Quicklime

There was an actual medieval profession of lime burner, who burned calcium-rich minerals such as limestone, chalk, marble, or even sea shells. This was done to produce quicklime, which had a lot of useful properties. Dying, tanning leather, making soap, producing fertilizers, concrete—all used calcium oxide, called "quicklime."

The name, first seen as quyk lym in the late 1300s, comes from Latin calx viva, "lime quick"—using "quick" in the older sense of "living" because it was such an active substance. The ancient world discovered its usefulness for mortar (after being mixed with water to make a slurry). Limestone blocks of the pyramids have quicklime plaster. Rome used quicklime for construction extensively, and it is even found in the Great Wall of China.

The Ancient World also used it as a weapon in warfare. Powdered quicklime could be catapulted at enemies; its irritability in a person's eyes made them easy prey when the attacker engaged. Enough quicklime coming into contact with enough water could cause severe burns. King Henry III of England's (1216 - 1272) navy destroyed a French fleet by blinding the sailors with quicklime. (This was always a perilous gambit, since the wind might blow the power back to you.)

In the Middle Ages, when coal mining became cheaper and more widespread in the 12th century, burning to make quicklime was easier. It was used as mortar, plaster, for floors, and in frescoes.

One mis-use of quicklime in the Middle Ages was with corpses: it was thought to speed up decomposition, so sprinkling quicklime liberally when one needed a mass grave (after warfare, or in some responses to the Bubonic Plague) was thought to be efficient. It was also supposed to "sterilize" cesspits and counteract diseases they might engender. The truth is, however, that quicklime is actually a preservative; small amounts are sometimes used in flour to increase its acidity and act as a preservative and a leavener. Quicktime can cover the stench of decomposition, which may be why people thought it "got rid of the corpse" faster.

For many years I have read how Roman concrete became harder and more durable over time, defying logic. Very recently it was discovered that quicklime was the reason for its "self-healing" nature; here's a link to learn more.

I wanted to include a link to the reference above to Henry III, and I've discovered that I have mentioned him many times over 1263 blog posts, but have never given him his own entry. I'll will fix that oversight next time.

The Colosseum

The Roman Colosseum was begun under Emperor Vespasian in 72 CE and finished in 80 by his son, Emperor Titus. Stories of its use as a gladiatorial arena and a site for races, animal spectacles, and even nautical battles are well-known. 

When the Visigoths attacked Rome, the siege prevented the deceased from being buried in the cemeteries outside the walls, and so the area around the Colosseum became a large burial site. After the Fall of Rome and the sacking by the Visigoths, attempts were made to repair and utilize it, but the budget and management no longer existed for "bread and circuses." 

A series of earthquakes and restoration attempts took place over the next few centuries. Eventually its management fell to the most influential institution in Rome: the papacy. Between the 9th and 14th centuries, this extensive structure had many new uses, managed by the priests of Santa Maria Nova. Its underground tunnels and compartments, where staff and fighters and animals were once housed and fed and trained, became apartments and shops. The open arena was left as a sort of common area for people working and living in the building. "Row houses" were built against the north side.

(There was even a moment in 1200 when it became the home to a single wealthy family, the Frangipani.)

The illustration here is a 16th century woodcut showing the round design, but an earthquake in 1349 (as if they weren't dealing with enough tragedy with the Bubonic Plague) caused part to collapse, and its use as a rental property faded away. Also, the move of the papacy to Avignon caused Rome's population to dwindle, and the need for housing in the Colosseum (and therefore the need and income to maintain it) also dwindled.

After the return of the popes to Rome, the building (what was left) became the home of a religious order. Over the centuries, other purposes were found. One pope wanted to make it a wool factory to provide alternate jobs for the city's prostitutes. A cardinal in 1671 wanted to use it for bullfights. Both plans failed to materialize.

The Colosseum became a source of building material. The lead piping that carried water was taken and melted for other uses. The iron clamps that held stone blocks together were pried out and re-forged. The stone itself—marble and travertine—was taken and used for other buildings.

Some of the marble was burned to make quicklime. What was quicklime, and what was its use in the Middle Ages? I'll tell you tomorrow.