“What’s all this?” inquired Cubitt. “There’s your beer.”

“Abel said he was going to put it in a pot and shove it in a rat-hole,” explained Parish. “I think he’s filled with due respect for its deadliness, Luke, really. He’s going to block the hole up and everything.”

“The chemist had no business to give you Scheele’s, much less this infernal brew. He ought to be struck off the books. The pharmacopœial preparation would have been quite strong enough. He could have diluted even that to advantage.”

“Well, God bless us,” said Cubitt hastily, and took a pull at his beer.

“What happens, actually, when someone’s poisoned by prussic acid?” asked Parish.

“Convulsion, clammy sweat, and death.”

“Shut up!” said Cubitt. “What a filthy conversation!”

“Well — cheers, dears,” said Parish raising his tankard.

“You do get hold of the most repellent idioms, Seb,” said his cousin. “Te saluto!”

“But not moriturus, I trust,” added Parish. “With all this chat about prussic acid! What’s it look like?”

“You bought it.”

“I didn’t notice. It’s a blue bottle.”

“Hydrocyanic acid,” said Watchman with his barrister’s precision, “is, in appearance, exactly like water. It is a liquid miscible with water, and this stuff is a dilution of hydrocyanic acid.”

“The chemist,” said Parish, “put a terrific notice on it. I remember I once had to play a man who’s taken cyanide. ‘Fool’s Errand,’ the piece was; a revival with whiskers on it but not a bad old drama. I died in a few seconds.”

“For once the dramatist was right,” said Watchman. “It’s one of the sudden poisons. Horrible stuff! I’ve got cause to know it. I was once briefed in a case where a woman took—”

“For God’s sake,” interrupted Norman Cubitt violently, “shut up, both of you. I’ve got a poison phobia.”