“I do, indeed,” said Hanslet warmly. “What’s more, the Home Office people say that a dose of the stuff would produce almost immediate paralysis, and death within a few minutes. The incrustation was potassium carbonate all right, almost certainly the result of putting caustic potash on the place. But that only makes the business more puzzling. If Copperdock poisoned himself, how did he have time to apply the caustic potash before he was paralysed? If someone else did it, why should they apply the caustic, and how did they get in and out of the house? Remember, Whyland’s man Waters had the place under observation all the time.”

“Then you are inclined to favour the theory of suicide?” asked the Professor.