White phosphorus spontaneously ignites in air. Red phosphorus does not. White phosphorus is kept in water to prevent it from burning.

I had a classmate who would buy red phosphorus since it was cheaper, and then distill it (boil it to a gas and condense the gas) to make white phosphorus.

I thought that was insanely dangerous.

But not as insane as someone who thinks the President of the United States would go into a war zone and shoot tracer rounds.

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