-- heat the magnet red-hot in a flame
-- drop it on the floor several times, or beat it with a hammer
-- place it in a strong, rapidly alternating external magnetic field
If there are no windows, then the illumination in the room depends
only on the room and what's in it, not on anything outside.
The time of day has no effect. The other things all do.
Dalton's <span>law of partial pressures
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