Saltpetre, potassium nitrate, is added to food to give meat products a nicer colour. One winter in the 70s when we were living in Connecticut, my dad went to a New York drug store to buy saltpetre for our traditional Christmas ham. And the elderly druggist winked at him and said this odd thing.
“Hehe, it’s an old army trick!”
As my dad told us later that night, he had to ask what on Earth the guy meant. And then he learned that the druggist thought he was going to take the saltpetre as an anaphrodisiac, to decrease his sex drive. Supposedly the US armed forces did this as a matter of course to improve discipline and troop morale, adding saltpetre to the rations.
Now I find that this idea, that somehow stuck with me, is a widespread piece of unfounded folklore. Saltpetre does not decrease a man’s sex drive, and the armed forces have never added it to rations.
A few years later I learned, though, that you can mix saltpetre with sugar and make your own fireworks.