The Franck-Hertz experime
The Franck-Hertz experiment used a tube filled with this element in a gaseous state, and various isotopes of this element were used to change in the critical temperature of superconductors due to the isotope effect. Found together with chlorine in calomel and sulfur in vermilion, it can be obtained from cinnabar, and forms alloys with other metals called amalgams. For 10 points, name this only element this is liquid at room temperatures, whose symbol is Hg.
The Franck-Hertz experiment used a tube filled with this element in a gaseous state, and various isotopes of this element were used to change in the critical temperature of superconductors due to the isotope effect.
mercury [accept Hg before it is read]