British, 12 inch shells displayed at the Royal Australian Navy Heritage Centre (2008). On the right is a Mk 6A Capped Common pointed shell, (formerly) filled with Shellite 70/30 Shellite (known as Tridite in US service) is an explosive mixture of

picric acid Picric acid is an organic compound with the formula (O2N)3C6H2OH. Its IUPAC name is 2,4,6-trinitrophenol (TNP). The name "picric" comes from (''pikros''), meaning "bitter", due to its bitter taste. It is one of the most acidic phenols. Like ot ...

and dinitrophenol or picric acid and

hexanitrodiphenylamine Hexanitrodiphenylamine (abbreviated HND), is an explosive chemical compound with the formula C12H5N7O12. Since it is made from readily available raw materials, HND was used extensively by the Japanese and less extensively by Nazi Germany during W ...

in a ratio of 70/30. It was typically used as a filling in

Royal Navy The Royal Navy (RN) is the naval warfare force of the United Kingdom. It is a component of His Majesty's Naval Service, and its officers hold their commissions from the King of the United Kingdom, King. Although warships were used by Kingdom ...

armour-piercing shells during the early part of the 20th century.

History

Shellite originated after

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 ...

as a development of lyddite (picric acid). During the war, lyddite-filled,

armour-piercing Armour-piercing ammunition (AP) is a type of projectile designed to penetrate armour protection, most often including naval armour, body armour, and vehicle armour. The first, major application of armour-piercing projectiles was to defeat the t ...

shells had been found to be shock-sensitive, with a tendency to prematurely detonate upon impact rather than after penetrating the target's armour plate.Preston et al, p.83 Shellite was less sensitive, and also had the advantage of a low

melting point The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state of matter, state from solid to liquid. At the melting point the solid and liquid phase (matter), phase exist in Thermodynamic equilib ...

, that allowed it to be easily melted and poured into shell casings during manufacture.Zukas et al, p.38 The first trials of shellite took place in 1921, when the British

monitor Monitor or monitor may refer to: Places * Monitor, Alberta * Monitor, Indiana, town in the United States * Monitor, Kentucky * Monitor, Oregon, unincorporated community in the United States * Monitor, Washington * Monitor, Logan County, Wes ...

experimentally fired different types of 15 inch (381 mm) shell at , point-blank range against the surrendered German battleship . During

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 ...

, Shellite continued to be used in naval shells. It was used in the British

Disney bomb The Disney bomb, also known as the Disney Swish, officially the 4500 lb Concrete Piercing/Rocket Assisted bomb was a 4,500lb bunker buster bomb developed during the World War II, Second World War by the British Royal Navy to penetrate harde ...

, a type of concrete-piercing bomb.

Legacy

Shellite-filled munitions may still be encountered in the wrecks of sunken

warships A warship or combatant ship is a naval ship that is used for naval warfare. Usually they belong to the navy branch of the armed forces of a nation, though they have also been operated by individuals, cooperatives and corporations. As well as ...

. They are considered hazardous as, over time, picric acid will react to form

crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...

s of metal

picrate A picrate is a salt containing the anion (O2N)3C6H2O− or an ester derivative of the picrate anion. These salts are often produced by reactions of picric acid (2,4,6-trinitrophenol). The picrate ion is intensely yellow, although many of its salt ...

s, such as

iron picrate Iron is a chemical element; it has symbol Fe () and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's out ...

. These crystals are extremely shock sensitive and it is recommended that wrecks that contain shellite

munition Ammunition, also known as ammo, is the material fired, scattered, dropped, or detonated from any weapon or weapon system. The term includes both expendable weapons (e.g., bombs, missiles, grenades, land mines), and the component parts of oth ...

s not be disturbed in any way.Albright, p.78 The hazard may reduce when the shells become corroded enough to admit

seawater Seawater, or sea water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has approximat ...

as these materials are

water-soluble In chemistry, solubility is the ability of a substance, the solute, to form a solution with another substance, the solvent. Insolubility is the opposite property, the inability of the solute to form such a solution. The extent of the solub ...

References

;Citations ;Bibliography * * * *{{cite book , title=Explosive Effects and Applications , publisher=Springer , author1=Zukas, Jonas , author2=Walters, William W. , author3=Walters, William P. , year=2002, isbn=0387955585 Explosives Naval artillery