Mercury is the only metal that exists in a liquid state. All other metals like iron, copper or aluminium are all solids. Mercury is also called ‘quick silver’. Although it is a liquid yet it possesses all the metallic properties. It is also a conductor of heat and electricity. It freezes at –39°C and boils at 359°C. It does not stick with the walls of the glass vessels. It shines like silver. It is 13.6 times heavier than water. All these unique properties make mercury very useful for us.
Mercury is used in thermometers. It can measure temperatures from –39° to 359° Mercury is also used in barometers which measure the pressure of the atmosphere. Normal atmospheric pressure equals 760 mm of mercury. Although mercury is poisonous, yet it is used in the manufacture of several medicines and disinfectants. About one-third of the total production of mercury each year is used for medicinal purposes.
In nature, mercury is usually found in a combined state. Its chief ore is cinnabar. It is a red ore and is obtained from many kinds of rocks. In olden days cinnabar was used for making red pigments. When the alchemists were trying to make gold by artificial methods, they invariably used mercury in their experiments. Today mercury is used in the manufacture of several paints, caustic soda, chlorine and electrical equipments. The vermilion that Indian ladies use is nothing but a compound of mercury.