High explosives

Picric Acid

German designation : Granatfüllung 88

French designation : Melinite

British designation : Lyddite

Japanese designation : Shimose

Italian designation : Pertite

Picric Acid or Trinitrophenol – C₆H₂-OH-(NO₂)₃ – is a lemon-yellow crystalline solid high explosive, only slightly soluble in cold water, but soluble in alcohol, benzene, and other organic solvents. Its melting point is 122° C, its specific gravity 1.77 and its detonation velocity 7350 m/s. It is not as toxic as T.N.T., but also produces fumes when molten explosives are packed in loading shells. Picric Acid is entirely stable and has about the same sensitivity to shock or friction as T.N.T. It requires a primer of dry gun-cotton or picric powder (Ammonium Picrate) to detonate it. The smoke produced by the detonation of Picric acid is nearly black, but when it exploded only the colour of the smoke produced is yellow.

It was used especially by nations which have Krupp equipments, but at the beginning of 19^th century German Army replaced it with Trotyl (T.N.T.). The Melinite, used by French Army, was Picric Acid with the addition of a little of mineral oil.

Trinitrotoluol or Trinitrotoluene (T.N.T.)

German designation : Füllpulver 02

Trinitrotoluol – C₆H₂-CH₃-(NO₂)₃ –, called Trotyl in Germany and Tolite in France, is crystalline high explosive, nearly white in colour, almost insoluble in water, but soluble in hot alcohol or in benzol. Its specific gravity is 1.654, and its melting point is 80.1° C. Its detonation velocity is 6900 m/s. T.N.T. does not produce poisonous fumes, and it does not form explosive salts when in contact with metals. When ignited it burns slowly with a sooty flame. It is insensitive to shock and friction, which reduces the risk of unexpected detonations. When detonated it explodes with about the same force of Picric Acid. T.N.T. is a very safe explosive, but it needs to detonate a strong fulminate primer. In order to reduce the fulminate primer Krupp introduced progressive detonation. The smoke produced by the detonation of T.N.T. is nearly black, but when it exploded only the colour of the smoke produced is white to blue-grey.

T.N.T. was first prepared in 1863 by German chemist Joseph Wilbrand and originally used as a yellow dye. Its potential as an explosive was not appreciated for several years mainly because it was very difficult to detonate and because it was less powerful than alternatives. The German Army adopted it as a filling for artillery shell only in 1902.

Amatol

German designation : Füllpulver 60/40

It is a crystalline high explosive, yellow or brownish in colour, made from a mechanical mixture of T.N.T. and ammonium nitrate (NH₄NO₃). Amatol exploits the synergy between T.N.T. and ammonium nitrate. T.N.T. has a high detonation velocity and good brisance, but is comparatively expensive and complex to manufacture and is also deficient in oxygen. Ammonium nitrate has a fairly low detonation velocity and correspondingly low brisance, but is extremely cheap and easy to manufacture. Moreover it contains a surplus of oxygen which T.N.T. can use during detonation. Depending on the ratio of ingredients used, Amatol leaves a residue of white or grey smoke after detonation. It is moisture-absorbing, insensitive to friction, but may be detonated by severe impact. It is hygroscopic and should not be stored in containers made from copper or brass, as it can form dangerous compounds.

The Füllpulver 60/40, used by German Army during WW1, was composed by 60% T.N.T., and 40% ammonium nitrate. Its detonation velocity was 5500 m/s.

Ammonal

It consists of 75% ammonium nitrate, 5% carbon, and 20% metallic alluminium. At the beginning of 20^th Century various similar compositions were used, in some of which the carbon was replaced by a hydro-carbon such as heavy oil, while others contained chlorate of potash to make the composition livelier. The later forms of Ammonal introduced contained a portion of T.N.T. The British Army employed Ammonal for their mines from early 1915. It comprised a mixture of 65% ammonium nitrate, 15% T.N.T., 17% coarse aluminium and 3% charcoal by weight. Its detonation velocity was 4580 m/s.

Ammonal is not easy to detonate without fulminate, but it can be made to explode with great violence by the use of a primer of ammonia powder. The violence of the explosion is due to the very high temperature generated by the burning of the aluminium dust. All forms of Ammonal are strongly hygroscopic, and liquefy when exposed to the air. They useless unless kept inside a shell under a metallic seal.

Schneiderite

It is a form of Ammonal used by Schneider for H.E. shell busters. It consisted of 11% dinitronaphthalene, 88% ammonium nitrate (NH₄NO₃) and 1% resin, intimately incorporated together by grinding in a black powder mill, and loaded by compression. It is a fine straw-yellow powder. As all kinds of Ammonal, also Schneiderite was very hygroscopic. It was generally used by the nations which adopted Schneider equipments.

Ecrasite

It is a mixture of ammonium cresylate with picric acid. It is a bright yellow solid which is unaffected by moisture, shock or fire. It is waxy to touch and melts at about 100 °C. When subjected to open flame, it burns without detonation, unless confined. It is insensitive to friction and requires a detonator for initiation.

Ecrasite was invented in 1888-1889 by Siersch and Kubin, and was used in Austria to load artillery shells, but it was later abandoned in favour of Ammonal. Its general adoption was hindered by several unexplained explosions during loading into shells.

Astralite

It is yellowish-grey in colour and usually consists of ammonium nitrate, woodmeal, dinitrotoluene with traces of T.N.T., a small amount of Nitroglycerine and usually some Nitrocellulose. Its explosive effect is fairly powerful, but not of excessive violence. Its detonation velocity was 4000 m/s. It was employed by the German Army in Minenwerfer shells.

Westphalite

Produced in Germany starting from 1893, it was composed by 90% ammonium nitrate, potassium nitrate and organic elements.

Roburite

It was produced in Germany starting from 1886. At first it was composed by 90% ammonium nitrate and 10 % dinitrochlorobenzene, later by 55%-88% ammonium nitrate, 0,5 % potassium permanganate, 7 % dinitrobenzene or 12% T.N.T., dinitrochlornaphthalene and other organic elements.

Donarite

It consisted of 55%-84% Ammonium nitrate, up to 22% Nitroglykol, and 11%-16% T.N.T. + Dinitrotoluene.

Remarks:

At the beginning of WW1 German Army used as replacement for the more expensive Füllpulver 02 some ammonium-nitrate-carbon explosives, such as Donarite, Roburite or Westfalite. They were too sensitive against the shock of firing and caused so many bore premature, that at the beginning of 1915 all these shells had to be withdrawn from the front. The problem was solved with the introduction of the Füllpulver 60/40.