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Castillo de San Marcos National Monument
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Did You Know?
Black, or gun, powder is a mix of potassium nitrate, sulfur, and charcoal used as a propellant charge in cannons. Burning rapidly when ignited, it expands 600 times its volume creating pressures that can hurl a cannonball up to 3.5 miles! Castillo de San Marcos National Monument, Florida
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Last Updated: April 28, 2008 at 13:32 EST |