Sprengel explosives are a generic class of materials invented by

Hermann Sprengel Hermann Sprengel FRS (29 August 1834 – 14 January 1906) was a German-British chemist who discovered the explosive nature of picric acid in 1873, patented safety explosives and invented the mercurial air pump. Life He was born at Schill ...

in the 1870s. They consist of

stoichiometric Stoichiometry refers to the relationship between the quantities of reactants and products before, during, and following chemical reactions. Stoichiometry is founded on the law of conservation of mass where the total mass of the reactants equ ...

mixtures of strong

oxidiser An oxidizing agent (also known as an oxidant, oxidizer, electron recipient, or electron acceptor) is a substance in a redox chemical reaction that gains or " accepts"/"receives" an electron from a (called the , , or ). In other words, an oxid ...

s and reactive fuels, mixed just prior to use in order to enhance safety. Either the oxidiser or the fuel, or both, should be a liquid to facilitate mixing, and intimate contact between the materials for a fast reaction rate. Sprengel suggested

nitric acid Nitric acid is the inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but older samples tend to be yellow cast due to decomposition into oxides of nitrogen. Most commercially available nitri ...

, nitrates and chlorates as oxidisers, and nitro

aromatic In chemistry, aromaticity is a chemical property of cyclic ( ring-shaped), ''typically'' planar (flat) molecular structures with pi bonds in resonance (those containing delocalized electrons) that gives increased stability compared to satur ...

s (e.g. nitrobenzene) as fuels. Other Sprengel explosives used at various times include charcoal with

liquid oxygen Liquid oxygen—abbreviated LOx, LOX or Lox in the aerospace, submarine and gas industries—is the liquid form of molecular oxygen. It was used as the oxidizer in the first liquid-fueled rocket invented in 1926 by Robert H. Goddard, an app ...

(an

oxyliquit An Oxyliquit, also called liquid air explosive or liquid oxygen explosive, is an explosive material which is a mixture of liquid oxygen (LOX) with a suitable fuel, such as carbon (as lampblack), or an organic chemical (e.g. a mixture of soot and ...

), "Rackarock", and

ANFO ANFO ( ) (or AN/FO, for ammonium nitrate/fuel oil) is a widely used bulk industrial explosive. It consists of 94% porous prilled ammonium nitrate (NH4NO3) (AN), which acts as the oxidizing agent and absorbent for the fuel, and 6% number 2 fue ...

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 ...

(oxidiser) mixed with a fuel oil (fuel), normally diesel, kerosene, or

nitromethane Nitromethane, sometimes shortened to simply "nitro", is an organic compound with the chemical formula . It is the simplest organic nitro compound. It is a polar liquid commonly used as a solvent in a variety of industrial applications such as in ...

. Eventually ANFO supplanted all others because its oxidiser was the safest, and - due to its widespread use as a

fertiliser A fertilizer (American English) or fertiliser (British English; see spelling differences) is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from ...

agriculture Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people t ...

- also the cheapest. "Rackarock" consisted of potassium chlorate and nitrobenzene. It was provided in the form of permeable cartridges of the chlorate, which were placed in wire baskets and dipped in the nitrobenzene for a few seconds before use. For underwater use, it could be provided in cans instead. It was famously used in the massive submarine demolition of Flood Rock, a navigational hazard in Long Island Sound in 1885. The charge of over a hundred

tonne The tonne ( or ; symbol: t) is a unit of mass equal to 1000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton ( United State ...

s of explosive (laid in

tunnel A tunnel is an underground passageway, dug through surrounding soil, earth or rock, and enclosed except for the entrance and exit, commonly at each end. A pipeline is not a tunnel, though some recent tunnels have used immersed tube cons ...

s 20 metres below sea level) destroyed approximately 600,000 tonnes of rock.

References

{{Reflist Explosives

See also

References