A powder mill was a
mill
Mill may refer to:
Science and technology
* Factory
* Mill (grinding)
* Milling (machining)
* Millwork
* Paper mill
* Steel mill, a factory for the manufacture of steel
* Sugarcane mill
* Textile mill
* List of types of mill
* Mill, the arithmetic ...
where
gunpowder
Gunpowder, also commonly known as black powder to distinguish it from modern smokeless powder, is the earliest known chemical explosive. It consists of a mixture of sulfur, charcoal (which is mostly carbon), and potassium nitrate, potassium ni ...
is made from
sulfur
Sulfur ( American spelling and the preferred IUPAC name) or sulphur ( Commonwealth spelling) is a chemical element; it has symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms ...
,
saltpeter
Potassium nitrate is a chemical compound with a sharp, salty, bitter taste and the chemical formula . It is a potassium salt of nitric acid. This salt consists of potassium cations and nitrate anions , and is therefore an alkali metal nitrate ...
and
charcoal
Charcoal is a lightweight black carbon residue produced by strongly heating wood (or other animal and plant materials) in minimal oxygen to remove all water and volatile constituents. In the traditional version of this pyrolysis process, ca ...
.
Milling steps
Crude grinding and mixing operations such as the
Frankford Powder-Mill of
Philadelphia
Philadelphia ( ), colloquially referred to as Philly, is the List of municipalities in Pennsylvania, most populous city in the U.S. state of Pennsylvania and the List of United States cities by population, sixth-most populous city in the Unit ...
were a
cottage industry
The putting-out system is a means of subcontracting work, like a tailor. Historically, it was also known as the workshop system and the domestic system. In putting-out, work is contracted by a central agent to subcontractors who complete the p ...
until the
Industrial Revolution
The Industrial Revolution, sometimes divided into the First Industrial Revolution and Second Industrial Revolution, was a transitional period of the global economy toward more widespread, efficient and stable manufacturing processes, succee ...
brought improved product quality through the following procedures:
*
Charcoal
Charcoal is a lightweight black carbon residue produced by strongly heating wood (or other animal and plant materials) in minimal oxygen to remove all water and volatile constituents. In the traditional version of this pyrolysis process, ca ...
was often manufactured nearby from locally available trees, but the heating retorts were typically separated from the other buildings to minimize fire danger. Trees with low value as sources of
lumber
Lumber is wood that has been processed into uniform and useful sizes (dimensional lumber), including beams and planks or boards. Lumber is mainly used for construction framing, as well as finishing (floors, wall panels, window frames). ...
were debarked, dried, and cut to uniform length to fit into iron retorts with
cast iron
Cast iron is a class of iron–carbon alloys with a carbon content of more than 2% and silicon content around 1–3%. Its usefulness derives from its relatively low melting temperature. The alloying elements determine the form in which its car ...
doors. The
retort
In a chemistry laboratory, a retort is a device used for distillation or dry distillation of substances. It consists of a sphere, spherical vessel with a long downward-pointing neck. The liquid to be distilled is placed in the vessel and heat ...
s were carefully packed to leave as little air space as possible, and the retort doors were closed and sealed with clay to prevent entry of air as the retorts were heated by external fires. Volatile gas generated by the heating process was vented through a small
flue
A flue is a duct, pipe, or opening in a chimney for conveying exhaust gases from a fireplace, furnace, water heater, boiler, or generator to the outdoors. Historically the term flue meant the chimney itself. In the United States, they a ...
at the top of each retort. After the external fires were extinguished, the retorts were allowed to cool before the doors were opened to remove the charcoal.
* High purity
sulfur
Sulfur ( American spelling and the preferred IUPAC name) or sulphur ( Commonwealth spelling) is a chemical element; it has symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms ...
usually required little preparation other than grinding to a powder. Separate grinding mills reduced cool charcoal and sulfur to fine powders.
[
* Crude ]saltpeter
Potassium nitrate is a chemical compound with a sharp, salty, bitter taste and the chemical formula . It is a potassium salt of nitric acid. This salt consists of potassium cations and nitrate anions , and is therefore an alkali metal nitrate ...
(KNO3) was dissolved in a pot of boiling water. After boiling, a small amount of floating glue might be added to the hot water to aid skimming off floating impurities. The hot solution was then carefully decanted to avoid suspending insoluble solid impurities settled to the bottom of the pot. The hot decanted liquid was distributed into shallow wooden vats where evaporative cooling
An evaporative cooler (also known as evaporative air conditioner, swamp cooler, swamp box, desert cooler and wet air cooler) is a device that cools air through the evaporation of water. Evaporative cooling differs from other air conditioning sy ...
would remove excess water. Purified potassium nitrate
Potassium nitrate is a chemical compound with a sharp, salty, bitter taste and the chemical formula . It is a potassium salt of nitric acid. This salt consists of potassium cations and nitrate anions , and is therefore an alkali metal nit ...
recrystallized while the cooling solution was gently agitated with broad hoes to prevent formation of large 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.[
* Powdered sulfur and charcoal were combined in appropriate ratios with moist saltpeter crystals, and the moist paste was mixed and compacted by kneading beneath heavy rotating wheels in a press mill.][
* The compressed cake was transferred to a corning mill or kernelling mill to be cut into pieces of approximately correct size by ]bronze
Bronze is an alloy consisting primarily of copper, commonly with about 12–12.5% tin and often with the addition of other metals (including aluminium, manganese, nickel, or zinc) and sometimes non-metals (such as phosphorus) or metalloid ...
