Editing Potassium nitrate (section)

=== Nitre bed ===<!-- Redirect from [[Nitre bed]] -->
A ''nitre bed'' is a similar process used to produce nitrate from excrement. Unlike the leaching-based process of the nitrary, however, one mixes the excrements with soil and waits for soil microbes to convert amino-nitrogen into nitrates by [[nitrification]]. The nitrates are extracted from soil with water and then purified into saltpeter by adding wood ash. The process was discovered in the early 15th century and was very widely used until the Chilean mineral deposits were found.<ref>{{cite journal |last1=Narihiro |first1=Takashi |last2=Tamaki |first2=Hideyuki |last3=Akiba |first3=Aya |last4=Takasaki |first4=Kazuto |last5=Nakano |first5=Koichiro |last6=Kamagata |first6=Yoichi |last7=Hanada |first7=Satoshi |last8=Maji |first8=Taizo |display-authors=3|title=Microbial Community Structure of Relict Niter-Beds Previously Used for Saltpeter Production |journal=PLOS ONE |date=11 August 2014 |volume=9 |issue=8 |pages=e104752 |doi=10.1371/journal.pone.0104752|pmid=25111392 |pmc=4128746 |bibcode=2014PLoSO...9j4752N |doi-access=free}}</ref>

The Confederate side of the American Civil War had a significant shortage of saltpeter. As a result, the [[Nitre and Mining Bureau]] was set up to encourage local production, including by nitre beds and by providing excrement to government nitraries. On November 13, 1862, the government advertised in the Charleston Daily Courier for 20 or 30 "able bodied Negro men" to work in the new nitre beds at Ashley Ferry, S.C. The nitre beds were large rectangles of rotted manure and straw, moistened weekly with urine, "dung water", and liquid from privies, cesspools and drains, and turned over regularly. The National Archives published payroll records that account for more than 29,000 people compelled to such labor in the state of Virginia. The South was so desperate for saltpeter for gunpowder that one Alabama official reportedly placed a newspaper ad asking that the contents of chamber pots be saved for collection. In South Carolina, in April 1864, the Confederate government forced 31 enslaved people to work at the Ashley Ferry Nitre Works, outside Charleston.<ref>{{cite news |last1=Ruane |first1=Michael |title=During the Civil War, the enslaved were given an especially odious job. The pay went to their owners |url=https://www.washingtonpost.com/history/2020/07/09/national-archives-slavery-payroll-receipts-civil-war-confederacy/ |newspaper=Washington Post |access-date=10 July 2020}}</ref>

{{anchor|LeConte}}Perhaps the most exhaustive discussion of the niter-bed production is the 1862 [[Joseph LeConte|LeConte]] text.<ref name="LeConte">{{cite book|url=http://docsouth.unc.edu/imls/lecontesalt/leconte.html|title=Instructions for the Manufacture of Saltpeter|author=Joseph LeConte|publisher=South Carolina Military Department|location=Columbia, S.C.|page=14|year=1862|access-date=2007-10-19|url-status=live|archive-url=https://web.archive.org/web/20071013174033/http://docsouth.unc.edu/imls/lecontesalt/leconte.html|archive-date=2007-10-13}}</ref> He was writing with the express purpose of increasing production in the [[Confederate States]] to support their needs during the [[American Civil War]]. Since he was calling for the assistance of rural farming communities, the descriptions and instructions are both simple and explicit. He details the "French Method", along with several variations, as well as a "Swiss method". N.B. Many references have been made to a method using only straw and urine, but there is no such method in this work.

====French method====
[[Anne Robert Jacques Turgot|Turgot]] and [[Lavoisier]] created the ''Régie des Poudres et Salpêtres'' a few years before the [[French Revolution]]. Niter-beds were prepared by mixing [[manure]] with either [[mortar (masonry)|mortar]] or wood ashes, common earth and organic materials such as [[straw]] to give porosity to a compost pile typically {{convert|4|ft|m}} high, {{convert|6|ft|m}} wide, and {{convert|15|ft|m}} long.<ref name="LeConte"/> The heap was usually under a cover from the rain, kept moist with [[urine]], turned often to accelerate the decomposition, then finally [[Leaching (chemical science)|leached]] with water after approximately one year, to remove the soluble [[calcium nitrate]] which was then converted to potassium nitrate by filtering through [[potash]].

====Swiss method====
[[Joseph LeConte]] describes a process using only urine and not dung, referring to it as the ''Swiss method''. Urine is collected directly, in a sandpit under a stable. The sand itself is dug out and leached for nitrates which are then converted to potassium nitrate using potash, as above.<ref>{{Cite book |last=LeConte |first=Joseph |url=https://docsouth.unc.edu/imls/lecontesalt/menu.html |title=Instructions for the Manufacture of Saltpetre. |publisher=Charles P. Pelham, State Printer |year=1862}}</ref>