon system. Ammunition is both expendable weapons (e.g., bombs, missiles, grenades, land mines) and the component parts of other weap ...

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 An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An exp ...

such as

mercury fulminate Mercury(II) fulminate, or Hg(CNO)2, is a primary explosive. It is highly sensitive to friction, heat and shock and is mainly used as a trigger for other explosives in percussion caps and detonators. Mercury(II) cyanate, though its chemical formu ...

were often used as a

detonator A detonator, frequently a blasting cap, is a device used to trigger an explosive device. Detonators can be chemically, mechanically, or electrically initiated, the last two being the most common. The commercial use of explosives uses electri ...

, in combination with an

explosive booster {{unreferenced, date=August 2011 An explosive booster is a sensitive explosive charge that acts as a bridge between a (relatively weak) conventional detonator and a low-sensitivity (but typically high-energy) explosive such as TNT. By itself, the ...

charge such as

tetryl 2,4,6-Trinitrophenylmethylnitramine commonly referred to as tetryl ( C7 H5 N5 O8) is an explosive compound used to make detonators and explosive booster charges. Tetryl is a nitramine booster explosive, though its use has been largely superseded ...

. The explosive charges hidden in HMS ''Campbeltown'' during the St. Nazaire Raid of 1942 contained amatol. The British X class

midget submarine A midget submarine (also called a mini submarine) is any submarine under 150 tons, typically operated by a crew of one or two but sometimes up to six or nine, with little or no on-board living accommodation. They normally work with mother ships, ...

s 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 (german: Vergeltungswaffe 1 "Vengeance Weapon 1") was an early cruise missile. Its official Ministry of Aviation (Nazi Germany), Reich Aviation Ministry () designation was Fi 103. It was also known to the Allies as the buz ...

and

V-2 rocket The V-2 (german: Vergeltungswaffe 2, lit=Retaliation Weapon 2), with the technical name ''Aggregat 4'' (A-4), was the world’s first long-range guided ballistic missile. The missile, powered by a liquid-propellant rocket engine, was developed ...

s also contained amatol. A derivative of amatol is

amatex Amatex is a military explosive consisting of 51% ammonium nitrate Ammonium nitrate is a chemical compound with the chemical formula . It is a white crystalline salt consisting of ions of ammonium and nitrate. It is highly soluble in water and h ...

, consisting of 51% ammonium nitrate, 40% TNT, and 9%

RDX RDX (abbreviation of "Research Department eXplosive") or hexogen, among other names, is an organic compound with the formula (O2N2CH2)3. It is a white solid without smell or taste, widely used as an explosive. Chemically, it is classified as a ...

(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. The vast majority of the region is covered by Russ ...

and China. Generally comprising a 20/80 mixture of TNT and ammonium nitrate it is typically used for

quarrying A quarry is a type of open-pit mine in which dimension stone, rock, construction aggregate, riprap, sand, gravel, or slate is excavated from the ground. The operation of quarries is regulated in some jurisdictions to reduce their environ ...

mining Mining is the extraction of valuable minerals or other geological materials from the Earth, usually from an ore body, lode, vein, seam, reef, or placer deposit. The exploitation of these deposits for raw material is based on the economic via ...

. 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 Mullica Township is a township in Atlantic County, in the U.S. state of New Jersey. As of the 2020 United States census, the township's population was 5,816, a decrease of 331 (−5.4%) from the 2010 census count of 6,147, which in turn reflec ...

during

. After the war, the town was dismantled. The

Atlantic City Speedway The Atlantic City Speedway was a board oval racing track located near Hammonton, New Jersey. The track was built in 1926, and hosted eight American Automobile Association American Automobile Association (AAA – commonly pronounced as "T ...

was built on part of the Amatol site in 1926. The site (including the speedway) is presently (2020) abandoned.

References

Sources