Mercury is so dense that you can float cannon balls in it.

Mercury is actually the densest liquid. It's 13 times as dense as water. It's even denser than lead! The reason that you can float cannon balls in a tub of mercury is the same reason you can float a piece of wood on water. Anything can float if it's less dense than the fluid it's floating on. Mercury is even denser than the cannon balls!



Mercury (play /ˈmɜrkjəri/ or /ˈmɜrkəri/) is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver (play /ˈkwɪksɪlvər/ ) or hydrargyrum (play /haɪˈdrɑrdʒɪrəm/), from "hydr-" water and "argyros" silver. Mercury is the only metal that is liquid at standard conditions for temperature and pressure; the only other element that is liquid under these conditions is bromine.[1] With a freezing point of −38.83 °C and boiling point of 356.73 °C, mercury has one of the narrowest ranges of its liquid state of any metal. A heavy, silvery d-block metal, mercury is also one of the five metallic chemical elements that are liquid at or near room temperature and pressure,[2][3] the others being caesium, francium, gallium, and rubidium.

Mercury occurs in deposits throughout the world mostly as cinnabar (mercuric sulfide). The red pigment vermilion is mostly obtained by reduction from cinnabar. Cinnabar is highly toxic by ingestion or inhalation of the dust. Mercury poisoning can also result from exposure to water soluble forms of mercury (such as mercuric chloride or methylmercury), inhalation of mercury vapor, or eating seafood contaminated with mercury.

Mercury is used in thermometers, barometers, manometers, sphygmomanometers, float valves, some electrical switches, and other scientific apparatus, though concerns about the element's toxicity have led to mercury thermometers and sphygmomanometers being largely phased out in clinical environments in favor of alcohol-filled, digital, or thermistor-based instruments. It remains in use in scientific research applications and in amalgam material for dental restoration. It is used in lighting: electricity passed through mercury vapor in a phosphor tube produces short-wave ultraviolet light which then causes the phosphor to fluoresce, making visible light.