A saltpetre works or nitrary is a place of production of

potassium nitrate Potassium nitrate is a chemical compound with the chemical formula . This alkali metal nitrate salt is also known as Indian saltpetre (large deposits of which were historically mined in India). It is an ionic salt of potassium ions K+ and nitr ...

saltpetre Potassium nitrate is a chemical compound with the chemical formula . This alkali metal nitrate salt is also known as Indian saltpetre (large deposits of which were historically mined in India). It is an ionic salt of potassium ions K+ and nitra ...

used primarily for the manufacture of

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, carbon (in the form of charcoal) and potassium nitrate (saltpeter). Th ...

. The saltpeter occurs naturally in certain places like the "Caves of Salnitre" (

Collbató Collbató () is a municipality in the ''comarca'' of the Baix Llobregat in Catalonia, Spain. It is situated on the southern slopes of Montserrat. The area has been inhabited since at least 4000 BC, as shown by Neolithic remains found in caves a ...

) known since the Neolithic. In the "Cova del Rat Penat", guano (bat excrements) deposited over thousands of years became saltpeter after being leached by the action of rainwater.

Manufacture

The process involved burial of excrements (human or animal) in the fields prepared for that purpose beside the nitraries, watering them and waiting until the leaching process did its job; after a certain time, operators gathered the saltpeter that "came out" to the ground surface by

efflorescence In chemistry, efflorescence (which means "to flower out" in French) is the migration of a salt to the surface of a porous material, where it forms a coating. The essential process involves the dissolving of an internally held salt in water, or ...

. Then they transported it to be concentrated by

ebullition Boiling is the rapid vaporization of a liquid, which occurs when a liquid is heated to its boiling point, the temperature at which the vapour pressure of the liquid is equal to the pressure exerted on the liquid by the surrounding atmosphere. Ther ...

in the boiler plant.

History

Besides " Montepellusanus", during the thirteenth century (and beyond) the only supply of

saltpeter Potassium nitrate is a chemical compound with the chemical formula . This alkali metal nitrate Salt (chemistry), salt is also known as Indian saltpetre (large deposits of which were historically mined in India). It is an ionic salt of potassium ...

across Christian Europe (according to "De Alchimia" in 3 manuscripts of Michael Scot, 1180–1236) was "found in Spain in Aragonia in a certain mountain near the sea", (which can only be Catalonia): ''saraceni apellant ipsum borax et credunt quod sit alumen.'' ''Et in Hispania invenitur versus Argoniam in quodam monte juxta mare. et apellant ipsum hispani alumen acetum activum.'' In fact in 1561,

Elizabeth I of England Elizabeth I (7 September 153324 March 1603) was Queen of England and Ireland from 17 November 1558 until her death in 1603. Elizabeth was the last of the five House of Tudor monarchs and is sometimes referred to as the "Virgin Queen". Eli ...

at war with Philip II of Spain, became unable to import the saltpeter (of which the

Kingdom of England The Kingdom of England (, ) was a sovereign state on the island of Great Britain from 12 July 927, when it emerged from various History of Anglo-Saxon England, Anglo-Saxon kingdoms, until 1 May 1707, when it united with Kingdom of Scotland, ...

had no home production), and had to pay "300 pounds gold" to the German captain Gerrard Honrik for the manual "Instructions for making salpeter to growe" (the secret of the "Feuerwerkbuch" -the nitraries-). In 1783,

Giuseppe Maria Giovene Giuseppe Maria Giovene (23 January 1753 – 2 January 1837) was an Italian archpriest, naturalist, agronomist, geologist, meteorologist, entomologist and ichthyologist. elogio-storico, pag. 9, note 8 He is best known for his studies on the "nit ...

and

Alberto Fortis Alberto Fortis (1741–1803) was a Venetian writer, naturalist and cartographer. Life His real name was Giovanni Battista Fortis (his religious name was ''Alberto'') and he was born in Padua on either 9 or 11 of November 1741. He journeyed exten ...

together discovered a "natural nitrary" in a doline close to

Molfetta Molfetta (; Molfettese: ) is a town located in the northern side of the Metropolitan City of Bari, Apulia, southern Italy. It has a well restored old city, and its own dialect. History The earliest local signs of permanent habitation are a ...

, Italy, whose name is Pulo di Molfetta. The two scientists discovered that saltpeter formed inside the walls of the caves of the doline, under certain conditions of humidity and temperature. Prior to the discovery, nitraries were widespread all over the Kingdom of Naples. Manure was collected by the government and used to make

, which was a key ingredient for gunpowder. After the discovery, it was suggested that manure could be used for agriculture, in order to increase the production, rather than to make gunpowder. The discovery also generated issues; in particular, it was initially challenged by some scholars. Subsequently, chemist Giuseppe Vairo and his pupil Antonio Pitaro confirmed the discovery. This undoubtedly damaged producers of artificial saltpetre, and some scholars, most likely supported by the producers, tried to dismiss the discovery. Following the above discovery, naturalists sent by academies from all Europe came in large number to visit Pulo di Molfetta, since the saltpeter was a fundamental ingredient in the production of

and these deposits were of considerable strategic interest. Soon, the government started to extract saltpetre from Pulo di Molfetta and today the doline still contains the remains of the ancient plant used to extract saltpetre, making it a site of

industrial archaeology Industrial archaeology (IA) is the systematic study of material evidence associated with the industrial past. This evidence, collectively referred to as industrial heritage, includes buildings, machinery, artifacts, sites, infrastructure, docu ...

. Pulo di Molfetta is currently not open to tourists. Short thereafter,

discovered that saltpetre also formed in other caves of Apulia. elogio-storico, pagg. 9-10 lettera-a-fortis-1784

References

Bibliography

* * * {{cite book , title=Lettera del Sig. canonico D. Giuseppe Maria Giovene, Vicario generale di Molfetta, al Sig. Abate Alberto Fortis, contenente varie osservazioni sulla nitrosità naturale della Puglia , author=Giuseppe Maria Giovene , date=7 August 1784 , location=

, url=https://books.google.com/books?id=hr3g4qMtHfsC&pg=PA309 , ref=lettera-a-fortis-1784 History of mining Nitrogen

Manufacture

History

See also

References

Bibliography