- or zinc
Zinc is a chemical element; it has symbol Zn and atomic number 30. It is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodic tabl ...
-toothed wheels.[
* Kernelling mill products were sorted by size using leather ]sieve
A sieve (), fine mesh strainer, or sift is a tool used for separating wanted elements from unwanted material or for controlling the particle size distribution of a sample, using a screen such as a woven mesh or net or perforated sheet m ...
s. Oversize product was returned to the kernelling mill, while undersize product was returned to the press mill.[
* Sorted kernels of desired size were dried and mixed with ]graphite
Graphite () is a Crystallinity, crystalline allotrope (form) of the element carbon. It consists of many stacked Layered materials, layers of graphene, typically in excess of hundreds of layers. Graphite occurs naturally and is the most stable ...
to be tumbled in glazing mill barrels. Graphite coating reduced the tendency of grains to stick together in storage.[
* Glazed product was typically packaged in wooden kegs. Filled kegs were transported away from the mill as soon as possible to a powder magazine for wholesale distribution. The potential for destructive energy release from powder magazine accidents required the magazines to be distant from both the powder mill and other places of business or habitation.][
]
Explosions
Gunpowder is very easily ignited by static electricity
Static electricity is an imbalance of electric charges within or on the surface of a material. The charge remains until it can move away by an electric current or electrical discharge. The word "static" is used to differentiate it from electric ...
or lightning strike
A lightning strike or lightning bolt is a lightning event in which an electric discharge takes place between the atmosphere and the ground. Most originate in a cumulonimbus cloud and terminate on the ground, called cloud-to-ground (CG) lightning ...
s, and most powder mills experienced occasional accidental explosion
An explosion is a rapid expansion in volume of a given amount of matter associated with an extreme outward release of energy, usually with the generation of high temperatures and release of high-pressure gases. Explosions may also be generated ...
s. Powder mill explosions typically destroyed an entire building and killed those working in the vicinity of the building. Explosions might throw flaming debris which could ignite other buildings. Successful mills were typically built as an arrangement of separate buildings to minimize the loss from any single building explosion. Buildings were separated by enough distance to minimize the risk of being damaged by an explosion in an adjacent building. Buildings were usually built of stone with one weak wooden wall and roof to direct the force and debris from an accidental explosion toward a river or an open field.[
]
Power supply
Powder mills were originally powered by windmill
A windmill is a machine operated by the force of wind acting on vanes or sails to mill grain (gristmills), pump water, generate electricity, or drive other machinery.
Windmills were used throughout the high medieval and early modern period ...
s, water mill
A watermill or water mill is a mill that uses hydropower. It is a structure that uses a water wheel or water turbine to drive a mechanical process such as milling (grinding), rolling, or hammering. Such processes are needed in the production ...
s or horse mills. Despite later availability of steam engine
A steam engine is a heat engine that performs Work (physics), mechanical work using steam as its working fluid. The steam engine uses the force produced by steam pressure to push a piston back and forth inside a Cylinder (locomotive), cyl ...
s, the older power sources did not require a fire to generate steam
Steam is water vapor, often mixed with air or an aerosol of liquid water droplets. This may occur due to evaporation or due to boiling, where heat is applied until water reaches the enthalpy of vaporization. Saturated or superheated steam is inv ...
, and avoided the possibility of sparks which might ignite the gunpowder. Some 20th-century powder mills used electric power. Before the availability of safe electrical power, some of the most successful mills were built along rivers where water could be distributed through a power canal to individual buildings and intermediate products could be floated from one building to the next. The power canal offered a supply of firefighting water, and the adjacent river was a relatively safe direction to focus explosion debris. Where water transport was impractical, intermediate products were often transported in wagons pulled by draft animals. The wagons were often built entirely of wood held together with wooden pegs, and draft animals were usually unshod to avoid sparks from steel shoes or nails.[
]
In the United States
The 1810 census reported 208 powder mills in the United States.[ In 1802, the ]DuPont
Dupont, DuPont, Du Pont, duPont, or du Pont may refer to:
People
* Dupont (surname) Dupont, also spelled as DuPont, duPont, Du Pont, or du Pont is a French surname meaning "of the bridge", historically indicating that the holder of the surname re ...
family started their industrial enterprises in the United States
The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...
by building the Eleutherian Mills on the Brandywine Creek in Delaware
Delaware ( ) is a U.S. state, state in the Mid-Atlantic (United States), Mid-Atlantic and South Atlantic states, South Atlantic regions of the United States. It borders Maryland to its south and west, Pennsylvania to its north, New Jersey ...
. Four mills were manufacturing 69 percent of United States gunpowder when gunpowder production peaked during the American Civil War
The American Civil War (April 12, 1861May 26, 1865; also known by Names of the American Civil War, other names) was a civil war in the United States between the Union (American Civil War), Union ("the North") and the Confederate States of A ...
