Nitrary

A  nitrary is a place of production of potassium nitrate or saltpetre used primarily for the manufacture of gunpowder. The saltpetre occurs naturally in certain places like the "Caves of Salnitre" (Collbató) known since the Neolithic –Cova del rat penat– the guano (bat excrements) deposited over thousands of years became saltpetre after being leached by the action of meteoric water.

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 saltpetre that "came out" to the ground surface by efflorescence. Then they transported it to be concentrated by ebullition it in the boiler plant.

History
Besides "Montepellusanus", during the thirteenth century (and beyond) the only supply of saltpetre across Christian Europe (according to "De Alchimia" in 3 manuscripts of Michael Scot, 1180-1236)  and has been found in Spain in Aragon in a certain mountain near the sea ... and the same hispanic they called it: alumen acetum activum " 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 at war with Philip II of Spain, became unable to import the saltpetre (of which the Kingdom of England had no home production), and had to pay "300 pounds gold" to the german captain Gerrard Honrik for the manual "Instructions for making salpetre to growe" (the secret of the "Feuerwerkbuch" -the nitraries-)