Here's a last word on saltpetre, FYI.

That saltpetre, potasium nitrate, is put in institutional foods to quell the sexual urge is one of the classic urban legends, old wives tales, superstitions or whatever you want to call it. In addition to being a nitrogen source for the making of gunpowder it was for years a curing agent to preserve meat in the days before refrigeration and especially necessary for military rations; in salted pork and salt beef (known fondly to the soldiers as "salt horse"). It has since been replaced by sodium nitrate, the cure of choice for foods such as bacon.