Nadine Misiaszek, Age 11, Of New York Mills, N.Y., for her question:

Most of our supplies of silvery mercury are taken from a rosy red ore called Cinnabar. Another name for cinnabar is mercuric sulphide, which means that it Contains both mercury and sulphur. The trick is to remove the sulfur from the ore, Leaving the mercury behind.  Currents of very hot air are sent through the rocky cinnabar. This drives out the sulphur from the ore, and it escapes as a gas. The mercury, mixed with a few impurities, is left behind. When purified, it is the silvery liquid we use to fill our thermometers and barometers.