Mercury melts at approximately minus 38 degrees Fahrenheit, making it the densest elemental liquid known. It is the only common metal that exists as a liquid at room temperature. Its boiling point is about 674 F.
Mercury is very volatile, and despite its high boiling point relative to water, it readily releases vapor into the air. This vapor is very dangerous, as it is toxic to humans. It can be absorbed through the respiratory tract, the digestive tract or the skin. It builds up in the body with exposure over time, and can eventually cause severe illness or death at high enough levels.