"A world construed out of blood and blood's alcahest"
The Alchymist, In Search of the Philosopher’s Stone by Joseph Wright (1771)
Public DomainThe Alchymist, In Search of the Philosopher’s Stone, by Joseph Wright (1771) - Credit: Derby Museum and Art Gallery

Alkahest (McCarthy sometimes employs archaic spelling or one all of his own devising) was a mystical substance sought after by alchemists.

The name is thought to have been invented by the Swiss alchemist Paracelsus, who believed the element alkahest was the elusive Philosopher’s Stone.

As alkahest was said to possess the ability to dissolve all other substances it presented the problem of containing the substance since it would inevitably dissolve the container.