Saltpetre works

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A saltpetre works or nitrary is a place of production of potassium nitrate or saltpetre used primarily for the manufacture of gunpowder. The saltpeter occurs naturally in certain places like the "Caves of Salnitre" (Collbató) known since the Neolithic. In the "Cova del Rat Penat", guano (in this case, bat excrements) deposited over thousands of years became saltpeter after being leached by the action of rainwater.

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