A DANGEROUS CURIOSITY. A POWDER OF IMPOSSIBLE AGE. A SLOW, HIDEOUS DEVOLUTION. _THE NOVEL OF THE WHITE POWDER_ is one of ARTHUR MACHEN'S most famous and psychologically terrifying short stories, exploring the theme of hidden, degenerative horror disguised as medicinal science. The story is told by the narrator, who recounts the tragic case of his scholarly friend, FRANCIS LEICESTER. Francis is highly educated but fragile, and he overworks himself preparing for an important examination. His doctor prescribes him a WHITE POWDER to help calm his nerves and improve his sleep. The horrifying climax comes when the narrator realizes the WHITE POWDER WAS MISLABELED. It was not a medicinal bromide, but a compound of ancient, terrifying significance: a chemical agent that causes the user to DEVOLVE into a primal, pre-human state. The final, unspeakable horror is the discovery of Francis Leicester's ultimate fate--;a horrifying, fluid mess of primordial material, reduced to the state of a terrifying, sentient slime. _THE NOVEL OF THE WHITE POWDER_ is a masterpiece of early weird fiction, demonstrating Machen's unique power to merge scientific rationale with the profound dread of biological and cosmic degeneration.