Mercury(II) fulminate
Encyclopedia
Mercury fulminate, or Hg(CNO)2, is a primary explosive. It is highly sensitive to friction
and shock
. It is mainly used as a trigger for other explosives in percussion cap
s and blasting cap
s. Mercury(II) cyanate, though its formula is identical, has a different atomic arrangement; the cyanate
and fulminate
anions are isomer
s.
First used as a priming composition in small copper caps after the 1830s, mercury fulminate quickly replaced flint
s as a means to ignite black powder charges in muzzle loading
firearm
s. Later, during the late 19th century and most of the 20th century, mercury fulminate or potassium chlorate
became widely used in primers for self-contained rifle and pistol ammunition
. Mercury fulminate has the distinct advantage over potassium chlorate of being non-corrosive, but it is known to weaken with time. Today, mercury fulminate has been replaced in primers by more efficient chemical substances. Those are non-corrosive, less toxic and more stable over time: lead azide, lead styphnate
and tetrazene
derivatives. In addition, none of these compounds replacing Hg(II) fulminate requires mercury for manufacture, supplies of which can be unreliable in wartime.
in nitric acid
and adding ethanol
to the solution. It was first prepared by Edward Charles Howard
in 1800. The crystal structure
of this compound was only determined in 2007.
Silver fulminate
can be prepared in a similar way, but this salt is even more unstable than mercury fulminate; it can even explode under water.
Friction
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and/or material elements sliding against each other. There are several types of friction:...
and shock
Shock (mechanics)
A mechanical or physical shock is a sudden acceleration or deceleration caused, for example, by impact, drop, kick, earthquake, or explosion. Shock is a transient physical excitation....
. It is mainly used as a trigger for other explosives in percussion cap
Percussion cap
The percussion cap, introduced around 1830, was the crucial invention that enabled muzzleloading firearms to fire reliably in any weather.Before this development, firearms used flintlock ignition systems which produced flint-on-steel sparks to ignite a pan of priming powder and thereby fire the...
s and blasting cap
Blasting cap
A blasting cap is a small sensitive primary explosive device generally used to detonate a larger, more powerful and less sensitive secondary explosive such as TNT, dynamite, or plastic explosive....
s. Mercury(II) cyanate, though its formula is identical, has a different atomic arrangement; the cyanate
Cyanate
The cyanate ion is an anion with the chemical formula written as [OCN]− or [NCO]−. In aqueous solution it acts as a base, forming isocyanic acid, HNCO. The cyanate ion is an ambidentate ligand, forming complexes with a metal ion in which either the nitrogen or oxygen atom may be the electron-pair...
and fulminate
Fulminate
Fulminates are chemical compounds which include the fulminate ion. The fulminate ion, is a pseudohalic ion, acting like a halogen with its charge and reactivity. Due to the instability of the ion, fulminate salts are friction-sensitive explosives. The best known is mercury fulminate, which has...
anions are isomer
Isomer
In chemistry, isomers are compounds with the same molecular formula but different structural formulas. Isomers do not necessarily share similar properties, unless they also have the same functional groups. There are many different classes of isomers, like stereoisomers, enantiomers, geometrical...
s.
First used as a priming composition in small copper caps after the 1830s, mercury fulminate quickly replaced flint
Flint
Flint is a hard, sedimentary cryptocrystalline form of the mineral quartz, categorized as a variety of chert. It occurs chiefly as nodules and masses in sedimentary rocks, such as chalks and limestones. Inside the nodule, flint is usually dark grey, black, green, white, or brown in colour, and...
s as a means to ignite black powder charges in muzzle loading
Muzzleloader
A muzzleloader is any firearm into which the projectile and usually the propellant charge is loaded from the muzzle of the gun . This is distinct from the more popular modern designs of breech-loading firearms...
firearm
Firearm
A firearm is a weapon that launches one, or many, projectile at high velocity through confined burning of a propellant. This subsonic burning process is technically known as deflagration, as opposed to supersonic combustion known as a detonation. In older firearms, the propellant was typically...
s. Later, during the late 19th century and most of the 20th century, mercury fulminate or potassium chlorate
Potassium chlorate
Potassium chlorate is a compound containing potassium, chlorine and oxygen atoms, with the molecular formula KClO3. In its pure form, it is a white crystalline substance. It is the most common chlorate in industrial use...
became widely used in primers for self-contained rifle and pistol ammunition
Cartridge (firearms)
A cartridge, also called a round, packages the bullet, gunpowder and primer into a single metallic case precisely made to fit the firing chamber of a firearm. The primer is a small charge of impact-sensitive chemical that may be located at the center of the case head or at its rim . Electrically...
. Mercury fulminate has the distinct advantage over potassium chlorate of being non-corrosive, but it is known to weaken with time. Today, mercury fulminate has been replaced in primers by more efficient chemical substances. Those are non-corrosive, less toxic and more stable over time: lead azide, lead styphnate
Lead styphnate
Lead styphnate , whose name is derived from styphnic acid, is an explosive used as a component in primer and detonator mixtures for less sensitive secondary explosives....
and tetrazene
Tetrazene
Tetrazene is a chemical compound with the molecular formula N4H4. In IUPAC nomenclature, derivatives of this compound are known collectively as tetrazenes. The most common of such derivatives is tetrazene explosive , which is used for sensitization of priming compositions....
derivatives. In addition, none of these compounds replacing Hg(II) fulminate requires mercury for manufacture, supplies of which can be unreliable in wartime.
Preparation
Mercury(II) fulminate is prepared by dissolving mercuryMercury (element)
Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum...
in nitric acid
Nitric acid
Nitric acid , also known as aqua fortis and spirit of nitre, is a highly corrosive and toxic strong acid.Colorless when pure, older samples tend to acquire a yellow cast due to the accumulation of oxides of nitrogen. If the solution contains more than 86% nitric acid, it is referred to as fuming...
and adding ethanol
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...
to the solution. It was first prepared by Edward Charles Howard
Edward Charles Howard
Edward Charles Howard FRS the youngest son of Charles Howard, 11th Duke of Norfolk, was a British chemist who has been described as the first chemical engineer of any eminence....
in 1800. The crystal structure
Crystal structure
In mineralogy and crystallography, crystal structure is a unique arrangement of atoms or molecules in a crystalline liquid or solid. A crystal structure is composed of a pattern, a set of atoms arranged in a particular way, and a lattice exhibiting long-range order and symmetry...
of this compound was only determined in 2007.
Silver fulminate
Silver fulminate
Silver fulminate is an explosive, ionic, fulminic acid salt of silver.Silver fulminate is a primary explosive that has very little practical value due to its extreme sensitivity to impact, heat, pressure and electricity...
can be prepared in a similar way, but this salt is even more unstable than mercury fulminate; it can even explode under water.