When applying, first clean the stigmata with niter, smear them with resin of terebinth, and bandage for five days...
www.theatlantic.com At the cave, calcium nitrate, also called niter, is leached from dry soil.
en.wikipedia.org Finally, the water was boiled off leaving niter crystals usable, after drying, for making gunpowder.
en.wikipedia.org In addition, it has been used to describe some forms of quartzite, bauxite, kaolinite, laterite, chalcedony, opal, and soda niter.
en.wikipedia.org Niter for the manufacture of gunpowder, copper, lead, iron, coal, zinc, and other such materials as might be required for the prosecution of the war.
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