Saltpeter

[Luis Fok]

[Potassium] nitrate (KNO3), a substance used in explosives (usually [gunpowder]) and fertilizers.
Contrary to popular urban legend, saltpeter has no effect on [libido], and too many side effects (high fever, etc.) to be used even if it did.

[Jessica]

a salty-tasting white powder used to preserve meat, and also used in producing explosives and fertilizers (= substances that help plants grow)