“But that’s ridiculous!” cried Pender, warmly.

“You think so, do you? That’s what most people would say. But I wouldn’t trust ’em. Not with sulphate of thanatol to be bought for two pence at any chemist’s.”

“Sulphate of what?” asked Pender sharply.

“Ah! you think I’m giving something away. Well, it’s a mixture of that and one or two other things — all equally ordinary and cheap.

For nine pence you could make up enough to poison the entire Cabinet. Though of course one wouldn’t polish off the whole lot at once; it might look funny if they all died simultaneously in their baths.”

“Why in their baths?”

“That’s the way it would take them. It’s the action of the hot water that brings on the effect of the stuff, you see. Any time from a few hours to a few days after administration. It’s quite a simple chemical reaction and it couldn’t possibly be detected by analysis. It would just look like heart failure.”

Pender eyed him uneasily. He did not like the smile; it was not only derisive, it was smug, it was almost gloating, triumphant! He could not quite put the right name to it.

“You know,” pursued the man, pulling a pipe from his pocket and beginning to fill it, “it is very odd how often one seems to read of people being found dead in their baths. It must be a very common accident. Quite temptingly so. After all, there is a fascination about murder. The thing grows upon one — that is, I imagine it would, you know.”

“Very likely,” said Pender.

“I’m sure of it. No, I wouldn’t trust anybody with that formula — not even a virtuous young man like yourself.”

The long white fingers tamped the tobacco firmly into the bowl and struck a match.

“But how about you?” said Pender, irritated. (Nobody cares to be called a virtuous young man.) “If nobody is fit to be trusted—”