saltpetre-making

The gathering, elutriation, purification and crystallisation of saltpetre (potassium saltpetre, lime saltpetre). Saltpetre, as the indispensable element of gun powder became an extremely important chemical during the proliferation of firearms. Methods of saltpetre-making were established in the late Middle Ages. In locations providing the right circumstances for saltpetre-making, the Turks also demanded the keeping of saltpetre pits and obliged people to deliver the half-ready substance. Most famous were the saltpetre pits of county Szabolcs and Debrecen the surroundings of which provided a regular income-supplement for those poor village and town's people who collected various substances containing saltpetre. In certain places saltpetre forms in large quantities, providing that the decomposition of organic substances which enter the soil comes into contact with the right kind of bacteria and is dissolved by moisture in the soil and rainwater. Following the evaporation of this solution which is brought up to the soil's surface as a result of the its capillary nature, saltpetre crystals crystallise out onto the surface. This was swept up, scraped and heaped up in a pile. This crystal powder was then steeped in lye. In wooden tubs, - which contained a straw and sand-made filter layer - this powder was dissolved in water and drained. The gained liquid lye was placed into a copper boiler where it was heated up, treated with lye than cooled down. After this, the cold liquid was again boiled up in copper boilers and diluted with potassium carbonate. The cooling-boiling up procedure was repeated several times until the liquid was completely clear of impurities. The ready-made, purified saltpetre was stored and distributed in barrels.

TI