Skip to content

Mercury, from antiquity to the present, part I

March 30, 2010

alchemical symbol for mercury

Mercury: a chemical element, metal  

Chemical symbol: Hg  

Atomic number: 80  

Melting point: −38.83 °C  

Boiling point: 356.73 °C  

Appearance: silvery-white liquid  

Mercury metal is unique in that it appears as a liquid at the room temperature, unlike most metals, which are solid (only four other metals might be liquid on a warm day: caesium, francium, gallium, bromine, and rubidium). Another unique trait is that Mercury can create amalgams, which are liquid alloys with other metals, and have some very interesting uses.  

Mercury compounds are known since pre-historic times, and along with pure metallic mercury, they are deeply entwined with human history. Mercury is very prominent in the fields of alchemy, chemistry, and medicine, and it has a way of reflecting the beliefs and thoughts of a society whenever and wherever it appears.  

In this post I intend to introduce you to the fascinating history of Mercury, and to the history of chemistry in general.  

The ancient origins of Mercury  

Since Mercury in its metal form is rarely found in nature, the mineral Cinnabar (HgS, an ionic compound) was the most common form in use during pre-historic times. This mineral has a reddish-brown color, and when it is artificially made, it’s called Vermilion.  

Due to its intense color, Cinnabar was used as a pigment during pre-historic times in Europe, central America and china. The Mayans in Honduras used to paint the skeletons of their royalty, but the Italian ancestors preferred to paint the skulls of their cattle.  

Cinnabar-painted Mayan woman in Copan  

At around 500 BC, the Romans began to mine the Cinnabar in Almaden, Spain (probably the oldest functional mine, it was operational for 2500 years and only recently closed). At this point in time, they did not know how to extract the Mercury from the mineral, despite the fact that drops of mercury formed spontaneously on the mineral itself. Workers in the mines were prisoners, minor offenders such as thieves, which were only sentenced to slave labor. In effect, they were sentenced death, due to mercury poisoning. Life expectancy of the workers was 3 years from the day they started working.  

Only after two hundred years, at around 300 BC, Greek philosophers began to mention the metallic mercury in their writings. Theophrastus and Aristotle mention the mercury as Argentum Vivum or “living silver” (also known as Quicksilver, ‘quick’ being the English word used a long, long time ago to describe something living. They really did believe it was a living entity. More on that in Mercury pt.II). The name Argentum Vivum refers only to the naturally occurring metallic mercury, because they still did not know how to extract the mercury out of the Cinnabar.  

The first production of mercury from Cinnabar was by sublimation, and is first mentioned around 50BC, in the writings of Dioscorides and Vitruvius. Principally, the Cinnabar was heated in an iron caldron, covered with a lid. The ionic mercury was reduced by the iron to metallic mercury, and then the mercury condenses on the lid (just like water vapor condenses on the lid of a cooking pot). Mercury produced in this manner was considered different than the naturally occurring mercury (Argentum Vivum), so it was called Hydrargyrum (liquid silver) by the naturalist Pliny. The name Hydrargyrum is the origin of the chemical symbol we use today: Hg.  

In Pliny’s time, metallic mercury was known to form amalgams with other metals, a trait that was used in the extraction and cleaning of silver and gold from various ores. Gold and silver are naturally found in their metal form, but they are mixed with different minerals. To extract the precious metals, the minors would pulverize the rocks to a fine powder, and then mix the powder with the liquid mercury. The gold or silver would form amalgams with the mercury, and thus separate from the minerals. To separate the silver or gold from the amalgam, the minors would boil the amalgam and allow the mercury to evaporate. What was left in the pot was (relatively) clean silver or gold. This was an extremely dangerous task, since mercury vapors are very toxic.  

The cinnabar compound was known to be toxic since it was first mined, but only around 150 AD the Greek healer Galen (Galen of Pergamum) determined that metallic mercury is toxic. Remember this, because others have forgotten. More on this in Mercury pt.III.

Advertisements
One Comment
  1. bribelle permalink

    epic picture of the red skeleton dude!

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: