1. Lead properties

Lead was used very early on by all the great ancient civilizations: the Egyptians (7,000 to 5,000 B.C.) for glazing pottery, the Chinese from the 4th millennium for making coins. As early as the 5th century, the Athenians exploited the lead mines of Laurium for the silver associated with this metal. The Greco-Romans were particularly interested in Iberian mines. Pliny the Elder (23 to 79 AD) confirms that lead seems to have been in use for 6,500 years.

During the reign of Emperor Titus (79 to 81), some 40,000 people were apparently employed in the production of lead pipes and sheets. This use was so important that, under Constantine...