Gay-Lussac's law states that if you decrease the temperature of a gas at constant volume, the pressure decreases by a corresponding amount. This is easy to carry out experimentally. But in practice is it possible to perform this the other way round, i.e. decrease the pressure and thus cause the temperature to drop, while keeping volume constant?
It seems to me that in order to reduce the pressure, you would go about lowering the chamber's volume by removing air from it. However, this would also remove a proportional number of moles from the chamber, so the temperature would remain unchanged.