Mercury, also known as quicksilver due to its appearance, is a transition metal in the periodic table. It is the only metal that is a liquid at room temperature. Mercury is massive in elemental terms; a chunk of iron can float on mercury. Compared to other metals, it does not conduct heat well; however, it conducts electricity fairly well. Mercury is an unreactive metal that does not corrode in air unless hydrogen sulfide is present in some way, similar to silver. Mercury can form mercury(II) oxide when heated in air.
No one is credible for discovering mercury, since the element was known since ancient times. Mercury was found in Egyptian tombs that date at 2000 BC. In China, people thought ingesting mercury would give them eternal life. China's first emperor, Qín Shǐ Huáng Dì, is said to have been buried in a tomb with rivers of flowing mercury, since he died from drinking a mixture of mercury and powdered jade recommended by his alchemist, Xu Fu, because he wanted to live forever.
Mercury is extremely poisonous and has to be used carefully. When mercury is spilled, there are complex ways to clean it up. Smaller drops should be combined to a larger drop on hard surfaces to be removed more easily. Vacuum cleaners and brooms should not be used, as they can spread mercury even more. Afterwards, elements such as sulfur or zinc powder should be sprinkled over the place, then collected and cleaned away. It is not easy to clean mercury entirely off clothing, so it is best not to use them anymore. Breathing in mercury vapor is highly dangerous, but ingesting mercury in liquid form is less dangerous.