| | FIREPOWER AND FERTILIZERS |
 | | Saltpeter was the ingredient that was most difficult to obtain, and since it is the major ingredient in gunpowder best suited for military use, it was the supply of nitrate that became strategically important. |
 | | The saltpeter supplier would send out teams of collectors who would locate promising places to dig (abandoned privies and dungheaps) by tasting the soil before digging it out and carting it off to be boiled, strained and evaporated to produce saltpeter of the required purity. |
 | | Eventually a saltpeter industry grew up, based on artificial nitre beds, in which layers of decaying organic matter, old mortar, and earth were built up in a compost heap about a meter high, and sprinkled regularly with blood and/or urine. |
| www-geology.ucdavis.edu /~cowen/~GEL115/115CH16fertilizer.html (3237 words) |