Alkahest

Alkahest is a hypothetical "universal solvent" which can dissolve every other substance, including gold. The Swiss alchemist Philippus Paracelsus described alkahest in the early 16th century. Because of its perceived invaluable medicinal qualities, alchemists of the time were concerned with its plausibility and existence.

Alkahest in The Case of the Toxic Spell Dump
Alkahest was widely used as a weapon in the First Sorcerous War. However, it was deemed too potent for "civilized" warfare, and was not used in the Second Sorcerous War.

Literary comment
In this metaphorical context, alkahest is analogous to the role of poison gas in World War I.