Bronze disease is a form of corrosion that affects bronze artifacts. It manifests itself as either a powdery green substance on the surface of the metal or as a warty or waxy film over the surface of an artifact. To the untrained eye, it may simply resemble a natural patina. However, while a patina is not destructive, bronze disease most certainly is. In reality, “bronze disease” is not the result of bacteria, as the name would suggest, but the result of a complex chemical reaction. It is known as bronze disease because the reaction produces a green powder on the surface of bronze artifacts that resembles a fungus. This corrosion is much like rust on iron. This corrosion is caused by a circular set of reactions that involve the chlorides of a copper alloy and water. Bronze disease is triggered by the presence of water in this equation. It might take just one humid day to activate the reactions and begin the destructive chain. The actual chemical reaction is still not fully understood, though the chemistry of corrosion has been studied for some 150 years. However, the basic understanding of the process indicates that the presence of **cuprous chloride in copper alloys reacts with water to create hydrochloric acid.** The acid then eats away at the bronze, and in turn reacts with the copper. This second equation produces the visual manifestation of the disease: that dreaded green fuzz. Generally, the fuzz covers pockmarks caused by the hydrochloric acid.