. They were the DuPont mill, the Hazard Powder Company of Hazardville, Connecticut
Hazardville is a section of the town of Enfield, Connecticut, United States, in Hartford County. It is a census-designated place (CDP) that had a total population of 4,599 as of the 2010 census.
History
Hazardville originated as an indu ...
, the Oriental Powder Company of Windham, Maine
Windham is a town in Cumberland County, Maine, United States. The population was 18,434 at the 2020 census. It includes the villages of South Windham and North Windham. It is part of the Portland-South Portland-Biddeford metropolitan area.
...
, and the Laflin Powder Company of Newburgh, New York
Newburgh is a City (New York), city in Orange County, New York, United States. With a population of 28,856 as of the 2020 United States census, 2020 census, it is a principal city of the Kiryas Joel–Poughkeepsie–Newburgh metropolitan area. ...
. The Confederate Powderworks of Augusta, Georgia
Augusta is a city on the central eastern border of the U.S. state of Georgia (U.S. state), Georgia. The city lies directly across the Savannah River from North Augusta, South Carolina at the head of its navigable portion. Augusta, the third mos ...
produced 6,000 tonnes of gunpowder from 1862 to 1865, but was dismantled after the war. The Laflin company merged into the Laflin & Rand Powder Company after the war, and with the other three large northern mills formed the United States Gunpowder Trade Association in 1872 including the American Powder Mills of Maynard, Massachusetts, the Austin Powder Company of Glenwillow, Ohio
Glenwillow is a village (United States)#Ohio, village in Cuyahoga County, Ohio, United States. The population was 994 at the 2020 United States census, 2020 census. A suburb of Cleveland, it is a part of the Greater Cleveland, Cleveland metropoli ...
, and the Miami Powder Company of Goes Station, Ohio. Most smaller mills were unable to compete with this trade association, popularly known as the powder trust; although regionally important mills including the California Powder Works
California Powder Works was the first American explosive powder manufacturing company west of the Rocky Mountains. When the outbreak of the Civil War cut off supplies of gunpowder to California's mining and road-building industries, a local manufa ...
of Santa Cruz, California
Santa Cruz (Spanish language, Spanish for "Holy Cross") is the largest city and the county seat of Santa Cruz County, California, Santa Cruz County, in Northern California. As of the 2020 United States census, 2020 census, the city population ...
, the Equitable Powder Company of East Alton, Illinois, and the Great Western Powder Works of Kings Mills, Ohio
Kings Mills is a census-designated place in the northeastern corner of Deerfield Township, Warren County, Ohio, Deerfield Township of Warren County, Ohio, Warren County, Ohio, United States, on the western shore of the Little Miami River. The pop ...
successfully transitioned to manufacture of smokeless powder
Finnish smokeless powder
Smokeless powder is a type of propellant used in firearms and artillery that produces less smoke and less fouling when fired compared to black powder. Because of their similar use, both the original black powder formula ...
cartridges. As smokeless powder and high 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 exp ...
s replaced gunpowder for most purposes, DuPont became the major manufacturer of United States gunpowder until discontinuing production in 1971. Subsequent production for use in pyrotechnics
Pyrotechnics is the science and craft of creating fireworks, but also includes safety matches, oxygen candles, Pyrotechnic fastener, explosive bolts (and other fasteners), parts of automotive airbags, as well as gas-pressure blasting in mining, q ...
and antique firearm
A firearm is any type of gun that uses an explosive charge and is designed to be readily carried and operated by an individual. The term is legally defined further in different countries (see legal definitions).
The first firearms originate ...
s has been undertaken by smaller firms whose operations are often ended by the persistent hazard of accidental explosions.
Europe
Notable European mills include:
* Ballincollig Royal Gunpowder Mills, Cork, Ireland
Ireland (, ; ; Ulster Scots dialect, Ulster-Scots: ) is an island in the North Atlantic Ocean, in Northwestern Europe. Geopolitically, the island is divided between the Republic of Ireland (officially Names of the Irish state, named Irelan ...
* Faversham explosives industry
Faversham, in Kent, England, has claims to be the cradle of the UK's explosives industry: it was also to become one of its main centres. The first gunpowder plant in the UK was established in the 16th century, possibly at the instigation of the ab ...
, Faversham
Faversham () is a market town in Kent, England, from Sittingbourne, from London and from Canterbury, next to the Swale, a strip of sea separating mainland Kent from the Isle of Sheppey in the Thames Estuary. It is close to the A2 road (Great ...
, England
* Grenelle Mill - France
* Poudrerie nationale de Vonges, Vonges, Côte-d'Or, France
* Waltham Abbey Royal Gunpowder Mills
The Royal Gunpowder Mills are a former industrial site in Waltham Abbey, England.
It was one of three Royal Gunpowder Mills (disambiguation), Royal Gunpowder Mills in the United Kingdom of Great Britain and Ireland, United Kingdom (the others ...
, Waltham Abbey, Essex, England
References
{{Authority control
Firearm industry
Grinding mills