Another Experiment.
Heat some blue vitriol (sulphate of copper) in an iron ladle till all the water contained in the crystals is driven off, and the color changes to a gray. Take the lumps out without breaking them, and lay the dried blue vitriol on a plate. If this be moistened with water steam is produced; and if a slice of phosphorus is then laid on the sulphate of copper it ignites, demonstrating again that the condensation of a liquid produces heat. The addition of the water restores the blue color, thus proving that water was necessary to the composition of blue vitriol.